Digestive Diseases and Sciences, Vol. 37, No. 5 (May 1992), pp. 673-688

REVIEW ARTICLE

Cytomegalovirus Infection and Disease after Liver Transplantation An Overview ROBERT J. STRATTA, MD, MARK S. SHAEFFER, PharmD, RODNEY S. MARKIN, MD, PhD, R. PATRICK WOOD, MD, ALAN N. LANGNAS, DO, ELIZABETH C. REED, MD, JEREMIAH P. DONOVAN, MD, GAIL L. WOODS, MD, KATHLEEN A. BRADSHAW, RN, TODD J. PILLEN, PA, and BYERS W. SHAW, JR., MD

Cytomegalovirus is the single most important pathogen in clinical transplantation. Although much progress has been made in our understanding of the molecular biology and epidemiology of CMV infection and in our ability to diagnosis and treat CMV disease, it remains a major cause of morbidity but is no longer a major cause of mortality after liver transplantation. Risk factors for CMV disease after liver transplantation include donor and recipient serologic status, the use of antilymphocyte therapy, and retransplantation. CMV disease occurs early after transplantation, and the most frequent site of disease is the hepatic allograft. We have treated 79 patients with intravenous ganciclovir, with ultimate control of disease achieved in 69 patients (87.3%). Preliminary results using intravenous immunoglobulin and oral acyclovir for CMV prophylaxis in high-risk patients have been encouraging. In addition to producing clinical syndromes, CMV may have direct immunologic effects and is a marker of the net state of immunosuppression. KEY WORDS: acyclovir; cytomegalovirus; ganciclovir; immunoglobulin; immunosuppression; liver transplantation; OKT3.

CHARACTERISTICS OF CMV With advances in selective immunosuppression and diagnostic technology, cytomegalovirus (CMV) has become the single most important pathogen in clinical transplantation (1). Biologically, CMV is a double-stranded DNA-enveloped virus that is a member of the herpes virus group, which also includes herpes simplex (HSV I, II, VI), varicellazoster (VZ), and Epstein-Barr (EBV) viruses (2). CMV is the largest member of the human herpes Manuscript received January 8, 1991; accepted January 8, 1991. From the Departments of Surgery, Pharmacy Practice, Pathology and Microbiology, and Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska. Address for reprint requests: Dr. Robert J. Stratta, Department of Surgery, University of Nebraska Medical Center, 600 South 42nd Street, Omaha, Nebraska 68198-3280.

family, with considerable genomic and antigenic heterogeneity among different CMV strains (3). It is not known whether the antigenic variability among different CMV strains has any significant clinical consequences in terms of strain virulence or the risk of reinfection with multiple viral strains. However, all strains of CMV share three important characteristics with the other herpes viruses, which play an important role in determining clinical manifestations: (1) latency; (2) a strong propensity for cell association and lability; and (3) the potential for inducing malignant transformation (1, 2, 4). Although CMV is able to establish a life-long infection and to reactivate under specific conditions, the exact site of latency is not known. However, CMV is a highly cell-associated virus, with infection spreading by direct cell to cell contact. It has been suggested that a subset of white blood cells may

Digestive Diseases and Sciences, Vol. 37, No. 5 (May 1992)

0163-2116/91/0500-0673506.50/09 1992PlenumPublishingCorporation

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STRATTA ET AL provide a possible site for latent infection (5, 6). After initial exposure to CMV, the virus remains dormant but is capable of being reactivated under certain conditions. The most important factors thus far defined that produce reactivation of latent CMV infection are immunosuppression, allograft rejection, and pregnancy (7, 8). Under these circumstances, CMV emerges from its latent state and is capable of causing clinical disease.

BIOPSY / BRUSHINGS / WASHINGS

/Y IMMUNOPEROXIDASE

(LONG-TERM)

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Fig l. Management algorithm of tissue specimens for the diag-

DEFINITION OF CMV INFECTION VERSUS DISEASE For purposes of discussion, the definition of CMV infection versus disease is an important distinction. CMV infection is defined as isolation or identification of CMV from any site (blood, urine, sputum, or stool) or positive seroconversion (presence of CMV-IgM or fourfold increase in CMV-IgG titers) in the absence of clinical symptoms (such as fever, arthralgias, dyspnea, gastrointestinal symptoms, visual disturbances) or objective clinical findings (leukopenia, pulmonary infiltrates, hepatitis, retinitis, enteritis). In contrast, CMV disease is defined as invasive or symptomatic CMV infection with histologic evidence of viral cytopathic effect or a positive CMV culture from a deep tissue specimen in the setting of suggestive clinical manifestations (9). Specimens used for the diagnosis of CMV disease include liver or lung biopsy, endoscopic mucosal biopsy or brushing, bronchoscopic mucosal biopsy or brushing, bronchoalveolar lavage, and cerebrospinal fluid. The presence of positive bloOd cultures or seroconversion in the setting of symptomatic infection is also considered sufficient to establish the diagnosis of CMV disease. Disseminated CMV disease is defined as clinical or laboratory evidence of localized CMV disease in two or more noncontiguous sites or CMV disease at one site in the presence of positive peripheral blood cultures. A management algorithm for the detection o f CMV disease is illustrated in Figure 1. In contrast to other infections, CMV disease is a diagnosis usually made by the pathologist (10). Histologic or cytologic examination of the tissue specimen is initially performed for the presence of CMV. The spectrum of changes typical of a CMV-infected cell are shown in Figure 2. Histologic detection for CMV is further enhanced by the use of hybridization techniques with a complementary DNA probe or immunohistochemical staining with immunoper674

nosis of CMV disease. See text for details, eDNA indicate complementary DNA.

oxidase (Figure 3) (11). Viral cultures of tissue specimens also are performed, including the use of direct immunofluorescence in shell vial culture to detect CMV early antigen (Figure 4) (12, 13). Specific antiviral therapy is reserved only for proven CMV disease. EPIDEMIOLOGY OF CMV

CMV is a ubiquitous agent, with 45-80% of people developing CMV antibodies at some time during their lives (1, 7, 8, 14, 15). Seroprevalence depends on age, sex, and socioeconomic background. Although most CMV infections are asymptomatic in the general population, the potential severity of CMV infections in immunosuppressed transplant recipients is well established (1, 4, 7, 10, 15-19). There are three potential sources of CMV infection in the transplant setting: (1) the donor organ; (2) cellular blood products (packed cells and platelets); and (3) reactivation of endogenous virus (I, 15). Infections are thought to represent either primary exposure (seropositive allograft or blood products into a seronegative recipient), reactivation of latent virus, or reinfection with a second viral strain. There is no known animal reservoir for human CMV. The most important source of CMV infection after solid organ transplantation is the allograft. Ho et al (20) and Betts et ai (21) first provided epidemiologic evidence for transmission of CMV via the transplanted kidney in 1975. Since this time, CMV has been demonstrated to be efficiently transmitted by the heart, heart/lung, liver, and bone marrow harvested from donors who are seropositive for CMV antibody (17, 22-26). CMV appears to be present in the donor organ in a latent form (perhaps in passenger leukocytes) and becomes reactivated after transplantation (6). However, the site of viral Digestive Diseases and Sciences, Vol. 37, No. 5 (May 1992)

CMV DISEASE AFTER LIVER TRANSPLANTATION

Fig 2. Typical changes in a hepatocyte transformed by CMV characterized by cytoplasmic granules, mtranuclear inclusions with a prominent nuclear rim, and cellular enlargement (hematoxylin--eosin, original magnification x350).

latency in donor organs and factors responsible for reactivation remain conjectural. Dummer et al (18) reported the prevalence of CMV infection in 81 renal, 17 heart, and 21 liver transplant recipients (determined by CMV shedding or serologic rises in antibody titer) to be 78% in patients receiving cyclosporine and 76% in patients receiving azathioprine. Singh et al (17) studied 121 consecutive adult liver transplant patients and found a 59% incidence of CMV infection. Symptomatic and disseminated CMV disease was more common after primary infection (88% vs 32% in patients without primary infection), especially in patients receiving OKT3 therapy. The donor organ appeared to be the most important source of CMV infection. Sayage et al (27) reported a 39. I% incidence of CMV infection in 151 liver transplant recipients, with a 28.5% incidence of culture-positive disease and 15.2% rate of symptomatic disease. The rate of CMV infection was much higher (48.8% vs 26.2%) in patients treated for rejection. Dussaix and Wood found a 52.2% incidence of primary CMV infection among 23 seronegative pediatric liver transplant recipients, Digestive Diseases and Sciences, Vol. 37, No. 5 (May 1992)

but no cases of CMV occurred in 17 seropositive pediatric patients (28). At our center, we have performed 341 orthotopic liver transplants in 295 patients (173 adults, 122 children) over a four-year period. A total of 79 patients (26.8%) experienced one or more episodes of documented CMV disease. Donor and recipient CMV serologic status were highly predictive for the subsequent development of CMV disease (Figure 5). In all serologic combinations, the incidence of CMV disease was slightly higher in adults. Primary CMV exposure (seropositive allograft into a seronegative recipient) was associated with a 78.6% incidence of CMV disease. When both the donor and recipient were CMV seropositive, the incidence of CMV disease was 53.7%, which represents the frequency of both CMV reactivation and reinfection. In seropositive recipients receiving a seronegative allograft, the incidence of CMV disease was 31.3%, which represents both reactivation and cases of transfusion-associated CMV. When both donor and recipient were seronegative, the incidence of CMV disease was 22.2%, which is related

675

STRATTA ET AL

Fig 3. Immunoperoxidaseenhancementof CMV-infectedcells with staining of intranuclearinclusions and nuclear membrane (original magnification x 350). to the transfusion of blood products. Table 1 shows the distribution of CMV serologic status in our donor and recipient pool. Approximately 55% of donors were seronegative and 76% of recipients were seropositive at the time of transplantation. The incidence of seropositivity was higher in adult donors. Figure 6 illustrates the lack of an effect of CMV serologic status on actuarial patient survival when both donor and recipient serology were known (N = 211). Although CMV is known to be transmitted by blood transfusion, the risk of transfusion-acquired CMV infection is lower (10-30%) (29, 30). In addition, transplant recipients with primary CMV infection as a result of blood transfusion (seronegative donor and recipient) appears to be less ill than those who acquire CMV from the donor organ (15). In patients seropositive for CMV antibody prior to transplantation, reactivation of endogenous virus occurs frequently, approaching an incidence of 100% in some reports (17, 22, 23). Recent studies in

676

allograft recipients have demonstrated a higher incidence of CMV infection in seropositive recipients of seropositive allografts compared to those receiving seronegative allografts (15, 31). This provides indirect evidence that superinfection with a second viral strain transmitted from the donor may occur rather than reactivation of a latent strain (32). The overall incidence of CMV infection in liver transplant recipients ranges from 35-60%, with over half of these patients developing CMV disease (9, 15, 17, 27). CLINICAL PRESENTATION AND MANIFESTATIONS The likelihood of developing CMV disease (invasive CMV infection) is related to viral load as well as to the net state of immunosuppression (1). The net state of immunosuppression in transplant recipients is determined by the intensity of immunosuppressive therapy, the degree of granulocytopenia, Digestive Diseases and Sciences, Vol. 37, No. 5 (May 1992)

CMV DISEASE AFTER LIVER TRANSPLANTATION

Fig 4. Detection of early antigen in shell vial culture by direct immunofluorescent staining of cultured fibroblasts lnlected w~th UMV (original magnification x400).

injury to primary mucocutaneous barriers, metabolic effects, preexisting immunity to the virus, the allograft reaction, and the immunomodulating effects of other pathogens. Infectious complications remain a major cause of morbidity and mortality in liver transplant recipients, with most series reporting ~ 60-80% incidence of infection (17, 18, 33-35). Risk factors for infection include preoperative morbidity, prolonged antibiotic use, operating time, number of operations, and the magnitude of antirejection therapy (33). CMV infection most commonly occurs in the first three months following transplantation (9, 15-17). Many patients will remain asymptomatic and simply shed virus when infected (36). However, transplant patients with CMV disease may have protean clinical manifestations such as fever, malaise, arthralgias, leukopenia, thrombocytopenia, hepatitis, interstitial pneumonitis, enteritis, chorioretinitis, and disseminated disease. The most common and often only symptom associated with CMV infection Digestive Diseases and Sciences, Vol. 37, No. 5 (May 1992)

is fever (15). This is variable in duration and can last up to one month. Leukopenia also occurs commonly and may be the only sign of CMV infection (16, 22). Thrombocytopenia is less common than leukopenia. The hepatic allograft is the most common site of CMV disease after liver transplantation (9, 27). CMV hepatitis is usually characterized by fever, malaise, jaundice, anorexia, cholestasis, and an elevation in serum transaminases. Bronsther et al (37) reported on 17 cases of CMV hepatitis after liver transplantation and emphasized the importance of liver biopsy in differentiating this entity from rejection and other causes of allograft dysfunction. In our liver transplant population, we have noted 51 cases of CMV hepatitis, with the diagnosis made at a mean time of 45 days after transplantation. CMV has been associated with a variety of gastrointestinal symptoms and appears to have a predilection for the right side of the colon and the duodenum (38). Alexander et al (39) per677

STRATTA ET AL ACTUARIAL PATIENT SURVIVAL, 7/85 TO 7 / 8 9

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Fig 6, Actuarial patient survival according to donor and recipient CMV serologic status.

CMV SEROLOGIC STATUS Fig 5. The effect of donor and recipient CMV serologic status on the incidence of CMV disease after liver transplantation, See text for details.

formed routine endoscopic procedures in liver transplant recipients and reported a 33% prevalence of gastrointestinal CMV infection. One of the most feared consequences of CMV infection is CMV pneumonitis, presenting as fever, hypoxemia, and diffuse interstitial infiltrates (24, 40-42). In spite of specific antiviral therapy, the mortality of CMV pneumonitis in bone marrow transplant recipients remains at 40-50%. In liver transplant patients, pneumonitis is the most frequent site of recurrent CMV disease and is often found in conjunction with other pulmonary pathogens such as Pneumocystis carinii or Candida. Chorioretinitis due to CMV infection is an uncommon manifestation that occurs late after solidorgan transplantation (43). Disseminated CMV disease is an ominous finding that is usually fatal. The incidence of clinical syndromes due to CMV is two to three times more common in patients with primary CMV exposure as opposed to reactivation disease, and primary disease appears to have a shorter incubation period (17, 36). However, in an individual patient, the timing and severity of the TABLE 1. CMV SEROLOGIC STATUS

CMV seropositive CMV seronegative CMV unknown

678

Donor ( N = 341)

Recipient (N = 295)

114 (33.4%) 142 (41.7%) 85 (24.9%)

196 (66.5%) 60 (20.3%) 39 (13.2%)

clinical syndrome can vary, making it impossible to differentiate between primary and reactivation disease on the basis of clinical indicators. A variety of less common clinical syndromes such as encephalitis and skin ulcerations due to vasculitis have been attributed to CMV in the transplant setting (2, 7). Table 2 illustrates the clinical patterns of CMV disease in liver transplant recipients at our center. The initial site of CMV disease was usually the liver, while recurrent disease often involved extrahepatic sites (especially pulmonary). Gastrointestinal CMV usually presented as gastroduodenitis, but could involve any site along the alimentary tract. The majority of cases of CMV disease (both initial and recurrent) were confined to single organ involvement (83.7%), at which time specific antiviral therapy was initiated with ganciclovir. Two cases of refractory disseminated CMV disease occurred in spite of ganciclovir therapy, with the diagnosis confirmed on postmortem examination. TABLE 2. CLINICAL SPECTRUMOF CMV DISEASE Site

Initial Site

Recurrent C M V

Liver Hepatitis alone Hepatitis and pneumonitis Hepatitis and enteritis Disseminated Lung Pneumonitis alone Pneumonitis and enteritis Disseminated Gastrointestinal tract Enteritis alone Total

44 (55.7%) 35 6 2 1 30 (38.0%) 22 1 1 14 (17.7%) 11 79

7 (29.2%) 3 3 0 1 16 (66.7%)* 12 0 1 4 (16.7%) 4 24

*P < 0.05.

Digestive Diseases and Sciences, Vol. 37, No. 5 (May 1992)

CMV DISEASE AFTER LIVER TRANSPLANTATION # CASES 40 30 20 10 0

1

2 3 4-6 ONSET AFTER OLT (MONTHS)

7-12

Fig 7. The time course of CMV disease after liver transplantation.

Most cases of CMV disease occurred in the first three months after transplantation at a mean of 38 days (range 8-290 days), with only four cases developing after the first three months (Figure 7). Primary CMV disease usually involved the hepatic allograft resulting in CMV hepatitis, with the timing similar to other patterns of CMV disease. However, primary CMV disease was associated with a high relapse rate (45.4% vs 21% in patients without primary CMV disease, P < 0.01) when compared to other modes of CMV transmission. After stopping ganciclovir therapy, the mean time to recurrent CMV disease was 33 days (range 5-103 days). FACTORS AFFECTING SEVERITY OF CMV INFECTION The spectrum and severity of clinical CMV infection is somewhat dependent on the type of organ transplant received, although considerable overlap exists. The most severe CMV infections are seen in bone marrow transplant recipients (24, 41). Although the incidence of CMV infection varies widely in solid-organ transplant recipients, a major predisposing factor is the pretransplant CMV serologic status of the donor and recipient (20, 21, 25, 26, 31, 32). In general, patients experiencing primary CMV infection have more severe clinical illness than patients experiencing CMV reactivation or reinfection (36). Recipients of living-related renal allografts experience less morbidity associated with CMV infection when compared to those receiving cadaveric allografts (44, 45). This observation suggests that two other major exogenous factors may influence the course of CMV infection after transplantation; the immunosuppressive regimen and the intensity of rejection. The level of immunosuppressive therapy is known to influence CMV infection in transplant recipients (44, 46-48). Both high doses of corticoDigestive Diseases and Sciences, Vol. 37, No. 5 (May 1992)

steroids and the use of antithymocyte globulin have been associated with a higher incidence and severity of CMV infection in renal transplant recipients. The incidence of CMV infection reported in renal allograft recipients receiving cyclosporine and prednisone has ranged from 28% to 75%, with clinically overt disease documented in approximately 10% (18, 49-51). With cyclosporine-prednisone immunosuppression, a number of investigators have noted the potentiating effect of antilymphocyte preparations on the subsequent development of overt CMV disease (45, 50, 52). In addition, the prophylactic use of antilymphocyte globulin in a quadruple immunosuppressive protocol has been associated with an increased risk of infectious complications, including CMV (53). The introduction of OKT3 into liver transplantation has likewise resulted in higher rates of CMV disease (9, 17, 27). The effect of allograft rejection on the course of CMV infection is more difficult to demonstrate. However, there is indirect evidence that the allogeneic reaction after solid-organ transplantation or graft-versus-host disease after bone marrow transplantation may enhance or induce CMV infection (2, 7). RISK FACTORS FOR CMV DISEASE

In our recipient population, univariate analysis revealed a number of risk factors predictive for the subsequent development of CMV disease. Independent risk variables included donor CMV seropositivity, the use of antilymphocyte therapy (especially OKT3), and retransplantation, which accounted for 57 cases (72%) of CMV disease. The presence of donor CMV seropositivity irrespective of recipient serologic status was an independent predictor for the subsequent development of CMV disease (58.8% vs 29.4%, P < 0.001) (Figure 5). The single most important risk factor for CMV disease was primary CMV exposure. However, treatment with OKT3 or ATGAM accounted for the majority of cases (56%) or CMV disease in our experience. The use of antilymphocyte therapy was highly associated with the subsequent development of CMV disease (52.5% vs 25.2%, P < 0.01). CMV disease after antilymphocyte therapy usually involved the hepatic allograft (69.0% of cases), suggesting an interaction between CMV and the allograft reaction. The onset of CMV disease occurred at a mean of 15 days after completion of antilymphocyte therapy. Finally, the incidence of CMV disease after 679

STRATTA ET AL retransplantation was significantly greater than that after primary tiransplantation (51.5% vs 27.5%, P = 0.01). In patients requiring retransplantation for acute rejection, the incidence of CMV disease was 83.3%. Adult recipients had a higher rate of CMV disease (31.8% vs 19.7%, P = 0.02), which may be related to donor seropositivity. The intraoperative red blood cell transfusion requirement did not impact significantly on the incidence of CMV disease. The mean (-+ SD) intraoperative packed red blood cell transfusion requirement in adults and children was 15.0 -+ 12.8 and 3.7 -+ 3.1 units, respectively. Massive transfusions (>20 units in adults, >5 units in children) did not place patients at a higher risk for developing CMV disease (P = 0.20). CLINICAL EFFECTS In addition to producing clinical syndromes, CMV may have direct immunosuppressive effects, potentiate other infections, induce allograft dysfunction or chronic injury, provide rejection by up-regulation of class II HLA antigen expression, and have oncogenicity potential (1, 2, 4, 7, 15, 54, 55). CMV and the immune system appear to exert reciprocal effects on each other. CMV not only causes clinical disease directly, but is itself immunosuppressive. A variety of humoral and cellmediated immune responses have been described in association with CMV, including leukopenia, inverted T-helper/T-suppressor cell ratios, augmented cytotoxic T-cell responses, activation of natural and antibody-dependent killer cells, increased circulating immune complexes with production of IgG and IgM antibodies, depressed cell-mediated immunity, decreased alveolar macrophage function, and the elaboration of lymphokines and interferons (55). The pathogenesis of these immunosuppressive effects is not well defined. However, patients with CMV infections are at greater risk for superinfection with opportunistic pathogens such as gram-negative bacteria, fungi, and Pneumocystis carinii (54). In addition to contributing to the net state of immunosuppression, CMV may interact with the allograft reaction to induce dysfunction or provoke rejection. Although the exact sequence of events is still controversial, most data suggest that allograft rejection precedes active CMV infection (4). Increases in immunosuppression during allograft rejection may be responsible for the occurrence of CMV infection, but the continuous allogeneic stim-

680

ulation by the graft may also be important. Conversely, there is growing evidence that CMV infection induces class I and II major histocompatibility complex (MHC) antigen expression via release of interferons, which may further contribute to or precipitate allograft rejection (56-59). A more direct form of immune injury to the allograft may occur because of sequence homology and immunologic cross-reactivity between an immediate early antigen of human CMV and the HLA-DR beta chain (60). In addition, CMVinfected cells produce a glycoprotein similar to MHC class I antigens (61). Thus, it is speculated that immune injury triggered by CMV could be directed at cells that bear either the appropriate HLA-DR antigen or the particular class I antigen. This form of allograft injury may have a different pathogenesis, histological appearance, and clinical course than does classical allograft rejection. Paya et al (62) reported on a group of liver transplant recipients with the pathological findings of focal necrosis and clustering of neutrophils within the liver lobules, a picture distinct from that of typical hepatic allograft rejection. These pathological findings occurred in the setting of CMV viremia but in individuals without histological or culture evidence of CMV hepatitis. In addition, O'Grady et al (63) have postulated that CMV infection in association with donor and recipient DR antigen matching may precipitate chronic allograft injury manifesting as the vanishing bile duct syndrome. While the inevitable tapering of immunosuppressive therapy during an active CMV infection appears to be a plausible explanation for an increased incidence of rejection episodes following CMV infection, other immunologic phenomena and indirect effects of CMV infection may be involved. Finally, the evidence that human CMV infection is associated with cancer is at best circumstantial and remains to be determined in the transplant population. PROPHYLAXIS AND TREATMENT OF CMV INFECTION AND DISEASE Efforts to control the effects of CMV infection can be categorized as preventive and therapeutic strategies. Methods of preventing CMV infection include: (1) selection of livers from CMV seronegative donors; (2) use of CMV seronegative blood products; (3) passive immunization with immunoglobulin; (4) active immunization with a vaccine; (5) prophylaxis with immunomodulators such as alphaDigestive Diseases and Sciences, Vol. 37, No. 5 (May 1992)

CMV DISEASE AFTER LIVER TRANSPLANTATION interferon; (6) prophylaxis with specific antiviral agents such as acyclovir, ganciclovir, and foscarnet (phosphonoformate); and (7) combination strategies. Another way of preventing CMV disease is to avoid overimmunosuppression. Whether the above regimens should be considered for all liver transplant recipients or specifically identified high-risk patients remains controversial. Rakela et al suggested that the concept of "protective matching" (transplanting a CMV seronegative recipient with a liver from CMV seronegative donor) should be applied in clinical liver transplantation to prevent primary CMV infection (25). Although the incidence of CMV infection varies widely in transplant recipients, a major predisposing factor is the pretransplant CMV serologic status of the donor and recipient. In our patient population, primary CMV exposure is characterized by a high rate of disease transmission (nearly 80%) and is prone to recurrence. However, with the emergence of ganciclovir as a safe and effective therapy, the presence of CMV disease does not have an adverse effect on either patient or graft survival. Since donor CMV seropositivity is a significant risk factor for the subsequent development of CMV disease irrespective of recipient serologic status, we currently do not advocate protective matching of seronegative donors and seronegative recipients because of the critical shortage of donor organs. However, we do believe that there may be a role for prophylaxis against CMV disease in the setting of primary CMV exposure. The use of CMV seronegative or leukocyte-poor blood products is another approach to reducing CMV transmission (64). Since CMV is probably latent in the white blood contaminant of the transfused product, CMV transmission may occur with platelet as well as with red blood cell transfusions. The use of CMV-negative blood products is an effective method of preventing this mode of transmission. Similarly, preliminary results using leukocyte-poor preparations (filtered or frozen blood products) are encouraging (64). In contrast to other forms of solid-organ transplantation, transfusion requirements may be monumental after liver transplantation, thus limiting the practicality of the above strategies. At the present time, our current policy is to have 20 units of CMV seronegative blood available for each liver transplant. If the transplant requires more than 20 units, then compatible blood is administered without regard to CMV reactivity. Digestive Diseases and Sciences, Vol. 37, No. 5 (May 1992)

Passive administration of antibody with intravenous immunoglobulin or high-titer CMV hyperimmune globulin has met with limited success after transplantation. The beneficial effect of passive immunization has been attributed to its ability to neutralize CMV (15). Alternatively, the globulin preparation may exert its effect through potentiation of antibody-dependent cell-mediated cytotoxicity responses or blocking cytotoxic T-cell recognition of virus-infected cells by antibodies directed toward MHC antigens rather than viral antigens. In animal models, the administration of immunoglobulin appears to reduce CMV dissemination and hastens viral clearance (65). In human trials, passive antibody prophylaxis has been associated with a decrease in disease severity. In controlled prospective studies of CMV infection in seronegative bone marrow transplant recipients, the administration of CMV hyperimmune plasma, intravenous globulin, and CMV hyperimmune globulin has been associated with a decrease in the incidence of symptomatic CMV infection and interstitial pneumonia, particularly in patients not receiving leukocyte transfusions (66-69). The effect on the incidence of CMV shedding was variable and may be product dependent. In contrast, Bowden et al were unable to demonstrate a beneficial effect of CMV hyperimmune globulin in bone marrow transplant recipients at risk for primary CMV infection (64). Due to differences in study design and product variability in CMV antibody titers, the dosage, frequency, duration, and efficacy of immunoglobulin therapy remains to be determined. In a controlled multicenter study by Snydman and coworkers, a protective effect of CMV hyperimmune globulin was reported when given prophylactically to renal transplant patients in the first four months after transplant (70). A significant reduction in CMV disease was observed, even when patients were grouped according to therapy for allograft rejection. In a recent open-label trial with CMV hyperimmune globulin, comparable results were found (71). Chou reported that the administration of CMV hyperimmune globulin to renal transplant patients reduced the incidence of primary CMV disease from 60% to 21% (P < 0.01) and the incidence of CMV pneumonia from 17% to 4% (P = 0.26) (72). In 18 cardiac transplant recipients, Schafers et al (73) reported that the use of CMV hyperimmune globulin reduced the incidence of primary CMV disease from 80% to 54% (P = NS) when compared to historical controls, but there was no

681

STRATTA ET AL effect on disease severity. Bell et al (74) reported on the efficacy of CMV hyperimmune globulin in reducing the incidence of CMV infection in patients at risk for primary CMV exposure following liver transplantation. In contrast, Dussaix and Wood noted no beneficial effect of CMV hyperimmune globulin prophylaxis in pediatric liver recipients at risk for primary CMV infection (28). The efficacy of the prophylactic administration of immunoglobulin preparations in liver transplant recipients has not been well studied. Effective immunization with attentuated live CMV vaccine is currently being investigated. Preliminary trials using the Towne strain CMV vaccine have been carried out in both human volunteers and seronegative renal allograft recipients (75, 76). Although the vaccine is immunogenic and has been shown to modify the severity of CMV disease in patients who develop primary CMV infection after renal transplantation, it does not prevent superinfection with other CMV strains. The live nature of the vaccine raises the potential problems of oncogenicity, establishment of latency, and reactivation or reversion to a more virulent phenotype. Following transplantation, all evidence of a cell-mediated immune response is lost, so the protectiveness of this particular vaccine must be questioned. Further, since vaccination only gives limited immunity to the Towne strain, and given the fact that even natural infection does not confer immunity to superinfection with other strains of CMV, it is unlikely that vaccination with a monovalent CMV vaccine can really be effective in preventing CMV disease. Alternative approaches to immunization, including the use of subunit vaccines or anti-idiotype vaccines directed toward neutralizing CMV epitopes, are currently under study. Other prophylactic strategies reported are of antiviral origin. Cheeseman et al (47) in 1979 and Hirsch et al (77) in 1983 showed that interferonalpha, when given prophylactically to renal transplant recipients, decreased the incidence of clinical CMV disease as well as the incidence of superinfection with opportunistic pathogens. However, a strong correlation between administration of interferon-alpha and irreversible rejection has been noted, even with cyclosporine immunosuppression (78). Further experience with interferon therapy for recurrent or de novo hepatitis after liver transplantation has likewise been associated with a high rate of allograft rejection (79). Therefore, prophylactic

682

administration of interferon cannot be recommended at this time. Until recently, the prophylactic use of an antiviral drug for the prevention of CMV infection has been hampered by the lack of agents with proven efficacy against CMV (80). Although acyclovir has limited activity against CMV in vitro and is not effective in the treatment of CMV disease, it may be of benefit prophylactically. Meyers et al (81) reported that the use of high-dose intravenous acyclovir in bone marrow transplant recipients significantly reduced the incidence and severity of CMV infection. Balfour et al (82) reported a similar effect in renal transplant recipients receiving high dose oral acyclovir. In both studies, the use of prophylactic acyclovir was randomized, with treatment starting on the day of transplantation and continuing for 30 days. Gluckman et al (83) reported a beneficial effect of oral acyclovir in preventing CMV disease after bone marrow transplantation. Freise et al (84) compared low-dose (400 mg/day) to high-dose (3200 mg/day) acyclovir in liver transplant recipients and noted no difference in CMV infection but a reduced incidence of CMV pneumonitis. Other studies have reported no effect of acyclovir prophylaxis, especially when used in lower doses (85). Phosphonoformate (foscarnet) is active against CMV in vitro (86-89). With the limited information available from open trials in which there were various transplant populations studied with unknown CMV serologic status, the efficacy of foscarnet for the treatment of CMV cannot be evaluated. There are no reports of prophylaxis with foscarnet in transplant recipients. Ganciclovir (DHPG) is a new antiviral drug that is quite active against CMV in vitro and in vivo (90-94). Similar to acyclovir, it is a congener of deoxyguanosine, which is phosphorylated and incorporated into the replicating viral DNA with subsequent inhibition of viral DNA chain elongation and DNA polymerase. Prospective clinical trials examining the potential efficacy of prophylactic ganciclovir in transplant recipients are currently underway. Dussaix and Wood reported that the use of prophylactic CMV hyperimmune globulin coupled with early ganciclovir therapy for proven CMV infection reduced the severity of CMV disease in seronegative pediatric liver transplant recipients (28). Concurrent use of immunoglobulin preparations with acyclovir has been studied as a treatment for viral Digestive Diseases and Sciences, Vol. 37, No. 5 (May 1992)

CMV DISEASE AFTER LIVER TRANSPLANTATION 100 NO PROPHYLAXIS

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Fig 8. The beneficial effect of prophylaxis with intravenous immunoglobulin and oral acyclovir on reducing the incidence of CMV disease in two high-risk patient groups.

infections in bone marrow and solid-organ transplant recipients (64, 68-71, 81, 85). However, conflicting results have been reported, and the use of these drugs after liver transplantation has been studied adequately. In our hepatic allograft recipient population, CMV disease occurs early after liver transplantation and can be related to well-defined risk factors. In recipients with primary CMV exposure, requiring OKT3 therapy, or undergoing retransplantation, the risk of developing CMV disease is above 50%. On the basis of these study findings, we have begun a trial of CMV prophylaxis in these high-risk patient groups. In seronegative recipients receiving livers from seropositive donors, we administer intravenous acyclovir (5 mg/kg every 8 hr) immediately after transplantation until oral intake is resumed, at which time oral acyclovir is started (400 mg five times per day in adults, 200 mg five times per day in children) and continued for three months. In addition, patients receive intravenous immunoglobulin (Gamma-Gard, Baxter-Hyland, Glendale, California; 0.5 g/kg) at weekly intervals for six weeks. A total of 38 patients at our center have had primary CMV exposure. Twenty patients were historical controls, while the next 18 received the above prophylaxis for CMV infection. The two groups were comparable with respect to demographic characteristics, total transfusions received, level of immunosuppressive therapy, and other perioperative variables. CMV prophylaxis resulted in a dramatic reduction in the incidence of CMV disease (75% vs 16.7%, Figure 8). In the 15 control patients who developed CMV disease, the mean Digestive Diseases and Sciences, Vol. 37, No. 5 (May 1992)

time of diagnosis was 42 days (range 19-120 days) after transplantation. Patterns of primary CMV disease included hepatitis (9), gastroenteritis (3), pneumonitis (2), and one case of CMV syndrome (neutropenia with a mononucleosis syndrome with CMV excretion). All cases were treated with intravenous ganciclovir, with five patients developing viral relapse after stopping ganciclovir. Ganciclovir retreatment was successful in all five patients. In the group receiving prophylaxis, only three patients developed CMV disease (two hepatitis, one gastroenteritis) at a mean time of 39 days after transplantation. All cases were responsive to an initial course of ganciclovir. There was no difference in patient and graft survival between control and treated patients. Therefore, it appears that intravenous immunoglobulin plus acyclovir is a safe and effective regimen in preventing CMV infection and disease in liver transplant patients with primary CMV exposure. We are currently conducting a randomized trial of CMV prophylaxis in patients receiving OKT3 therapy. Patients are randomized either to receive no treatment (control group) or prophylaxis with intravenous immunoglobulin (0.5 g/kg Gamma-Gard on days 1, 3, and 5 of OKT3 therapy, then at weekly intervals three times) and oral acyclovir in doses as above. The incidence of viral disease in the treatment group has been reduced successfully by the regimen of prophylaxis (72% vs 36%; Figure 8). However, this difference is due predominantly to a higher incidence of HSV and EBV disease in the control group. To date, there is no difference in the incidence of CMV disease in the two groups. We have not yet randomized any retransplant recipients into a CMV prophylaxis protocol. Clinical management of CMV disease consists of: (1) early detection of CMV infection followed by initiation of specific antiviral therapy; (2) a variable reduction in immunosuppression; (3) optimizing nutritional and metabolic support; (4) prophylaxis and/or treatment of superinfection; (5) selective use of intravenous immunoglobulin; and (6) surveillance viral cultures and titers to monitor the response to therapy. Surveillance viral monitoring consists of: (1) serial CMV IgM and IgG titers, usually at weekly intervals; (2) serial CMV cultures (blood, urine, throat, and sputum), usually at weekly intervals and when clinically indicated; and (3) biopsy and viral culture of deep tissue specimens whenever clinically indicated.

683

STRATTA ET AL Clinical experience with ganciclovir for CMV disease in liver transplant recipients is limited. Erice et al (95), Harbison et al 06), Paya et al (97), and Sayage et al (27) reported on the efficacy of ganciclovir therapy for severe CMV infections in I, 9, 12, and 19 hepatic allograft recipients, respectively. Our experience with ganciclovir therapy in 79 patients after liver transplantation represents the largest reported series to date. Once the diagnosis of CMV disease was established, specific antiviral therapy was begun with intravenous ganciclovir (DHPG, Syntax Research, Palo Alto, California) in a dose of 5 mg/kg every 12 hr for 14 days. Dosage adjustments were made on the basis of level of renal function as follows: serum creatinine -4.5 mg/dl, 1.25 mg/kg every 24 hr. The majority of patients required only the standard two-week course of ganciclovir therapy. The efficacy of ganciclovir therapy was determined by clinical response, surveillance viral cultures, and repeat evaluation of tissue specimens when indicated. In our early experience with ganciclovir, cyclosporine therapy was stopped and steroids were reduced (10-20 mg intravenous methylprednisolone or oral prednisone daily). However, this therapeutic regimen was associated with an unacceptably high incidence of allograft rejection. With increased experience with ganciclovir, we currently continue maintenance steroids and slightly reduce the cyclosporine dosage, aiming for 24-hr trough levels of 600-800 ng/ml by fluorescence polarization immune assay (Abbott TDX, Abbott Diagnostic Division, Abbott Park, Illinois). The mean duration of ganciclovir therapy in our liver transplant recipients with CMV disease was 16.1 days (range 3-52). A prompt and lasting response, characterized by clinical improvement and negative viral cultures, was documented in 58 cases (73.4%). Seventeen patients (21.5%) developed recurrent CMV disease after ganciclovir therapy (16 within three months, mean 31 days), including seven with two recurrences. Eleven patients were successfully retreated with ganciclovir, so that CMV disease was ultimately controlled in 87.3% of cases. Multiorgan CMV involvement was less responsive to ganciclovir therapy. Significant adverse drug effects, including leukopenia and thrombocytopenia, occurred in five patients (6.3%), with only one requiring drug withdrawal. Seventeen deaths

684

C M V vs NO C M V DISEASE 7 / 8 5 to 7 / 8 9 100 % S U R V I V A L

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20 0

*

0

I

1

NO CMV DISEASE

(n=189)

CMV DISEASE

(n=79)

m

I

2

I

I

*

3

4

YEARS

Fig 9. Actuarial patient survival in liver transplant recipients with and without CMV disease. No significant difference was noted.

occurred (14 due to sepsis), and five patients (6.3%) had evidence of CMV on postmortem examination. Persistent CMV disease further contributed to the loss of four allografts, with two successfully retransplanted. No cases of ganciclovir-resistant CMV disease were documented. In patients surviving for at least one month after transplantation (through the period of greatest risk for CMV disease), actuarial patient survival was similar in recipients with or without CMV disease (Figure 9). The presence of CMV disease was not an inadequate risk factor for either graft loss or patient death in this series. Ganciclovir is a safe and effective agent for the treatment of CMV disease after liver transplantation. An important advantage of ganciclovir therapy has been the ability to treat CMV disease effectively without major dosage reductions in immunosuppressive therapy, thus avoiding the subsequent development of rejection. At present, immunosuppressive therapy is decreased only in the setting of life-threatening CMV disease. Furthermore, we advocate the selective use of intravenous immunoglobulin therapy plus ganciclovir for rapidly progressive sepsis in the setting of CMV disease despite the institution of specific antiviral therapy. SUMMARY AND FUTURE PROSPECTS

In summary, CMV disease is a frequent source of morbidity after orthotopic liver transplantation. The importance of an aggressive diagnostic approach and high index of clinical suspicion cannot be overstated. Risk factors for the development of CMV disease include donor seropositivity, the use of antilymphocyte preparations, and retransplantation. CMV disease after primary CMV exposure or antilymphocyte therapy usually involves the heDigestive Diseases and Sciences, Vol. 37, No. 5 (May 1992)

CMV DISEASE AFTER LIVER TRANSPLANTATION patic allograft, while recurrent CMV disease is usually extrahepatic in location. CMV disease usually occurs in the first three months after transplantation, with viral relapse appearing within two months after completion of ganciclovir therapy. CMV disease that develops after antilymphocyte therapy usually occurs within one month. Ganciclovir has revolutionized the treatment of CMV disease after liver transplantation. The availability of ganciclovir has resulted in successful treatment of CMV disease without dramatic reductions in basal immunosuppression. CMV is a marker of the net state of immunosuppression, and the presence of CMV disease is an index of morbidity that signifies overimmunosuppression. Since CMV disease occurs early after transplantation and can be related to well-defined risk factors, investigation of prophylactic strategies is warranted to reduce the incidence and/or severity of CMV disease after liver transplantation. During the past decade, an abundance of data has emerged regarding basic properties of CMV, information about transmission of the virus, early diagnosis with new technology, pathophysiology, and its relation to the immune system. As the impact of CMV becomes more clear, it is apparent that we are just beginning to make inroads as to the pathogenesis and clinical management of CMV. Prospects for the future include: (1) solving the problem of viral latency and how to prevent reactivation; (2) developing a laboratory test that distinguishes CMV infection from disease; (3) delineating the pathogenesis of viral-induced allograft injury; (4) testing and implementing effective regimens of prophylaxis; and (5) developing specific therapy against established clinical disease. With the introduction of new and more potent immunosuppressive drugs, we will continue to be challenged to find ways of modifying the myriad effects of CMV in all facets of organ transplantation.

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4. Van Son WJ, The TH: Cytomegalovirus infection after organ transplantation: An update with special emphasis on renal transplantation. Transplant Int 2:147-164, 1989 5. Schier R, Nelson JA, Oldstone MBA: Detection of human cytomegalovirus in peripheral blood lymphocytes in a natural infection. Science 230:1048-1051, 1985 6. Gnann JW Jr, Ahlnen J, Svalander C, Olding L, Oldstone MBA, Nelson J: Inflammatory cells in transplanted kidneys are infected by human cytomegalovirus. Am J Pathol 132:239-248, 1988 7. Rubin RH: Infection in the renal transplant patient. In Clinical Approach to Infection in the Compromised Host. RH Rubin, LS Young (eds). New York, Plenum Medical, pp 553-605, 1981 8. Alford CA Jr, Britt WJ: Cytomegalovirus. In Virology. BN Fields (ed). New York, Raven Press, 1985, pp 629-660 9. Stratta ILl, Shaefer MS, Markin RS, Wood RP, Kennedy EM, Langnas AN, Reed EC, Woods GL, Dovovan JP, Pillen TJ, Duckworth RM, Shaw BW Jr: Clinical patterns of cytomegalovirus disease after liver transplantation. Arch Surg 124:1443-1450, 1989 10. Markin RS, Stratta RJ, Woods GL: Infection after liver transplantation. Am J Surg Pathol 14(suppl 1):64-78, 1990 11. Masih AS, Linder J, Shaw BW Jr, Wood RP, Donovan JP, White R, Markin RS: Rapid identification of cytomegalovirus in liver allograft biopsies by in-situ hybridization. Am J Surg Pathol 12:362-367, 1988 12. Thiele GM, Bicak MS, Young A, Kinsey J, White RJ, Purtilo DT: Rapid detection of cytomegalovirus by tissue culture, centrifugation, and immunofluorescence with a monoclonal antibody to a early nuclear antigen. J Virol Methods 16:327338, 1987 13. Paya CV, Smith TF, Ludwig J, Hermans PE: Rapid shell vial culture and tissue histology compared with serology for the rapid diagnosis of cytomegalovirus infection in liver transplantation. Mayo Clin Proc 64:670-675, 1989 14. Gold N, Nankervis GA: Cytomegalovirns. In Viral Infections of Humans, Epidemiology and Control. AS Evan (ed). New York, Plenum Press, 1982, pp 167-186 15. Preiksaitis JK: Cytomegalovirus infection in transplant recipients. Immunol Allergy Clin North Am 9:137-151, 1989 16. Peterson PK, Balfour HH Jr, Marker SC, Fryd DS, Howard ILl, Simmons RL: Cytomegalovirus disease in renal allograft recipients: A prospective study on the clinical features, risk factors and impact on renal transplantation. Medicine 59:283-300, 1980 17. Singh N, Dummer JS, Kusne S, Breining MK, Armstrong JA, Makowka L, Starzl TE, Ho M: Infections with cytomegalovirus and other herpes viruses in 121 liver transplant recipients: Transmission by donated organ and effect of OKT3 antibodies. J Infect Dis 158:124-131, 1988 18. Dummer JS, Hardy A, Poorsattar A, Ho M: Early infections in kidney, heart, and liver transplant recipients on cyclosporine. Transplantation 36:259-267, 1983 19. Pollard RB: Cytomegalovirus infections in renal, heart, heart-lung, and liver transplantation. Pediatr Infect Dis J 7:$97-S102, 1988 20. Ho M, Suwansirikul S, Dowling JN, Youngblood LA, Armstrong JA: The transplanted kidney as a source of cytomegalovirus infection. N Engl J Med 293:1109-1112, 1975

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37. Bronsther O, Makowka L, Jaffe R, Demetris HA, Breinig MK, Ho M, Esquivel CO, Gordon RD, Iwatsuki S, Tzakis A, Marsh JW Jr, Mazzaferro V, Van Thiel D, Starzl TE: Occurrence of cytomegalovirus hepatitis in liver transplant patients. J Med Virol 24:423-434, 1988 38. Sutherland DER, Chan FY, Foucar E, Simmons RL, Howard ILl, Najarian JS: The bleeding cecal ulcer in transplant patients. Surgery 86:386-398, 1979 39. Alexander JA, Cuellar RE, Fadden RJ, Genovese JJ, Gavaler JS, Van Thiel DH: Cytomegalovirus infection of the upper gastrointestinal tract before and after liver transplantation. Transplantation 46:378-382, 1988 40. Peterson PK, Balfour HH Jr, Fryd DS, Ferguson R, Kronenberg R, Simmons RL: Risk factors in the development of cytomegalovirus-related pneumonia in renal transplant recipients. J Infect Dis 48:1121, 1983 41. Winston DJ, Gale RP, Meyer DV, Young LS: Infectious complications of human bone marrow transplantation. Medicine 58:1-31, 1979 42. Pecego R, Hill R, Applebaum FR, Amos D, Buckner CD, Fefer A, Thomas ED: Interstitial pneumonitis following autologous bone marrow transplantation. Transplantation 42:515-517, 1986 43. Palestine AG: Clinical aspects of cytomegalovirus retinitis. Rev Infect Dis 10(3):$515, 1988 44. Pass RF, Whitley RJ, Diethelm AG, Whelchel JD, Reynolds DW, Alford CA: Cytomegalovirus infection in patients with renal transplants: Potentiation by antithymocyte globulin and an incompatible graft. J Infect Dis 142:9-17, 1980 45. Rubin RH, Tolkoff-Rubin N, Oliver D, Rota TR, Hamilton J, Betts RF, Pass RF, Hillis W, Szmuness W, Farell ML, Hirsch MS: Multi-center seroepidemiologic study of the impact of cytomegalovirus infection on renal transplantation. Transplantation 40:243-249, 1985 46. Velasco N, Catto GRD, Edward N, et al. The effect of the doses of steroids on the incidence of cytomegalovirus infections in renal transplant recipients. J Infect 9:69-78, 1984 47. Cheeseman SH, Rubin RH, Stewart JA, Tolkoff-Rubin NE, Cosimi AB, Cantell K, Gilbert TJ, Winkle S, Herrin JT, Black PH, Russell PS, Hirsch M: Control clinical trial of prophylactic human-leukocyte interferon in renal transplantation: Effects on cytomegalovirus and herpes simplex infection. N Engl J Med 300:1345-1349, 1979 48. Rubin RH, Cosimi AB, Hirsch MS, Herrin JT, Russell PS, Tolkoff-Rubin NE: Effect of anti-thymocyte globulin on cytomegalovirus infection in renal transplant recipients. Transplantation 31:143-145, 1981 49. Lewis RM, Johnson PC, Golden D, Van Buren CT, Kerman RH, Kahan BD: The adverse impact of cytomegalovirus infection on clinical outcome in cyclosporine-prednisone treated renal allograft recipients. Transplantation 45:353359, 1988 50. Najarian JS, Fryd DS, Strand M, Canafax DM, Ascher NL, Payne WD, Simmons RL, Sutherland DER: A single institution, randomized prospective trial of cyclosporine versus azathioprine-antilymphocyte globulin for immunosuppression in renal allograft recipients. Ann Surg 201:142-157, 1985 51. Harris KR, Saeed AA, Digard NJ, Whiteford K, Geoghegan TA, Lee HA, Slapak M: Cytomegalovirus titers in kidney transplant donor and recipient: Influence of cyclosporine-A. Transplant Proc 16:31-33, 1984 Digestive Diseases and Sciences, Vol. 37, No. 5 (May 1992)

CMV DISEASE A F T E R LIVER T R A N S P L A N T A T I O N 52. Bia MJ, Andiman W, Gaudio K, Kliger A, Siegel N, Smith D, Flye W; Effect of treatment with cyclosporine versus azathioprine on incidence and severity of cytomegalovirns infection post-transplantation. Transplantation 40:610-614, 1985 53. Stratta RJ, D'Alessandro AM, Armburst MJ, Pirsch JD, Sollinger HW, Kalayoglu M, Belzer FO: Sequential antilymphocyte globulin/cyclosporine immunosuppression in cadaveric renal transplantation: Effect of duration of ALG therapy. Transplantation 47"96-102, 1989 54. Chaterjee SN, Fiala M, Weiner J: Primary cytomegalovirus and opportunistic infections: Incidence in renal transplant recipients. JAMA 240:2446, 1978 55. Rook AH: Interactions of cytomegalovirus with the human immune system. Rev Infect Dis 10(suppl 3):$460-$467, 1988 56. Von Willebrand E, Pettersson E, Ahonen J, Hayry P: CMV infection, class II antigen expression and human kidney allograft rejection. Transplantation 42:364-367, 1986 57. Van Es A, Baldwin WM, Oljens PJ, Tanke HJ, Ploem JS, Van Es LA: Expression of HLA-DR on T-lymphocytes following renal transplantation, an association with graft rejection episodes and cytomegalovirus infection. Transplantation 37:65-69, 1984 58. Grundy JE, Ayles HM, McKeating JA, Butcher RG, Griffiths PD, Poulter LW: Enhancement of class I HLA-antigen expression by cytomegalovirus infection: Role and amplification of the virus. J Med Virol 25:483-495, 1988 59. Van Dorp W, Jonges E, Burggeman CA, Daha MR, Van Es LA, Woude FJ: Direct induction of MHC class I, but not class II, expression on endothelial cells by cytomegalovirus infection. Transplantation 48:469-472, 1989 60. Funjinami RS, Nelson JA, Walker L, Oldstone MBA: Sequence homology and immunologic cross-reactivity of human cytomegalovirus with HLA-DR beta chain: A means for graft rejection and immunosuppression. J Virol 62:100-105, 1988 61. Beck S, Barrell BG: Human cytomegalovirus encodes a glycoprotein homologous to MHC class I antigens. Nature 331:269-271, 1988 62. Paya CV, Hermans PE, Wisner RH, et al: Cytomegalovirus hepatitis in liver transplantation: Prospective analysis of 93 consecutive orthotopic liver transplantations. J Infect Dis (in press) 63. O'Grady JE, Alexander GJM, Sutherland S, Donaldson PT, Harvey F, Portman B, Calne RY, Williams R: Cytomegalovirus infection and donor/recipient HLA antigens: Interdependent co-factors in pathogenesis of vanishing bile duct syndrome after liver transplantation. Lancet 2:302-305, 1988 64. Bowden RA, Sayers M, Flournoy N, Newton B, Banaji M, Thomas ED, Meyers JD: Cytomegalovirus immune globulin and seronegative blood products to prevent primary cytomegalovirus infection after marrow transplantation. N Engl J Med 314:1006-1010, 1986 65. Rubin RH, Wilson EJ, Barrett LV, Medearis DN: The protective effects of hyperimmune anti-murine cytomegalovirus antiserum against lethal viral challenge: The case for passive-active immunization. Clin Immunol Immunopathol 39:151-158, 1986 66. Condie RM, O'Reilly RJ: Prevention of cytomegalovirus infection by prophylaxis with an intravenous hyperimmune native unmodified cytomegalovirus globulin. Am J Med 76:134, 1984 Digestive Diseases and Sciences, Vol. 37, No. 5 (May 1992)

67. Meyers JD, Leszczynski J, Zaia JA, Flournoy N, Newton B, Snydman DR, Wright GG, Levin MJ, Thomas ED: Prevention of cytomegalovirus infection by cytomegalovirus immunoglobulin after marrow transplantation. Ann Intern Med 98:442-446, 1983 68. Winston DJ, Ho WG, Lin CH, Bartoni K, Budinger MD, Gale RP, Champlin RE: Intravenous immunoglobulin for prevention of cytomegalovirus infection and interstitial pneumonia after bone marrow transplantation. Ann Intern Med 106:12-18, 1987 69. Winston DJ, Pollard RB, Ho WG, Gallagher JG, Rasmussen LE, Huang SN, Lin CH, Gossett TG, Merigan TC, Gale RP: Cytomegalovirus immune plasma in bone marrow transplant recipients. Ann Intern Med 97:11-18, 1982 70. Snydman DR, Werner BG, Heinze-Lacey B, Berardi VP, Tilney NL, Levey AS, Strom TB, Carpenter LB, Levey RH, Harmon WE, Zimmerman CE, Shapiro ME, Steinman T, Logerfo F, Idelson B, Schroeter PJ, Levin MJ, Mclver J, Leszczynski J, Grady GF: Use of cytomegalovirus immunoglobulin to prevent cytomegalovirus disease in renal transplant recipients. N Engl J Med 317:1049-1054, 1987 71. Snydman DR, Werner BG, Tilney NL, Kerkman RL, Milford EL, Cho SI, Bush HL, Levey AS, Strom TB, Carpenter CV, Berardi VP, Levey RH, Harmon WE, Zimmerman CE, Tenny A, Heinze-Lacey B, Shapiro ME, Steinman T, Logerfo F, Idelson B, Mclver J, Leszczynski J, Grady GF: Further analysis of primary cytomegalovirus disease prevention in renal transplant recipients with a cytomegalovirus immunoglobulin: Interim comparison of a randomized and open-label trial. Transplant Proc 20(suppl 8):24-30, 1988 72. Chou S: Neutralizing antibody responses to reinfecting strains of cytomegalovirus in transplant recipients. J Infect Dis 160:16-21, 1989 73. Schafers HJ, Milbradt H, Flick J, Wahlers TH, Fieguth HG, Haverich A: Hyperimmunoglobulin for cytomegalovirus prophylaxis following heart transplantation. Clin Transplantation 2:51-56, 1988 74. Bell R, Sheil AGR, McDonald JA, McCaughan GW: The role of CMV immunoprophylaxis in patients at risk of primary CMV infection following orthotopic liver transplantation. Transplant Proc 21:3781-3782, 1989 75. Plotkin SA, Friedman HM, Fleisher GR, Dafoe DC, Grossman RA, Smiley ML, Starr SE, Woldaver C, Friedman AD, Barker CF: Towne-vaccine induced prevention of cytomegalovirus disease after renal transplantation. Lancet 1:528530, 1984 76. Balfour HH Jr, Welo PK, Sachs GW: Cytomegalovirus vaccine trial in 400 renal transplant candidates. Transplant Proc 17:81-83, 1985 77. Hirsch M, Schoole RT, Cosimi AB, Russell PS, Delmonico FL, Tolkoff-Rubin NE, Herrin JT, Cantell K, Farrell M, Rota TR, Rubin RH: Effects of interferon-alpha on cytomegalovirus reactivation syndromes in renal transplant recipients. N Engl J Med 308:1489-1493, 1983 78. Kovarik J, Mayer G, Pohanka E, Schwartz M, Traindl O, Graf H, Smolen J: Adverse effect of low-dose prophylactic human recombinant leukocyte interferon-alpha treatment in renal transplant recipients. Transplantation 45:402-405, 1988 79. Rakela J, Wooten RS, Batts KP, Perkins JD, Taswell HF, Krom RAF: Failure of interferon to prevent recurrent hep-

687

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80. 81.

82.

83.

84.

85.

86.

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88.

atitis-B infection in hepatic allograft. Mayo Clin Proc 64:429-432, 1989 Verheyden JPH: Evolution of therapy for cytomegalovirus infection. Rev Infect Dis 10(3):$477, 1988 Meyers JD, Reed EC, Shepp DH, Thornquist M, Danliker PS, Vicary CA, Flournoy N, Kirk LE, Kersey JH, Thomas ED, Balfour HH Jr: Acyclovir for prevention of cytomegalovirus infection and disease after allogeneic marrow transplantation. N Engl J Med 318:70-75, 1988 Balfour HH Jr, Chace BA, Stapleton JT, Simmons RL, Fryd DS: A randomized placebo-control trial of oral acyclovir for the prevention of cytomegalovirus disease in recipients of renal allografts. N Engl J Med 320:1381-1387, 1989 Gluckman E, Devergie A, Melo R, et al: Prophylaxis of herpes infections after bone marrow transplantation by oral acyclovir. Lancet 2:706-708, 1983 Freise CE, Roberts JP, Ascher NL: Comparison of three CMV prophylaxis protocols in 107 liver transplant recipients. Transplantation 1991 (in press) Fletcher CV, Chinnock BJ, Chace B, Balfour HH Jr: Pharmacokinetics and safety of high-dose oral acyclovir for suppression of cytomegalovirus disease after renal transplantation. Clin Pharmacol Ther 44:158-163, 1988 Ahlmen J, Wijnween AC, Brynger H, Lycke E: Clinical experience with phosphonoformate (foscarnet) treatment of viral disease following renal transplantation. Scand J Urol Nephrol 92:41, 1985 Klintmalm G, Loonquist B, Oberg B, et al: Intravenous foscarnet for the treatment of severe cytomegalovirus infection in allograft recipients. Scand J Infect Dis 17:157-163, 1985 Ringden O, Lonnquist B, Paulin T, et al: Pharmacokinetics, safety, and preliminary clinical experience using foscarnet in

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the treatment of cytomegalovirus infections in bone marrow and renal transplant recipients. J Antimicrob Agents Chemother 17:373, 1986 Oberg B: Anti-viral effects of phosphonoformate (PFA, foscarnet sodium). Pharmac Ther 19:387-415, 1983 Collaborative DHPG treatment study group: Treatment of serious cytomegalovirus infections with DHPG in patients with AIDS and other immunodeficiencies. N Engl J Med 314:801-805, 1986 Matthews T, Boehme R: Anti-viral activity and mechanism of action of ganciclovir. Rev Infect Dis 10(3):$490--$494, 1988 Levin MJ: Anti-viral therapy of herpes virus infection in renal transplant recipients. Transplant Proc 20(suppl 8):1923, 1988 Plotkin SA, Drew WL, Felsenstein D, Hirsch MS: Sensitivity of clinical isolates of human cytomegalovirus to DHPG. J Infect Dis 152:833-834, 1985 Whitley R: Ganciclovir: Have we established clinical value in the treatment of cytomegalovirus infections? Ann Intern Med 108:452-454, 1988 Erice A, Jordan MC, Chace BA, Fletcher C, Chinnock BJ, Balfour HH Jr: Ganciclovir treatment of cytomegalovirus disease in transplant recipients and other immunocompromised hosts. JAMA 257:3082-3087, 1987 Harbison MA, De Girolamini PC, Jenkins RL, Hammer SM: Ganciclovir therapy of severe cytomegalovirus infections in solid-organ transplant recipients. Transplantation 46:82-88, 1988 Paya CV, Hermans PE, Smith TF, Rakela J, Wiesner RH, Krom RAF, Torres VE, Sterioff S, Wilkowski CJ: Efficacy of ganciclovir in liver and kidney transplant recipients with severe cytomegalovirus infection. Transplantation 46:229234, 1988

Digestive Diseases and Sciences, Vol. 37, No. 5 (May 1992)