452
Evaluation of Three Rapid Enzyme Immunoassays and Cell Culture for Detection of Respiratory Syncyfial Virus J. Mendoza*, A. Rojas, J.M. Navarro, C. Plata, M. de la Rosa
Three rapid enzyme immunoassay techniques for the detection of respiratory syncyfial virus antigen (Becton Dickinson Directigen RSV, Abbott RSV Testpack and Abbott RSV E I A ) a n d cell culture were evaluated in a total of 250 nasal washings. The sensitivity and specificity were 62 % and 76 % respectively for Directigen, 64 % and 86 % for RSV Testpack, and 76 % and 81% for RSV EIA, taking cell culture as the reference method. Agreement between cell culture and EIA techniques was 79 % (70 positive and 128 negative results). All three EIA techniques gave positive results in 69 samples (52 positive and 17 negative in the cell culture). In 121 samples all three EIA techniques gave negative results (103 negative and 18 positive in the cell culture). Using the cell culture technique 46 strains other than respiratory syncytial virus were isolated.
The respiratory syncytial virus (RSV) is the commonest cause of respiratory infection during infancy, affecting mainly children under six years of age. Rapid diagnosis of the infection permits prompt treatment with ribavirin in those cases serious enough to warrant use of this drug, and avoids an increase in intrahospital RSV infections (1-3). The techniques used to detect RSV in clinical samples include enzyme immunoassays (EIA) (4-14), direct immunofluorescence (4, 9, 12) and conventional cell culture techniques or the shellvial method (9-11). In the period 1989-1990 we prospectively evaluated the performance of the following three commercial EIA techniques for detection of RSV in nasal washings: Directigen (D-RSV) (Becton Dickinson, Cockeysville, MD, USA), RSV Servicio de Microbiologia, Hospital Regional de Especialidades Virgen de las Nieves, E-19014 Granada, Spain.
Eur. J, Clin. Microbiol. Infect. Dis.
Testpack (TP-RSV) and RSV EIA (E-RSV) (both Abbott Laboratories, North Chicago, IL, USA). All samples were also tested by cell culture. Materials and Methods. We tested the different methods in a total of 275 nasal washings from pediatric patients (less than two years old) diagnosed as having acute respiratory infection requiring hospitalization. The samples were collected within 24 h of admission by injecting 10-20 ml of saline solution into one nostril and simultaneously aspirating the other with a catheter connected to a sterile specimen trap (15). The samples were sent to the laboratory without transport medium and processed within three hours. All samples were centrifuged at 700 x g for 5 min to obtain the supernatant. For the cell culture techniques, D-RSV and TP-RSV, we used fresh samples; the samples Used for E-RSV had previously been frozen at -70 °C (4) immediately upon arrival at the laboratory and were processed two months after collection. Samples which were inadequately absorbed onto the D-RSV or TPRSV membrane were excluded from further study. All kits were used according to the manufacturer's instructions. For cell culture we used Hep-2, Veto (Flow Irvine, UK), LLC-MK2 and MDCK cells (Whittaker, USA) and human embryo lung fibroblasts (prepared in our laboratory). All cells used in cultures were prepared inhouse twice weekly. The maintenance media used were Minimun Essential Medium (MEM) with 2 % inactivated fetal bovine serum (FBS) for Hep-2, MEM-1% FBS for Vero, MEM-10 % FBS for fibroblasts and MEM plus 2 ~tg/ml trypsin for LLC-MK and MDCK cells. The culture tubes were incubated at 35 °C in a stationary rack and were observed daily for 15 days for the typical cytopathic effect. The presence of RSV was confirmed by visualization of typical syncytia in 25 % or more of the cells, and by direct immunofluorescence of cells scraped from the monolayer (4, 6, 9). Hemadsorption (9), direct immunofluorescence or the characteristic cytopathic effect of cells of the monolayer were also used to detect and identify other viruses. Results and Discussion. Nineteen samples were not absorbed on D-RSV, and seven were not absorbed on TP-RSV; these samples were excluded from further study. Table 1 shows the results for each E I A technique and cell culture. Agreement between cell culture and the three EIA techniques was 79 % (70 positive and 128 negative
Vol. 11, 1992
453
,--.....__
T a b l e 1: R e s u l t s o b t a i n e d u s i n g D i r e c t i g e n R S V ( D - R S V ) , A b b o t t R S V T e s t p a c k ( T P - R S V ) , Abbott RSV EIA (E-RSV) and cell culture for detection of respiratory syncytial virus in 250 nasal washing specimens.
No. reactive
Cell culture
D-RSV
TP-RSV
E-RSV
52 10
+ +
+ +
+ -
+ +
8 5 7 18
+ + + +
-
+ + -
+ + -
I 17 2
+ -
+ + +
+ +
+ -
1 15
-
+ +
-
+ -
1
-
-
+
-
10
-
-
-
+
103
.
.
results). All three E I A techniques yielded positive results in 69 samples (52 positive and 17 negative in the cell culture). In 121 samples all three EIA techniques yielded negative results (103 negative and 18 positive in the cell culture). The Sensitivity and specificity were 62 % and 76 % Spectively for Directigen, 64 % and 86 % for V Testpack, and 76 % and 8 1 % for RSV EIA, taking cell culture as the reference method. As the presence of'nonviable virus in the sample (due to inadequate preservation or neutralization With antibodies) made it impossible to use cell culture as the only reference method, the results of at least two immunological methods were used to validate these results (12). RSV was detected by the immunological tests in 91 samples, cell culture in 101 and by both techniques combined in 122 samples. The sensitivity of the EIA techniques and cell culture was 75% and 83% respectively. The mean time until detection of the cytopathic effect for RSV was 6.3 days (range 4-14 days). On Cell culture the following organisms were isolated: 101 RSV, 2 adenovirus, 5 enterovirus, 18 influenza A virus, 3 influenza B virus, 1 parainfluenza 1, 2 parainfluenza 2 and 15 rhinovirus Strains. All three EIA techniques were positive for one isolate each of adenovirus, influenza A, Parainfluenza 1, parainfluenza 2 and rhinovirus. Three rhinovirus strains were isolated on cell culture; of these one was positive in the E-RSV and two were positive in the D-RSV. Rhinovirus and RSV were isolated in one case, in which E-RSV Was the only enzymatic test to yield a positive result. An analysis of the cross-reactions between
.
.
the EIA techniques with different RSV isolates showed no important differences between the three methods. Two cross-reactions were detected only with D-RSV, two only with E-RSV and none with TP-RSV. In five cases all three E I A techniques were positive for different viruses (adenovirus, influenza A, rhinovirus, parainfluenza 1 and parainfluenza 2). The lack of cross-reactions with a specific type of virus suggests the coexistence of RSV and the other virus in these samples. The fact that there was failure to isolate these other organisms on cell culture may have been due to their lack of viability in the sample, or to interference between the two types of virus. In our study E-RSV was the most sensitive and TP-RSV the most specific of the immunological tests. While the specificity was similar to that reported in other studies, the sensitivity was lower for both TP-RSV (4, 6-8, 13) and D-RSV (4, 5, 8, 12, 14). The diminished sensitivity of the enzymatic tests in our study may have been due to the use of freshly-prepared monolayers, which make the cell culture more sensitive (10), and the use of supernatant, which may reduce the sensitivity of these tests (16). Some authors use freeze-thawing (5, 12) as well as blocking assays (5) to improve the results of EIAs, but these techniques are not suitable for the expensive bedside tests evaluated in this study. We can offer no explanation for the lower sensitivity of the E-RSV in this study, as compared to a previous report (11), since the samples were frozen before assay, a procedure that increases the sensitivity of EIAs. In the diagnosis of
454
RSV the main advantages of EIAs, as opposed to cell culture, are the ability to detect nonviable viral particles in the sample, and the ease and speed with which the results are obtained (15 min with D-RSV, 20 min with TP-RSV, and 5 hours with E-RSV). D-RSV occasionally produced results which were difficult to interpret. TP-RSV, which had 86 % specificity in the present study, would seem to be the best choice for RSV screening during out-breaks in risk populations with a diagnosis of acute respiratory infection, in whom a positive result with TP-RSV would make the search for other viral pathogens unnecessary. Forty-six strains of viruses other than RSV were found in 250 patients during the epidemic; according to our criteria only six (2.5 %) of these patients also had RSV. In such situations further diagnostic procedures such as conventional cell culture or shell-vial culture could be reserved for negative cases.
References 1. Demers RR, Parker J, Frankel LR, Smith DW: Administration of ribavirin to neonatal and pediatric patients during mechanical ventilatiom Respiratory Care 1986, 31: 1188-1196. 2. MacDonald NE, Hall CB, Suffin SC, Alexson C, Harris PJ, Manning JA: Respiratory syncytial viral infection in infants with congenital heart diseases. New England Journal of Medicine 1982, 307: 397--400. 3. Goldmann DA: Nosocomial viral infections: recent developments and new strategies. European Journal of Clinical Microbiology & Infectious Diseases 1989, 8: 75-81. 4, Halstead DC, Todd S, Fritch G: Evaluation of five methods for respiratory syncytial virus detection. Journal of Clinical Microbiology 1990, 28: 1021-1025. 5. Kok T, Barancek K, Burrell C J: Evaluation of Becton Dickinson Directigen test for respiratory syncytial virus in nasopharyngeal aspirates. Journal of Clinical Microbiology 1990, 28: 1458-1459. 6. Swierkosz EM, Flanders R, Melvin L, Miller JD, Kline MW: Evaluation of the Abbott Testpack RSV enzyme immunoassay for detection of respiratory syncytial virus in nasopharyngeal swab specimens. Journal of Clinical Microbiology 1989, 27: 1151-1154. 7. Wren CG, Bate B J, Masters HB, Launer BA: Detection of respiratory syncytial virus antigen in nasal washings by Abbott Testpack enzyme immunoassay. Journal of Clinical Microbiology 1990, 28: 1395-1397. 8. Rothbarlh PH, Hermns MC, Schrijnemakers P: Reliability of two new test kits for rapid diagnosis of respiratory syncytial virus infeetion. Journal of Clinical Microbiology 1991, 29: 824-826. 9. Grover S, Watkins P, Orvell C, Booth J: Comparison of direct immunofluorescence of exfoliated cells, tissue culture immunofluorescence and conventional virus isolation for the diagnosis of respiratory syncytial virus infections. Serodiagnosis and Immunotherapy in Infectious Diseases 1990, 4: 59--66.
Eur. J. Clin. Microbiol. Infect. Dis.
20. Johnston SLG, Siegel CS: Evaluation of direct immunofluoreseence, enzyme immunoassay, centrifugation culture, and conventional culture for the detection of respiratory syncytial virus. Journal of Clinical Microbiology 1990, 28: 2394-2397. 11. Mendoza J, Navarro JM, Rojas A, de la Rosa M: Evaluation of immunofluorescence, two enzyme immunoassays and the shell-vial assay for detection of respiratory syncytial virus. European Journal of Clinical Microbiology & Infectious Diseases 1991,10: 40-42. 12. Warier JL, Whitehurs N J, Todd SJ, Shalaby H, Wall L: Comparison of Direetigen RSV with viral isolation and direct immunofluoreseence for identification of respiratory syncytial virus. Journal of Clinical Microbiology 1990, 28: 480--483. 13. Thomas EE, Book LE: Comparison of two rapid methods for detection of respiratory syncytial virus (Testpack RSV and Ortho RSV ELISA) with direct immunofluorescence and virus isolation for the diagnosis of pediatric RSV infection. Journal of Clinical Microbiology 1991, 29: 632-635. 14. Hornsleth A: A rapid test for detection of respiratory syncytial virus in nasopharyngeal secretion. European Journal of Clinical Microbiology & Infectious Diseases 1990, 9: 356-358. 15. Frayha H, Castrician0 S, Mahony J, Chernesky M: Nasopharyngeal swabs and nasopharyngeal aspirates are equally effective for the diagnosis of viral respiratory disease in hospitalized children. Journal of Clinical Microbiology 1989, 27: 1387-1389. 16. Chonmaitree T, Bessette-Henderson BJ, Hepler R, Lucia 14."Comparison of three rapid diagnostic techniques for detection of respiratory syncytial virus from wash specimens. Journal of Clinical Microbiology 1987, 25: 746-747.
Prevalence of Genital Human Papillomavirus Infections in Patients at a Sexually Transmitted Diseases Clinic Y.L. Chang 1, C.Y. Lin 1, C.J. Tseng 2, H.S. Cheng 3, H.C. Lin 4, C.C. Pao 1 .
The human papillomavirus was detected in cervicovaginal cells by the polymerase chain reaction in 14 of 37 (37.8 %) patients attending a sexually transmitted disease (STD) clinic and in 6 of 43 healthy young women (14.0%) undergoing 1Department of Biochemistry, 2Department of Obstetrics and Gynecology, and 3Department of Family Medicine, Chang Gung Medical College and Memorial Hospital, 259 WenHwa Road, KweiShan, TaoYuan, Taiwan 333. 4Taipei Municipal Venereal Disease Control Institute, Taipei, Taiwan.
Evaluation of Three Rapid Enzyme Immunoassays and Cell Culture for Detection of Respiratory Syncyfial Virus J. Mendoza*, A. Rojas, J.M. Navarro, C. Plata, M. de la Rosa
Three rapid enzyme immunoassay techniques for the detection of respiratory syncyfial virus antigen (Becton Dickinson Directigen RSV, Abbott RSV Testpack and Abbott RSV E I A ) a n d cell culture were evaluated in a total of 250 nasal washings. The sensitivity and specificity were 62 % and 76 % respectively for Directigen, 64 % and 86 % for RSV Testpack, and 76 % and 81% for RSV EIA, taking cell culture as the reference method. Agreement between cell culture and EIA techniques was 79 % (70 positive and 128 negative results). All three EIA techniques gave positive results in 69 samples (52 positive and 17 negative in the cell culture). In 121 samples all three EIA techniques gave negative results (103 negative and 18 positive in the cell culture). Using the cell culture technique 46 strains other than respiratory syncytial virus were isolated.
The respiratory syncytial virus (RSV) is the commonest cause of respiratory infection during infancy, affecting mainly children under six years of age. Rapid diagnosis of the infection permits prompt treatment with ribavirin in those cases serious enough to warrant use of this drug, and avoids an increase in intrahospital RSV infections (1-3). The techniques used to detect RSV in clinical samples include enzyme immunoassays (EIA) (4-14), direct immunofluorescence (4, 9, 12) and conventional cell culture techniques or the shellvial method (9-11). In the period 1989-1990 we prospectively evaluated the performance of the following three commercial EIA techniques for detection of RSV in nasal washings: Directigen (D-RSV) (Becton Dickinson, Cockeysville, MD, USA), RSV Servicio de Microbiologia, Hospital Regional de Especialidades Virgen de las Nieves, E-19014 Granada, Spain.
Eur. J, Clin. Microbiol. Infect. Dis.
Testpack (TP-RSV) and RSV EIA (E-RSV) (both Abbott Laboratories, North Chicago, IL, USA). All samples were also tested by cell culture. Materials and Methods. We tested the different methods in a total of 275 nasal washings from pediatric patients (less than two years old) diagnosed as having acute respiratory infection requiring hospitalization. The samples were collected within 24 h of admission by injecting 10-20 ml of saline solution into one nostril and simultaneously aspirating the other with a catheter connected to a sterile specimen trap (15). The samples were sent to the laboratory without transport medium and processed within three hours. All samples were centrifuged at 700 x g for 5 min to obtain the supernatant. For the cell culture techniques, D-RSV and TP-RSV, we used fresh samples; the samples Used for E-RSV had previously been frozen at -70 °C (4) immediately upon arrival at the laboratory and were processed two months after collection. Samples which were inadequately absorbed onto the D-RSV or TPRSV membrane were excluded from further study. All kits were used according to the manufacturer's instructions. For cell culture we used Hep-2, Veto (Flow Irvine, UK), LLC-MK2 and MDCK cells (Whittaker, USA) and human embryo lung fibroblasts (prepared in our laboratory). All cells used in cultures were prepared inhouse twice weekly. The maintenance media used were Minimun Essential Medium (MEM) with 2 % inactivated fetal bovine serum (FBS) for Hep-2, MEM-1% FBS for Vero, MEM-10 % FBS for fibroblasts and MEM plus 2 ~tg/ml trypsin for LLC-MK and MDCK cells. The culture tubes were incubated at 35 °C in a stationary rack and were observed daily for 15 days for the typical cytopathic effect. The presence of RSV was confirmed by visualization of typical syncytia in 25 % or more of the cells, and by direct immunofluorescence of cells scraped from the monolayer (4, 6, 9). Hemadsorption (9), direct immunofluorescence or the characteristic cytopathic effect of cells of the monolayer were also used to detect and identify other viruses. Results and Discussion. Nineteen samples were not absorbed on D-RSV, and seven were not absorbed on TP-RSV; these samples were excluded from further study. Table 1 shows the results for each E I A technique and cell culture. Agreement between cell culture and the three EIA techniques was 79 % (70 positive and 128 negative
Vol. 11, 1992
453
,--.....__
T a b l e 1: R e s u l t s o b t a i n e d u s i n g D i r e c t i g e n R S V ( D - R S V ) , A b b o t t R S V T e s t p a c k ( T P - R S V ) , Abbott RSV EIA (E-RSV) and cell culture for detection of respiratory syncytial virus in 250 nasal washing specimens.
No. reactive
Cell culture
D-RSV
TP-RSV
E-RSV
52 10
+ +
+ +
+ -
+ +
8 5 7 18
+ + + +
-
+ + -
+ + -
I 17 2
+ -
+ + +
+ +
+ -
1 15
-
+ +
-
+ -
1
-
-
+
-
10
-
-
-
+
103
.
.
results). All three E I A techniques yielded positive results in 69 samples (52 positive and 17 negative in the cell culture). In 121 samples all three EIA techniques yielded negative results (103 negative and 18 positive in the cell culture). The Sensitivity and specificity were 62 % and 76 % Spectively for Directigen, 64 % and 86 % for V Testpack, and 76 % and 8 1 % for RSV EIA, taking cell culture as the reference method. As the presence of'nonviable virus in the sample (due to inadequate preservation or neutralization With antibodies) made it impossible to use cell culture as the only reference method, the results of at least two immunological methods were used to validate these results (12). RSV was detected by the immunological tests in 91 samples, cell culture in 101 and by both techniques combined in 122 samples. The sensitivity of the EIA techniques and cell culture was 75% and 83% respectively. The mean time until detection of the cytopathic effect for RSV was 6.3 days (range 4-14 days). On Cell culture the following organisms were isolated: 101 RSV, 2 adenovirus, 5 enterovirus, 18 influenza A virus, 3 influenza B virus, 1 parainfluenza 1, 2 parainfluenza 2 and 15 rhinovirus Strains. All three EIA techniques were positive for one isolate each of adenovirus, influenza A, Parainfluenza 1, parainfluenza 2 and rhinovirus. Three rhinovirus strains were isolated on cell culture; of these one was positive in the E-RSV and two were positive in the D-RSV. Rhinovirus and RSV were isolated in one case, in which E-RSV Was the only enzymatic test to yield a positive result. An analysis of the cross-reactions between
.
.
the EIA techniques with different RSV isolates showed no important differences between the three methods. Two cross-reactions were detected only with D-RSV, two only with E-RSV and none with TP-RSV. In five cases all three E I A techniques were positive for different viruses (adenovirus, influenza A, rhinovirus, parainfluenza 1 and parainfluenza 2). The lack of cross-reactions with a specific type of virus suggests the coexistence of RSV and the other virus in these samples. The fact that there was failure to isolate these other organisms on cell culture may have been due to their lack of viability in the sample, or to interference between the two types of virus. In our study E-RSV was the most sensitive and TP-RSV the most specific of the immunological tests. While the specificity was similar to that reported in other studies, the sensitivity was lower for both TP-RSV (4, 6-8, 13) and D-RSV (4, 5, 8, 12, 14). The diminished sensitivity of the enzymatic tests in our study may have been due to the use of freshly-prepared monolayers, which make the cell culture more sensitive (10), and the use of supernatant, which may reduce the sensitivity of these tests (16). Some authors use freeze-thawing (5, 12) as well as blocking assays (5) to improve the results of EIAs, but these techniques are not suitable for the expensive bedside tests evaluated in this study. We can offer no explanation for the lower sensitivity of the E-RSV in this study, as compared to a previous report (11), since the samples were frozen before assay, a procedure that increases the sensitivity of EIAs. In the diagnosis of
454
RSV the main advantages of EIAs, as opposed to cell culture, are the ability to detect nonviable viral particles in the sample, and the ease and speed with which the results are obtained (15 min with D-RSV, 20 min with TP-RSV, and 5 hours with E-RSV). D-RSV occasionally produced results which were difficult to interpret. TP-RSV, which had 86 % specificity in the present study, would seem to be the best choice for RSV screening during out-breaks in risk populations with a diagnosis of acute respiratory infection, in whom a positive result with TP-RSV would make the search for other viral pathogens unnecessary. Forty-six strains of viruses other than RSV were found in 250 patients during the epidemic; according to our criteria only six (2.5 %) of these patients also had RSV. In such situations further diagnostic procedures such as conventional cell culture or shell-vial culture could be reserved for negative cases.
References 1. Demers RR, Parker J, Frankel LR, Smith DW: Administration of ribavirin to neonatal and pediatric patients during mechanical ventilatiom Respiratory Care 1986, 31: 1188-1196. 2. MacDonald NE, Hall CB, Suffin SC, Alexson C, Harris PJ, Manning JA: Respiratory syncytial viral infection in infants with congenital heart diseases. New England Journal of Medicine 1982, 307: 397--400. 3. Goldmann DA: Nosocomial viral infections: recent developments and new strategies. European Journal of Clinical Microbiology & Infectious Diseases 1989, 8: 75-81. 4, Halstead DC, Todd S, Fritch G: Evaluation of five methods for respiratory syncytial virus detection. Journal of Clinical Microbiology 1990, 28: 1021-1025. 5. Kok T, Barancek K, Burrell C J: Evaluation of Becton Dickinson Directigen test for respiratory syncytial virus in nasopharyngeal aspirates. Journal of Clinical Microbiology 1990, 28: 1458-1459. 6. Swierkosz EM, Flanders R, Melvin L, Miller JD, Kline MW: Evaluation of the Abbott Testpack RSV enzyme immunoassay for detection of respiratory syncytial virus in nasopharyngeal swab specimens. Journal of Clinical Microbiology 1989, 27: 1151-1154. 7. Wren CG, Bate B J, Masters HB, Launer BA: Detection of respiratory syncytial virus antigen in nasal washings by Abbott Testpack enzyme immunoassay. Journal of Clinical Microbiology 1990, 28: 1395-1397. 8. Rothbarlh PH, Hermns MC, Schrijnemakers P: Reliability of two new test kits for rapid diagnosis of respiratory syncytial virus infeetion. Journal of Clinical Microbiology 1991, 29: 824-826. 9. Grover S, Watkins P, Orvell C, Booth J: Comparison of direct immunofluorescence of exfoliated cells, tissue culture immunofluorescence and conventional virus isolation for the diagnosis of respiratory syncytial virus infections. Serodiagnosis and Immunotherapy in Infectious Diseases 1990, 4: 59--66.
Eur. J. Clin. Microbiol. Infect. Dis.
20. Johnston SLG, Siegel CS: Evaluation of direct immunofluoreseence, enzyme immunoassay, centrifugation culture, and conventional culture for the detection of respiratory syncytial virus. Journal of Clinical Microbiology 1990, 28: 2394-2397. 11. Mendoza J, Navarro JM, Rojas A, de la Rosa M: Evaluation of immunofluorescence, two enzyme immunoassays and the shell-vial assay for detection of respiratory syncytial virus. European Journal of Clinical Microbiology & Infectious Diseases 1991,10: 40-42. 12. Warier JL, Whitehurs N J, Todd SJ, Shalaby H, Wall L: Comparison of Direetigen RSV with viral isolation and direct immunofluoreseence for identification of respiratory syncytial virus. Journal of Clinical Microbiology 1990, 28: 480--483. 13. Thomas EE, Book LE: Comparison of two rapid methods for detection of respiratory syncytial virus (Testpack RSV and Ortho RSV ELISA) with direct immunofluorescence and virus isolation for the diagnosis of pediatric RSV infection. Journal of Clinical Microbiology 1991, 29: 632-635. 14. Hornsleth A: A rapid test for detection of respiratory syncytial virus in nasopharyngeal secretion. European Journal of Clinical Microbiology & Infectious Diseases 1990, 9: 356-358. 15. Frayha H, Castrician0 S, Mahony J, Chernesky M: Nasopharyngeal swabs and nasopharyngeal aspirates are equally effective for the diagnosis of viral respiratory disease in hospitalized children. Journal of Clinical Microbiology 1989, 27: 1387-1389. 16. Chonmaitree T, Bessette-Henderson BJ, Hepler R, Lucia 14."Comparison of three rapid diagnostic techniques for detection of respiratory syncytial virus from wash specimens. Journal of Clinical Microbiology 1987, 25: 746-747.
Prevalence of Genital Human Papillomavirus Infections in Patients at a Sexually Transmitted Diseases Clinic Y.L. Chang 1, C.Y. Lin 1, C.J. Tseng 2, H.S. Cheng 3, H.C. Lin 4, C.C. Pao 1 .
The human papillomavirus was detected in cervicovaginal cells by the polymerase chain reaction in 14 of 37 (37.8 %) patients attending a sexually transmitted disease (STD) clinic and in 6 of 43 healthy young women (14.0%) undergoing 1Department of Biochemistry, 2Department of Obstetrics and Gynecology, and 3Department of Family Medicine, Chang Gung Medical College and Memorial Hospital, 259 WenHwa Road, KweiShan, TaoYuan, Taiwan 333. 4Taipei Municipal Venereal Disease Control Institute, Taipei, Taiwan.
