913
ANTI-HCV RESULTS IN IMPLICATED AND NON-IMPLICATED DONORS
conventional smallpox vaccine were a new product it would be unlikely to get a product licence for general use. The results reported by Cooney et al may aid our understanding of the factors that determine the human virulence of vaccinia virus. Animal studies have shown that vaccinia recombinants which have the foreign gene inserted into the vaccinia thymidine kinase gene, and which are therefore TK-, tend to be attenuated.3.4However, the recombinant used by Cooney et al was also TK - ,sand produced results in man similar to that of the conventional TK+ vaccine. In fact in the two subjects tested who had not previously had smallpox vaccine the effect if anything was more severe than the conventional vaccine. Thus, whatever its attenuating effect in animals, it seems that inactivation of the thymidine kinase gene of vaccinia does not necessarily attenuate the virulence of the virus for man. University of Liverpool, Department of Medical Microbiology, Liverpool L69 3BX, UK
DERRICK BAXBY
1. Fenner F, Henderson DA, Arita I, et al. Smallpox and its eradication. Geneva: WHO, 1988 2. Buller RML, Smith GL, Cremer K, et al. Decreased virulence of recombinant vaccinia virus expression vectors is associated with a thymidine kinase-negative
phenotype. Nature 1985; 317:
i
I
I
I
i
*Upper limrt of normal 40 U/I, ALT= alanine transferase t4-RIBA testing done on follow-up samples 20-35 mo postdonation +=pos!tMe,-=negat!ve
(structural) region of the HCV genome, have been coated in bands on nitrocellulose strips in addition to the 5-1-1 and C-100 antigens present in the first generation RIBA. The antigen band intensities are compared with weak positive and moderate positive control bands, and a response of 1 + or greater (up to 4 + ) to any two or more HCV antigens is interpreted as a positive result. We have tested samples from 9 implicated donors in our prospective post-transfusion hepatitis study,* each of whom was associated with 1 of the 9 post-transfusion HCV cases. In addition, 26 non-implicated C-100 ELISA positive donations, not associated with recipient hepatitis, were analysed. All 26 non-implicated ELISA-positive donor samples were non-reactive for the antigens C33c and C22 in 4-RIBA (table). All the implicated donors, however, showed reactivity for both antigens, including donors 2, 5, and 8, who were not detected by ELISA and were non-reactive for antigens 5-1-1 and C-100 in RIBA. In view of our experience, antibodies to the new antigens C33c and C22 seem to predict infectivity with high sensitivity, and their addition in the primary HCV screening assay is important. FREJA EBELING Finnish Red Cross Blood Transfusion Service, SF-00310 Helsinki, Finland
RUTH NAUKKARINEN GUNNAR MYLLYLÄ JUHANI LEIKOLA
1. Ebeling F, Naukkarinen R, Leikola J. Recombinant immunoblot assay for hepatitis C virus antibody as predictor of infectivity. Lancet 1990; 335: 982-83.
813-14.
3. Buller RML, Moss B Genetic basis for vaccinia virus virulence. In: Quinnan GV Jr, ed. Vaccinia viruses as vectors for vaccine antigens. New York: Elsevier, 1985: 37-46. 4. Rodriguez D, Rodriguez J-R, Rodriguez JF, et al. Highly attenuated vaccinia virus mutants for the generation of safe recombinant viruses. Proc Natl Acad Sci USA 5. Hu
1989; 86: 1287-91. S-L, Kosowski SG, Dallrymple JM. Expression of AIDS virus envelope gene in recombinant vaccinia viruses. Nature 1986; 320: 537-40.
Exacerbations of asthma in salmeterol
patients on
SIR,-Sears and colleagues’ paper on the effects of regular fenoterol’ has prompted concern about the safety of long-term use of regular p-agonists. On the basis of a small crossover trial Sears et al proposed that long-term treatment with regular fenoterol led to a deterioration in asthma and its control. They also suggested that such an effect might apply to other p-agonists. On the basis of data on over 2000 patients during the clinical development of salmeterol, a long acting inhaled &bgr;z-agonist, we drew different conclusions (Jan 5, p 43). Nevertheless it is pertinent that these concerns are raised now, since guidelines are being drawn up worldwide for the management of asthma, coinciding with the advent of new longer acting inhaled &bgr;z-agonists. Because salmeterol controls symptoms so effectively there is a possibility that it might mask any underlying deterioration. If so, the number of exacerbations would be a useful indicator of disease control. For the purpose of this study, an exacerbation was defined as any worsening of an asthma symptom recorded as an adverse event. Serious exacerbations were defined as those that caused death, were life-threatening, or resulted in hospital admission. In several large controlled clinical trials during the development of salmeterol the number of serious exacerbations was less in patients treated with salmeterol (12%,n 4658) than in those on control treatments such as other 0-agonists or theophyllines (2%; =
n = 3466).
Safety of recombinant vaccinia vaccines SIR,-Dr Cooney and colleagues’ report (March 9, p 567) of a trial of a recombinant vaccinia vaccine is of great interest for at least two reasons other than the fact that the vaccine expresses an HIV
antigen. Their conclusion that the recombinant vaccine is safe is based on direct comparison of the effects of the vaccine and conventional smallpox vaccine; both vaccines gave similar results. Thus for the recombinant to be considered safe it follows that Cooney et al regard conventional smallpox vaccine as safe-a conclusion with which many will disagree. The side-effects of smallpox vaccination are well known,’ and most workers interested in the development of recombinant vaccinia vaccines have emphasised the need for the vector to be attenuated further if such vaccines are to gain acceptance 2’ It is not altogether fanciful to suggest that if
a
A more detailed analysis of exacerbation rates in patients treated with salmeterol has been done for one of the pivotal development studies in which inhaled salmeterol 50 Ilg twice daily (n 361) was compared with salbutamol (n 358) over one year in patients with =
=
NUMBER OF PATIENTS WITH ASTHMA EXACERBATIONS
ANTI-HCV RESULTS IN IMPLICATED AND NON-IMPLICATED DONORS
conventional smallpox vaccine were a new product it would be unlikely to get a product licence for general use. The results reported by Cooney et al may aid our understanding of the factors that determine the human virulence of vaccinia virus. Animal studies have shown that vaccinia recombinants which have the foreign gene inserted into the vaccinia thymidine kinase gene, and which are therefore TK-, tend to be attenuated.3.4However, the recombinant used by Cooney et al was also TK - ,sand produced results in man similar to that of the conventional TK+ vaccine. In fact in the two subjects tested who had not previously had smallpox vaccine the effect if anything was more severe than the conventional vaccine. Thus, whatever its attenuating effect in animals, it seems that inactivation of the thymidine kinase gene of vaccinia does not necessarily attenuate the virulence of the virus for man. University of Liverpool, Department of Medical Microbiology, Liverpool L69 3BX, UK
DERRICK BAXBY
1. Fenner F, Henderson DA, Arita I, et al. Smallpox and its eradication. Geneva: WHO, 1988 2. Buller RML, Smith GL, Cremer K, et al. Decreased virulence of recombinant vaccinia virus expression vectors is associated with a thymidine kinase-negative
phenotype. Nature 1985; 317:
i
I
I
I
i
*Upper limrt of normal 40 U/I, ALT= alanine transferase t4-RIBA testing done on follow-up samples 20-35 mo postdonation +=pos!tMe,-=negat!ve
(structural) region of the HCV genome, have been coated in bands on nitrocellulose strips in addition to the 5-1-1 and C-100 antigens present in the first generation RIBA. The antigen band intensities are compared with weak positive and moderate positive control bands, and a response of 1 + or greater (up to 4 + ) to any two or more HCV antigens is interpreted as a positive result. We have tested samples from 9 implicated donors in our prospective post-transfusion hepatitis study,* each of whom was associated with 1 of the 9 post-transfusion HCV cases. In addition, 26 non-implicated C-100 ELISA positive donations, not associated with recipient hepatitis, were analysed. All 26 non-implicated ELISA-positive donor samples were non-reactive for the antigens C33c and C22 in 4-RIBA (table). All the implicated donors, however, showed reactivity for both antigens, including donors 2, 5, and 8, who were not detected by ELISA and were non-reactive for antigens 5-1-1 and C-100 in RIBA. In view of our experience, antibodies to the new antigens C33c and C22 seem to predict infectivity with high sensitivity, and their addition in the primary HCV screening assay is important. FREJA EBELING Finnish Red Cross Blood Transfusion Service, SF-00310 Helsinki, Finland
RUTH NAUKKARINEN GUNNAR MYLLYLÄ JUHANI LEIKOLA
1. Ebeling F, Naukkarinen R, Leikola J. Recombinant immunoblot assay for hepatitis C virus antibody as predictor of infectivity. Lancet 1990; 335: 982-83.
813-14.
3. Buller RML, Moss B Genetic basis for vaccinia virus virulence. In: Quinnan GV Jr, ed. Vaccinia viruses as vectors for vaccine antigens. New York: Elsevier, 1985: 37-46. 4. Rodriguez D, Rodriguez J-R, Rodriguez JF, et al. Highly attenuated vaccinia virus mutants for the generation of safe recombinant viruses. Proc Natl Acad Sci USA 5. Hu
1989; 86: 1287-91. S-L, Kosowski SG, Dallrymple JM. Expression of AIDS virus envelope gene in recombinant vaccinia viruses. Nature 1986; 320: 537-40.
Exacerbations of asthma in salmeterol
patients on
SIR,-Sears and colleagues’ paper on the effects of regular fenoterol’ has prompted concern about the safety of long-term use of regular p-agonists. On the basis of a small crossover trial Sears et al proposed that long-term treatment with regular fenoterol led to a deterioration in asthma and its control. They also suggested that such an effect might apply to other p-agonists. On the basis of data on over 2000 patients during the clinical development of salmeterol, a long acting inhaled &bgr;z-agonist, we drew different conclusions (Jan 5, p 43). Nevertheless it is pertinent that these concerns are raised now, since guidelines are being drawn up worldwide for the management of asthma, coinciding with the advent of new longer acting inhaled &bgr;z-agonists. Because salmeterol controls symptoms so effectively there is a possibility that it might mask any underlying deterioration. If so, the number of exacerbations would be a useful indicator of disease control. For the purpose of this study, an exacerbation was defined as any worsening of an asthma symptom recorded as an adverse event. Serious exacerbations were defined as those that caused death, were life-threatening, or resulted in hospital admission. In several large controlled clinical trials during the development of salmeterol the number of serious exacerbations was less in patients treated with salmeterol (12%,n 4658) than in those on control treatments such as other 0-agonists or theophyllines (2%; =
n = 3466).
Safety of recombinant vaccinia vaccines SIR,-Dr Cooney and colleagues’ report (March 9, p 567) of a trial of a recombinant vaccinia vaccine is of great interest for at least two reasons other than the fact that the vaccine expresses an HIV
antigen. Their conclusion that the recombinant vaccine is safe is based on direct comparison of the effects of the vaccine and conventional smallpox vaccine; both vaccines gave similar results. Thus for the recombinant to be considered safe it follows that Cooney et al regard conventional smallpox vaccine as safe-a conclusion with which many will disagree. The side-effects of smallpox vaccination are well known,’ and most workers interested in the development of recombinant vaccinia vaccines have emphasised the need for the vector to be attenuated further if such vaccines are to gain acceptance 2’ It is not altogether fanciful to suggest that if
a
A more detailed analysis of exacerbation rates in patients treated with salmeterol has been done for one of the pivotal development studies in which inhaled salmeterol 50 Ilg twice daily (n 361) was compared with salbutamol (n 358) over one year in patients with =
=
NUMBER OF PATIENTS WITH ASTHMA EXACERBATIONS
