M. Beld et al., HEPATITIS-C VIRUS SEROTYPE-SPECIFIC CORE AND NS4 ANTIBODIES IN INJECTING DRUG-USERS PARTICIPATING IN THE AMSTERDAM COHORT STUDIES, Journal of clinical microbiology, 36(10), 1998, pp. 3002-3006
In the present study, the RIBA HCV serotyping SIA was evaluated with a
cohort of injecting drug users, Serotyping may be a rapid and cost-ef
fective method of determining genotypes in cohort studies. In this stu
dy, hepatitis C virus (HCV) antibody-positive sera from a cohort of 33
1 chronically infected injecting drug users, of which 167 were coinfec
ted with human immunodeficiency virus (HIV),were serotyped by the RIBA
HCV Serotyping SIA. Among the 331 specimens, serotype-specific antibo
dies were detected in 250 (sensitivity, 75.5%), in which serotype 1 wa
s predominant (57.2%), followed by serotype 3 (26.8%). Among the 331 s
pecimens, 164 were HIV negative, and serotype-specific antibodies were
detected in 151 (sensitivity, 92.1%), in which serotype 1 was predomi
nant (59.6%), followed by serotype 3 (33.8%), For a subset of 58 sampl
es taken from 19 chronically infected HCV seroconverters with a mean f
ollow-up of 5 Sears, serotypes were compared with genotypes, which wer
e determined by a line probe assay (HCV LiPa) and by direct sequencing
of the products obtained by nested PCR of the 5' untranslated region.
Among the 58 samples with known genotypes, serotype-specific antibodi
es were detected in 38 (total sensitivity, 65.5%), with a specificity
of 78.9%. Thirty of these serotypeable samples revealed a serotype tha
t corresponded to the genotype in the 58 samples (total positive predi
ctive value, 51.7%). Of the 58 samples, 23 were coinfected with HIV an
d when these were excluded, the total sensitivity increased to 76.5%,
with a total specificity of 80.8% and a total positive predictive valu
e of 61.8%. The serotyping assay showed a high total sensitivity (96.3
%) for samples positive by HCV RIBA, version 3.0, with four bands, We
conclude that the sensitivity of the RIBA HCV serotyping SU is limited
by the immunocompetence of the HCV-infected host. In general, samples
from HIV-negative individuals containing genotype la had higher sensi
tivity, specificity, and concordance in the serotyping assay compared
with genotyping, whereas samples containing genotype 3a were found to
be more cross-reactive and untypeable, Therefore, the prevalence of ge
notypes other than genotype 1 could be underestimated if they are dete
rmined by serotyping, and improvements in specificity are recommended.