SEROTYPING AND GENOTYPING OF HEPATITIS-C VIRUS (HCV) STRAINS IN CHRONIC HCV INFECTION

Hepatitis C virus (HCV) genotypes can be established by methods based on PCR typing and serological typing. The accuracy of these methods de pends on their sensitivity and specificity. These should be compared w ith the reference method, direct sequencing, and analysis of viral gen omes. Among the serologic methods recently developed, the performance of a new serotyping assay (RIBA HCV 3.0 SIA, Chiron corporation, Emery ville) was assessed using a panel of 147 well-characterized French iso lates from chronic hepatitis C patients. Definitive genotypes of the i solates were established by direct sequencing in 5' NC and in some cas es in NS-5B. HCV serotypes 1, 2, and 3 were determined by measuring ty pe specific antibodies to core and NS-4 derived peptide antigens. Of t he 147 sera, serotypic-specific antibodies were detected in 136 (sensi tivity, 92.5%). The specificity of the RIBA SIA HCV serotyping assay w as 92.6% (including samples with mixed results); without these, the sp ecificity was 80.1%. Analysis of the 28 discrepant samples showed that (1) a different serotype was found in 18 samples including five for g enotype 1, three for genotype 2, two for genotype 3, five for genotype 4, and three for genotype 5, and that (2) ten patients showed a react ivity with mixed serotypes, one had circulating antibodies to type 1 o r 2, and nine had circulating antibodies to type 1 or 3. In summary, e xcept for genotypes 4 and 5, the results of the test were well correla ted (85.7%) with those of direct sequence genotyping. The former test is rapid and does not require the strict HCV RNA storage and preservat ion conditions of the latter. This new method may thus be considered a s an alternative for HCV typing. However, although it is convenient, i ts lower sensitivity compared to the molecular typing method and the d iscrepant results limit its routine use in a clinical context. (C) 199 1 Wiley-Liss, Inc.