ASSESSMENT OF COMMERCIAL ENZYME-IMMUNOASSAY FOR HEPATITIS-C VIRUS SEROTYPING

Aims-To assess a commercial enzyme immunoassay (ELA) for the serotypin g of hepatitis C virus (HCV) for routine use in a diagnostic laborator y setting, as well as for noting the serotype prevalence of selected s pecimens. Methods-Seventy six serum specimens, submitted to the labora tory for routine hepatitis studies between May 1992 and February 1996 and stored at -20 degrees C, were evaluated. These specimens were cate gorised into specific hepatic, renal, and paediatric clinical conditio ns. The specimens all tested positive for HCV antibodies on a screenin g EIA, with confirmation on a recombinant immunoblot assay (RIBA). Cer tain specimens were also HCV RNA positive by the reverse transcription polymerase chain reaction (RT-PCR). All the specimens were serotyped using the newly developed serotyping EIA. Results-Twenty seven (35.5%) specimens were typable. Type 5 predominated (56%), followed by type 1 (33%), types 1 and 6 (7%) and type 3 (4%). The serotype 5 specimens s howed 85% and 90% reactivity with recombinant antigens c100-3 and c22- 3c, respectively; serotype 1 specimens showed 75% and 100% reactivity with these antigens. All serotype 5 specimens reacted with the c33-c a ntigen, but only 60% of serotype 1 specimens reacted with this antigen . The differences in the reactivity of the serotype 5 and serotype 1 s pecimens for c33-c antigen in the RIBA were significant, but no signif icant differences in reactivity for antigens c-1-1, c100-3, and c22-3 were noted. Serotype 3 specimens showed equal reactivity with all four antigens used in the RIBA. Conclusion-The serotyping EW was easy to u se, rapid, and cost effective compared with molecular assays. This ass ay seems to be ideal for the routine diagnostic laboratory setting, bu t could not be used for certain clinical specimens. The demonstration of serotypes 5, 1, and 3 was not unexpected in this cohort. The occurr ence of serotype 6, although concurrent and more Likely to be a false cross reaction with serotype 1 peptides, requires confirmation by mole cular genotyping before it can be claimed that this type is present in South Africa.