Serotyping strip immunoblot assay for assessing hepatitis C virus strains in dialysis patients

Recent accumulated evidence shows that dialysis patients are a high-risk gr oup for hepatitis C virus (HCV) infection. Assessment of HCV genotype distr ibution among dialysis patients may be important because specific viral gen otypes are associated with different clinical manifestations, disease progr ession, and response to antiviral therapy. However, polymerase chain reacti on-based methods are cumbersome and unsuitable for analyzing large cohorts of dialysis patients with HCV. Instead, this information can be obtained by using a novel recombinant immunoblot assay (RIBA) recently developed for d etermining HCV serotype. The RIBA HCV serotyping strip immunoblot assay (SI A; Chiron Corporation, Emeryville, CA), is based on an immunoblot strip wit h five lanes of immobilized serotype-specific HCV peptides from the nonstru ctural (NS4) and core regions of the genomes of HCV types 1, 2, and 3. HCV serotype is deduced by determining the greatest intensity of reactivity to the NS4 serotype-specific HCV peptide band in relation to the internal cont rol band (human immunoglobulin G) intensity on each strip. HCV core peptide reactivity is used only in the absence of NS4 reactivity. We compared RIBA HCV serotyping SIA with genotyping using sera from a large (n = 107) cohor t of HCV-infected patients undergoing chronic hemodialysis (HD). We success fully serotyped 79 of 107 patients (74%) undergoing HD. We found a remarkab le concordance (65 of 70 results; 93%) between RIBA HCV serotyping SIA and genotyping (line probe assay [LiPA]) techniques (kappa = 0.786) with sera f rom viremic patients infected with a known genotype. Only 5 of 70 patients (7%) had apparently discordant results. In a subset of patients (28 of 107 patients; 26%) not typed by RIBA HCV serotyping SIA, most (24 of 28 patient s; 86%) were successfully genotyped by LiPA technology. It was possible to assess serotype reactivity in some patients (9 of 107 patients; 7%) who cou ld not be genotyped. The distribution of HCV serotypes was associated with the antibody response against HCV proteins and the patterns of reactivity b y RIBA HCV 2.0 SIA. In conclusion, (1) we found good agreement between sero typing and genotyping methods in our large cohort of dialysis patients infe cted with HCV; (2) the impaired immunocompetence conferred by uremia may li mit serotyping analysis in some HCV-infected patients undergoing HD; (3) RI BA HCV serotyping SIA may be useful in tracking transmission routes for HD patients who cleared the virus and have only anti-HCV antibody; and (4) the distribution of HCV serotypes was associated with the antibody response ag ainst HCV proteins and the patterns of reactivity by RIBA HCV 2.0 SIA. Asse ssment of HCV strains appears to be very useful in the routine clinical act ivity of nephrologists within HD units because consistent biological differ ences among HCV strains exist. RIBA serotyping SIA is a simple, inexpensive , and highly reproducible assay to obtain information about HCV types in th e HD setting. (C) 2000 by the National Kidney Foundation, Inc.