The use of a recombinant immunoblot assay in the interpretation of anti-hepatitis C virus reactivity among prospectively followed patients, implicated donors, and random donors.

Samples from prospectively followed recipients, their respective donors, and a cohort of random donors were used to evaluate the specificity and efficacy of a recombinant immunoblot assay (RIBA) as an adjunct to anti-hepatitis C virus (HCV) testing by enzyme immunoassay (EIA). RIBA reacted (RIBA+) in 100 percent of patients who developed hepatitis associated with anti-HCV seroconversion documented by EIA and in 100 percent of the EIA-positive (EIA+) donors implicated in these cases. In contrast, RIBA reacted in none of 10 recipients who were EIA+ but did not develop hepatitis, in none of 7 EIA+ patients with hepatitis B or cytomegalovirus infection, in 33 percent of EIA+ donors who were not implicated in hepatitis transmission, and in 37 percent of EIA+ random donors. Hence, the vast majority of EIA+ individuals who have ancillary evidence of HCV infection react on RIBA, whereas the majority of EIA+ individuals in low-risk settings do not react (RIBA-negative, or RIBA-). There was a strong association between RIBA reactivity and the presence of a surrogate marker (elevated alanine aminotransferase [ALT] and/or antibody to hepatitis B core antigen); 43 percent of RIBA+ implicated donors had a surrogate marker as compared to none of 14 EIA+, RIBA- donors. Among EIA+ random donors, 77 percent of those with a surrogate marker were RIBA+, as compared with 29 percent of those without a surrogate marker. In addition, in EIA+ donors, RIBA reactivity correlated with the extent of ALT elevation; 86 percent of those with an ALT greater than 135 IU per L were RIBA+ compared with 18 percent of those with an ALT less than 30 IU per L.(ABSTRACT TRUNCATED AT 250 WORDS)