Detection of three types of hepatitis C virus in blood donors: investigation of type‐specific differences in serologic reactivity and rate of alanine aminotransferase abnormalities

The serologic reactivity and epidemiology associated with different hepatitis C virus (HCV) variants were investigated in a cohort of 113 anti‐HCV‐positive donors. In Scotland, HCV type 1 accounted for one‐ half of all infections; 40 percent of subjects were infected with HCV type 3, and the remainder were infected with type 2. Reactivity with the NS‐4‐encoded antigens in the first‐generation anti‐c100 assay was absent in 68 percent of donors infected with types 2 and 3, as compared with 10 percent for those infected with type 1. Even when combined with surrogate marker testing, first‐generation tests would have failed to detect 12 percent of HCV‐infected blood donors. The age distribution, incidence of past infection with hepatitis B virus, and reported risk factors were similar in donors infected with types 1 and 3 (mean ages were 31.9 and 29.9; 18 and 17.5% were positive for antibody to hepatitis B core antigen; and 47 and 48% had past intravenous drug abuse). However, the distributions of alanine aminotransferase levels were significantly different in those infected with type 3 (abnormally raised in 83%) and those infected with type 1 (55% abnormal alanine aminotransferase; p < 0.05) or type 2 (60%; p < 0.01) and those who were nonviremic (8%; p < 0.0001). These data suggest that HCV type 1 is the most common HCV infection in blood donors and that infection with HCV type 3 may be associated with more severe liver disease, because of more recent infection or because of a greater inherent pathogenicity of type 3 variants.