Prevalence of antibodies to recombinant hepatitis C virus protein C100-3 and of elevated transaminase levels in blood donors from Northern Germany.

Antibody to recombinant hepatitis C virus protein C100-3 (anti-C100-3) was assayed by a first generation enzyme-linked immunosorbent assay (ELISA; Ortho Diagnostics) in 116,700 blood donors who had not been tested before. Total prevalence of repeatably positive donors was 0.72% (n = 842). Prevalence increased significantly from 0.42% at 18-27 years of age to 1.26% at greater than or equal to 58 years. Donors with elevated serum transaminase levels were significantly more often anti-C100-3 positive, but in 98.7% of donors with current or 99.1% with previous transaminase elevations, anti-C100-3 was not found. Elevated transaminases were more often associated with positive anti-C100-3 in females than in males. However, in the total donor population no significant differences of anti-C100-3 prevalence were found between the sexes. During follow up at three subsequent blood donations, 1.08% of donors were positive at least once, but only 0.48% were consistently positive. The cutoff of the Ortho ELISA was not in the minimum of the frequency distribution between positive and negative samples, but far within the range of the negative signals, i.e. the test is likely to produce a significant number of false-positive results. In retesting positive samples with two ELISAs from other producers only a 22% to 65% agreement was found. In a low prevalence group such as German blood donors, the first generation ELISAs for anti-C100-3 produced more false than specific positive results. Most donors with elevated alanine aminotransferase (ALT) are anti-C100-3 negative.