Hepatitis C virus antibody prevalence among human immunodeficiency virus-1-infected individuals: analysis with different test systems.

Sera of 383 human immunodeficiency virus (HIV)-1-infected individuals from Frankfurt (Main)/Germany were assayed by two hepatitis C virus (HCV) screening tests (Abbott second generation, Ortho second generation). This population showed a prevalence for reactivity with both tests of 20.8% (80/383). Examination of all reactive sera (91/383) by a supplemental assay (Chiron RIBA 2) gave for 46 sera a positive, for 33 sera an indeterminate, and for 12 sera a negative result. Further analysis focussed on these RIBA 2-indeterminate and -negative samples. Analysis of the sera using an in-house Western blot with three different Escherichia coli-expressed HCV proteins revealed that none of the RIBA 2-negative, but 24 of the 33 RIBA 2-indeterminate sera, including 3 of 4 c33c (NS3)-reactive samples, were reactive with a recombinant core protein. Twenty-one of 22 c22-3 (core) indeterminates stained the core antigen in the in-house Western blot and 3 of them in addition a NS5 moiety. HCV-polymerase chain reaction (PCR) was positive for 14 of the 24 RIBA 2-indeterminate sera, but for none of the RIBA 2-negative or Western blot nonreactive samples. Discrepant results between the two screening tests could not be explained by differences in the antigen compositions (i.e., a NS3-NS4 moiety of 111 amino acids present in the Ortho enzyme-linked immunosorbent assay (ELISA), not present in the Abbott or RIBA 2 assays).