Analysis of hepatitis C virus RNA prevalence and surrogate markers of infection among seropositive voluntary blood donors.

A novel reverse transcription polymerase chain reaction assay has been developed that uses drop-in-drop-out primers for the heminested amplification of hepatitis C virus complementary DNA. This assay has been used for analysis of the prevalence of hepatitis C virus RNA in a set of 53 plasma specimens from blood donations that were repeatedly reactive for hepatitis C virus antibodies with the first-generation enzyme immunoassay. Of 21 specimens that were also reactive for hepatitis C virus antibodies by a four-antigen recombinant immunoblot assay (recombinant immunoblot assay 2), 20 (95%) contained detectable levels of hepatitis C virus RNA. Cryoprecipitate in three specimens reactive in the recombinant immunoblot assay led to an apparent failure of detecting hepatitis C virus RNA, but repeat tests of redissolved cryoprecipitate subsequently revealed hepatitis C virus RNA. Hepatitis C virus RNA was also detected in plasma from 5 of 29 donors nonreactive by recombinant immunoblot assay. However, evidence of viremia in these donors could not be confirmed on follow-up specimens collected more than 1 yr later. Our results demonstrate that the presence of recombinant immunoblot assay reactivity nearly always indicates hepatitis C viremia and suggest that viremia may be transient or fluctuating among some individuals who are nonreactive for hepatitis C virus antibodies by the recombinant immunoblot assay.