Low prevalence of particle-associated reverse transcriptase activity in serum from patients with non A - non B hepatitis.

Sera from 367 patients presumed to have NANB hepatitis were screened for reverse transcriptase activity. In 29 cases significantly increased enzyme activities could be observed. In contrast, sera from 338 patients did not contain significant reverse transcriptase activities. 207 healthy individuals, 7 patients with hepatitis A and 6 patients with hepatitis B who served as controls were all negative for reverse transcriptase activity. The specificity of the enzyme assay was demonstrated by estimation of reverse transcriptase activity in sera from 10 "healthy" HIV-1-antibody positive individuals. In 3 out of 10 cases significant reverse transcriptase activity was observed associated with the human immunodeficiency virus. Our results indicate that the presence of particle-associated reverse transcriptase activity in serum from patients with NANB hepatitis is indicative of the presence of a retrovirus-like agent in these cases. However, the relatively low prevalence of reverse transcriptase positive cases associated with the NANB hepatitis makes it rather questionable whether this agent is a frequent and specific factor in the etiology of NANB hepatitis.