Follow-up of hepatitis C virus infection in chimpanzees: determination of viraemia and specific humoral immune response.

Chimpanzees were inoculated intravenously with the H strain of hepatitis C virus (HCV), and analysed for viraemia using the polymerase chain reaction and for a humoral immune response using first and second generation anti-HCV ELISAs and an immunoblot assay (4-RIBA). In all seven chimpanzees studied, viraemia occurred several weeks before a significant increase in serum alanine transferase (ALT) activity, whereas the first circulating anti-HCV antibodies became detectable at the time of significant increase in ALT levels, provided the second generation ELISA or 4-RIBA was used. On the basis of the duration of viraemia the chimpanzees studied could be assigned to two different groups: those in which viraemia disappeared in conjunction with or shortly after seroconversion, and those remaining viraemic for many weeks after the appearance of antibodies.

Reliable screening anti HIV with a new ultrasensitive ELISA procedure.

Based on the competitive principle a new enzyme linked immunosorbent assay (ELISA) was developed for the reliable detection of Anti HIV. By introducing a sequential competitive procedure a detection limit of Anti HIV was achieved, which exceeded Western blot analysis by factor 8 to 16 as measured with dilutions of 14 well characterized sera. The relevance of this ultrasensitive feature could be demonstrated by a sensitivity value of 100% as evaluated by testing a total of 218 confirmed Anti HIV positive sera as well as by clear cut positive results obtained with 3 specimens derived from early stages of HIV infection.