Experimental vaccine activities of recombinant E1 and E2 glycoproteins and hypervariable region 1 peptides of hepatitis C virus in chimpanzees.

A chimpanzee was immunized with two recombinant envelope glycoproteins E1 and E2 of hepatitis C virus (HCV), strain HCV-N2, and the hypervariable region 1 (HVR1) peptides of a different isolate, HCV-#6, then received an intravenous inoculation of 10 chimpanzee infectious doses of HCV-#6. With high humoral immune response against E1 and E2 but a low response against HVR1, the vaccinee became infected with the HCV. However, after increasing the titer of anti-HVR1 against HCV-#6, the vaccinee showed protection. Neutralization of HCV-#6 with the antiserum from this protected vaccinee was achieved by inoculation of this mixture into another chimpanzee. These results suggest that vaccination with a peptide-vaccine of homologous HVR1 is effective in the chimpanzee.