Evaluation of Safety and Efficacy of Bivalent Hepatitis B Vaccine in Chimpanzees

摘要

The bivalent form of an aqueous HB vaccine developed by Purcell and Gerin has been evaluated for safety and efficacy in chimpanzees. Intravenous inoculation of 5 chimpanzees with 500 micrograms of vaccine and 2 with 50 micrograms failed to reveal the presence of any residual infectivity in the vaccine. A dose response study revealed 100% protective efficacy against challenge with 10 to the 3.5 power C.I.D.(50) of live HBV 6 months after immunization with two 50 microgram doses and 75% protection in animals similarly immunized with doses of 20, 10 and 5 microgram HBsAg. Immunized animals which were susceptible to challenge infection were those with weak or absent Anti-HBs responses. Protection after immunization with 50 microgram doses persisted for 12 months in 4/4 animals and for 24 months in 3/4 animals.