The protection of chimpanzees against hepatitis B viral infection using a recombinant yeast-derived hepatitis B surface antigen.

In order to determine the efficacy of the SmithKline Biologicals recombinant DNA yeast-derived hepatitis B vaccine in inducing protection against hepatitis B infection, two chimpanzees were injected intramuscularly with 20 micrograms according to a 0-, 1-, and 2-month schedule. After the second dose, the vaccinated animals already showed a significant antibody response. One month after the last injection, the animals were challenged with hepatitis B virus. The vaccinated animals were protected while the two unvaccinated controls showed all signs of hepatitis B infection. One year after vaccination, antibodies remained high and were comparable with levels produced by plasma-derived vaccines.