• Chimpanzee;
  • oLHβ subunit;
  • immunization;
  • monkey;
  • pregnancy;
  • progesterone

ABSTRACT: Antibody to ovine LHβ (oLHβ) subunit and equine chorionic gonadotropin (eCG) were produced in adult male chimpanzees and evaluated for cross reactivity with oLH, human chorionic gonadotropin (hCG) and eCG by in vitro and in vivo methods. Chimpanzee antiserum to eCG failed to cross-react with hCG, but antibody raised against oLHβ subunit effectively neutralized not only exogenously administered hCG but also endogenous pituitary LH and monkey (Macaca radiata) chorionic gonadotropin. Chimpanzee antiserum to oLHβ when administered early in pregnancy reduced progesterone levels and terminated gestation in bonnet monkeys. Our data suggest that active immunization of chimpanzee, an ape that is very close to human, with oLHβ subunit leads to production of antibodies that are likely to affect both normal cycle as well as pregnancy.