Immune response of owl monkeys to topical vaccination with irradiated Chlamydia trachomatis

The conjunctivae of owl monkeys were topically vaccinated with purified Chlamydia trachomatis organisms that had been inactivated by 60Co irradiation and lyophilized onto an inert carrier. Vaccinated monkeys developed antibody in serum and tears, while control animals given a placebo had no detectable titers. When challenged 35 days after the start of administration of the vaccine, all monkeys showed evidence of infection. The vaccinated group had a longer course of disease and more ocular discharge than did controls. Antibody levels in both serum and tears were nearly 10-fold higher after infection in vaccinated animals than in controls.