Use of Enteric Vaccines in Protection against Chlamydial Infections of the Genital Tract and the Eye of Guinea Pigs

Guinea pigs in a test group were fed living guinea pig inclusion conjunctivitis (GPIC) organisms classified as Chlamydia psittaci in 60% yolk-sac suspensions as enteric vaccines, while animals in a control group received uninfected yolk sac. Seven test animals and 14 control animals were challenged 11 or 22 days later with 1,000 50% infectious doses of GPIC organisms in either the conjunctiva or the vagina. Evidence of protection from mucosal infection in both sites was noted in test animals. Clinically, the disease was less severe, and microbiologically, lower percentages of mucosal cells were infected. The results suggest that enteric vaccination against mucosal infections of the eye and the genital tract with chlamydial agents is possible. Chlamydial infections of the conjunctivae are the leading cause of blindness in the world; chlamydial infections of the genital tract are among the most frequent sexually transmitted diseases. An effective vaccine against these mucosal infections is needed. We present here studies in guinea pigs suggesting that immunization via the gut may induce protection against chlamydial infection in the eye and the genital tract. Over 70 years ago the concept of oral vaccination of humans against disease was first contemplated; this procedure has been used sporadically