THE INFLUENCE OF LOCAL ANTICHLAMYDIAL ANTIBODY ON THE ACQUISITION ANDPERSISTENCE OF HUMAN OCULAR CHLAMYDIAL INFECTION - IGG ANTIBODIES ARENOT PROTECTIVE

In order to study the effect of antichlamydial antibodies in ocular se cretions on resistance to ocular chlamydial infection and clearance of this infection, we have performed linked longitudinal studies in a Ga mbian village in which trachoma is endemic. We have measured IgG and I gA antibody levels to a local serotype B isolate of Chlamydia trachoma tis by amplified enzyme immunoassay, and chlamydial antigen levels in conjunctival swabs using a commercially available immunoassay which de tects chlamydial glycolipid. Having previously demonstrated that shari ng a bedroom with a case of active trachoma is a risk factor for acqui sition of the disease, we have analysed the effect of IgG and IgA anti body on the acquisition and persistance of clinical trachoma after con trolling for age, sex, exposure to infection and for the presence of c hlamydial antigen using a Poisson regression model. We have found that the presence of antichlamydial IgG in ocular secretions of disease-fr ee subjects is associated with an increased incidence of trachoma. IgA antibody shows an opposite trend, but this is not statistically signi ficant. One possible explanation of these findings is that antichlamyd ial IgG antibodies enhance the infectivity of C. trachomatis for the h uman eye; this could have major implications for the development of a chlamydial vaccine.