Antigen conformation dependence of Chlamydia trachomatis infectivity neutralization.

Chlamydia trachomatis infections cause the most common notifiable diseases in the United States, reflecting the successful adaptation of these organisms to persist in their obligate human host population. Antigenic variation of the quantitatively predominant major outer membrane protein (MOMP) is considered to play an important role in this adaptation as a means of immune evasion. The relative capacity of murine polyvalent sera produced following infection, recovery, and challenge to neutralize infectivity was highly serovar-specific and dependent upon thermolabile antigens. The structural complexity of these immunodominant antigens was mimicked by chlamydial MOMP expressed in Escherichia coli, as antibodies that neutralize infectivity by recognition of conformation-dependent antigens were specifically removed from sera following absorption using MOMP expressed in E. coli.