Immunoblots of outer-membrane proteins of chlamydiae with sera from turkeys experimentally exposed to avian and mammalian Chlamydia psittaci.

Outer-membrane protein (OMP)-enriched preparations from avian (turkey/TT3 and parrot/VS1) and mammalian (sheep abortion/B577) strains of Chlamydia psittaci were compared by immunoblotting using sera from turkeys exposed to these strains. Turkeys inoculated with avian chlamydiae became infected and developed strong serological responses, but turkeys inoculated with B577 failed to develop detectable serological responses. Sera from turkeys exposed to either of the two avian strains could be differentiated on the basis of immunoreaction patterns with OMPs of homologous and heterologous strains. Fewer bands and often weaker reactions were detected using sera from TT3- and VS1-inoculated birds with the heterologous avian strain. Sera from turkeys inoculated with either avian strain reacted with the 97,400-molecular weight (MW) protein. The sera reacted with the major outer-membrane protein (MOMP) of the homologous strains but not consistently with the MOMP of the heterologous strain. Results suggest that the 97,400-MW protein is highly immunogenic for turkeys and antigenically more complex than the MOMP.