Two new serovars of Chlamydia psittaci from North American birds

USDA, Agricultural Research Service, National Animal Disease Center, Ames, IA 50010, USA.

Five Chlamydia psittaci isolates (1 turkey, 1 psittacine, 1 human, and 2 pigeon isolates) failed to react with serovar-specific monoclonal antibodies to known avian and mammalian C. psittaci serovars and were presumed to represent 1 or more new serovars. The isolates were characterized using restriction endonuclease analysis of the whole genome, polymerase chain reaction-restriction fragment length polymorphism of the major outer membrane protein genome, monoclonal antibody comparisons, and growth in tissue culture. Monoclonal antibodies were produced to the human isolate (MP) and to the psittacine isolate (VS225). The monoclonal antibody results show that the isolates represent 2 new avian serovars (serovars E and F). The restriction fragment length polymorphism analysis of the major outer membrane protein genome demonstrated that the isolates are distinct. The whole genome restriction endonuclease analysis data and the growth patterns in tissue culture indicate that the new serovars are similar to avian serovars recognized previously. A subspecies monoclonal antibody that reacted with serovars A and B also reacted with serovar E, indicating that these serovars are closely related. The results show that these isolates represent 2 new avian serovars, making them the fifth and sixth avian serovars identified in North American birds.