Members of the genus Chlamydia are strict obligate intracellular pathogens that exhibit marked differences in host range and tissue tropism despite sharing a remarkable level of genomic synteny. These pathobiotype differences among chlamydiae are also mirrored in their early interactions with cultured mammalian host cells. Chlamydial attachment and entry is known to trigger
protein tyrosine phosphorylation. In this study, we examined the kinetics and pattern of
protein tyrosine phosphorylation induced by
infection with a comprehensive collection of chlamydial strains exhibiting diversity in host, tissue, and disease tropisms. We report new findings showing that
protein tyrosine phosphorylation patterns induced by
infection directly correlate with the pathobiotype of the infecting organism. Patterns of
protein tyrosine phosphorylation were induced following early
infection that unambiguously categorized chlamydial pathobiotypes into four distinct groups: (i) Chlamydia trachomatis
trachoma biovars (serovars A to H), (ii) C. trachomatis
lymphogranuloma venereum biovars (serovars L1 to L3), (iii) C. muridarum, and (iv) C. pneumoniae and C. caviae. Notably, chlamydia-infected murine and human epithelial cells exhibited the same
protein tyrosine phosphorylation patterns; this is indirect evidence suggesting that the phosphorylated
protein(s) is of chlamydial origin. If our hypothesis is correct, these heretofore-uncharacterized
proteins may represent a novel class of bacterial molecules that influence pathogen-host range or tissue tropism.