B-205. Interspecies Gene Transfer within Strains of the Genus Chlamydia

R. J. Suchland1, K. M. Sandoz2, D. D. Rockey2, W. E. Stamm1;
1Univ. of Washington, Seattle, WA, 2Oregon State Univ., Corvallis, OR.

Lateral gene transfer (LGT) has been demonstrated in Chlamydia trachomatis in cell culture by detecting genetic recombinants resulting from the co-infection of strains having dissimilar drug resistance markers grown within the same Chlamydia inclusion. Studies using selected same-species as well as interspecies recombinants would be very useful for functional analysis of allelic differences between strains within the genus Chlamydia. Our experiments demonstrate not only same-species LGT, but also LGT between strains of Chlamydia trachomatis, Chlamydia muridarum and Chlamydia suis. Various combinations of co-infections using ofloxacin (OFL) and rifampin (RIF) mutant strains of C. trachomatis; L3/RIF, L2/OFL and J/6276RIF; C. muridarum; MoPn/OFL; and C. suis; S45/RIF were infected onto host cells and grown in drug free media and the resulting progeny were subjected to selection for strains with both the OFL and RIF resistance markers. Resulting surviving Chlamydia were cloned from independent experiments, OFL and RIF resistant levels were determined, and species/serovar determined by MOMP monoclonal antibody labeling. Progeny clones carrying both resistance markers were recovered from each attempted cross. MOMP labeling determined that at least one recombinant from each parental strain was recovered in each cross. Resistant parental strains had predetermined unique, MICs for each antibiotic and the appropriate MIC was consistently present within the derived recombinant strains. These LGT studies not only confirm recombination within chlamydial species, but also demonstrate recombination between different species of Chlamydia.