Persistence, Immune Response, and Antigenic Variation of Mycoplasma genitalium in an Experimentally Infected Pig-Tailed Macaque (Macaca nemestrina)

Abstract

ABSTRACTMycoplasma genitaliumis a sexually transmitted pathogen associated with several acute and chronic reproductive tract disease syndromes in men and women. To evaluate the suitability of a pig-tailed macaque model ofM. genitaliuminfection, we inoculated a pilot animal withM. genitaliumstrain G37 in the uterine cervix and in salpingeal pockets generated by transplanting autologous Fallopian tube tissue subcutaneously. Viable organisms were recovered throughout the 8-week experiment in cervicovaginal specimens and up to 2 weeks postinfection in salpingeal pockets. Humoral and cervicovaginal antibodies reacting to MgpB were induced postinoculation and persisted throughout the infection. The immunodominance of the MgpB adhesin and the accumulation ofmgpBsequence diversity previously observed in persistent human infections prompted us to evaluate sequence variation in this animal model. We found that after 8 weeks of infection, sequences withinmgpBvariable region B were replaced by novel sequences generated by reciprocal recombination with an archived variant sequence located elsewhere on the chromosome. In contrast,mgpBregion B of the same inoculum propagated for 8 weeksin vitroremained unchanged. Notably, serum IgG reacted strongly with a recombinant protein spanning MgpB region B of the inoculum, while reactivity to a recombinant protein representing the week 8 variant was reduced, suggesting that antibodies were involved in the clearance of bacteria expressing the original infecting sequence. Together these results suggest that the pig-tailed macaque is a suitable model to studyM. genitaliumpathogenesis, antibody-mediated selection of antigenic variantsin vivo, and immune escape.