Chlamydia caviae infection alters abundance but not composition of the guinea pig vaginal microbiota. vaginal metagenome

In human the vaginal microbiota is thought to be the first line of defense again pathogens including Chlamydia trachomatis. Most animal models do not share the human vaginal microbiota composition and structure but are composed of a wide array of strict anaerobes, some of which found in the human microbiota of women with conditions such as bacterial vaginosis. The guinea pig has been extensively used as a model to study chlamydia infection using Chlamydia caviae, because it shares anatomical and physiological similarities with human, such as a squamous vaginal epithelium as well as some of the long-term outcomes caused by chlamydial infection. In this study, we aimed to evaluate the guinea pig - C. caviae model of genital infection as a surrogate for studying the role of the vaginal microbiota in the early steps of infection in human C. trachomatis genital infection. We used culture-independent molecular methods to characterize the relative abundance and absolute abundance of bacterial phylotypes in the guinea pig vaginal microbiota in animal non-infected, mock-infected or infected by C. caviae. We showed that the guinea pig vaginal microbiota has a different bacterial composition and abundance than that of human. Furthermore, C. caviae had a profound effect on the absolute abundance of bacterial phylotypes but not on the composition of the guinea pig vaginal microbiota. Our findings compromise the validity of the guinea pig – C. caviae model to study the role of the vaginal microbiota during the early steps of sexually transmitted infections or in priming the host response.