Impacts of Trichomonas vaginalis-Mycoplasma hominis co-culture

Trichomonas vaginalis, the causative agent of trichomoniasis the most common non-viral sexually transmitted disease worldwide can provoke several clinical symptoms (e.g., vaginal itching, odour, inflammation), and infection during pregnancy can seriously affect the foetus. However, approximately 50% of all infections with T. vaginalis (mainly in men) do not cause illness and thus remain undetected. The differences between T. vaginalis strains causing symptoms and those not causing symptoms have not been completely elucidated yet. Interaction of T. vaginalis with Mycoplasma hominis a small cell wall-lacking bacterium that is also known as a pathogen of the urogenital tract has been reported in up to 94% of clinical isolates of the parasite. This interaction is assumed to enhance pathogenicity of the parasite in vitro, and an influence of this close relationship on the drug susceptibility of T. vaginalis is discussed. The overall goal of the project is to elucidate the impacts of this interaction on several behaviour of both pathogens, as well as the benefit(s) for the respective organism. First, optimization in order to create a stable in vitro co-culture of T. vaginalis with M. hominis and characterization of the requirements for perpetuation will be investigated. For this purpose, different strains of T. vaginalis will be co-cultured with various strains of M. hominis and culture conditions will be varied (e.g. pH- level, calcium-content, duration of co-cultivation). In addition, the role of ecto-ATPases concerning the establishment of a stable co-culture will be highlighted. During the three-year duration of the project it is aimed to further characterize these T. vaginalis/M.hominis co-cultures in detail. This characterization comprises the role of this interplay in cytotoxicity and drug sensitivity of T. vaginalis and M. hominis, and investigations concerning a possible transport-function of T. vaginalis for the bacteria to host cells or other bacteria-free T. vaginalis. Moreover, localization of the bacteria inside their parasite and human hosts, as well as changes in the transcriptome of the human host-cells due to infection with M. hominis will be investigated. In sum, this project aims to add knowledge to the in large parts unexplored field of interaction between single-cell pathogens and to highlight respective benefits when getting in contact with host cells.

Trichomonas vaginalis, a sexually transmitted parasite, and Mycoplasma hominis a sexually transmitted bacterium, are two pathogens that can live together in symbiosis, meaning that they be of use for one another. This symbiosis has been discovered rather recently and not been investigated in detail. The major achievement of this project was the establishment of a large collection of well-characterized strains of T. vaginalis and M. hominis in artificial and natural symbioses. This enabled me to reproducibly investigate the influences of various isolates of T. vaginalis and M. hominis on each other for the first time. Moreover, this strain collection will be the basis for follow-up projects. I was able to show, that the drug tolerance of both organisms was enhanced upon contact with the respective other symbiosis partner, in two cases this enhancement was statistically significant. In one isolate of M. hominis, changes in the genes responsible for resistance to the drugs investigated were shown to be induced upon contact with T. vaginalis. Interestingly, it was demonstrated that natural and artificial symbioses show differences in their behaviour. In conclusion, this project answered several important questions and set a solid basis for a follow-up project.