La Jolla, CA, December 4, 2018 -- In work that was funded in part by a seed grant from the UCSD Center for Microbiome Innovation, a team made up of scientists from UCSD Biomedical Sciences and the UCSD Department of Pediatrics used next-generation sequencing to characterize the vaginal microbiota of one of the most common strains of mice used in biomedical research, and gain a better understanding of the usefulness of this animal model for future translational work.
The work was recently published by Vrbanac et al in the December issue of BMC Microbiology.
Katy Patras, of the Nizet lab and one of the authors of the paper, shared with us the importance and impact of the study where researchers examined the effect of the reproductive cycle on the stability of the microbiota and the effects of the introduction of group B Streptococcus (GBS) into the mouse vagina.
What does the vaginal microbiota typically look like in the average woman?
Vaginal commensal bacteria, or microbiota, is intimately linked to women’s health and control of reproductive tract infections. In humans, there are five distinct types of vaginal microbial communities, four of which are dominated by a single bacterium from the Lactobacillus taxon. The presence of Lactobacillus is associated with lower risk of vaginal infection and other gynecological diseases.
Why study the vaginal microbiota of mice?
Historically, mice have been used as a model to study human vaginal infections, but to date, the mouse vaginal microbiota has not been fully described using modern bacterial sequencing methods. Integrating detailed knowledge of the mouse vaginal microbiota into vaginal infection studies can provide a more direct translational application for these models to human bacterial pathogens.
What is the potential impact on women’s health?
GBS is a leading cause of newborn infection and babies are first exposed to GBS if the mother is vaginally colonized. They found that similarly to human, mouse vaginal microbial communities can also be classified into five distinctive types, one of which is dominated by Lactobacillus. The reproductive cycle, characterized by hormonal fluctuation, did not impact the stability of the vaginal microbiota. When the human pathogen GBS was introduced, surprisingly, a subset of mice had GBS become the dominant vaginal bacteria. Other mice, with a community where Staphylococcus was the main bacteria, were more likely to have GBS ascend into the uterus. This finding may have important implications during pregnancy since GBS can cause a type of uterine infection called chorioamnionitis. Together, these findings reveal that the mouse vaginal microbiota is quite diverse, and influences the ability of human pathogens to colonize the vaginal tract.
How does this impact future research?
The vaginal microbiota should be taken into consideration in mouse models of human vaginal infection, and research should be expanded to include other common strains of mice used for biomedical research.
The first author, Alison Vrbanac, is a PhD student in the UCSD Biomedical Sciences Graduate Program and is a joint trainee in the labs of Rob Knight and Victor Nizet in the UCSD Department of Pediatrics. Other contributing authors include postdoctoral fellows Angelica Riestra, Alison Coady, and Katy Patras of the Nizet lab.