Fecal and vaginal microbiota of vaccinated and non-vaccinated pregnant elk challenged with Brucella abortus

Authors: Tibbs-Cortes, Bienvenido; RAHIC-SEGGERMAN, FAITH - Iowa State University; SCHMITZ-ESSER, STEPHAN - Iowa State University; Boggiatto, Paola; Olsen, Steven; Putz, Ellie

Submitted to: Frontiers in Veterinary Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/2/2024
Publication Date: 1/30/2024
Citation: Tibbs-Cortes, B.W., Rahic-Seggerman, F.M., Schmitz-Esser, S., Boggiatto, P.M., Olsen, S.C., Putz, E.J. 2024. Fecal and vaginal microbiota of vaccinated and non-vaccinated pregnant elk challenged with Brucella abortus. Frontiers in Veterinary Science. 11. https://doi.org/10.3389/fvets.2024.1334858.
DOI: https://doi.org/10.3389/fvets.2024.1334858

Interpretive Summary: The bacterium Brucella abortus causes abortions and infertility in cattle and chronic fever and joint inflammation in humans. This bacteria can be found in elk in the American Northwest. These elk can spread B. abortus to cattle herds, causing disease and economic loss as well as threatening public health. Vaccinating elk against the bacterium is a promising solution to prevent them from carrying and transmitting disease, but further information about how the elk immune system functions is necessary. Bacteria that are naturally found in elk (the microbiota) may affect the elk immune system and therefore could play a role in B. abortus infection and vaccination. We analyzed the bacteria in the feces and vagina of pregnant elk which were challenged with B. abortus. Half of these elk also received a B. abortus vaccine to allow us to look at interactions between the microbiota and B. abortus vaccination. We found that vaccinated and unvaccinated elk had different microbiota, and we saw that the elk microbiota also changed over pregnancy and birth. Vaccinated elk also had different proportions of bacteria that cause reproductive diseases. Thus, we found that there is interaction between the gut and vaginal microbiota of elk and B. abortus vaccination and that B. abortus vaccination could affect elk reproductive health.

Technical Abstract: Brucella abortus is the causative agent of brucellosis in cattle and in humans, resulting in economic losses in the agricultural sector and representing a major threat to public health. Elk populations in the American Northwest are reservoirs for this bacterium and transmit the agent to domestic cattle herds. To mitigate the transmission of brucellosis by elk, one potential strategy is vaccination of elk populations against B. abortus; however, knowledge of the elk immune response to B. abortus infection and vaccination is lacking. To investigate interactions between microbiome and B. abortus infection and vaccination, we analyzed the fecal and vaginal microbial communities of B. abortus-vaccinated and unvaccinated elk challenged with B. abortus during the periparturient period. We observed that the elk fecal and vaginal microbiota are similar to those of other ruminants, and these microbial communities were affected both by time of sampling and by vaccination status. Notably, we observed that taxa representing ruminant reproductive tract pathogens tended to increase in abundance in the elk vaginal microbiome following parturition. Furthermore, many of these taxa differed significantly in abundance depending on vaccination status, indicating that vaccination against B. abortus affects the elk vaginal microbiota with potential implications for animal reproductive health. This study is the first to analyze the vaginal microbiota of any species of the genus Cervus and is also the first to assess the effects of B. abortus vaccination and challenge on the vaginal microbiome.