SEX-biased transmission and Infection dynamics in BATs – SEXIBAT

The emergence of zoonotic infectious diseases is a recurrent phenomenon with major public health and economic consequences. Some of recent outbreaks, such as those caused by Middle East Respiratory Syndrome and Ebola viruses, have highlighted the necessity of understanding processes driving the transmission of infectious agents within animal populations. However, the heterogeneity of animal populations is often a major challenge for the study of infection dynamics in wildlife. Among the possible sources of heterogeneity, sexually dimorphic life-history strategies of reservoir hosts have gained attention over the last decade but their potential role in infection dynamics remain overlooked.
This project aims at elucidating how sexually dimorphic behavioral and physiological strategies shape population-level infection dynamics in bats, acknowledged as important reservoirs of emerging pathogens. We hypothesize an asynchronous, but complementary, role of females and males in the spatiotemporal infection dynamics. Specifically, male-biased dispersal could favor the spread of infectious agents between colonies38, giving males a pivotal role in the spatial transmission of infection. We expect spread to be seasonal, occurring during the mating season, and to correlate with reproductive state-mediated lowered immunity in males. On the contrary, females should be the key host for epidemic transmission to pools of susceptible individuals (juveniles) during the birthing season. Maternity colonies would favor higher contact rates, due to synchronized aggregation, and higher susceptibility to infection, resulting from pregnancy-related immunomodulation.
To test these hypotheses, we will use an original biological system within an insular context of transmission that facilitates the investigation of natural populations: the medically important bat-borne paramyxoviruses and the tropical bat species, Mormopterus francoismoutoui, endemic to Reunion Island. This project is based on extensive field investigations of bat colonies, including the capture and release of bats. Using population genetics and phylodynamic approaches, we will first analyze the role of male-biased dispersal in spatial transmission among colonies and that of female-biased aggregation in epidemic transmission, and how both these processes drive the evolution of viral diversity. We will then assess the role of sex-biased immunity during reproduction in infection dynamics by combining transcriptomics and targeted qPCR methods. This multidisciplinary approach will provide new and original results for understanding the ecology and epidemiology of bat-borne diseases, and will help at decrypting the mechanisms driving pathogen transmission and evolution in this important animal reservoir. Moreover, identifying how each sex contributes to the emergence, spread, and persistence of infection may be key to disease prevention and management.
The 3-years project will be hosted in the research unit “Processus Infectieux en Milieu Insulaire Tropical” (PIMIT), a laboratory located in a state of the art technological platform on Reunion Island. This research will also benefits from the strong and complementary expertise of local and international partners with which the coordinator has developed solid collaborations in the past.