Biological Factors in Fleas: Determinants of Physiology and Pathogen Transmission

Vector-borne diseases are caused by pathogens transmitted by hematophagous arthropods (vectors) and affect millions of people worldwide. The rat flea, Xenopsylla cheopis, is a major vector for several pathogens, including Yersinia pestis, the causative agent of bubonic plague. Despite periodic outbreaks of this and other flea-borne diseases, research on flea biology remains neglected. Understanding the biological processes underlying flea physiology and their ability to transmit human pathogens is crucial for comprehending the dynamics of flea-borne diseases and implementing sustainable control strategies. This project aims to uncover the biological FACTORS in fleas that contribute to pathogen transmission, with a specific focus on the plague agent. Under identical experimental conditions, different rat flea strains exhibit variations in blood feeding, colony development, and Y. pestis infection, leading to the hypothesis that strain-specific biological factors in fleas impact their physiology and the transmission of the plague agent. Through comparative studies between flea strains from regions with high or low plague prevalence, FACTORS aims to uncover the role of (1) genes expressed in the gut, (2) flea-associated microbiota, and (3) immune cells in flea feeding, development, and Y. pestis infection, all of which dictate pathogen transmission. FACTORS will address a largely neglected area of flea biology, generating profound insights into the biological processes contributing to the dynamics of plague, while also identifying new targets for the development of innovative vector control strategies. This aligns with the UN Sustainable Development Goal of promoting health and well-being. Additionally, the training in soft skills, expanded networks, and the excellence of science resulting from this fellowship will be invaluable for the applicant's career goal of becoming a distinguished scientist.