Impact of gut microbiome on tick susceptibility to Borrelia

Ixodid ticks (Acari: Ixodidae) are obligate hematophagous ectoparasites that feed on the blood of various terrestrial vertebrates. However, their main importance lies in their ability to maintain and transmit a multitude of disease-causing agents of medical and veterinary importance, including bacteria from the Borrelia burgdorferi complex, which cause Lyme borreliosis. In addition to pathogenic microorganisms, ticks harbour a very diverse group of endosymbionts and commensals that collectively comprise the microbiome, of which the majority are in their guts. A growing body of research suggests that non-pathogenic microbes in tick guts may affect the acquisition and colonization of tick-borne pathogens. While the development of high-throughput sequencing technologies in the last decade has significantly improved a descriptive understanding of the tick microbiome, molecular and mechanistic insights into the microbiome and its bacterial components require further investigation. The progress is largely hindered by the lack of efficient and precise tools for microbiome manipulation. In this project, we will study the role of the gut microbiome of Ixodes ricinus tick in the infection success of Borrelia afzelii. A variety of cultivation-based, molecular, and next-generation sequencing methods, as well as experimental manipulation of the tick gut microbiome by selective immune targeting of keystone bacteria, will be applied to investigate the molecular complexity and functionality of the tripartite tick-Borrelia-microbiome interactions. This project aims (i) to characterize the taxonomic composition, functional profile, and spatial organization of the gut-specific microbiome of I. ricinus in response to B. afzelii infection; (ii) to identify the keystone bacterial profile associated with B. afzelii colonization and transmission; (iii) to evaluate how selective removal of the keystone species modify the outcome of B. afzelii infection and transmission; and (iv) to identify and describe the molecular and metabolic pathways that are influenced by the bacterial community modification. Our research will facilitate the discovery of specific microbial and/or genetic patterns that are critical for B. afzelii persistence and transmission between the tick and the mammalian host. The application of this knowledge will pave the way for the development of alternative strategies to control both Lyme borreliosis and its tick vector. The project headed by Dr. Adnan Hodžic (PI, Uni Wien) will involve Prof. David Berry (Uni Wien), and the collaboration partner Dr. Alejandro Cabezas-Cruz (INRAE, France).