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).