Project Details
Projekt
In vivo evolution of pathogen virulence; host immunity, microbiota, and pathogen interactions
Applicant
Maryam Keshavarz, Ph.D.
Subject Area
Evolution, Anthropology
Term
since 2024
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 425876005
Interactions between bacterial pathogens, host immune responses, and the gut microbiota shape bacterial virulence. Studies have shown how microbial components, acting as regulator, have an effect on immune effectors, such as antimicrobial peptides (AMPs) induction, both in local and systemic host immunity. AMPs can also control both the composition and bacterial loads of gut microbes. Variations in AMPs expression can lead to changes in bacterial loads, exerting selective pressure that favours strains or variants of bacteria with enhanced virulence traits in a population. Therefore, balanced interactions between gut microbiota and host AMPs are critical for maintaining the normal gut microbiome, leading to host fitness. Studying the effects of bipartite interactions (host-pathogens, host-microbiota) on bacterial virulence evolution is important, but it is not enough to fully understand pathogen virulence evolution. Due to the occurrence of multiple interactions within one host, it is necessary to investigate tripartite interactions including the host, pathogen, and microbiota. The knockdown of AMPs in Tenebrio molitor, the host for this project, resulted in high mortality and altering the colonization of Pseudomonas entomophila in the presence of gut microbiota which can potentially affect the competition dynamics among different bacterial strains. However, it remains unexplored whether downregulation of AMPs effects P. entomophila virulence evolution in the presence and absence of gut microbiota. In this project, prior to virulence evolutionary experiment, I propose to examine the bidirectional interaction between host-AMPs and gut microbiota by 1. determining the transcriptional level of AMPs both in the presence and absence of gut microbiota and 2. in RNAi-treated larvae (Toll-TmDorx2, Imd-TmRelish and -TmImd), then 3. I will assess whether gene knockdowns influence the gut microbiota. For evolutionary experiment, 4. I will test whether downregulation of AMPs effects P. entomophila virulence evolution in the presence and absence of gut microbiota through passaging within host and using a mathematical and statistical to analyze the virulence decomposition. The results from this proposal will give insight into the mechanisms and pressures underlying bacterial virulence evolution.
DFG Programme
Research Units
