A Novel Tick Protein Supports Integrity Of Gut Peritrophic Matrix Impacting Existence Of Gut Microbiome And Lyme Disease Pathogens

The peritrophic matrix (PM) is an acellular membrane that covers the gut epithelium in arthropods and physically separates it from the lumen. The structure is thought to play an important role in tick biology. The PM is also known to impact the persistence of tick-borne pathogens likeBorrelia burgdorferi, although limited information is available about its molecular constituents or their biological significance. Herein, we characterise a novel PM-associated gut protein inIxodes scapularisticks, annotated asPeritrophicMembraneChitinBindingProtein (PM_CBP), for its role in the integrity and function of the matrix. The PM_CBP displays homology to the chitin deacetylase metalloenzyme, shows upregulation during tick feeding, and is localized at the luminal surface of the gut epithelium. The structural integrity of the PM was impaired both by the knock down ofPM_CBPexpression via RNA interference and by treatment with anti-PM_CBP antibodies, as revealed by its electron microscopic appearance. Additionally, the duration of tick engorgement on mice and the passage of experimentally-inoculated fluorescent dextran molecules across the PM are affected by the knock down ofPM_CBPexpression. The transfer of anti-PM_CBP antibodies into the tick gut impacted the overall composition of the resident microbiome, and also influencedB. burgdorferiacquisition in ticks and its transmission to mice. Taken together, these data highlight the biological significance of theIxodesPM and suggest that the targeting of its molecular constituents may contribute to the development of novel interventions against tick-borne infections.