Unraveling bacterial signaling in inter-species vibrio interactions in host-colonization stages

The National Institute of Allergy and Infectious Diseases awarded the Trustees of Indiana University $153,560 on October 16, 2026, under the Allergy and Infectious Diseases Research program (CFDA 93.855) to support research on bacterial signaling in inter-species Vibrio interactions during host-colonization stages.

The research investigates mechanisms of multi-species bacterial interactions and their impact on host colonization and disease incidence in Vibrio communities. Vibrio species are significant environmental human pathogens in aquatic and marine environments that cause vibriosis disease, including gastroenteritis, necrotizing fasciitis, and sepsis. Transmission occurs through consumption of raw shellfish or exposure of open wounds to seawater. The study examines quorum sensing and bacterial signaling between Vibrio species in mixed communities to understand pathogenesis mechanisms, addressing the gap between existing single-species culture studies and natural multi-species environments where Vibrio bacteria exist in heterogeneous microbial communities on marine snow. Environmental changes are expanding Vibrio's geographic range and increasing human infection rates, making understanding of multi-species transmission mechanisms urgent.

Place of performance is Bloomington, Indiana. The period of performance extends from October 16, 2026, through April 30, 2029. This is a project grant, the assistance type supporting research at public and nonprofit institutions.

Abstract

Vibrio species are some of the most significant environmental human pathogens in aquatic and marine environments. People can get infected by eating raw shellfish or by getting a cut or puncturing their skin while handling raw seafood, such as oysters or crabs. In the fishing community, this is often called "flesh-eating disease" or "saltwater sores". Another way to get infected with vibrio is by direct exposure of an open wound, cut, sore, puncture, or burn to seawater, which can happen when swimming, surfing, or simply enjoying a good time on the beach. Vibrio causes vibriosis disease (gastroenteritis, necrotizing fasciitis, sepsis, death). Vibrio bacteria optimally grow in warm aquatic environments with low to moderate salinity, parameters that have historically acted as an "environmental block" to their spread in natural ecosystems. However, environmental changes - and associated weather patterns - are altering these geographical constraints and increasing vibrio spread, exposure, and rates of human infection. In natural environments, vibrio exists in heterogeneous microbial communities living off of marine snow in the ocean. Filter-feeding shellfish, such as oysters and clams, take up these marine snow aggregates and become vector of transmission. Because vibrio bacteria are expanding to new areas, IT is important to determine mechanisms of the multi-species interactions in the vibrio mixed communities and their impact on host-colonization and disease incidence. Most of the fundamental studies to understand vibrio colonization have been performed in single-species cultures. Thus, studies of mixed species communities that drive colonization and transmission are needed to determine how mechanisms of pathogenesis in hosts. The overall hypothesis is that bacterial signaling between species, specifically quorum sensing, drives bacterial adaptation and host colonization. By determining signaling and colonization mechanisms of mixed vibrio community, better models can be developed to respond to the public health risks of vibrio pathogenicity in vibrio-human interactions and lead to the identification of potential key pathways that can be used as targets for therapeutic design in infection treatments. The objective of this proposal is to use physiological and molecular approaches to investigate vibrio interactions of single- and multi-species bacteria and their impact on bacterial growth, abundance, and host colonization via two aims: 1) identify multi-species bacterial interactions and their effect on bacterial growth and abundance using artificial marine snow, and 2) determine the effect of vibrio inter-species colonization mechanisms and the role of quorum sensing in oyster host colonization. These experiments will provide the basic mechanistic link involved in the adaptation and host-colonization of multi-species vibrio communities. Because vibrio colonization of marine snow and oysters are a key source of vibrio transmission, the results of this study will inform the field on which systems to target to block vibrio oyster colonization and spread of this major human pathogen.