Development of rotavirus-based enterotoxigenic Escherichia coli dual vaccines

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Project Summary Diarrheal diseases account for 1 in 10 child deaths worldwide. Rotavirus (RV) and enterotoxigenic Escherichia coli (ETEC) are major etiological causes of acute gastroenteritis and severe diarrhea worldwide, together resulting in approximately 300,000 deaths each year, mostly in children under the age of five. Current RV vaccines have limited efficacy in endemic countries and no direct antivirals are available. No vaccine is licensed for ETEC. Our overall objectives are to better understand the biology of RV and ETEC and to use that information to develop therapeutic interventions to alleviate diarrhea and sequelae. In preliminary studies, we utilized an improved RV reverse genetics system developed by our lab and generated a recombinant murine RV that encodes the protruding domain of the human norovirus VP1 protein. We found that this RV-based viral vector induces a robust antigen-specific serum IgG and fecal IgA responses in inoculated mouse pups. Based on these data, we constructed several new recombinant RVs that express ETEC heat-labile and heat-stable toxins. We hypothesize that one or more novel RV-ETEC dual vaccine candidates will induce a protective humoral immune response in mice and reduce pathogen burden and pathogenesis from subsequent RV and ETEC infections. To test this hypothesis, we have developed a highly tractable murine RV reverse genetics method, disease relevant neonatal and adult mouse models, and several innovative primary human small bowel organoid cultures, which will provide an unprecedented resolution of understanding of the immunogenicity and protective efficacy of our vaccine candidates. In Aim 1, we will characterize RV replication and define the immunological responses of our dual vaccines in neonatal mice. In Aim 2, we will examine the efficacy of the recombinant RV- ETEC dual vaccines in protecting immunized mice from RV and ETEC challenges in adult mice. Collectively, we expect our proof-of-principle study to start to establish the utility of RVs as an innovative live-attenuated mucosal vaccine platform to encode foreign antigens and broadly protect against common enteric pathogens.