Host Factors That Influence Coxsackievirus B3 Replication and Pathogenensis

Abstract

Enteric viruses are infectious human pathogens that initiate infection in the gastrointestinal tract. They follow a fecal-oral route of transmission and are spread by contamination of food, water, or contact between individuals. Furthermore, enteric viruses also cause significant morbidity, mortality, and economic burdens yearly. Coxsackievirus (CV) is commonly isolated among enteric viruses and is an etiological agent of hand, foot, and mouth disease, hemorrhagic conjunctivitis, and myocarditis. The virus predominantly infects infants and young children and accounts for 11% of the fatality rate in neonates. Despite CV’s impact on human health, there are no treatments or vaccines for CV infections. Using a mouse model to study a key CV, Coxsackievirus B3 (CVB3), our laboratory has found two critical factors that impact CVB3 replication and pathogenesis. First, we have demonstrated that intestinal bacteria enhance intestinal CVB3 replication. We found that certain specific bacteria (Salmonella enterica) and its cell wall components, like lipopolysaccharides (LPS), enhanced CVB3 stability and infectivity in vitro. Additionally, we found that particular constituents of LPS are required for stability to occur. These data suggest that specific bacteria may be integral in maintaining CVB3 infectivity in the intestine. Besides virus-microbiome interaction, CVB3 is also impacted by sex hormones. Using castrated mice models, we observed a sex bias to CVB3 infection, with male mice succumbing to CVB3-induced disease at an increased rate compared to female mice. Our data suggest that testosterone, a predominant male sex hormone, enhanced CVB3 intestinal replication and viral dissemination to organs in male and female mice, but lethality only in male mice. Moreover, testosterone also affected the immune response by reducing the activation of the CD8+ T cells. CD8+ T cells are required to clear the viral infection and are integral in vaccine development. In contrast, we found an enhanced CD8+ T cell response in female mice to CVB3 infection, suggesting a sex-dependent T cell response that may underlie the sex bias in disease. Overall, these data represent an essential advancement in the CV field and will help develop future therapeutics and aid in vaccine design to limit CV infections.