Enteroviruses initiate infection in the gastrointestinal tract, and sex is often a biological variable that impacts infection. The role of sex hormones on enterovirus pathogenesis, however, is unclear. Previous data indicate that sex hormones can influence intestinal replication of Coxsackievirus B3 (CVB3), an enterovirus in the Picornavirus family. To determine if testosterone promotes CVB3 infection, male mice were castrated and provided placebo or testosterone-filled capsules. We found that testosterone-treated mice shed significantly more CVB3 in the feces and succumbed to CVB3-induced disease at a higher rate than castrated mice given a placebo. Treatment of male mice with an androgen receptor antagonist, flutamide, protected male mice from CVB3-induced lethality, further confirming the role of testosterone in viral pathogenesis. We also observed higher viral loads in peripheral tissues of testosterone-treated mice and an increase in the cytokine and chemokine response. Finally, we found that testosterone treatment in female mice increased fecal CVB3 shedding but had no impact on viral lethality. Overall, these data indicate that testosterone and androgen receptor signaling can promote CVB3 replication in the intestine and enhance CVB3 lethality in a sex-dependent manner.

Biological sex plays a significant role in the outcomes of various infections and diseases. The impact of sex hormones on the intestinal replication and dissemination of Coxsackievirus B3 remains poorly understood.

Sex is a significant contributor to the outcome of human infections. Males are frequently more susceptible to viral, bacterial, and fungal infections, which is often attributed to a weaker immune response. In contrast, a heightened immune response in females enables better pathogen elimination but leaves females more predisposed to autoimmune diseases. Unfortunately, the underlying basis for sex-specific immune responses remains poorly understood. Here, we show a sex-specific difference in the CD8+ T cell response to an enteric virus, Coxsackievirus B3 (CVB3). We found that CVB3 induced expansion of CD8+ T cells in female mice but not in male mice. CVB3 also increased the proportion and number of CD11ahiCD62Llo CD8+ T cells in female mice, indicative of activation. Further, this response was independent of the inoculation route and type I interferon. Using a recombinant CVB3 virus expressing a model CD8+ T cell epitope, we found that the expansion of CD8+ T cells is viral-specific and not due to bystander activation. These data demonstrate that CVB3 induces a sex-dependent CD8+ T cell response and highlight the importance of sex-specific immune responses to viral pathogens.

Enteric viruses infect the mammalian gastrointestinal tract and lead to significant morbidity and mortality worldwide. Data indicate that enteric viruses can utilize intestinal bacteria to promote viral replication and pathogenesis. However, the precise interactions between enteric viruses and bacteria are unknown. Here we examined the interaction between bacteria and Coxsackievirus B3, an enteric virus from the picornavirus family. We found that bacteria enhance the infectivity of Coxsackievirus B3 (CVB3) in vitro . Notably, specific bacteria are required as Gram-negative Salmonella enterica , but not Escherichia coli , enhanced CVB3 infectivity and stability. Investigating the cell wall components of both S. enterica and E. coli revealed that structures in the O-antigen or core of lipopolysaccharide, a major component of the Gram-negative bacterial cell wall, were required for S. enterica to enhance CVB3. To determine if these requirements were necessary for similar enteric viruses, we investigated if S. enterica and E. coli enhanced infectivity of poliovirus, another enteric virus in the picornavirus family. We found that while E. coli did not enhance the infectivity of CVB3, E. coli enhanced poliovirus infectivity. Overall, these data indicate that distinct bacteria enhance CVB3 infectivity and stability, and specific enteric viruses may have differing requirements for their interactions with specific bacterial species. Importance Previous data indicate that several enteric viruses utilize bacteria to promote intestinal infection and viral stability. Here we show that specific bacteria and bacterial cell wall components are required to enhance infectivity and stability of Coxsackievirus B3 in vitro . These requirements are likely enteric virus-specific as the bacteria for CVB3 differs from poliovirus, a closely related virus. Therefore, these data indicate that specific bacteria and their cell wall components dictate the interaction with various enteric viruses in distinct mechanisms.

Enteric viruses infect the mammalian gastrointestinal tract and lead to significant morbidity and mortality worldwide. Data indicate that enteric viruses can utilize intestinal bacteria to promote viral replication and pathogenesis. However, the precise interactions between enteric viruses and bacteria are unknown. Here we examined the interaction between bacteria and Coxsackievirus B3, an enteric virus from the picornavirus family. We found that bacteria enhance the infectivity of Coxsackievirus B3 (CVB3) in vitro. Notably, specific bacteria are required as gram-negative Salmonella enterica, but not Escherichia coli, enhanced CVB3 infectivity and stability. Investigating the cell wall components of both S. enterica and E. coli revealed that structures in the O-antigen or core of lipopolysaccharide, a major component of the gram-negative bacterial cell wall, were required for S. enterica to enhance CVB3. To determine if these requirements were necessary for similar enteric viruses, we investigated if S. enterica and E. coli enhanced infectivity of poliovirus, another enteric virus in the picornavirus family. We found that, in contrast to CVB3, these bacteria enhanced the infectivity of poliovirus in vitro. Overall, these data indicate that distinct bacteria enhance CVB3 infectivity and stability, and specific enteric viruses may have differing requirements for their interactions with specific bacterial species.