Enteric viruses leverage bacteria to boost infectivity and disinfection resistance

Enteric viruses remain a major global health concern and are responsible for hundreds of thousands of deaths globally each year. Traditionally, they were considered to transmit and infect hosts as free individual particles. However, growing evidence indicates that their co-occurrence with bacteria poses elevated health risks, yet the mechanisms of virus-bacteria interactions and their impacts on viral transmission remain poorly understood. In this study, we demonstrated that environmental bacteria such as Bacillus subtilis can markedly enhance the infectivity of the enteric virus Coxsackievirus B3 (CVB3), a known cause of severe viral myocarditis in children, by up to 13.75-fold. Further mechanistic investigation revealed that the bacteria promote viral infectivity by enhancing viral attachment to and escape from host cells. We also identified soluble bacterial cell wall components, such as peptidoglycan and lipoteichoic acid, as key contributors to CVB3 infectivity enhancement. Moreover, bacteria increased viral resistance to disinfection, reducing UV₂₅₄ inactivation of CVB3 from ∼2 to 0.67-1.46 log₁₀ removal and allowing viral persistence under free chlorine dosage of 10 mg min L^-1. Collectively, these findings revealed that bacteria and bacterial remnants in aquatic environments can increase the risk of viral transmission, underscoring the urgent need to develop improved water treatment and pathogen control strategies to safeguard public health.