Polystyrene microplastics significantly facilitate influenza A virus infection of host cells

Microplastics (MPs) are emerging pollutants which exist in various environments and pose a potential threat to human health. However, the effect of MP on respiratory pathogens-infected organisms is unknown. In order to explore the effect of MP on respiratory pathogen infection, we studied the effect of polystyrene microplastics (PS) on influenza A virus (IAV)-infected A549 cells. Western blot, qPCR, and viral plaque assay demonstrated that PS could promote IAV infection. Further study by bioluminescence imaging showed that a large number of IAV could be enriched on PS and entered cells through endocytosis. Meanwhile, the expression of IFITM3 in cells was significantly reduced. In addition, our results showed that PS down-regulated IRF3 and its active form P-IRF3 by down-regulating RIG-I and inhibiting TBK1 phosphorylation activation, which then significantly reduced IFN-β expression and affected the cellular innate antiviral immune system. Taken together, our results indicate the potential threat of MPs to respiratory diseases caused by IAV and provide new insights into human health protection.