Anti-IAV Polyclonal antibody

Influenza A virus (IAV) causes annual epidemics of respiratory disease in humans, often complicated by secondary coinfection with bacterial pathogens such as Staphylococcus aureus. Here, we report that the S. aureus secreted protein lipase 1 enhances IAV replication in vitro in primary cells, including human lung fibroblasts. The proviral activity of lipase 1 is dependent on its enzymatic function, acts late in the viral life cycle, and results in increased infectivity through positive modulation of virus budding. Furthermore, the proviral effect of lipase 1 on IAV is exhibited during in vivo infection of embryonated hen's eggs and, importantly, increases the yield of a vaccine strain of IAV by approximately 5-fold. Thus, we have identified the first S. aureus protein to enhance IAV replication, suggesting a potential role in coinfection. Importantly, this activity may be harnessed to address global shortages of influenza vaccines. IMPORTANCE Influenza A virus (IAV) causes annual epidemics and sporadic pandemics of respiratory disease. Secondary bacterial coinfection by organisms such as Staphylococcus aureus is the most common complication of primary IAV infection and is associated with high levels of morbidity and mortality. Here, we report the first identified S. aureus factor (lipase 1) that enhances IAV replication during infection via positive modulation of virus budding. The effect is observed in vivo in embryonated hen's eggs and greatly enhances the yield of a vaccine strain, a finding that could be applied to address global shortages of influenza vaccines.

Humans and avian species are prone to influenza viral infection, which may cause serious clinical consequences. Many studies have documented the critical role of host factors in the influenza virus life cycle based on human models, but knowledge about their roles in birds is very limited. In this study, using immunoprecipitation coupled with mass spectrometry, a total of 72 potential interacting proteins of influenza nucleoprotein (NP) were identified in DF-1 cells. Among these proteins, avian chaperonin containing TCP1 subunit 5 (CCT5) was demonstrated to interact with influenza A virus (IAV) NP directly, as well as polymerase basic protein 1 (PB1) and polymerase basic protein 2 (PB2) but not with polymerase acidic protein (PA). Further investigation showed that viral infection profoundly elevated the expression level of cellular CCT5, whose expression, in turn, promoted the nuclear export of NP, as well as viral polymerase activity, thereby facilitating the replication of IAV. The obtained results suggested an important role of avian CCT5 in supporting influenza virus replication, which may serve as an anti-influenza target.