PRRSV promotes bacterial infection by remodeling actin cytoskeleton and cell membrane proteins

An important reason why porcine reproductive and respiratory syndrome virus (PRRSV) is difficult to control effectively is that it often causes severe secondary bacterial infections, which are usually attributed to the immunosuppression caused by PRRSV. However, the mechanism by which PRRSV infection leads to increased susceptibility of cells to bacterial infection has been largely overlooked. We revealed that PRRSV induced actin cytoskeleton rearrangement by upregulating FLNA expression, thereby aggravating bacterial invasion. PRRSV increased bacterial adhesion by promoting the ITGα5 expression, and the upregulation of ITGα5 could induce FLNA-mediated actin cytoskeleton rearrangement. Furthermore, we found that H1N1 and porcine circovirus type 2 infection also significantly promoted the expression of FLNA and ITGα5 and increased the infection of multiple bacteria. These results suggest that FLNA and ITGα5 play important roles in virus-induced secondary bacterial infection.