Enteric pathogenicity characterization of emerging parainfluenza virus 5 in western China

Parainfluenza virus 5 (PIV5) is a member of the Paramyxoviridae family and causes respiratory symptoms in various animal species. Although the virus has been frequently detected among fecal samples, no study has described its infection of the intestine. Recently, diarrhea with low mortality has spread on pig farms in Gansu, China. Next-generation sequencing confirmed the emergence of PIV5 among the samples. The PIV5 strain was then successfully isolated and characterized in vitro. Further animal tests revealed that PIV5 can result in respiratory symptoms and mild diarrhea in piglets. Immunohistochemical staining confirmed PIV5 infection resulted in steatosis and contributed to diarrhea. A retrospective investigation revealed that the number of cases of PIV5 infection has increased since 2020. Overall, our study is the first to present data indicating that PIV5 infection leads to diarrhea. Although it has low pathogenicity, PIV5 may pose a potential threat to pig production in China.