Generation of a Porcine Cell Line Stably Expressing Pig TMPRSS2 for Efficient Isolation of Viruses from Pigs with Respiratory Diseases

Pigs are important animals for meat production but can carry several zoonotic diseases, including Japanese encephalitis virus, Nipah virus, and influenza viruses. Several Orthomyxoviridae and Coronavirinae respiratory viruses require cleavage of envelope proteins to acquire viral infectivity and consequently need a host protease or the addition of exogenous trypsin for efficient propagation. Host TMPRSS2 is a key protease responsible for viral cleavage. Stable expression of human TMPRSS2 in African green monkey-derived Vero cells can enhance the porcine epidemic diarrhea virus. However, considering the narrow host tropism of viruses, a porcine cell line expressing pig TMPRSS2 could be optimal for replicating pig-derived viruses. Herein, we generated and evaluated a pig-derived PK-15 cell line stably expressing pig TMPRSS2. This cell line markedly and specifically enhanced the growth of influenza viruses. Therefore, PK-15 cells expressing pig TMPRSS2 could be a valuable and promising tool for virus isolation, vaccine production, and virological studies.