The Cell Tropism of Porcine Respiratory Coronavirus for Airway Epithelial Cells Is Determined by the Expression of Porcine Aminopeptidase N

Abstract

Porcine respiratory coronavirus (PRCoV) infects the epithelial cells in the respiratory tract of pigs, causing a mild respiratory disease. We applied air–liquid interface (ALI) cultures of well-differentiated porcine airway cells to mimic the respiratory tract epithelium in vitro and use it for analyzing the infection by PRCoV. As reported for most coronaviruses, virus entry and virus release occurred mainly via the apical membrane domain. A novel finding was that PRCoV preferentially targets non-ciliated and among them the non-mucus-producing cells. Aminopeptidase N (APN), the cellular receptor for PRCoV was also more abundantly expressed on this type of cell suggesting that APN is a determinant of the cell tropism. Interestingly, differentiation-dependent differences were found both in the expression of pAPN and the susceptibility to PRCoV infection. Cells in an early differentiation stage express higher levels of pAPN and are more susceptible to infection by PRCoV than are well-differentiated cells. A difference in the susceptibility to infection was also detected when tracheal and bronchial cells were compared. The increased susceptibility to infection of bronchial epithelial cells was, however, not due to an increased abundance of APN on the cell surface. Our data reveal a complex pattern of infection in porcine differentiated airway epithelial cells that could not be elucidated with immortalized cell lines. The results are expected to have relevance also for the analysis of other respiratory viruses.

Time-dependent viral interference between influenza virus and coronavirus in the infection of differentiated porcine airway epithelial cells

“…The tracheas were collected from pigs obtained from a local slaughterhouse. PTECs were harvested from the porcine trachea as previously described [ 16 , 21 ]. Briefly, PTECs were initially maintained in bronchial epithelial cell growth medium (Lonza).…”

“…The samples were blocked with 1% BSA, then incubated with a monoclonal mouse anti-coronavirus-antibody (FIPV3-70; 1:1000, Thermo Fischer, Scientific) followed by Alexa Fluor® 488 conjugated secondary antibody staining (Thermo Fisher). The primary antibody is directed to the nucleocapsid protein of feline coronavirus and related porcine coronaviruses [ 15 , 21 ]. Ciliated cells were stained by Cy3-labeled antibody against β-tubulin (1:400; Sigma-Aldrich, MO, USA).…”

“…Recently, we compared the virulence of SIV and PRCoV, respectively, in ALI culture systems and highlighted virus-specific infection signatures [ 16 , 21 ]. In contrast to the infection by PRCoV, infection of ALI cultures by SIV induced the loss of ciliated cells due to apoptosis [ 16 ].…”

Porcine Coronaviruses: Overview of the State of the Art

“…Aminopeptidase N (APN), the cellular receptor for PRCV was also more abundantly expressed on this type of cell suggesting that APN is a determinant of the cell tropism (Peng et al . 2020 ). Common clinical findings of PRCV are dyspnea, tachypnea, sneezing, coughing, fever, anorexia and delayed growth (Halbur et al .…”

“…It was shown in recent studies, that PRCV preferentially targets non-ciliated and among them the non-mucus-producing cells. Aminopeptidase N (APN), the cellular receptor for PRCV was also more abundantly expressed on this type of cell suggesting that APN is a determinant of the cell tropism (Peng et al 2020). Common clinical findings of PRCV are dyspnea, tachypnea, sneezing, coughing, fever, anorexia and delayed growth (Halbur et al 2003;Jung et al 2009;Vannier 1990) (Table 1).…”