The spike but not the hemagglutinin/esterase protein of bovine coronavirus is necessary and sufficient for viral infection.
The spike (S) and hemagglutinin/esterase (HE) of bovine coronavirus (BCV) are the two envelope proteins that recognize the same receptor-determinant of 9-O-acetylneuraminic acid on host cells. However, the precise and relative roles of the two proteins in BCV infectivity remain elusive. To unequivocally determine their roles in viral cytopathogenicity, we developed a system in which phenotypically chimeric viruses were generated by infecting a closely related mouse hepatitis virus (MHV) in cells that stably express an individual BCV protein (S or HE). The chimeric viruses were then used to infect human rectal tumor (HRT)-18 cells that are permissive to BCV but are nonsusceptible to MHV. Using this approach, we found that the chimeric virus containing the BCV S protein on the virion surface entered and replicated in HRT-18 cells; this was specifically blocked by prior treatment of the virus with a neutralizing antibody specific to the BCV S protein, indicating that the BCV S protein is responsible for initiating chimeric virus infection. In contrast, chimeric viruses that contain biologically active and functional BCV HE protein on the surface failed to enter HRT-18 cells, indicating that the BCV HE protein alone is not sufficient for BCV infection. Taken together, these results demonstrate that the S protein but not the HE protein of BCV is necessary and sufficient for infection of the chimeric viruses in HRT-18 cells, suggesting that BCV likely uses the S protein as a primary vehicle to infect permissive cells.
Popova
Rada
R
Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
Zhang
Xuming
X
D000818:Animals; D002417:Cattle; D002460:Cell Line; D018352:Coronavirus Infections / Q000821:virology*; D017938:Coronavirus, Bovine / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D006389:Hemagglutinins, Viral / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D006517:Murine hepatitis virus / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D064370:Spike Glycoprotein, Coronavirus; D014407:Tumor Cells, Cultured; D014759:Viral Envelope Proteins / Q000235:genetics / Q000378:metabolism*; D014760:Viral Fusion Proteins / Q000235:genetics / Q000378:metabolism*
D006389:Hemagglutinins, Viral; D008562:Membrane Glycoproteins; D011993:Recombinant Fusion Proteins; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins; D014760:Viral Fusion Proteins; C060814:hemagglutinin esterase; C578557:spike glycoprotein, SARS-CoV; C578553:spike protein, mouse hepatitis virus