Interspecies aminopeptidase-N chimeras reveal species-specific receptor recognition by canine coronavirus, feline infectious peritonitis virus, and transmissible gastroenteritis virus.

We report that cells refractory to canine coronavirus (CCV) and feline infectious peritonitis virus (FIPV) became susceptible when transfected with a chimeric aminopeptidase-N (APN) cDNA containing a canine domain between residues 643 and 841. This finding shows that APN recognition by these viruses is species related and associated with this C-terminal domain. The human/canine APN chimera was also able to confer susceptibility to the porcine transmissible gastroenteritis virus (TGEV), whereas its human/porcine homolog failed to confer susceptibility to CCV and FIPV. A good correlation was observed between the capacity of CCV, FIPV, and TGEV to recognize the different interspecies APN chimeras and their ability to infect cells derived from the relevant species. As an exception, TGEV was found to use a human/bovine APN chimera as a receptor although itself unable to replicate in bovine cells.