Characterization of determinants involved in the feline infectious peritonitis virus receptor function of feline aminopeptidase N.

Abstract

Feline aminopeptidase N (fAPN) is a major cell surface receptor for feline infectious peritonitis virus (FIPV), transmissible gastroenteritis virus (TGEV), human coronavirus 229E (HCV 229E) and canine coronavirus (CCV). By using chimeric molecules assembled from porcine, human and feline APN we have analysed the determinants involved in the coronavirus receptor function of fAPN. Our results show that amino acids 670-840 of fAPN are critically involved in its FIPV and TGEV receptor function whereas amino acids 135-297 are essential for the HCV 229E receptor function. We also demonstrate that a chimeric molecule assembled from human and porcine APN is able to act as a receptor for FIPV. This is surprising as neither human nor porcine APN by themselves mediate FIPV infection. These results suggest that different determinants in the APN protein are involved in mediating the coronavirus receptor function.The Coronaviridae are enveloped viruses with a large nonsegmented RNA genome of positive polarity. On the basis of serological and genetic data they are separated into three different groups (Siddell, 1995). Some members of group 1 [i.e. transmissible gastroenteritis virus (TGEV), feline infectious peritonitis virus (FIPV) and human coronavirus (HCV) 229E] have been demonstrated to utilize aminopeptidase N (APN) as cell surface receptor (Delmas et al., 1992 ;Yeager et al., 1992 ;Tresnan et al., 1996). APN is a type II glycoprotein, belongs to the family of membrane-bound metalloproteases (Olsen et al., 1988) and is expressed in a variety of tissues (Delmas et al., 1994).Although human APN (hAPN) and porcine APN (pAPN) have a sequence similarity of 78 % at the amino acid level,

Phage displayed peptides recognizing porcine aminopeptidase N inhibit transmissible gastroenteritis coronavirus infection in vitro

“…Therefore, it would be interesting to screen the ligands of sialoglycoprotein and analyze their roles in the context of TGEV infection. There are no structural data and only limited functional information regarding the spike glycoproteins of coronaviruses in serogroup 1, which includes HCoV-229E, TGEV, FCoV, and CCoV, although they all use APN as a receptor to enter cells (Benbacer et al, 1997;Bonavia et al, 2003;Delmas et al, 1992;Hegyi and Kolb, 1998;Yeager et al, 1992). Therefore, the peptides identified in this study or the high homologous regions in the S proteins could be major RBDs of viral S proteins.…”

The Molecular Biology of Coronaviruses

“…Curiously, fAPN can serve as a receptor not only for FIPV but also for CCoV, TGEV, and HCoV-229E (Tresnan et al, 1996). These contrasting properties have been used as the framework for dissecting the basis of species-specific or -nonspecific function, through the construction and analysis of chimeric receptors (Benbacer et al, 1997;Delmas et al, 1994a;Hegyi and Kolb, 1998;Kolb et al, 1996Kolb et al, , 1997. However, chimera construction has not revealed a single linear determinant for virus binding.…”

Feline infectious peritonitis

“…After a cat becomes infected with FCoV by ingestion (or, rarely, by inhalation), the main site of viral replication is the intestinal epithelium. The specific receptor for FCoV (at least FCoV serotype I) is an enzyme, aminopeptidase-N, found in the intestinal brush border [60][61][62]. Replication of FCoV in the cytoplasm can cause destruction of intestinal epithelium cells.…”