Receptor Usage and Cell Entry of Porcine Epidemic Diarrhea Coronavirus

Abstract

e Porcine epidemic diarrhea coronavirus (PEDV) has significantly damaged America's pork industry. Here we investigate the receptor usage and cell entry of PEDV. PEDV recognizes protein receptor aminopeptidase N from pig and human and sugar coreceptor N-acetylneuraminic acid. Moreover, PEDV infects cells from pig, human, monkey, and bat. These results support the idea of bats as an evolutionary origin for PEDV, implicate PEDV as a potential threat to other species, and suggest antiviral strategies to control its spread. P orcine epidemic diarrhea coronavirus (PEDV) causes largescale outbreaks of diarrhea in pigs and an 80 to 100% fatality rate in suckling piglets (1-3). Since 2013, PEDV has swept throughout the United States, wiped out more than 10% of America's pig population in less than a year, and significantly damaged the U.S. pork industry (4-6). No vaccine or antiviral drug is currently available to keep the spread of PEDV in check. PEDV belongs to the ␣ genus of the coronavirus family (7,8), which also includes porcine transmissible gastroenteritis coronavirus (TGEV), bat coronavirus 512/2005 (BtCoV/512/2005), and human NL63 coronavirus (HCoV-NL63). Although both PEDV and TGEV infect pigs, PEDV is genetically more closely related to BtCoV/512/ 2005 than to TGEV, leading to the hypothesis that PEDV originated from bats (9).Receptor binding and cell entry are essential steps in viral infection cycles, critical determinants of viral host range and tropism, and important targets for antiviral interventions. An envelope-anchored spike protein mediates coronavirus entry into cells. The spike ectodomain consists of a receptor-binding subunit, S1, and a membrane fusion subunit, S2. S1 contains two domains, an N-terminal domain (S1-NTD) and a C-terminal domain (S1-CTD), both of which can potentially function as receptor-binding domains (RBDs) (Fig. 1A) (10, 11). The ability of coronavirus RBDs to recognize receptor orthologs from different species is one of the most important determinants of coronavirus host range and tropism (8,(12)(13)(14). HCoV-NL63 S1-CTD recognizes human angiotensin-converting enzyme 2 (ACE2), whereas TGEV S1-CTD recognizes porcine aminopeptidase N (APN), and its S1-NTD recognizes two sugar coreceptors, N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc) (15-18). Usage of sugar coreceptors is linked to the enteric tropism of coronaviruses (18,19). It has been shown that PEDV uses porcine APN as its receptor (20). However, it is not known whether PEDV recognizes APN from other species or whether it uses sugar coreceptors. Addressing these questions will be critical for understanding the host range, tropism, and evolutionary origin of PEDV, for evaluating its potential risk to other species, particularly humans, and for developing effective vaccines and antiviral drugs to curb the spread of PEDV in pigs and to other species.To characterize the receptor usage of PEDV, here we identified the two S1 domains of PEDV based on the sequence similarity between PEDV and TGEV S1 subun...

Porcine gastroenteric viruses: pathogenesis and protection

“…Èíîãäà âåòðû äóëè â þãî-çàïàäíîì (Jengarn et al, 2015). Although PEDV is in general propagated in Vero cells, it efficiently infects a variety of cell types, including porcine intestinal epithelial cells (IECs) (Zhao et al, 2014)or human Huh 7 cells (Liu et al, 2015). It remains to be analyzed whether any of these cell systems would be suitable for effective PEDV isolation from biological samples.…”

Three Main Inducers of Alphacoronavirus Infection of Enterocytes: Sialic Acid, Proteases, and Low pH

“…In addition, the CoVs tyrosine and tryptophan residues are critical in forming the TGEV RBD-APN structure. HCoV-229E does not have a tyrosine in its RBD β1-β2 turn, hence it recognizes the human APN that lacks this form of glycosylation [20,34], meaning that HCoV-229E recognition of APN must be unique. There have been some studies that determined the structure of a protruding tip for binding to small APN cavities in this human α-CoV.…”

“…Sequence analyses of PEDV prototype and variant strains reveal that the N terminus of the S protein changes more easily than the C terminus. In addition, a previous report suggested an interaction of NTD of the S1 domain with a coreceptor [20,21]. Simplified graphic of the structural domains of the main coronaviruses' spike proteins.…”

“…Compared with the TGEV S domain, the related PRCoV lacks the NTD, which is related to enteric tropism. The TGEV or PRCoV RBD tips consist of 2 protruding β-turns (β1-β2 and β3-β4), each having a solvent-exposed aromatic residue (tyrosine or tryptophan) [20]. In the tertiary structure of the PRCoV RBD, 3 loops (β1-β2, β3-β4, and β5-β6) at the tips of the β-barrel domains are responsible for receptor binding.…”

“…PEDV has a 150-to 220-kDa spike glycoprotein with a homotrimeric structure. The PEDV S protein is also a type I transmembrane glycoprotein that contains 5 regions, a signal peptide (residues [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20], an S1 region (residues 21-793), an S2 region (residues 794-1385), a transmembrane domain (residues 1335-1358), and a cytoplasmic tail (residues 1359-1385) [19]. The S1 region is responsible for virus particle binding to the cellular receptors, whereas the S2 region participates in membrane fusion of the virus and host cells.…”