Nucleotide sequence and expression of the spike (S) gene of canine coronavirus and comparison with the S proteins of feline and porcine coronaviruses.
We have cloned, sequenced and expressed the spike (S) gene of canine coronavirus (CCV; strain K378). Its deduced amino acid sequence has revealed features in common with other coronavirus S proteins: a stretch of hydrophobic amino acids at the amino terminus (the putative signal sequence), another hydrophobic region at the carboxy terminus (the membrane anchor), heptad repeats preceding the anchor, and a cysteine-rich region located just downstream from it. Like other representatives of the same antigenic cluster (CCV-Insavc-1 strain, feline infectious peritonitis and enteric coronaviruses, porcine transmissible gastroenteritis and respiratory coronaviruses, and the human coronavirus HCV 229E), the CCV S polypeptide lacks a proteolytic cleavage site present in many other coronavirus S proteins. Pairwise comparisons of the S amino acid sequences within the antigenic cluster demonstrated that the two CCV strains (K378 and Insavc-1) are 93.3% identical, about as similar to each other as they are to the two feline coronaviruses. The porcine sequences are clearly more divergent mainly due to the large differences in the amino-terminal (residues 1 to 300) domains of the proteins; when only the carboxy-terminal parts (residues 301 and on) are considered the homologies between the canine, feline and porcine S polypeptides are generally quite high, with identities ranging from 90.8% to 96.8% . The human coronavirus is less related to the other members of the antigenic group. A phylogenetic tree constructed on the basis of the S sequences showed that the two CCVs are evolutionarily more related to the feline than to the porcine viruses. Expression of the CCV S gene using the vaccinia virus T7 RNA polymerase system yielded a protein of the expected M(r) (approximately 200K) which could be immunoprecipitated with an anti-feline infectious peritonitis virus polyclonal serum and which was indistinguishable from the S protein synthesized in CCV-infected cells.
Department of Infectious Diseases and Immunology, Veterinary Faculty, Utrecht University, The Netherlands.
J G
JG
Wesseling
H
H
Vennema
G J
GJ
Godeke
M C
MC
Horzinek
P J
PJ
Rottier
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002415:Cats; D003001:Cloning, Molecular; D017934:Coronavirus / Q000235:genetics*; D028941:Coronavirus 229E, Human; D017939:Coronavirus, Canine / Q000235:genetics*; D018076:DNA, Complementary; D004285:Dogs; D005814:Genes, Viral / Q000235:genetics*; D014644:Genetic Variation / Q000235:genetics; D006801:Humans; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D016366:Open Reading Frames; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D064370:Spike Glycoprotein, Coronavirus; D013552:Swine; D014759:Viral Envelope Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D015678:Viral Structural Proteins / Q000235:genetics*
D018076:DNA, Complementary; D008562:Membrane Glycoproteins; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins; D015678:Viral Structural Proteins; C578557:spike glycoprotein, SARS-CoV; C578553:spike protein, mouse hepatitis virus