Porcine respiratory coronavirus differs from transmissible gastroenteritis virus by a few genomic deletions

Abstract

The genome organization of porcine respiratory coronavirus (PRCV), a newly recognized agent which has a close antigenic relationship to the enteropathogenic transmissible gastroenteritis virus (TGEV), was studied. Genomic RNA from cell-cultured PRCV (French isolate RM4) was used to produce eDNA clones covering the genomic 3' end to the start of the spike (S) glycoprotein gene (7519 nucleotides). Six open reading frames (ORFs) were identified that allowed the translation of three coronavirus structural proteins and three putative non-structural (NS) polypeptides, homologous to TGEV ORFs designated NS3-1, NS4 and NS7. Pairwise alignment of PRCV nucleotide and amino acid sequences with sequence data available for three TGEV strains revealed a 96 % overall homology. However, the genome of PRCV exhibited two important distinctive features. The first was that the S gene lacked 672 nucleotides in the 5' region and encoded a truncated form of the S polypeptide, and secondly, the first NS ORF downstream of the S gene was predicted to be non-functional as a consequence of a double deletion. The significance ofgenomic deletions with respect to tissue tropism and evolution of coronaviruses is discussed.

Field Isolates of Transmissible Gastroenteritis Virus Differ at the Molecular Level from the Miller and Purdue Virulent and Attenuated Strains and from Porcine Respiratory Coronaviruses.

“…It has been shown that PRCV strains have a large deletion in the N-terminus of the S gene. The U.S.A. and European PRCV isolates had 681 nucleotide (227aa) and 672 nucleotide (224aa) deletions, respectively [30,37,49]. However, their antigenicity was similar in studies with monoclonal antibodies [41,50].…”

“…Sequence data revealed that PRCV has a large deletion in the 5' region of the S glycoprotein gene. It has been proposed that the deletion may be related to the differences observed in tissue tropism or pathogenicity between PRCV and TGEV strains [3,30,49]. Researchers have reported that PRCV strains replicate almost exclusively in the respiratory tract [15,48] and usually cause subclinical infections or only mild signs of respiratory disease.…”

Analysis of a 9.6 kb sequence from the 3' end of canine coronavirus genomic RNA

“…Consequently, this has an effect on pathogenicity, as deletions in the MHV-4 S coding sequence apparently result in a loss of ability to induce fatal encephalitis and the acquisition of a non-fatal demyelinating disease in mice (Parker et al, 1989). Polymorphism has also been observed in the S gene and in the region between the S and M genes for different strains of TGEV and the respiratory tract mutant, PRCV (Wesley et al, 1990;Rasschaert et al, 1990). In fact, an IBV strain (Port/322/85) has been reported which appears to have arisen as a result of recombination between the M and S genes from two other strains of IBV (Cavanagh et al, 1990b).…”

“…TGEV, PRCV and FIPV have been characterized in some detail and the genes encoding the structural proteins have been cloned and sequenced (de Groot et al, 1987;Vennema et al, 1991 ;Britton etal., 1988a, b;Rasschaert &Laude, 1987;Rasschaert et al, 1990). A comparison of the available FIPV amino acid sequences with the corresponding sequences of TGEV and PRCV has revealed that the structural genes are very closely related.…”

A Serodiagnostic ELISA Using Recombinant Antigen of Swine Transmissible Gastroenteritis Virus Nucleoprotein.

“…In our preliminary data, type A rotavirus specific rabbit serum (gifted from Dr. Tsunemitsu, Institute of Animal Health, Japan) also did not show any cross-reaction with the rN protein (data not shown), which suggested that the rnELISA can be used for the diagnosis of TGE among common swine diarrhea. Apart from the diseases listed above, it should be noted that our ELISA might not differentiate porcine respiratory coronavirus (PRCV), a non-enteropathogenic variant of TGEV, because the virus was different only at amino-terminal half of spike protein [6]. In fact, the sequence encoding N protein of TO14 was 97.7% identical with that of PRCV (the sequence data was obtained from GenBank with an accession No.…”