Isolation of an equine coronavirus from adult horses with pyrogenic and enteric disease and its antigenic and genomic characterization in comparison with the NC99 strain

Abstract

A new equine coronavirus was isolated from the feces of adult horses with pyrogenic and enteric disease. The disease outbreak was mainly observed among 2- to 4-year-old horses living in stables of a draft-horse racetrack in Japan. On comparing the isolated virus (isolate Tokachi09) with the equine coronavirus NC99 strain, no significant differences were observed in several biological properties such as hemagglutinating activity, antigenicity (in indirect immunofluorescence and neutralization tests), and one-step growth (in cell culture). The sequences of the nucleocapsid and spike genes of isolate Tokachi09 showed identical size (1341 and 4092 nucleotides, 446 and 1363 amino acids, respectively) and high similarity (98.0% and 99.0% at the nucleotides, 97.3% and 99.0% at the amino acids, respectively) to those of strain NC99. However, the isolate had a 185-nucleotide deletion from four bases after the 3'-terminal end of the spike gene, resulting in the absence of the open reading frame predicted to encode a 4.7-kDa nonstructural protein in strain NC99. These results suggest that the 4.7-kDa nonstructural protein is not essential for viral replication, at least in cell culture, and that the Japanese strain probably originated from a different lineage to the North American strain. This is the first equine coronavirus to be isolated from adult horses with pyrogenic and enteric disease.

Application of Transmission Electron Microscopy Techniques in the Veterinary Diagnosis of Viral Gastroenteritis in Livestock Animals

“…Respiratory problems, profuse aqueous diarrhea greenish to yellowish of putrid odor and discrete algia abdominal can also been observed [136,141,[144][145][146][147]. It is transmitted by the fecal-oral route, and signs tend to resolve in 1-4 days, although animals can continue shedding for several weeks [147].…”

“…The virus has been diagnosed more frequently in adult animals over 2 years of age [146,147,150]. However, outbreaks have been reported in foals from 5 days to 4 months of age [139,144,145,151] and in both adults and young animals [141].…”

“…Negative-staining technique (rapid preparation) (Figure 10) and immunoelectron microscopy ( Figure 11) has been widely used for direct visualization of viral particles [139,144,146,151,[154][155][156][157].…”

Development of an equine coronavirus–specific enzyme-linked immunosorbent assay to determine serologic responses in naturally infected horses

“…Amino acid sequences of the spike protein of EqCoV have been shown previously to be highly conserved among different strains of EqCoV. 13 The use of recombinant protein for …”

Evolving views on enteric viral infections of equines: an appraisal of key pathogens

“…Mainly the tissue tropism for ECoV infections have been found to be inside the gastrointestinal tract of young foals and horses (Miszczak et al, 2014;Fielding et al 2015;Pusterla et al, 2015b). Multiple ECoV outbreaks have occurred in the ÜSA and Japan (Oue et al, 2011;Oue et al, 2013;Pusterla et al, 2013). Besides the possible respiratory and mechanical transmission of coronaviruses in equines, infections spreads through fecal-oral route (Studdert, 1996;Anzai et al, 2001).…”