Coronaviruses Associated with Outbreaks of Transmissible Enteritis of Turkeys in Quebec: Hemagglutination Properties and Cell Cultivation

Abstract

Coronaviruses were observed by electron microscopy in the intestinal contents of turkeys in Quebec flocks where repeated outbreaks of enteritis occurred. Three isolates could be serially propagated in turkey embryos inoculated by the amniotic route with clarified intestinal contents. Purification and concentration of viral particles contained in intestinal contents of infected embryos were achieved by precipitation with polyethylene glycol and ultracentrifugation on sucrose density gradients. Three particle types were demonstrated: intact virions with a density of 1.18 to 1.20 g/ml and incomplete particles with densities of 1.14 and 1.24 g/ml. Hemagglutination of rabbit and guinea pig erythrocytes was demonstrated with the intact viral particles; the hemagglutinin was not dependent on incubation temperature. All the isolates were antigenically related, as shown by hemagglutination-inhibition. The turkey coronaviruses did not cross-react with antisera against coronaviruses of avian infectious bronchitis, porcine transmissible enteritis, bovine neonatal calf diarrhea, or mouse hepatitis. One of the Quebec isolates was shown to induce syncytia formation on its third passage in primary chicken-embryo kidney cell cultures. Electron-microscopic examination of infected cell-culture fluids revealed characteristics coronavirus particles identical to those found in intestinal contents of infected turkeys.

Antigenic and Polypeptide Structure of Turkey Enteric Coronaviruses as Defined by Monoclonal Antibodies

“…The origin of the nine tissue culture-adapted Quebec strains of TCV, listed in Fig. 9, has been reported (Dea et al, 1986;Dea & Tijssen, 1988a).…”

“…The tests were done as described elsewhere (Dea et al, 1979(Dea et al, , 1986. The serum neutralization (SN) titre was expressed as the reciprocal of the highest serum or ascitic fluid dilution neutralizing 100 TCIDs0 of the virus.…”

“…In the natural host, it infects and destroys the mature absorptive epithelial cells of the small and large intestines leading to an often severe diarrhoea in poults under 6 weeks of age, but only mild clinical signs in adults (Deshmukh et al, 1974;Pomeroy et al, 1978). The morphological and physicochemical characteristics of TCV resemble those of other members of the Coronaviridae (Ritchie et al, 1973;Panigrahy et al, 1973;Dea et al, 1986;Dea & Tijssen, 1988b). Little is known with respect to the molecular and antigenic structure of the virion, because of the difficulties in propagating TCV strains in conventional tissue culture systems and the lack of highly specific immunological probes (Deshmukh et al, 1973;Pomeroy, 1984).…”

Sequence analysis of the turkey enteric coronavirus nucleocapsid and membrane protein genes: a close genomic relationship with bovine coronavirus

“…The integral membrane protein (M), which is largely embedded in the lipid bilayer targets the site of virus morphogenesis (Tooze et al, 1984) and may be implicated in viral pathogenesis (Fleming et al, 1989), whereas the bulbous peplomer (S) protein is responsible for virus binding (Cavanagh & Davis, 1986;Koch et al, 1990) as well as virulence and tissue tropism (Wege et al, 1988). An additional surface protein (HE), responsible for haemagglutination, has been found in bovine coronavirus (BCV; King et al, 1985;Hogue et al, 1989;Parker et al, 1989), human respiratory coronavirus strain OC43 (HCV-OC43; Hogue & Brian, 1985), haemagglutinating encephalitis virus of swine (Callebaut & Pensaert, 1980), diarrhoea virus of infant mice (Sugiyama et al, 1986) and turkey coronavirus (TCV; Dea et al, 1986). The HE protein of BCV also exhibits an acetyl esterase receptor-destroying activity similar to the activity found in influenza C viruses (Vlasak et al, 1988).…”

Enteric viruses in turkey flocks: a historic review

“…A hemagglutination-inhibition test showed that there was no antigenic relationship between TCoV and other animal coronaviruses involved with enteric problems and it was considered an easy and applicable serological test by Dea et al (1986). The tests of Pomeroy et al (1975) were not able to produce an inactivated vaccine against coronaviruses infections.…”