Characterization of a new calicivirus isolated from feces of a dog

Abstract

Canine calicivirus (CaCV), isolated from feces of a dog with diarrhea, was readily propagated in cultures of canine cells and in a dolphin cell line. Serologic evidence indicated many dogs in at least one geographic area had been infected with CaCV, but its role as an etiologic agent of disease was not established. In cell culture most CaCV virions were strongly cell-associated making purification difficult. CaCV was established as a member of the Caliciviridae by morphology and physicochemical properties of virions (density, sedimentation rate, single major polypeptide, RNA genome size), although some of the properties differed slightly from those of previously described caliciviruses; evidence was also obtained for caliciviral RNA species in infected cells. Based on tests with antisera to numerous caliciviruses and presumed caliciviruses, CaCV appeared to be not closely related to any previously described virus except the stunting syndrome agent of chickens.

Identification of Canine Calicivirus Capsid Protein and Its Immunoreactivity in Western Blotting.

“…The apparent molecular weight of the capsid protein of CaCV No. 48 strain was similar to that of the CaCV described by Schaffer et al [13], RHDV [10] and NV [7] but slightly less than that reported for FCV [1,15,18]. The time course study of capsid protein synthesis revealed that the protein band was already detectable by the mouse serum at 2 hr PI.…”

“…The virus apparently replicated more efficiently in semiconfluent monolayer cells than in full sheets. Schaffer et al [13] observed that the early passaged virus required freshly plated or rapidly dividing cells. Furthermore, in contrast to FCV, it was not possible to obtain virus titers of more than 10 7 TCID 50 /ml in MDCK cells.…”

“…Attempts had been made to reproduce the original disease by experimentally infecting puppies with CaCV [9,13]. In this study, the puppies were inoculated orally or intravenously and the immune response was monitored by MNT and western blotting to confirm the presence of antibodies reactive in western blot and the immunogenicity of the capsid protein.…”

“…These earlier isolates were found to be antigenically similar to FCV. In 1985, a calicivirus (CaCV) isolated from the feces of a dog with diarrhea was found to be not antigenically related to any previously described virus except to the stunting syndrome agent of chickens [13]. Two more isolates from cases of vesicular genital diseases were identified and based on neutralization tests, they appeared to be distinct from the previously reported canine and feline caliciviruses [3].…”

Laboratory efforts to cultivate noroviruses

“…The addition of a variety of additives, including proteases, hormones and intestinal contents, did not lead to successful NoV cultivation, although this approach has enhanced the growth of other caliciviruses; the addition of trypsin enhances the growth of canine calicivirus (Schaffer et al, 1985), and porcine enteric calicivirus (Cowden strain) was adapted to cell culture in a porcine kidney cell line after inclusion of ICP from gnotobiotic pigs (Flynn & Saif, 1988;Parwani et al, 1991). The nature of the necessary factor in the ICP has not yet been elucidated but it may affect replication by triggering a cellular cAMP-signalling pathway (Chang et al, 2002).…”