Feline caliciviruses (FCVs) isolated from cats with virulent systemic disease possess in vitro phenotypes distinct from those of other FCV isolates

Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
Journal of General Virology (Impact Factor: 3.18). 03/2007; 88(Pt 2):506-17. DOI: 10.1099/vir.0.82488-0
Source: PubMed


During the past decade, several outbreaks of severe systemic disease associated with Feline calicivirus (FCV) have occurred in the USA and the UK. This new disease has caused high mortality in the affected animals and has been termed virulent systemic (VS)-FCV disease. Currently, there are no genetic or in vitro diagnostic methods to distinguish viruses isolated from cases of VS-FCV disease from other isolates. Here, five in vitro properties, as well as the capsid and proteinase-polymerase (pro-pol) sequences, of a set of FCV isolates that included seven isolates from five distinct VS-FCV outbreaks ('VS isolates') were investigated. Although all of the FCV isolates investigated had similar kinetics of growth under single-cycle conditions, VS isolates infected tissue-culture cells more efficiently under multiple-cycle growth conditions. Moreover, it was found that cells infected with VS isolates showed cytopathic effects earlier than cells infected with non-VS isolates, although no difference in relative ATP levels were noted at times when morphological changes were first seen. Both VS- and other (non-VS) isolates of FCV demonstrated similar temperature stabilities. Phylogenetic analyses and alignments of the capsid and pro-pol regions of the genome did not reveal any conserved changes that correlated with virulence, and the VS isolates did not segregate into a unique clade. These results suggest that VS isolates have arisen independently several times since first being described and can spread more efficiently in tissue culture than other isolates when infected at low multiplicity.

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Available from: Justine Shotton, Jan 12, 2014
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    • "vaccines for FCV have been employed for over 20 years, a high incidence of mortality can occur in isolated outbreaks (Hurley et al., 2004; Ossiboff et al., 2007). Vaccine failure has been attributed to the absence of sterilizing immunity, occasional vaccine breakdowns, and in the case of the live vaccine, occasional vaccine-induced disease (Radford et al., 2006). "
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    • "VSD has been experimentally reproduced with four independent isolates of VS-FCV [15] [31] (Patricia A. Pesavento, unpublished data, 2005 and 2008). Analysis of the genomic sequences has shown that VS-FCV isolates seem to have arisen independently from different genetic backgrounds, however [32]. As yet, no genetic signature has been identified that can discriminate VS- FCV isolates from other FCV isolates. "
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