title: Recombinant feline coronaviruses as vaccine candidates confer protection in SPF but not in conventional cats.
abstract: Feline infectious peritonitis virus (FIPV) is a major pathogen of Felidae. Despite the extensive efforts taken in the past decades, development of the "ideal" live attenuated FIPV vaccine was not successful yet. In the present study, we provide data of immunisation experiments with a recombinant FCoV pair differing only in the truncation (PBFIPV-DF-2) or completion (PBFIPV-DF-2-R3i) of their ORF3abc regions. In our previous in vivo studies, these viruses proved to show the characters of low virulent or avirulent FCoV phenotypes, respectively. Therefore, we hypothesised the ability of these viruses, as possible vaccine candidates, in conferring protection in specific pathogen free (SPF) Domestic Shorthair as well as in conventional purebred British Shorthair cats. In SPF cats, after two oronasal and two intramuscular vaccinations with two weeks intervals, both vaccine candidates provided 100% protection against lethal homologous challenge with the highly virulent FIPV DF-2 strain. In contrast, the conventional purebred British Shorthair cats did not develop protection when they were immunised with the same vaccination regimes. In these groups 100% of the PBFIPV-DF-2-R3i immunised animals developed antibody-dependent enhancement (ADE). Prolonged survival was observed in 40% of the animals, while 60% showed fulminant disease course. Genetic and more probably immunological differences between the SPF and non-SPF purebred kittens can explain the different outcome of the vaccination experiment. Our data highlight the diverse immune responses between SPF and conventional cats and suggest a decisive role of previous infection by heterologous causative agents in the outcome of the vaccination against FIP.
authors: National Food Chain Safety Office, Veterinary Diagnostic Directorate, Budapest, Hungary. Electronic address: balintad@nebih.gov.hu.
authors: Ádám
authors: Á
authors: Bálint
authors: National Food Chain Safety Office, Directorate of Veterinary Medicinal Products, Budapest, Hungary.
authors: Attila
authors: A
authors: Farsang
authors: National Food Chain Safety Office, Veterinary Diagnostic Directorate, Budapest, Hungary.
authors: Levente
authors: L
authors: Szeredi
authors: Institute for Veterinary Medical Research, Centre for Agricultural Research, Hungarian Academy of Sciences, Budapest, Hungary.
authors: Zoltán
authors: Z
authors: Zádori
authors: Department of Virology, Immunobiology and Parasitology, National Veterinary Institute, SVA, Uppsala, Sweden.
authors: Sándor
authors: S
authors: Belák
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing; D002371:Cat Diseases / Q000276:immunology / Q000517:prevention & control; D002415:Cats / Q000276:immunology*; D018352:Coronavirus Infections / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary*; D016765:Coronavirus, Feline / Q000235:genetics* / Q000276:immunology*; D005243:Feces / Q000821:virology; D013047:Specific Pathogen-Free Organisms / Q000276:immunology*; D014611:Vaccination / Q000662:veterinary*; D014614:Vaccines, Synthetic / Q000276:immunology; D014765:Viral Vaccines / Q000276:immunology*
chemical_list: D057134:Antibodies, Neutralizing; D014614:Vaccines, Synthetic; D014765:Viral Vaccines
keywords: Feline coronavirus; Feline infectious peritonitis; Protection; Vaccine