PATHOGENICITY STUDIES OF FELINE CORONAVIRUS ISOLATES 79-1146 AND 79-1683

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  • 1 January 1984
    • journal article
    • research article
    • Vol. 45  (12) , 2580-2585
Abstract
Two feline coronavirus isolates were characterized by their disease-causing potential in cats. The 79-1683 feline coronavirus isolate caused an inapparent-to-mild enteritis when given oronasally to specific-pathogen-free kittens and was not a cause of feline infectious peritonitis (FIP). Target tissues for the virus were the mature apical epithelium of the small intestine, mesenteric lymph nodes, tonsils, thymus, and (to a lesser extent) the lungs. Inoculated kittens shed high numbers of virus in their feces for 14-17 days, but remained infectious to susceptible kittens for longer periods of time, as evidenced by contact-exposure studies. Because the 79-1683 isolate induced only enteritis, it was designated feline enteric coronavirus (FECV) 79-1683. The 79-1146 feline coronavirus isolate induced effusive abdominal FIP in specific-pathogen-fee kittens after oronasal and i.p. inoculation. Clinical signs of disease appeared within 12 to 14 days in almost all inoculated kittens. Because this isolate caused FIP, it was designated FIP virus (FIPV) 79-1146. Cross-protective immunity was not induced by the various coronavirus infections. Kittens preimmunized with the UCD strain of FECV (FECV-UCD) or with FECV-70-1683 were not immune to infection with FIPV-79-1146. Kittens previously inoculated with FECV-79-1683 were not immune to infection with FIPV-UCD1. In fact, preexisting heterologous FECV-79-1683 immunity often accelerated and enhanced the severity of disease caused by inoculation with FIPV-UCD1. This enhancing effect was not seen when FECV-UCD and FECV-79-1683 immune cats were challenge exposed with FIPV-79-1146. The FIPV-79-1146 caused disease only after an incubation period of 12-14 days, regardless of whether or not the kittens had preexisting feline coronavirus immunity and regardless of what FECV strain was used to induce that immunity. One kitten that recovered from FECV-79-1683 was immune to FIPV-79-1146 infection, and a second such kitten developed FIP.