Feline coronaviruses: differentiation of the types I and II by RT-PCR and their occurrence in Austrian cat populations

Feline coronaviruses (FCoV) show high variation in virulence. In addition, they are divided into two types according to some biological features. Only sporadic information is available about their regional occurrence, no inve stigations had been performed in Austrian cat populations. An RT-PCR was es tablished using two primer pairs amplifying parts of the spike protein gene . According to the FCoV type detected, the PCR products varied in size. 160 cats were investigated for the presence of FCoV types I and II by RT-PC R and for antibodies against coronaviruses (antigenic group 1) by immunoflu orescence. In order to avoid any influence of preferences of types causing Feline Infectious Peritonitis (FIP) only cats without specific signs of FIP were tested. 71.1 % of the cats were seropositive. Viral nucleic acid FCoV type I was detected in 18.8 %, type II in 11.9 %; in 4.4 % of these animal s both types were found. In total, 26.3 % of the cats tested positive for F CoV nucleic acid in blood. As it has to be assumed that in clinically healt hy, persistently infected cats only few cells of the intestinal tract may b e affected, the percentage of latent virus carriers in Austrian cat populat ions may be higher. No significant correlation was found between the results of the RT-PCR and the antibody titres. Therefore concerning the material of the presented stu dy the antibody titre does not give any information about the probability o f cats being latent virus carriers. The RT-PCR described was shown to be useful for epidemiological investigati ons concerning the FCoV types. First results could be achieved for the Aust rian cat populations. The question about the frequency of the FCoV types I and II causing FIP remains open.