DETECTION OF FELINE CORONAVIRUS TYPE-II I NFECTIONS IN BLOOD OF CATS USING A REVERSE-TRANSCRIPTASE POLYMERASE-CHAIN REACTION (RT-PCR)

In order to detect coronaviral RNA in blood samples of cats infected w ith feline coronaviruses type II a reverse transcriptase PCR (RT-PCR) was developed. 81 blood samples were tested in parallel for the presen ce of viral RNA by the RT-PCR and for antibodies using an immunofluore scence assay. 39 % of the clinically healthy cats without a special ri sk of coronavirus infection were seropositive and 57 % PCR-positive; i n the group of clinically healthy cats, but with a higher risk for inf ection, 85 % showed antibodies and 95 % were identified as virus carri ers; 100 % of the cats with symptoms of Feline Infectious Peritonitis (FIP) were seropositive and 90 % PCR-positive; in the group of cats wi th unspecific clinical symptoms 61 % were seropositive and 82 % PCR-po sitive. In 57 % of the seronegative animals viral RNA could be detecte d. As most of these cats were between 8 and 12 weeks of age, it is pro bable that the blood samples were collected during the time of serocon version after the first infection with feline coronaviruses. These res ults show that the RT-PCR proves helpful in identifying latent virus c arriers, not only among seropositive animals, but especially among ser onegative cats during the period of seroconversion. So it will be a to ol to prevent spreading of feline coronavirus infections into free cat teries. However, the RT-PCR is not suitable for diagnosing FIP, as a h igh percentage of virus carriers was detected among ill as well as hea lthy cats.