DETECTION OF FELINE CORONAVIRUS RNA IN FECES, TISSUES, AND BODY-FLUIDS OF NATURALLY INFECTED CATS BY REVERSE-TRANSCRIPTASE PCR

A nested reverse transcriptase PCR (RT-nPCR) was developed for the det ection of feline coronavirus (FCoV) RNA in the feces, tissues, and bod y fluids of infected cats. The RT-nPCR was targeted to the highly cons erved 3'-untranslated region of the viral genome and will detect most, if not all, feline coronaviruses in the field. With the RT-nPCR FCoV RNA was detected in plasma samples from experimentally infected cats a s early as 2 days postinoculation. FCoV RNA was also detected in serum , plasma, or ascitic fluid samples from 14 of 18 cats (78%) with natur ally occurring feline infectious peritonitis (FIP). The use of RT-PCR for FLP diagnosis is limited because of the occurrence of apparently h ealthy FCoV carriers. These asymptomatic cats shed the virus in the fe ces and, in a number of cases, also had detectable virus in the plasma . Because of the nature of FCoV infections, our RT-PCR assay with plas ma or serum cannot be used to establish a definite diagnosis of FIP. H owever, this assay does provide a new means to identify asymptomatic F CoV carriers. As such, RT-nPCR will be of use to screen cats before th eir introduction into FCoV-free catteries. Moreover, this assay provid es ah important tool to study the epidemiology of FCoV.