Cross-sectional quantitative RT-PCR study of feline coronavirus viremia and replication in peripheral blood of healthy shelter cats in Southern California

Abstract

Objectives The objectives of this study were to determine the prevalence of feline coronavirus (FCoV) viremia, and its replication in peripheral blood using quantitative RT-PCR (qRT-PCR) methodology in a population of 205 healthy shelter cats in Southern California, as well as to assess any possible connection to longitudinal development of feline infectious peritonitis (FIP). Methods The study was performed on buffy-coat samples from EDTA-anticoagulated whole blood samples of 205 healthy shelter cats. From 50 of these cats, fecal samples were also examined. FCoV genomic and subgenomic RNA in the buffy coats was amplified by a total FCoV RNA qRT-PCR. Evidence for FCoV replication in peripheral blood and feces was obtained by M gene mRNA qRT-PCR. Results Nine of 205 cats (4.4%) were viremic by the total FCoV RNA qRT-PCR, and one of these cats had evidence of peripheral FCoV blood replication by an FCoV mRNA qRT-PCR. The single cat with peripheral blood replication had a unique partial M gene sequence distinct from positive controls and previously published FCoV sequences. Neither seven of the nine viremic cats with follow-up nor the single cat with replicating FCoV with positive qRT-PCR results developed signs compatible with FIP within 6 months of sample collection. Conclusions and relevance FCoV viremia and peripheral blood replication in healthy shelter cats have a low prevalence and do not correlate with later development of FIP in this study population, but larger case-control studies evaluating the prognostic accuracy of the qRT-PCR assays are needed.

Prevalence of Feline Coronavirus Shedding in German Catteries and Associated Risk Factors

“…No increase in virus shedding could be found in any of these cats, indicating that stress had no influence on FCoV shedding in the examined population [43]. Although a shelter environment is assumed to be more stressful for cats than a breeding cattery environment, the prevalence of FCoV shedding in this population was higher than many of the prevalence previously reported from shelters [16,20,23,54]. Thus, also a breeding cattery environment with more than five cats might represent a stressful situation for the individual animal.…”

“…The prevalence of FCoV shedding has been investigated in several countries by testing fecal samples or rectal swabs for FCoV RNA by reverse transcriptase polymerase chain reaction (RT-PCR), and the results range from 31.8% to 100.0% [10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Crowded living conditions and sharing litter boxes have been discussed as predisposing factors, but there are only a limited number of studies prospectively evaluating risk factors for FCoV shedding.…”

Discrepancies between feline coronavirus antibody and nucleic acid detection in effusions of cats with suspected feline infectious peritonitis

“…In fact, they are not able to distinguish between enteric and virulent FCoVs, since no specific genetic markers have been identified for the latter strains. In addition, the enteric FCoVs have been proven to cause transient viremia and even have a low replication in the blood (Can-Sahna et al, 2007;Kipar et al, 2010;Fish et al, 2017), thus potentially being able to passively spread to the effusions associated to other diseases.…”

Diagnosis of Feline Infectious Peritonitis: A Review of the Current Literature

“…However, over the years, it has been shown that FCoV RNA could also be detected in the blood of asymptomatic cats and cats with diseases other than FIP [143,144]. Several studies evaluating the use of RT-PCR in serum, plasma or whole blood confirmed this finding of possible FCoV viremia in cats without FIP [16,80,106,145,146,147]. Additionally, a recent study demonstrated that FCoV viremia does not even predict the development of FIP, as none of the healthy cats that tested positive for genomic or replicating FCoV developed FIP or clinical illness within six months of testing [147].…”