Feline Infectious Peritonitis Virus (FIPV) is a coronavirus, an enveloped, positive-stranded RNA virus. There are many strains of feline coronaviruses. Strains of Feline Coronavirus that cause a mild intestinal disease (diarrhea) are called Feline Enteric Coronavirus (FECV). Strains that cause Feline Infectious Peritonitis (FIP) are thought to be a form of the enteric virus (FECV) that has mutated into the lethal FIPV in the affected cat. The specific mutations that cause low-virulence FECV strains to become high-virulence, FIP-causing strains are not unique and are still poorly understood. All cats that have FIPV also have FECV, whereas not all cats that carry FECV develop FIP (Simons et al., 2005).
Antibodies against Feline Coronavirus are found in 80-90% of the animals living in catteries or multiple-cat households, and in up to 50% of solitary cats; however only some 1-5% of the seropositive cats eventually come down with FIP. Avirulent FECV strains causing inconspicuous infections are responsible for the high seroprevalence (Simons et al., 2005).
FIP is the major infectious cause of mortality in cats (Paltrinieri et al., 2001). Infected cats may develop respiratory infection or intestinal problems. Many cats have nonspecific symptoms such as intermittent loss of appetite, depression, rough hair coat, weight loss, and fever. The hallmark of lethal effusive FIP is accumulation of fluid in abdomen or chest cavity. Noneffusive FIP usually develops slowly, with little fluid accumulation. Symptoms depend on the organs affected. The affected organs often develop a characteristic pyogranulomatous inflammation.
At present, there are no routine serological and virological assays available for an etiological diagnosis of FIP, or to distinguish avirulent FECVs from virulent FIPVs. Although serology is still used in the diagnosis of FIP, it is of very limited value. A definite diagnosis can only be made on the basis of histological examination of biopsy material or postmortem. An important event in FIP pathogenesis is the infection of monocytes and macrophages. Thus, avirulent FECVs remain largely confined to the digestive tract and typically do not spread beyond the intestinal epithelium and regional lymph nodes. FECVs that have entered the bloodstream do not replicate. Virulent FIPVs, on the other hand, leave the gut, enter the bloodstream, replicate in peripheral blood mononuclear cells (PBMC), generalize and reach different organ parenchymas via infected monocytes. FECVs can also be detected in peripheral blood, but do not replicate in PBMC.
Our lab has developed a quantitative PCR targeting subgenomic mRNA of the M gene of Feline Coronavirus with high sensitivity. Thus, our PCR specifically detects and quantifies the replicating virus as opposed to only detecting the presence of viral genomic RNA that may or may not be associated with active viral replication. This approach diagnoses FIP with very high specificity (Simons et al., 2005).
We offer now a panel of 3 FIP mRNA tests at a reduced cost of $95 MD Submission Form.
FIP mRNA Triple Test
Our internal evaluation of the FIP mRNA PCR has shown very high detection rates and FIP mRNA copy numbers in feces of young shelter cats, and much lower fecal detection rates and copy numbers in older and solitary cats. In FIP mRNA-positive cats with symptoms of FIP, FIP mRNA is consistently present at very low copy numbers (less than 5 copies / PCR = less than 100 copies / ml fluid) in blood or peritoneal effusion.
The FIP mRNA Triple Test offers PCR testing of three simultaneous samples from a cat with symptoms of FIP:
The rationale for this test is that: