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 multiple PCRs at a reduced cost: 2 samples ($130), 3 samples ($190), … see MD Submission Form .
In this FIP mRNA Multi-test, several independent samples from the same cat are examined. The aim of the FIP mRNA Multi Test is to maximize the predictive value for confirmation as well as exclusion of FIP (near 100% positive and negative predictive value).
In FIP mRNA-positive cats, FIP mRNA is consistently present at very low copy numbers (less than 5 copies / PCR = less than 100 copies / ml fluid) in the diseased tissue and effusions, and at even lower numbers in blood or buffy coat cells. This explains the historically difficult detection of the virus in FIP, and argues for extensive sampling to maximize diagnostic accuracy.
The FIP mRNA Multi-test offers PCR testing of multiple samples from a cat with symptoms of FIP. Preferred samples that maximize sensitivity are:
1. effusion fluid (ascites, pleural)
2. biopsy or aspirate of the tissue of an affected organ (e.g., kidney, enlarged lymph node)
The addition of a fecal sample will not increase the positive predictive value of the extra-intestinal samples, but negativity in this test will rule out concurrent intestinal feline coronavirus infection. This will increase the negative predictive value of the FIP mRNA Multi-test if all extra-intestinal samples are also negative.
The rationale for the FIP mRNA Multi-test is that:
1. Multiple sampling increases detection sensitivity over single sampling, therefore reducing false negative results;
2. Detection of FIP mRNA in any of the extra-intestinal samples confirms FIP with near 100% specificity;
3. Absence of FIP mRNA in the samples rules out replicating FIPV with high specificity;
4. Detection of FIP mRNA in an additional fecal sample, but not in the extra-intestinal samples, identifies an animal that carries the feline coronavirus or presently undergoes acute infection with the virus. Such animals may be developing FIP, and should be re-tested later or if they develop symptoms of FIP.