A diagnosis of feline infectious peritonitis is still among the worst concerns a cat owner can face; there is no cure available, and none on the horizon. The FIP virus (FIPV) is difficult to detect, and the disease is nearly always fatal. Therefore, detecting and eliminating this virus from the cat population remains a top priority of veterinary medicine.

The disease was first identified in the 1960s, and shown to be caused by a member of the coronavirus family of RNA viruses some ten years later. The first diagnostic problem arose when the virus proved exceptionally difficult to grow in culture, thus closing one usual route of diagnosis. By the 1980s FIPV had been demonstrated to belong to a huge family of closely related viruses, and to have numerous strains, each producing strain-specific effects. A closely related virus, named Feline Enteric Coronavirus (FECV) was found to be virtually indistinguishable from FIPV, but induced very different pathologic changes. A11 of these viruses and variants are impossible to distinguish by the usual methods, such as detection with monoclonal or polyclonal antibodies directed against the virus coat protein(s). Thus, previously developed tests for FIPV, including the coronavirus antibody titer test, are incapable of differentiating between pathogenic and nonpathogenic coronaviruses, or even between feline, canine or human coronaviruses. A positive titer in these tests is inconclusive and of little value in detecting and removing infected carrier cats from a multicat household or cattery.

Attempts to develop safe and efficacious vaccines against FIPV have been largely unsuccessful. This reflects the nature of FIPV which spreads via infected macrophages and monocytes. The resulting damage is due to an intense immune reaction and localized inflammatory response at tissue sites of viral colonization. In this situation, development of antibodies to the virus can aggravate the disease, making the use of vaccines problematical.

Another approach, that of isolating symptomatic cats, also rarely succeeds because of the unique characteristics of FIPV. Cats infected with FIPV have been shown to be most contagious between days 2-15 post infection, prior to the display of any symptoms. It is not known whether direct contact with infected nasal, oral, or digestive secretions is required to spread the disease, if contaminated food or water bowls are sufficient, or if the virus can even be airborne. The true incidence of carrier cats is also unknown, but may exceed 10% in multicat facilities or households. Diagnosis of symptomatic cats may be difficult since FIP can appear clinically in two forms. In the so-called effusive (or "wet") form, FIP cats develop large amounts of peritoneal fluid and die quickly, whereas in the dry form, symptoms include general lethargy, and a variety of nonspecific problems such as kidney and liver failure, and central nervous system involvement.

Even the symptoms of wet FIP mimic many other causes, including cancer and peritonitis. The definitive diagnosis of FIP is usually made post-mortem when histopathological examination of inflammatory lesions demonstrates classic FIP appearance.

The challenge, therefore, is to create a diagnostic test to distinguish relevant FIPV strains from the numerous other coronaviruses. Using powerful new technology developed through collaboration with Synbiotics Corp. and based upon the polymerase chain reaction (PCR), the presence of FIPV genes is detected rather than the coat viral protein(s) of existing tests.