There are two stages of FeLV: primary and secondary viremia. Primary viremia is the stage where the cat has the ability to destroy the virus with an immune response, and the infection is often transient. Once the virus progresses to secondary viremia, most cats will have the virus for life as it is now circulating in the blood stream. Diagnosis can be made on the basis of clinical signs and biochemical and laboratory testing. Different tests can be used to diagnose each stage of the virus. Enzyme Linked Immunosorbent-Assay (ELISA) tests detect the presence of antibodies, although they can also be modified to account for the presence of viral antigens in whole blood, serum, plasma, or saliva as well. The most common antigen detected by diagnostic tests such as ELISA or indirect immunofluorescent antibody assays is an antigen known as p27. ELISA tests can detect primary and secondary viremia. Indirect immunofluorescent antibody assay can only detect secondary viremia. Indirect immunofluorescent assays detect viral antigen in circulating WBCs and platelets. Techniques such as virus isolation and western blot can also be utilized. It is also common to obtain FeLV test kits that can be performed at the vet office. Monoclonal antibodies have also been used against the p27 core protein of the feline leukemia virus. In addition,cats that can fight off this retrovirus will have higher levels of Virus Neutralizing Antibody directed against gp70 (a virulent protein present on the envelope of the cell). PCR assays are also used to detect viral RNA or proviral DNA.
Feline Leukemia Virus snap test
AAFP, 2006; Hartmann et al., 2001; Levy et al., 2001; Lutz et al., 1983; Scott et al., 2007; Torres, 2005;