Anigen Rapid FIV Ab/FeLV Ag Testkit

FeLV is transmitted through close contact between cats. Generally, it is transmitted vertically and horizontally from infected queens to their kittens, and horizontally between cohabiting or feuding cats. There is an age-related increase in resistance to FeLV infection; Kittens are at the highest risk of becoming progressively infected. However, some studies have shown effective natural and experimental infection in adult cats. 

Progressively infected cats shed infectious viruses in body fluids, including saliva, nasal discharge, milk, urine, and feces.  Cats typically acquire FeLV via the oral route, but can also become infected through bite wounds. After virus exposure via the oronasal route, FeLV can first be found in the local lymphoid tissues; then it spreads to the periphery via monocytes and lymphocytes (primary viremia; see “Terminology” on page 24). During this primary viremia, the virus can infect the bone marrow.  Secondary viremia can occur after bone marrow infection, in which FeLV-containing leukocytes and platelets appear in the blood, resulting in the virus being detectable by an immunofluorescent antibody (IFA) test.

Based on molecular methods, the possible consequences of infection after FeLV exposure have been redefined. episodes of FeLV infection are now classified as abortive infection (comparable to the earlier “regressor cats”), regressive infection (comparable to the earlier “latent infection”, with or without prior “transient viremia”) and progressive infection ( comparable to the earlier „persistent viremia“). The probability of each result depends on the infection pressure and the cat’s immune status and has been described in experimental infections with certain pathogen-free cats.

Historically, exposure to FeLV has been reported to result in abortive infection in 20-30% of cats, regressive infection in 30-40% of cats, and progressive infection in 30-40% of cats.  However, large field studies testing simultaneously for p27 antigen, proviral DNA, viral RNA and virus-neutralizing antibodies have identified a higher proportion of cats suspected of having neutralizing antibodies based on a pattern of negative antigen and PCR testing abortive infections have occurred. In a study of 495 domestic cats in Germany, 4% were classified as having an abortive infection, 2% as progressive and 1% as regressive.In a study of 440 domestic cats in Australia, 11% were classified as presumptively abortive, 2% as presumptively regressive, and 0.5% as presumably progressive.

This suggests that abortive infection may be the most common outcome after exposure under typical conditions. In contrast, in two populations of cats in Australia (a group of 38 cats and a group of 51 cats) in which FeLV-infected and uninfected cats were mixed without separating healthy from clinically ill cats, 9% were considered abortive classified infection, 25% as regressive and 21% as progressive, suggesting that infection resistance can be compromised by intense infection pressure, comorbidities, and a stressful environment.

 Viral RNA is normally detectable in plasma by real-time reverse transcriptase-polymerase chain reaction (qRT-PCR) assays within 1 week of FeLV exposure, followed by proviral DNA detection by PCR within 2 weeks of exposure, and finally by FeLV- Antigen detection, which usually occurs after 30 days but may take longer in some cats. Not only cats with progressive infection go through the early stages, but also some cats with regressive infection. These regressively infected cats have similar proviral and plasmaviral RNA loads in their peripheral blood early in infection; However, unlike cats with progressive infection, their viral load decreases to undetectable levels over time.