Research overview: FeLV testing with ELISA and IFA

FeLV diagnosis centers on detecting viral p27 antigen. Point-of-care ELISA tests detect soluble antigen in blood and are highly sensitive for screening, while immunofluorescent antibody (IFA) testing detects antigen within blood cells and tends to indicate established, persistent infection. Discordant results between methods, and between time points, reflect the dynamic outcomes of exposure, prompting retesting protocols. PCR for proviral DNA adds the ability to identify regressive infections. This overview gathers diagnostic guidance across the literature rather than one citation, explaining the biological basis for each test, why guidelines recommend confirming positive screening results and retesting after intervals, and how combining antigen and molecular tests gives a clearer picture of an individual cat's true infection status.