Levy, J. K., P. C. Crawford, et al. (2008). "Differentiation of feline immunodeficiency virus vaccination, infection, or vaccination and infection in cats." J Vet Intern Med 22(2): 330-4.
Diagnosis of feline immunodeficiency virus (FIV) is complicated by the fact that no commercially available tests can differentiate between naturally infected cats and cats that have been vaccinated against FIV. After vaccination, cats produce antibodies that to date have been indistinguishable from those induced by natural infection. A discriminant enzyme-linked immunosorbent assay (ELISA) was developed that detects antibodies against formalin-treated FIV whole virus and untreated transmembrane peptide. In this study, blood samples from 73 uninfected and unvaccinated cats, 89 uninfected FIV-vaccinated cats, 99 unvaccinated FIV-infected cats, and 3 FIV-infected and vaccinated cats were tested. The discriminate ELISA correctly identified all uninfected cats, giving a specificity of 100%. Of the FIV-infected cats, 99 were correctly identified, giving a sensitivity of 97.1%. Other than virus isolation, which is not widely available and is time-consuming and expensive, this discriminate ELISA is the most reliable test for diagnosis of FIV. When this test becomes available at referral diagnostic laboratories, a new strategy for FIV testing would be to use the existing patient-side antibody assay as a screening test, and confirm positive results with the discriminant ELISA.
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Kusuhara, H., T. Hohdatsu, et al. (2007). "Serological differentiation of FIV-infected cats from dual-subtype feline immunodeficiency virus vaccine (Fel-O-Vax FIV) inoculated cats." Vet Microbiol 120(3-4): 217-25.
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