Evaluation of an autologous red cell agglutination test, VetRED FIV, for the presence of FIV antibody in cats.

A commercially available whole blood agglutination test, VetRED FIV, used for the detection of antibodies to feline immunodeficiency virus (FIV), was evaluated. The test is based on the use of a synthetic peptide conjugated to a non-agglutinating anti-feline red blood cell monoclonal antibody. The amino acid sequence of the synthetic peptide was derived from the predicted sequence of the transmembrane protein of FIV. The sensitivity and specificity of VetRED FIV was 100% when 34 known FIV-positive and 15 known FIV-negative cats were tested. These cats were part of studies on experimentally induced FIV infection, with their FIV status confirmed by virus isolation. Further, VetRED FIV was compared with another commercially available test for FIV antibody, PetChek in a field trial on 548 feline blood samples received by a diagnostic laboratory. Of the test results 94.2% (516/548) were in agreement: 112 were positive by VetRED FIV and PetChek; 404 were negative by both tests and 32 were discordant. These 5.8% discordant samples producing VetRED FIV-positive/PetChek-negative or VetRED FIV-negative/PetChek-positive were further assessed by Western blot assay. In the field trial, the sensitivity and specificity of VetRED FIV was 97% and 97%, respectively, comparable to the 98% sensitivity and 99% specificity for PetChek. The results from the trial also confirm the relatively high overall prevalence of FIV in Australian cats predominantly among mature male cats in the 9-12 year age group. Given the simplicity of the VetRED FIV procedure, it is concluded that VetRED FIV is a useful addition to the available commercial tests for FIV infection.