Evaluation of feline immunodeficiency virus and feline leukemia virus transmembrane peptides for serological diagnosis.

The general model for retrovirus transmembrane (TM) proteins proposed by Gallaher et al. (W. R. Gallaher, J. M. Ball, R. F. Garry, M. C. Griffin, and R. C. Montelaro, AIDS Res. Hum. Retroviruses 5:431-440, 1989) suggests that all retrovirus TM proteins may contain an immunodominant domain (Imd-TM peptide) located at the apex of the TM polypeptide. Although this Imd-TM peptide has been shown to be immunodominant in a variety of lentivirus infections, there has not been a detailed serological analysis of an oncovirus Imd-TM peptide as a diagnostic agent. We describe here an analysis of the antigenic properties and diagnostic potentials of the predicted Imd-TM peptides of feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) in serological assays of sera from infected cats. The results of these studies demonstrate that antibodies specific to the FIV Imd-TM peptide are detected within 2 weeks postinfection, are maintained at high levels for extended periods, and are not detectable in uninfected or FeLV-infected cats. In marked contrast, the FeLV Imd-TM peptide displayed only negligible levels of serological reactivity in FeLV-infected cats. These studies indicate that the peptide is a useful reagent for the detection of antibodies to FIV.