SEROLOGICAL DIAGNOSIS OF FELINE IMMUNODEFICIENCY VIRUS-INFECTION BASED ON SYNTHETIC PEPTIDES FROM ENV GLYCOPROTEINS

Feline immunodeficiency virus (FIV) is a lentivirus which infects dome stic cats, causing an acquired immunodeficiency syndrome (AIDS). The a im of the present work was the development of an immunoassay for the d iagnosis of FIV infection, using synthetic peptides from FIV envelope (Env) glycoproteins. Four peptides (8 to 11 amino acids long) correspo nding to group-specific epitopes of FIV Env extracellular (SU) or tran smembrane (TM) glycoproteins were synthesized. They were evaluated by enzyme-linked immunosorbent assay (ELISA) for immunoreactivity with se ra from naturally or experimentally FIV-infected cats. One of these, P 237, corresponds to a conserved nonapeptide of FIV TM, folded as a loo p between two cysteines. ELISA performed with P237 on 171 sera from FI V-infected cats and 46 sera from specific-pathogen-free cats showed no false positive cases and 100 % detection of infected cat sera. Moreov er, 47 pet cat sera which were negative with a whole virus-based-ELISA were tested with the P237 ELISA: 2 out of 47 showed reactivity. FIV i nfection of these two cats was confirmed by radio-immunoprecipitation assay. Temporal studies performed on serial serum samples from experim entally infected cats detected antibodies to P237 three to five weeks after inoculation of virus. Thus, the P237 ELISA is a sensitive and sp ecific immunoassay for early detection of antibodies to FIV. In additi on, this synthetic nonapeptide is easier to produce and purify than vi rus preparations or recombinant proteins.