Genetic and antigenic characterization of caev (caprine arthritis-encephalitis virus) recombinant transmembrane protein.

The env gene fragment of an Italian strain of Caprine Arthritis Encephalitis virus (CAEV) coding for the hydrophilic region of transmembrane protein was amplified, cloned and expressed in prokaryotic system as fusion protein with glutathione-S-transferase. Sequence analysis revealed 63 to 66% amino acid homology, when compared with three ovine lentiviruses and 83% when compared with one caprine lentivirus. The recombinant transmembrane protein was efficiently expressed, purified under denaturing conditions and used as antigen in western blotting and ELISA. Sera from clinically diseased goats strongly reacted in western blotting and naturally infected animals seroconverted between 20 and 33 weeks of age. An indirect ELISA performed with this antigen showed improved sensitivity in comparison with agar gel immunodiffusion test. Our results confirm that transmembrane protein is an important immunological marker in CAEV infection and its use as antigen may enhance the validity of serological diagnosis of Caprine Arthritis Encephalitis.