CAPRINE ARTHRITIS-ENCEPHALITIS LENTIVIRUS (CAEV) CHALLENGE OF GOATS IMMUNIZED WITH RECOMBINANT VACCINIA VIRUS EXPRESSING CAEV SURFACE AND TRANSMEMBRANE ENVELOPE GLYCOPROTEINS

This study evaluated infection and disease following caprine arthritis-encephalitis lentivirus (CAEV) challenge of goats with existent immune response to CAEV surface and transmembrane envelope glycoproteins. Six Saanen goats were vaccinated three times with recombinant vaccinia virus rWR63 expressing glycoproteins encoded by the CAEV-63 envelope gene. Two goats were immunized with rWRSC11, a control vaccinia virus derived from the pSC11 vaccinia expression plasmid without the CAEV envelope gene. One pair of rWR63 vaccinated goats received a booster immunization with recombinant surface glycoprotein in Freund's complete adjuvant, a second pair was boosted by intravenous inoculation with rWR63, and the third pair was boosted by immunization with HPLC purified native CAEV surface glycoprotein in Freund's complete adjuvant. All six goats vaccinated with rWR63 developed antibody responses to CAEV envelope glycoproteins; however, CAEV-63 neutralizing antibody was not detected. Neither of the rWRSC11-vaccinated goats developed CAEV reactive antibody. All goats were challenged by intravenous inoculation with 10(6) TCID50 CAEV-63. All goats became infected following challenge infection, shown by detection of serum antibody to CAEV core proteins and virus isolation. Existent CAEV-63 immune responses did not detectably alter the severity of inflammatory joint lesions at 24 weeks postchallenge.