VACCINATION AGAINST FELINE IMMUNODEFICIENCY VIRUS USING FIXED INFECTED-CELLS

Crandell feline kidney cells and feline thymocytes, either feline immu nodeficiency virus (FN) infected or uninfected, were fixed with parafo rmaldehyde and used to vaccinate cats. The cells were mixed with a 30: 70 water/mineral oil emulsion containing 250 mu g ml(-1) eta-(1-4)-N-a cetyl-muramyl-L-alanyl-D-isoglutamin. Eighteen specific pathogen-free cats were vaccinated three times with 3-week intervals and challenged 21 days after the final boost with a low dose of the homologous FIV-UT 113 strain. Eight out of ten cars that had received FIV-infected cell vaccines developed significant anti-FIV antibody titres to the envelop e and core antigens. Neutralizing antibodies were detectable at the mo ment of challenge in the sera of these animals. Within 5 weeks after c hallenge 15 out of 18 cats became viraemic. Three animals, two that ha d been vaccinated with FIV-infected thymocytes and did not develop ant ibody, and one that had received an uninfected thymocyte preparation, remained uninfected for 6 months. Upon rechallenge of the three animal s, two again resisted infection; these cats had been immunized with th e infected and the uninfected thymocyte preparations, respectively.