Control of Tissue Reactions in Monkeys Vaccinated with Viable Coccidioides immitis by Prevaccination with Killed Coccidioides immitis.

Converse, J. L. (U.S. Army Biological Laboratories, Fort Detrick, Frederick, Md.), G. A. Deauville, E. M. Snyder, J. G. Ray, and M. E. Seaquist. Control of tissue reactions in monkeys vaccinated with viable Coccidioides immitis by prevaccination with killed Coccidioides immities. J. Bacteriol. 90:783-788. 1965.-Control of undesirable tissue reactions resulting from the subcutaneous injection of 150 viable arthrospores of Coccidioides immitis (strain D-76) was obtained by four injections of formalin-killed arthrospores 14, 12, 8, and 4 weeks (total dose, 36 mg) before injection of the viable arthrospores. Only 6 and 12% of these vaccinated animals exhibited ulceration and lymphadenopathy, respectively, as compared with 100 and 83% of the animals receiving only the viable vaccine. Agar-gel immunodiffusion precipitin titers of approximately 1:64 were evident 3 months after vaccination in animals receiving both vaccines, as compared with 1:128 in those injected with the viable vaccine alone. The above data indicated that somatic reactions to injection of a viable vaccine could be eliminated by preinjection of a killed vaccine. However, 6 months after vaccination, respiratory challenge (7,500 strain Cash arthrospores) indicated that this treatment also impaired the protective effect of the viable vaccine. All animals receiving both vaccines developed mild pulmonary coccidioidomycosis, whereas only 50% of the animals receiving only the viable vaccine were infected. In addition, the group receiving both vaccines demonstrated a more rapid and higher postchallenge precipitin titer. All vaccinated animals (those receiving the killed, the viable, or a combination of the two vaccines) survived for 4 months after challenge, as compared with 88% mortality (50% within 14 days) in the nonvaccinated controls.