EXPERIMENTAL VIABLE VACCINE AGAINST PULMONARY COCCIDIOIDOMYCOSIS IN MONKEYS

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Abstract
Monkeys (Macaca mulatta) vaccinated by subcutaneous injection in the forearm with from 10 to 108 viable Coccidioides immitus arthro-spores were protected against respiratory challenge with approximately 7000 viable arthrospores administered 6 months after vaccination. Protection was evident from the healthy appearance throughout 4 months after respiratory challenge; negative chest X rays at 15, 30, 60, and 120 days; and only very minor histopathological pulmonary changes on autopsy at 120 days, with negative lung cultures in 80% of the animals. This was in striking contrast to the outward clinical appearance of control monkeys that were unvaccinated or had received nonviable arthrospore vaccines. These monkeys showed severe disease (loss of weight, accelerated respiration, severe coughing, general debilitation), positive X-rays, massive pulmonary destruction, positive lung cultures, and death of five of nine animals. The appearance of spherules (very few in number, accompanied by very minor pathological changes) in the lungs of some of the "dissemination controls" (subcutaneous viable vaccination without respiratory challenge) indicated possible dissemination from the primary cutaneous infection, although oral transmission from the cutaneous lesions could not be ruled out.