ABSTRACT
Sporotrichosis is a subcutaneous mycosis caused by Sporothrix schenckii. Zoonotic transmission to man can occur after scratches or bites of animals, mainly cats. In this study, the gamma radiation effects on yeast of S. schenckii were analyzed with a view of developing a radioattenuated vaccine for veterinary use. The cultures were irradiated at doses ranging from 1.0 to 9.0 kGy. The reproductive capacity was measured by the ability of cells to form colonies. No colonies could be recovered above 8.0 kGy, using inocula up to 10(7) cells. Nevertheless, yeast cells irradiated with 7.0 kGy already were unable to produce infection in immunosuppressed mice. Evaluation by the FungaLight™ Kit (Invitrogen) indicated that yeast cells remained viable up to 9.0 kGy. At 7.0 kGy, protein synthesis, estimated by the incorporation of [L-(35)S] methionine, continues at levels slightly lower than the controls, but a significant decrease was observed at 9.0 kGy. The DNA of 7.0 kGy irradiated cells, analyzed by electrophoresis in agarose gel, was degraded. Cytoplasmic vacuolation was the main change verified in these cells by transmission electron microscopy. The dose of 7.0 kGy was considered satisfactory for yeast attenuation since irradiated cells were unable to produce infection but retained viability, metabolic activity, and morphology.
Subject(s)
Gamma Rays , Sporothrix/radiation effects , Animals , DNA, Fungal/radiation effects , Fungal Vaccines/chemistry , Fungal Vaccines/radiation effects , Humans , Mice , Mice, Inbred BALB C , Sporothrix/growth & development , Sporothrix/metabolism , Sporothrix/pathogenicity , Sporotrichosis/microbiology , Sporotrichosis/therapy , Vaccines, Attenuated/chemistry , Vaccines, Attenuated/radiation effectsSubject(s)
Coccidioidomycosis/immunology , Fungal Vaccines , Leukocytes/immunology , Phagocytosis , Animals , Blood Sedimentation , Coccidioides , Complement Fixation Tests , Dogs , Fungal Vaccines/radiation effects , Humans , Injections, Intramuscular , Leukocyte Count , Male , Mice , Radiation Effects , Skin Tests , Spores, Fungal , Time Factors , VaccinationABSTRACT
An experimental irradiated ((60)Co) arthrospore vaccine against coccidioidomycosis protected approximately 75% of mice from death after an intraperitoneal challenge sufficient to kill approximately 90% of the nonimmunized control mice. Although the majority of the immunized mice became infected with Coccidioides immitis, the histologic lesions were substantially less severe than those in the nonimmunized controls, particularly in the pulmonary region. Although arthrospores irradiated with 1, 2, or 3 million roentgens lost their ability to multiply in various laboratory media (probably through interference with cell division), partial conversion to the parasitic phase (spherule) was observed after animal inoculation (rounding out of arthrospores into immature spherules, but without development of endospores). Duration of viability of these structures has yet to be determined.
