title: Gamma radiation effects on Sporothrix schenckii yeast cells.
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.
authors.affiliation: Laboratório de Radiobiologia, Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Rua Prof. Mario Werneck, s/n, Pampulha, Campus de UFMG, Caixa postal 941, Belo Horizonte, MG CEP 30123-970, Brazil.
authors.forename: Camila Maria de Souza
authors.initials: CM
authors.lastname: Lacerda
authors.forename: Estefânia Mara do Nascimento
authors.initials: EM
authors.lastname: Martins
authors.forename: Maria Aparecida
authors.initials: MA
authors.lastname: de Resende
authors.forename: Antero Silva Ribeiro
authors.initials: AS
authors.lastname: de Andrade
mesh_terms: D000818:Animals; D004271:DNA, Fungal / Q000528:radiation effects; D005657:Fungal Vaccines / Q000737:chemistry / Q000528:radiation effects; D005720:Gamma Rays; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D013175:Sporothrix / Q000254:growth & development / Q000378:metabolism / Q000472:pathogenicity / Q000528:radiation effects*; D013174:Sporotrichosis / Q000382:microbiology / Q000628:therapy; D014613:Vaccines, Attenuated / Q000737:chemistry / Q000528:radiation effects
chemical_list: D004271:DNA, Fungal; D005657:Fungal Vaccines; D014613:Vaccines, Attenuated