ABSTRACT
A quantitative assay was performed on the effects of gamma-irradiation (30-300 Gy) on intracellular proliferation of Toxoplasma gondii RH tachyzoites in human leukemic HL-60 cells and murine peritoneal macrophages by means of 3H-uracil uptake assay. Infected non- irradiation group (NI) and uninfected group (incubating only host cells) were prepared. The 3H-uracil uptake by tachyzoites of NI group 12-24 hrs after infection was 2,190-4,787 counts per minute for macrophages and 2,967-8,254 for HL-60 cells, whereas the irradiated tachyzoites revealed only 381-703 (100 Gy) and 218-408 (300 Gy) for macrophages, and 1,911-2,618 (30 Gy), 1,253-1,384 (70 Gy), 1,013-1,090 (100 Gy), and 483-588 (300 Gy) for HL-60 cells. The proliferation inhibition rate was similar in macrophages and HL-60 cells, for example, 89-94% and 80-94% respectively by 300 Gy, 12-24 hrs after infection. It is concluded that RH tachyzoites of T. gondii are severely affected by gamma-irradiation in their capability of intracellular proliferation.
Subject(s)
Humans , Mice , Animals , Cell Division/radiation effects , Cells, Cultured , Gamma Rays , HL-60 Cells/parasitology , Macrophages/parasitology , Mice, Inbred BALB C , Mice, Inbred ICR , Radiation Dosage , Toxoplasma/radiation effectsABSTRACT
The use of nuclear power through radiation for the destruction of microorganisms which cause food decay, infections and toxicosis, is specially for peacefull purposes. Toxoplasma gondii is a protozoa responsible for illness in humans and animals. One of the most common ways of transmission is through raw or poorly cooked meat. There is little information on the resistance of T. gondii to radiation. The objective of this research is to determine the Minimun Lethal Dose (MLD) of gamma radiation for these microorganisms. Suspensions of T. gondii containing approximately one million taquizoites/ml were irradiated with doses between 0.01 up to 0.15 HGy (kiloGray) and inoculated to mice. The surviving T gondii were re-irradiated with 0.01 up to 0.16 HGy. The irradiated protozoa were totally destroyed with 0.15 HGy dose (MLD). Taquizoites issued from live protozoa of 0.14 KGy, also were completely destroyed with dose of 0.15 KGy. No increase in resistance was observed regarding the non irradiated protozoa