Penentuan LD50 Penyakit Infeksi Toxoplasma gondii pada Mencit balb/c

Abstract

LD50 determination in toxoplasma gondii infection in balb/c mice Background: LD50 is a marker of virulence which is reflects degree of microorganism pathogenicity. LD50 of every pathogens to be used should be determined in order to choose an appropiate infective dose of agent under the study. Toxoplasma gondii RH strain has been maintained in the laboratory by serial passage in mice for several years, in which the biologic and laboratory conditions might has an effect on its virulence. The objective of this study was to determine LD50 of Toxoplasma gondii RH strain used for research in Biotechnology Laboratory Gajah Mada University. Methods: The design of the study was true experiment consisting three goups of 10 female balb/c mice aged 8–10 weeks that were infected with 101, 103 and 106 of Toxoplasma gondii RH strain/mice respectively, and being followed up to day 18. Homogeneity of mice before infection were analyzed by Levence statistic, while the effects of infection was analyzed by Anova. The number of dead mice in each group were recorded and LD50 was calculated base on proportional distance. Results: There was no weight difference between groups of mice before infection. The weight increased up to day 6 in group I and II, while group III after day 3 there was weight decrease. LD50 of Toxoplasma gondii was 1.39x103 which belonged to genotype II of pathogenicity classification. Conclusions: LD50 of Toxoplasma gondii was 1.39x103 which is lower than the original RH strain, and belonged to group II of genotype, which is often reported as the major cause of human and animal infections.