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本实验用紫外线诱变福氏志贺氏菌2a、3a型,使其发生了生化突变,耐药性突变和抗原性变异等现象。福氏2a菌对鼠李糖和蕈糖不发酵,经诱变后变为发酵株,对红霉素耐药变为敏感菌株。福氏3a菌株在各种糖培养基中可发生型抗原和群抗原丢失现象。诱变后的福氏2a-A_2菌在伊红美兰培养基上传代连续三次分化出福氏3a型菌。这种突变仅发生在极少数营养缺陷型菌株中。本实验选育出一株福氏3a-A_2 met~-(甲硫氨酸缺陷型)无毒株,免疫家免后的抗体血清效价比原始株高10倍,其免疫保护率为100％,此菌株可用于制作痢疾杆菌活菌苗。
In this experiment, we induced mutagenesis of Shigella flexneri 2a and 3a by ultraviolet light, which led to the phenomenon of biochemical mutation, drug resistance mutation and antigenic variation. The bacteria of Freund’s 2a did not ferment rhamnose and mushroom sugar and became mutagenized into fermentative strains, which became resistant strains to erythromycin. 3 strains of Fu Shi in a variety of sugar-based antigens and group antigen can be lost phenomenon. Mutagenized 2a-A_2 bacteria were cultured on Erigeron three generations successively for three generations to differentiate to form type 3 bacteria. This mutation occurs only in the very few auxotrophic strains. In this experiment, a strain of 3a-A 2 met ~ (methionine-deficient) non-virulent strain was bred. The serum antibody titer of the antibody was 10 times higher than that of the original strain, and its immune protection rate was 100% , This strain can be used to make Shigella live vaccine.