Smith H W, Huggins M B
J Gen Microbiol. 1980 Dec;121(2):387-400. doi: 10.1099/00221287-121-2-387.
From an O18ac:K1:H7 ColV+ strain of Escherichia coli (designated MW) that had caused meningitis in a human baby, mutant forms were isolated that lacked different combinations of its O, K and H antigens and its ColV plasmid. These characters were also transmitted by conjugation to E. coli K12 and the virulence, immunogenicity and other properties of the different forms of both strains were studied. All the forms of the MW strain that lacked either the O18 or K1 antigens or the ColV plasmid, but not the H7 antigen, were much less virulent for chickens and mice than the parent form of MW. Another form derived by N-methyl-N'-nitro-N-nitrosoguanidine (NTG) treatment of the parent strain and that possessed all these four characters was also much less virulent. Some of the forms of the K12 strain to which the characters had been transferred were slightly more virulent than the K12 parent, but the virulence of all of them, including one possessing the O18 and K1 antigens and the ColV plasmid, did not approach that of the MW parent. Pathogenesis studies in chickens and colostrum-deprived calves revealed that the loss of virulence exhibited by the forms of the MW strain that lacked O18, K1 and ColV and by the NTG-derived form was associated with decreased ability to invade the body. This was also the reason for the ow virulence of the forms of the K12 strain that had acquired these characters. Possession of both the O18 and K1 antigens was largely responsible for the ability of the different forms of the MW strain to survive in fresh chicken serum; organisms of K12 that possessed the K1 antigen survived as long as those of the parent form of the MW strain. A substantial degree of immunity against lethal infection with the parent form of the MW strain was produced in chickens and mice by all the forms of the MW and K12 strains that possessed the O18 antigen. The K1 and H7 antigens and the ColV plasmid produced no detectable immunity.
从一株曾导致一名人类婴儿患脑膜炎的大肠杆菌O18ac:K1:H7 ColV+菌株（命名为MW）中，分离出了缺乏其O、K和H抗原以及ColV质粒不同组合的突变形式。这些特性也通过接合作用传递给了大肠杆菌K12，并对两种菌株不同形式的毒力、免疫原性和其他特性进行了研究。MW菌株所有缺乏O18或K1抗原或ColV质粒但不缺乏H7抗原的形式，对鸡和小鼠的毒力都比MW的亲本形式低得多。通过N-甲基-N'-硝基-N-亚硝基胍（NTG）处理亲本菌株得到的另一种形式，具有所有这四个特性，其毒力也低得多。特性已转移至的K12菌株的某些形式比K12亲本的毒力略高，但包括一种具有O18和K1抗原以及ColV质粒的所有形式的毒力都未达到MW亲本的水平。在鸡和初乳缺乏的犊牛中进行的发病机制研究表明，缺乏O18、K1和ColV的MW菌株形式以及NTG衍生形式所表现出的毒力丧失与入侵机体的能力下降有关。这也是获得这些特性的K12菌株形式毒力低的原因。O18和K1抗原的存在在很大程度上决定了MW菌株不同形式在新鲜鸡血清中存活的能力；具有K1抗原的K12菌株的存活时间与MW菌株亲本形式的相同。所有具有O18抗原的MW和K12菌株形式在鸡和小鼠中都产生了对MW菌株亲本形式致死感染的相当程度的免疫力。K1和H7抗原以及ColV质粒未产生可检测到的免疫力。
