Shipley P L, Gyles C L, Falkow S
Infect Immun. 1978 May;20(2):559-66. doi: 10.1128/iai.20.2.559-566.1978.
K88 antigen, and important virulence factor in porcine enteropathogenic Escherichia coli (EEC), can be transferred along with the ability to ferment the trisaccharide raffinose (Raf). The plasmids from a number of EEC strains that encode these two properties were isolated and characterized. In most strains the K88 and Raf genes were found on a single nonconjugative plasmid approximately 50 x 10(6) daltons in size. This plasmid core was conserved with only slight variation among the strains tested. In some transconjugants, larger conjugative plasmids were observed that were apparently recombinants between the Raf/K88 plasmid and a transfer fa(tor. Occasionally plasmids carrying only the raffinose fermentation genes arose by deletion of a deoxyribonucleic acid segment of about 20 x 10(6) daltons that included the K88 antigen gene(s).
K88抗原是猪肠道致病性大肠杆菌（EEC）中的一种重要毒力因子，它可随发酵三糖棉子糖（Raf）的能力一起转移。从许多编码这两种特性的EEC菌株中分离并鉴定了质粒。在大多数菌株中，K88和Raf基因位于一个大小约为50×10⁶道尔顿的单一非接合性质粒上。该质粒核心在测试的菌株中仅略有变化，具有保守性。在一些转接合子中，观察到更大的接合性质粒，它们显然是Raf/K88质粒与转移因子之间的重组体。偶尔，通过缺失约20×10⁶道尔顿的包含K88抗原基因的脱氧核糖核酸片段，会产生仅携带棉子糖发酵基因的质粒。
