Evans D G, Evans D J
Infect Immun. 1978 Aug;21(2):638-47. doi: 10.1128/iai.21.2.638-647.1978.
Enterotoxigenic Escherichia coli (ETEC) belonging to serogroups O6 and O8 do not possess the H-10407-type colonization factor antigen (CFA/I). However, these frequently isolated ETEC were found to possess a second and distinct heat-labile surface-associated colonization factor antigen, termed CFA/II. Whereas CFA/I mediates mannose-resistant hemagglutination of human group A erythrocytes, CFA/II does not. CFA/II mediates mannose-resistant hemagglutination of bovine erythrocytes, and mannose-resistant hemagglutination is rapid only at reduced temperature (4 degrees C). Because CFA/II, like CFA/I, is spontaneously lost by many ETEC isolates in the laboratory, it was possible to produce specific anti-CFA/II serum by preparing antiserum against living cells of a prototype strain (PB-176) and adsorbing this serum with living and heat-treated cells of its CFA/II-negative derivative strain PB-176-P. This serum, which neutralized the colonization factor activity of CFA/II-positive strains in infant rabbits, was employed to confirm the presence of CFA/II on ETEC which exhibited mannose-resistant hemagglutination of bovine but not human erythrocytes. CFA/II, like CFA/I, mediates adherence of the bacteria to the mucosal surface of the small intestine, as demonstrated by indirect immunofluorescence. CFA/II appears to be an important virulence factor for humans since CFA/II-positive ETEC are frequently isolated from diarrhea cases, particularly travelers' diarrhea, in Mexico; these ETEC were not uncommon in a collection of isolates from Bangladesh. The O6:H16 strain of ETEC responsible for an outbreak of diarrhea in the United States was also shown to be CFA/II positive. CFA/I and CFA/II were never found on the same serotypes of ETEC, but 98% of the heat-stable and heat-labile enterotoxin-producing ETEC belonging to the frequently isolated serogroups O6, O8, O15, O25, O63, and O78 were positive for either CFA/I or CFA/II.
属于血清型O6和O8的产肠毒素大肠杆菌（ETEC）不具有H-10407型定植因子抗原（CFA/I）。然而，这些经常分离到的ETEC被发现具有第二种独特的与热不稳定表面相关的定植因子抗原，称为CFA/II。CFA/I介导人A群红细胞的甘露糖抗性血凝反应，而CFA/II则不介导。CFA/II介导牛红细胞的甘露糖抗性血凝反应，且甘露糖抗性血凝反应仅在低温（4℃）下迅速发生。由于CFA/II与CFA/I一样，在实验室中会被许多ETEC分离株自发丢失，因此可以通过制备针对原型菌株（PB-176）活细胞的抗血清并用其CFA/II阴性衍生菌株PB-176-P的活细胞和热处理细胞吸附该血清来制备特异性抗CFA/II血清。这种血清可中和婴儿兔中CFA/II阳性菌株的定植因子活性，用于确认在表现出对牛而非人红细胞甘露糖抗性血凝反应的ETEC上存在CFA/II。如间接免疫荧光所示，CFA/II与CFA/I一样，介导细菌粘附于小肠粘膜表面。CFA/II似乎是人类的一种重要毒力因子，因为CFA/II阳性的ETEC经常从腹泻病例中分离出来，特别是在墨西哥的旅行者腹泻病例中；在孟加拉国收集的分离株中，这些ETEC也并不罕见。在美国导致腹泻暴发的ETEC的O6:H16菌株也被证明是CFA/II阳性。CFA/I和CFA/II从未在相同血清型的ETEC上发现，但属于经常分离的血清型O6、O8、O15、O25、O63和O78的98%的产热稳定和热不稳定肠毒素的ETEC对CFA/I或CFA/II呈阳性。
