Inoue T, Tsuji T, Koto M, Imamura S, Miyama A
Department of Microbiology, Fujita Health University School of Medicine, Aichi, Japan.
FEMS Microbiol Lett. 1993 Apr 1;108(2):157-61. doi: 10.1111/j.1574-6968.1993.tb06092.x.
The DNA sequence of heat-labile enterotoxin from the chicken enterotoxigenic Escherichia coli 21d strain was determined by direct dideoxy sequencing of polymerase chain reaction (PCR)-amplified DNA and was compared with those of heat-labile enterotoxins from porcine and human enterotoxigenic E. coli strains EWD 299 and H 10407. The structural genes of the A and B subunits of chicken heat-labile enterotoxin were identical to those of human heat-labile enterotoxin from the human H 10407 strain. Moreover, 67 base pairs of the upstream and 60 base pairs of the downstream region of the chicken heat-labile enterotoxin gene were also identical to that of the human heat-labile enterotoxin from strain H 10407. However, the patterns of plasmids from the 21d and H 10407 strains were different. The 21d strain had no band corresponding to the 42-MDa plasmid of the H 10407 strain encoding the heat-labile enterotoxin gene but it had a smaller plasmid. These data suggest that although the DNA sequence of chicken heat-labile enterotoxin is identical to that of human heat-labile enterotoxin, the plasmid encoding the chicken heat-labile enterotoxin gene in the chicken might be different from that encoding the human heat-labile enterotoxin gene in the H 10407 strain.
通过对聚合酶链反应（PCR）扩增的DNA进行直接双脱氧测序，确定了鸡源产肠毒素大肠杆菌21d株热不稳定肠毒素的DNA序列，并将其与猪源和人源产肠毒素大肠杆菌菌株EWD 299和H 10407的热不稳定肠毒素的DNA序列进行了比较。鸡热不稳定肠毒素A和B亚基的结构基因与人类H 10407株热不稳定肠毒素的结构基因相同。此外，鸡热不稳定肠毒素基因上游的67个碱基对和下游区域的60个碱基对也与H 10407株人类热不稳定肠毒素的相同。然而，21d株和H 10407株的质粒图谱不同。21d株没有与H 10407株编码热不稳定肠毒素基因的42-MDa质粒相对应的条带，但它有一个较小的质粒。这些数据表明，尽管鸡热不稳定肠毒素的DNA序列与人类热不稳定肠毒素的DNA序列相同，但鸡体内编码鸡热不稳定肠毒素基因的质粒可能与H 10407株中编码人类热不稳定肠毒素基因的质粒不同。
