Bertin Y, Boukhors K, Pradel N, Livrelli V, Martin C
Laboratoire de Microbiologie, Centre de Recherche INRA de Clermont-Ferrand-Theix, 63122 St-Genès Champanelle, France.
J Clin Microbiol. 2001 Sep;39(9):3060-5. doi: 10.1128/JCM.39.9.3060-3065.2001.
At least 11 Stx2 variants produced by Shiga toxin-producing Escherichia coli (STEC) isolated from patients and animals have been described. The Stx2 subtyping of STEC isolated from healthy cows positive for stx(2) (n = 104) or stx(2) and stx(1) (n = 63) was investigated. Stx2vh-b, Stx2 (renamed Stx2-EDL933), and Stx2vh-a were the subtypes mostly detected among the bovine isolates (39.5, 39, and 25.5%, respectively). Stx2e was not present, and subtypes included in the Stx2d group (Stx2d-OX3a, Stx2d-O111, and Stx2d-Ount) were found infrequently among the isolates examined (8.5%). A combination of two distinct Stx2 subtypes was observed among 23.5% of the strains. For the first time, a combination of three subtypes (Stx2-EDL933/Stx2vh-b/Stx2d and Stx2vh-a/Stx2vh-b/Stx2d) was detected (3.5% of the isolates). In addition, bovine STEC harboring stx(1) and one or two stx(2) genes appeared highly cytotoxic toward Vero cells. A new Stx2 subtype (Stx2-NV206), present among 14.5% of the isolates, showed high cytotoxicity for Vero cells. Two amino acid residues (Ser-291 and Glu-297) important for the activation of Stx2 by human intestinal mucus were conserved on the Stx2-NV206 A subunit. The gene encoding Ehx enterohemolysin was prominent among STEC harboring stx(2)-EDL933 alone (78%) or a combination of stx(2)-EDL933 and stx(2)vh-b (85%). In addition, Stx2-EDL933 and/or Stx2vh-b subtypes were highly associated with other putative virulence factors such as Stx1 and EspP extracellular serine protease, but not with EAST1 enterotoxin.
已描述了至少11种由从患者和动物中分离出的产志贺毒素大肠杆菌（STEC）产生的Stx2变体。对stx(2)呈阳性（n = 104）或stx(2)和stx(1)呈阳性（n = 63）的健康奶牛中分离出的STEC进行了Stx2亚型分析。Stx2vh-b、Stx2（重新命名为Stx2-EDL933）和Stx2vh-a是在牛分离株中最常检测到的亚型（分别为39.5%、39%和25.5%）。未检测到Stx2e，并且在检测的分离株中很少发现Stx2d组中的亚型（Stx2d-OX3a、Stx2d-O111和Stx2d-Ount）（8.5%）。在23.5%的菌株中观察到两种不同的Stx2亚型组合。首次检测到三种亚型的组合（Stx2-EDL933/Stx2vh-b/Stx2d和Stx2vh-a/Stx2vh-b/Stx2d）（占分离株的3.5%）。此外，携带stx(1)和一个或两个stx(2)基因的牛STEC对Vero细胞具有高度细胞毒性。一种新的Stx2亚型（Stx2-NV206）存在于14.5%的分离株中，对Vero细胞显示出高细胞毒性。对人肠黏液激活Stx2重要的两个氨基酸残基（Ser-291和Glu-297）在Stx2-NV206 A亚基上保守。编码Ehx肠溶血素的基因在仅携带stx(2)-EDL933（78%）或stx(2)-EDL933和stx(2)vh-b组合（85%）的STEC中很突出。此外，Stx2-EDL933和/或Stx2vh-b亚型与其他推定的毒力因子如Stx1和EspP细胞外丝氨酸蛋白酶高度相关，但与EAST1肠毒素无关。
