... MB, LeJeune JT, Christopher-Hennings J, Chen DG, Hardwidge PR, Francis DH (2007). Differences in virulence among Escherichia coli O157:H7 strains isolated from humans during disease outbreaks ... healthy cattle and buffaloes in some provinces in Central Vietnam Bùi Thị Ba, Đào Hoài Thu, Đỗ Văn Tấn, Hoàng Huy Hòa, Vũ Khắc Hùng SUMMARY We determined the prevalence of variant genes of Shiga ... toxin gene (stx1, stx1c, stx2, stx2c, stx2d, stx2g, stx2) of 34 E. coli O157:H7 strains which were isolated from healthy cattle and buffaloes in some provinces in the central region of Vietnam....