Acta Veterinaria et Zootechnica Sinica ›› 2020, Vol. 51 ›› Issue (5): 1091-1100.doi: 10.11843/j.issn.0366-6964.2020.05.020

• PREVENTIVE VETERINARY MEDICINE • Previous Articles     Next Articles

Isolation, Identification, Virulence Gene Detection and Typing of Shigella from Yak

ZHANG Liwei, ZHANG Yibo, HAO He, WANG Wenya, SHI Xinxin, HAN Wang, TONG Xing, ZHANG Yongying, SHI Yuxiang, ZHU Zhen*   

  1. Collge of Life Sciences and Food Engineering, Hebei University of Engineering, Handan 056038, China
  • Received:2019-11-20 Online:2020-05-25 Published:2020-05-16

Abstract: The purpose of this experiment is to clarify the pathogenicity and molecular epidemic characteristics of Shigella from yak, and to provide new ideas for exploring the epidemic ways of Shigella and formulating reasonable control strategies. In 2017, 1 396 samples of yak anal cotton swabs were collected in Gansu, Qinghai and Tibet, and isolates were systematically identified by selective medium screening, biochemical identification and serum agglutination test. Seven virulence genes (ipaH, ipaBCD, ial, sen, set1A, set1B and stx) were detected by PCR. MLST typing of 15 pairs of housekeeping gene sequences provided by Mc MLST website database was carried out. Referring to the PulseNet experimental method of CDC in the United States, The chromosome of S. flexneri and S. sonnei were digested by restriction endonuclease NotⅠ and XbaⅠ, and PFGE analysis was performed on these isolates. The results showed that 41 strains were consistent with the biochemical characteristics of Shigella. They were divided into 4 biochemical phenotypes, B3 (36.59%) and B4 (32.35%) were the main biochemical phenotypes. Serum agglutination test identified 23 strains of S. flexneri, including four serotypes 1a (n=2), 2a (n=16), 2b (n=3), Xv (n=2); 18 strains were S. sonnei bacteria are divided into phase Ⅰ (n=12) and phase Ⅱ (n=6). A total of six virulence genes ipaH, ipaBCD, ial, sen, set1A, and set1B were detected, and the carrying rates were 100%, 92.68%, 73.17%, 70.73%, 26.83%, and 26.83%, respectively. There are 7 virulence genotypes, of which VT5 and VT7 are the main epidemic types, accounting for 43.9% and 24.39%, respectively, while Shigella carrying two or more virulence genes account for 92.68%. Fourty-one strains of Shigella were divided into 10 types of ST, of which ST100, ST116 and ST155 were the main epidemic types. S. flexneri of NotⅠ enzyme digestion was divided into 13 PTs, while S. sonnei was divided into 14 PTs by XbaⅠ enzyme digestion. The biochemical phenotype, serotype, ST, and PT type of Shigella isolated from yaks are both polymorphic and prevalent. The Shigella isolates carried the same virulence genes as human, and carrying rates of ipaH, ipaBCD, ial, and sen genes were higher, which posing a potential threat to public safety.

Key words: Shigella, yak, virulence genes, multilocus sequence typing, pulsed field gel elect-rophoresis

CLC Number: