Analysis of Fecal Source Escherichia Coli Lipopolysaccharide Core Type and Pathogenicity in Diarrhoeic Lambs from Ta'e Reclamation Area,Xinjiang Uygur Autonomous Region
[Objective]The aim of this study was to understand the core type,virulence genes and pathogenicity of Escherichia coli LPS of faecal origin in diarrhoeic lambs in Ta'e Reclamation Area,Xinjiang Uygur Autonomous Region.[Method]Four hundred and fifteen samples of diarrhoeic lambs were collected from Ta'e Reclamation Area,followed by isolation of Escherichia coli using identification medium.Then,the isolates were identified molecularly by amplification of the specific gene phoA of E.coli and 16S rDNA sequence analysis.PCR was used to determine the LPS core type and virulence gene carriage of the isolates.The correlation between LPS core type and virulence gene of the isolates was analyzed by Fisher's exact test.The pathogenicity of the isolates was determined by mouse infection test.[Result]Seventy-three E.coli strains were isolated and identified from 415 samples with an isolation rate of 17.6%(73/415).The Seventy-three E.coli LPS core types were mainly R1(57.53%),followed by R3(24.66%),R4(10.96%),K12(5.48%)and R2(1.37%).A total of 13 virulence genes were detected among the 25 virulence genes tested,with higher detection rates for genes such as mat(98.63%),yijP(91.78%),and ibeB(90.41%),and lower detection rates for genes irp2(16.44%),iucD(9.59%),and stx1(2.74%).No significant correlation was found between LPS core type and virulence genes.In addition,nine randomly selected strains were found to cause diarrhea and death in mice and were highly pathogenic to mice.[Conclusion]The above results indicate that LPS of E.coli from lambs in the Ta'e Reclamation Area is characterized by diverse phenotypes,carries various virulence genes,and has a certain pathogenicity,which should be considered in the production.
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