Isolation and diversity analysis of bovine Pasteurella multocida

Abstract:

[Objective] Our research focuses on the detection and the distribution of some important virulence genes in Pasteurella multocida associated with bovine respiratory disease (BRD).[Methods] In total 237 nasal swabs were collected from August 2017 to April 2018 in 8 areas of China. The bacteria were isolated to record the colony morphology and Gram staining, and phylogenetic tree based on the 16S rRNA gene sequences of the 31 isolates was drawn. Serotype classification was performed, and total 23 virulence factors were determined by PCR.[Results] In total 31 strains of P. multocida were identified from 237 samples. Serum typing found all the isolates were type A strains and phylogenetic tree showed the 31 strains related to HB01 strain (China), USDA-ARS-USMARC-60712, USDA-ARS-USMARC-60214, ATCC 43137 and 36950. PCR was used for detecting 23 virulence-associated genes occurred in those isolates, demonstrating that each P. multocida carried 17 to 19 virulence-associated genes with high concentration ratio.[Conclusion] Type A P. multocida were dominant strains in which 7 strains from different areas of China belong to one cluster, virulent genes tadD and hgbA were lost in this cluster as well as virulent hsf-1 was carried. The analysis result reminds the virulence genotyping distribution has relevant to serum typing.