Analysis Of Typing Identification Of Pasteurella Multocida And IL-1β, IL-6 Transcriptional Changes In Infected Chickens

Pasteurella multocida is an important pathogen that can cause common infections in humans and animals, causing fowl cholera, swine atrophic rhinitis, lung disease and other pasteurellosis. Pasteurellosis can be outbreaked in various regions of the world, they bring out great impact on the livestock and poultry farming. There are a variety of Pasteurella multocida serotype, differences between the genome of Pasteurella multocida isolates from different species. The presence of genomic differences between the different virulence strains.Thirty-six P. multocida isolates from different hosts in some areas of China were used to identify the capsule types and genotypes by multiplex capsular PCR, LPS-m PCR..And analysis. the phylogenetic through multilocus sequence typing method.They were found to be members of capsule serotypes A, B, and D and four different LPS genotype, included L1, L2, L3, and L6. The avian isolates are mainly classified of capsule type A, LPS genotype is L1. Seven different sequence types(STs) including ST129, ST8, ST58, ST5, ST13, ST50, and ST122 were identified by multilocus sequence type(MLST) and pasteurella from avian are mainly ST129.Twenty specific-pathogen-free chickens were randomly divided into 4 groups each on month 3.The treatment groups were injected 0.1m L avian Pasteurella multocida strain C48-1,50 CFU/m L; Pm72-4, 2×104CFU/m L; Pm731, 2×109CFU/m L. The control groups were inoculated with 0.1 m L PBS. Killing the chickens died after infection and killing all the chickens at day 14. Spleen was sampled for RNA extraction. SYBR Green quantitative real-time PCR method was applied to compare the relative expression quantity of TLR4、My D88、IL-1β and IL-6 genes and then study the molecular mechanisms of IL-1β and IL-6 activation after infection with the Pasteurella multocida.The results were showed: all 5 chickens died after infection with C48-1, and 2 chickens were alive after infection with Pm72-4, and 5 chickens were all survived after infection with Pm731 and of PBS. It showed that the C48-1 strain had a strong pathogenicity to SPF chickens, and it was a virulent strain. The pathogenicity of strain Pm72-4 was weak, and the strain Pm731 was not lethal to SPF chickens, belong to the weak strains. TLR4、My D88 and IL-6 genes expression levels were higher after injection C48-1 strain and the difference was significant(P<0.05). After injection strain Pm72-4 and Pm731 the gene expression levels were not significant(P>0.05).The expression levels of IL-1β gene was higher after injection C48-1, Pm72-4 and Pm731, but the difference with the control group was not significant(P> 0.05). It was indicated that after the infection of virulent strain C48-1 activated IL-6, but does not activate IL-1β, and IL-6 and IL-1β were not activated by the attenuated strain Pm72-4 and Pm731.This study provide a basis for the study of different strains of Pasteurella multocida virulence differences in the molecular mechanisms.