Investigation On Major Pathogen Detection Of Procine Arthritis And Genetic Variation Of Virulence Gene Of Pathogens In Pudong District

Swine arthropathy usually refers to the limbs joint disease which can cause porcine dyskinesia,it is a degenerative joint change occurred in function and structure under the combined effect of factors such as biology and mechanics.Clinical manifestations of sick pigs turn out to be one or more joint swelling and pain,and some accompanied by fever and other symptoms.Studies have shown that the pathogens causing the disease are mainly Streptococcus suis(S.suis),Haemophilus parasuis(HPS)and Erysipelothrix rhusiopathiae,etc.which can lead to reduced growth and reproductive performance,and decreased feed conversion rate,not only affect the normal production of the farm,but also increase the cost of breeding,which indicates a direct result of a higher rate of death and serious plagued pig farming.In this study,we investigated the incidence of swine arthropathy of pig farms in Pudong area,and the findings were based primarily on weight analysis,Pathogenic factor's weight values in piglets and breeding pigs' joint disease causative factors were 0.6140 and 0.4611 respectively,which means it is the main reason of swine arthropathy.Piglets joint disease incidence analysis showed that October to April was the peak incidence of swine arthropathy,and 30 to 60 days' old piglets had a high incidence.The seasonal incidence of swine arthropathy in replacement gilts and breeding pigs was not obvious,and the pathogenetic factors of them were diversified.Pathogen isolation and identification of swine joint disease showed that the pathogens which caused the swine arthropathy in this area include Streptococcus,Haemophilus parasuis,Erysipelothrix rhusiopathiae and staphylococcus.In order to simultaneously detect Streptococcus suis type2(S.suis 2),Haemophilus parasuis and Erysipelothrix rhusiopathiae,three pairs of specific primers were designed.Afterwards,multiple PCR which can detect these three pathogens simultaneously were developed and the reaction conditions were optimized.On the basis of the aforementioned work,we tested the sensitivity and specificity of the multiple PCR,and detected 72 pathological samples of swine arthropathy.The results turned out to be 2 Streptococcus suis type2,Haemophilus parasuis 1 and 2 Erysipelothrix rhusiopathiae,which were consistent with that of single PCR,at the same time showed the multiple PCR was sensitive,specific and rapid,and can be used in swine arthropathy important pathogen detection.We detected the virulence genes of the 2 S.suis 2 isolated from the athological samples of Pudong area,the results showed that distribution of virulence genes was gdh+/cps2J+/mrp+/epf+/sly+/orf2+/gapdh+,the virulence genes sequences analysis turned out to be that cps2 J and mrp had no gene mutation which indicated they were highly conserved;orf2,gdh and gapdh had gene mutation but had no influence to the structure,and were highly homologous with domestic and foreign reference strains.The independent genetic testing of the 2 Erysipelothrix rhusiopathiae revealed that the virulence genes detected were distributed in them,which was Cps-A+/Cps-B+/Cps-C+/Rsp-A+/Rsp-B+/SpaA+.The strain may be widespread and conditional pathogenic of the pig farm,its pathogenesis needs further study.This study finished the swine joint disease etiology and prevalence of the Pudong area,isolated the main pathogens,established the multiplex PCR method for the major pathogens,analyzed the virulence genes of isolated swine erysipelas and swine streptococcus bacteria,and accumulated etiology data for the integrated control of swine joint disease.