Effect Of Fourteen Kinds Of Traditional Chinese Medicine Monomer On The Virulence Factors Of Haemophilus Parasuis

Objective:The widespread of H.parasuis has caused huge economic losses to the swine industry.The virulence factors of H.Parasois are very complex,the role of virulence factors and the interaction among the mechanism of virulence factors are still unclear,which make the prevention and control of H.parasuis in pig farm more difficult.Therefore,the research on virulence factors of H.parasuis has become the focus of the study.This study focused on the selection of effective inhibitor of virulence factors of H.parasuis.and providing of a new theoretical basis for the prevention and control of the disease.Method:H.parasuis were isolated from clinical and identificated;the minimum inhibitory concentration(MIC)and the Minimum bactericidal concentration(MBC)of H.parasuis to fourteen kinds of traditional Chinese medicine monomer was detected according to the susceptibility method described by CLSI;The effect of fourteen monomers on the growth of H.parasuis and the expression of the potential virulence associated genes was studied by real-time PCR methods.Results:4 strains of H.parasuis were isolated and identified.In vitro susceptive study on 14 kinds of traditional Chinese medicine monomer to H.parasuis found that the antibacterial activity of baicalin,forsythin,gallic acid and curcumin were relativly weak,meanwhile,other ten kinds of traditional Chinese medicine monomer had antibacterial effect on H.parasuis,MIC value ranged between 8-128 ?g/mL.Luteolin and berberine hydrochloride have the MIC ranged between 8-32 ?g/mL.Four strains of H.parasuis showed no resistance to fourteen kinds of traditional Chinese medicine monomer.Further real-time PCR research found that the effect of the same monomer on selected H.parasuis strains was different,among them,2 were standard strains and 1 was clilical isolated strain.But the effect of Baicalin,quercetin,luteolin and gallic acid on the relative expression level of virulence genes of three strains have good inhibitory effect,which can effectively inhibit the expression of the outer membrane protein genes(OmpP-5 and OmpP-2),Hemolytic operon genes(hhdA and hhdB),Cytolethal distending toxin(cdtA and cdtC),Capsular formation related genes(capD),Biofilm formation related genes(gaIU and mviN),Transferrin binding protein(tbPA).Reducing the H.parasuis toxicity by inhibiting the expression of diferrent genes.Conclusions:4 strains of H.parasuis were isolated and identified in this study.Luteolin and berberine hydrochloride had antibacterial effect on H.parasuis with the MIC ranged between 8-32 ?g/mL.Four strains of H.parasuis showed no resistance to fourteen kinds of traditional Chinese medicine monomer.Fourteen kinds of Chinese medicinal herbs had different effects on the expression of virulence related genes of different H.parasuis strains.Main virulence factors of the three different strains may be different.Baicalin,quercetin,luteolin and gallic acid had good inhibitory effects on the expression of virulence related genes of three H.parasuis strains.Which could be used as candidate virulence inhibitors in H.parasuis study.