Effects Of HhdA On The Components And Main Biological Functions Of HPS Outer Membrane Vesicles

Haemophilus parasuis can cause Haemophilus' disease of pigs,which is clinically manifested as arthritis,meningitis,serositis and other symptoms,with a high fatality rate.It is one of the most serious bacterial infectious diseases threatening pig farms at home and abroad.Antibiotics are the main drugs for the prevention and treatment of this bacterium.Due to the continuous increase of drug-resistant strains in recent years,vaccine immunization has become the main method for the prevention and treatment of this bacterium.However,due to the numerous serotypes of this bacterium and the lack of effective cross-immunological protection,the development of a new and effective vaccine against haemophilus paraporus is extremely urgent.OMVs are nanostructured vesicles of Gram-negative bacteria that are released from the bacteria to the peripheral environment during the growth phase,contain of lipopolysaccharides,proteins,nucleic acids,hemolysin and so on.Theirs composition is not only a virulence factor that causes disease,but also has immunogenicity to be developed as a potential vaccine.Our previous studies have also confirmed that OMVs have good immunogenicity and inflammatory effects.Hemolysin is one of the potential toxin factors in Haemophilus paraporus.It not only exists in the bacteria,but also can be secreted outside of the bacteria with OMVs,In recent years,the effect of hemolysin on OMVs function has not been reported.This experiment selects the serotype strong pathogenic strains of type 5 H45 strains and their related hemolysin gene deletion strains ? hhdA(hemolysin of Haemophilus ducreyi)strains as the research object.Both were extracted and purified to obtain OMVs,and then the morphology of both OMVs was observed using transmission electron microscopy,and the protein components of OMVs were compared and analyzed.Furthermore,OMVs were used as immunogen to treat guinea pigs by nasal drops and injections.The effect of hhdA gene deletion on OMVs inflammatory was investIgAted by detecting early cytokines in guinea pigs and observing the tissue sections of guinea pigs.In addition,The effect of hhdA gene deletion on OMVs immunogenicity was investIgAted by detecting IgA antibody,IgG antibody,IFN-and IL8 cytokines in guinea pigs.The experiment results and conclusions:(1)The hhdA gene deletion had no significant effect on the morphology and protein composition of OMVs;(2)H45 OMVs can induce than ?hhdAH45 OMVs higher levels of IL-1? and IFN-? secretion,so the hhdA gene deletion can reduce the inflammatory properties of OMVs;(3)H45 OMVs can induce than ?hhdAH45 OMVs higher levels of IgG antibody response,but for the IL-8?IFN-? and IgA production no significant difference.Therefore,The hhdA gene deletion can reduce the humoral immune response of OMVs,but has no significant effect on mucosal immunity and cellular immunity.