Isolation And Characterization Of Staphylococcus Hyicus And Development Of Inactivated Vaccine

Staphylococcus hyicus(S.hyicus)is the pathogen of porcine exudative epidermitis(exudative epidermitis,EE),which can cause skin loss or even dehydration of piglets.The disease has been affecting the development of the global pig industry.At present,the prevalence and serotype of porcine exudative epidermitis in China is still unclear,and the infection of this disease also lacks effective prevention and treatment measures.In this study,the etiology,epidemiology,diagnostic methods and inactivated vaccines of exudative epidermitis were studied,which laid the foundation for the basic research of exudative epidermitis and the diagnosis and prevention of the disease.In order to investigate the prevalence of S.hyicus in Guangdong,collected 32 suspected cases of exudative epidermitis from nine urban areas in Guangdong Province.The strains were identified by bacterial morphology,culture characteristics,biochemical characteristics and PCR.Five types of toxic Staphylococcus were detected,and 80% were Staphylococcus hyicus.For the detection of Staphylococcus hyicus exfoliative toxin,the Exh A type accounted for 30%,Exh B type accounted for 15%,Exh C accounted for 16%,and Exh D type strain was not detected.The isolated CK-1 strain was used as a representative strain for studying biological characteristics.The results showed that the strain grew well in nutrient broth culture and LB medium,and the number of viable cells reached the highest at 16 h.The antibacterial sensitivity analysis of this strain is that it is resistant to penicillin and streptomycin,but sensitive to cephalosporin.The strain secrete exotoxin Exh A.Animal studies have shown that this strain is pathogenic to mice and piglets.In this study,the soluble expression vector of exfoliative toxin Exh A of S.hyicus was constructed by using the gene sequence of CK-1 as a template,and the isolated and purified protein can cause the onset of piglets and has good antigenicity.The ELISA method was established by using the purified protein as the antigen,and the agglutination test method was established by using the inactivated bacteria of S.hyicus as the antigen.Both of them have good specificity and reproducibility.In this study,a preliminary study on the Nano-adjuvant inactivated vaccine against Staphylococcus hyicus was carried out.The safety test results showed that the vaccine had no negative effects on piglets and pregnant sows,and could be stored at 4 °C for a long time.Immune protection tests have shown that the protection of piglets can reach 100%.This study provides data support for the prevalence of porcine exudative epidermitis in Guangdong,and lays a foundation for the establishment of antibody detection methods and the study of inactivated vaccines.