Purification And Immunogenicity's Study Of FbsA From Group B Streptoccus

Group B streptoccus(GBS)is an important human pathogen that causes pneumonia,sepsis and meningitis in neonates.It also poses a significant threat to immunocompromised adults,in whom it is responsible for cellulites, arthritis,endocarditis,uninary tract infections.The development of GBS vaccine has gone through three period:capsular polysaccharide vaccines,polysaccharide—protein conjugated vaccines,protein vaccines.At present,many surface proteins of GBS have been discovered.Protein vaccines and multivalent protein vaccines as new-type vaccines are looked forward to controlling infection of GBS.FbsA,a fibrinogen-binding protein located the surface of GBS,is considered an important virulence factor.FbsA protein promotes adherence of GBS to human epithelial,platelet aggregation,and protects GBS from opsonophagoposis.Therefore,the development of anti-FbsA strategies could represent an important achievement for the prevention and treatment of the infection of GBS.In this experimentation,we obtained the surface proteins of GBS by the grinding with glass bead.With isoelectric precipitation and polyacrylicacid precipitation,the alkalescence proteins are extracted from the bacterial surface.The alkalescence proteins were purified from the peakesⅡobtained by flowing through the Sephacryl S—100 H.R columns.SDS-PAGE and IEF analysis showed that molecule weight of the protein was 50KD with pI10.Westen blot showed that the purified protein can bind the antibody against FbsA.Antibody respose was evaluated in mice immunized by FbsA with different immunization proceduce and by variable antigen doses.The immune sera were detected with method of indirect ELISA,the results indicated that higher titer of antibody against FbsA was acquired by immunization of 5μg thrice.Immune neutralization of antisera against FbsA was reseach simply.