Immune reaction characteristics and the mechanism of anergy induced by recombinant enterotoxin a of Staphylococcus aureus

Abstract

To study immune reactions and the mechanism of anergy induced by recombinant enterotoxin A (rSEA) of Staphylococcus aureus. The gene encoding SEA was cloned from standard strain of S. aureus and high efficiently expressed in E. coli. After immunization with purified rSEA, mice were examined for production of specific antibody, subtype of IgG, cytokine mRNA levels such as IFN-γ, IL-2 secretion and T-cell surface PD-1 expression. Results showed that high levels of specific antibodies were produced in two weeks of primary immunization shot. During this time, humoral immune reactions prevailed (IgG2a/ IgG1 < 1). During the early phase, Th1 type cytokine mRNA is expressed at a higher level than Th2 type, indicating cellular immune reaction prevailed. Splen- ocyte IFN-γ secretion was significantly decreased after boosting immunization. The PD-1 expression was detected by a flow cytometry examination in the surface of T- lymphocytes which were induced by rSEA, and the expression of PD-1 molecules increased along with the number of boosting and the time after immunization