Immunogenicity and protective efficacy of selected antigens in the mouse model.
(A) Female DBA/2 mice were vaccinated three times with indicated antigens. At week 2 post vaccination, PBMCs were stimulated with the vaccine antigen for 72 hours and secretion of IFNγ was analyzed by ELISA. (B) The serum IgG against the indicated antigens was measured by indirect ELISA. Antibody titers were measured by the reaction of a series of 10-fold dilution of sera with the antigen. The Antibody titration from the sera of 4 mice are shown. Bars indicate means ± SEM. (C) The serum IgG against the indicated antigens was measured by indirect ELISA using pooled sera taken from eight mice two weeks after a sublethal intraperitoneal GAS infection. (D–G) Mice were vaccinated three times s.c. with indicated antigens. Six weeks after the final vaccination, mice received an intradermal infection with 107 GAS bacteria (MGAS5005). 4 days post infection the number of bacteria in a skin biopsy covering the entire affected area was determined. A t-test was used to calculate the p-value. All the antigens were tested in at least two independent experiments. For spy1228/spy1801/spy0469 results from two such experiments are shown.