Alcaligenes lipid a

Female BALB/c mice (age, 7 wk) were purchased from CLEA Japan (Tokyo, Japan) and used for experiments after pre-breeding for 1 wk. All experiments were approved by the Animal Care and Use Committee of the National Institutes of Biomedical Innovation, Health and Nutrition (Approval No. DSR01-1R2) and conducted in accordance with their guidelines. Mice were subcutaneously immunized with PBS (vehicle control), Stx2B-C-CPE, endotoxin-free Stx2B-C-CPE without or with aluminum adjuvant (BIKEN, Osaka, Japan), endotoxin-free Stx2B-C-CPE without or with Alcaligenes lipid A (Peptide Institute, Osaka, Japan) [9] , or endotoxin-free Stx2B-C-CPE without or with both aluminum adjuvant and Alcaligenes lipid A once weekly for 2 consecutive weeks. Serum was collected 1 week after the last immunization. The immunization schedule followed the previous study [1] .