Immunization with a Hemagglutinin-Derived Synthetic Peptide Formulated with a CpG-DNA-Liposome Complex Induced Protection against Lethal Influenza Virus Infection in Mice
(A) BALB/c mice (N = 3/group) were injected i.p. with a DOPE:CHEMS (1∶1 ratio) complex, each peptide encapsulated in the DOPE:CHEMS complex (DOPE:CHEMS + peptide), or each peptide and Lipoplex(O) (Lipoplex(O)+peptide) on three occasions. The antisera were collected, and then amounts of each peptide-specific total IgG were assayed by ELISA. (B) Kinetics of IgG production in response to immunization with the complex of hH5N1 HA233 peptide and Lipoplex(O). Three BALB/c mice were injected i.p. with hH5N1 HA233 peptide and Lipoplex(O) on three occasions. The sera were collected one day before each injection and 10 days after the final injection, and amounts of the hH5N1 HA233 peptide-specific total IgG, IgG1, IgG2a and IgM were assayed by ELISA.