Intranasal Immunization of Mice with Influenza Vaccine in Combination with the Adjuvant LT-R72 Induces Potent Mucosal and Serum Immunity Which Is Stronger than That with Traditional Intramuscular Immunization

Immunization of mice by the intranasal route with influenza virus hemagglutinin in combination with the mutant Escherichia coli heat-labile enterotoxin R72 (LT-R72) induced significantly enhanced serum and mucosal antibodies, surpassing, in most cases, responses achieved by traditional intramuscular immunization using inactivated split influenza vaccine. Furthermore, intranasal immunization with LT-R72 induced a potent serum immunoglobulin G2a response, indicating that this adjuvant has Th1 character.