Resistance to influenza A virus infection by antigen-conjugated CpG oligonucleotides, a novel antigen-specific immunomodulator

Oligodeoxynucleotides (ODN) containing CpG motifs (CpG) act as modulators that bias the immune response towards a Th1-dominant phenotype. To investigate this effect further, we examined the protective effects of a covalently linked conjugate between CpG-ODN and HA-2kd antigen in mice infected with influenza A virus. The conjugated form of CpG-ODN and HA-2kd was more efficient in regulating influenza A virus than the unconjugated mixture of CpG-ODN and HA-2kd. The antigen-conjugated CpG-ODN induced an immune response with a Th1-dominant cytokine pattern characterized by the secretion of high levels of HA-2kd-specific interferon-gamma and IgG2a (Th1), which were only slightly induced by HA-2kd alone. These findings support the use of CpG-ODN-Ag conjugates as novel Ag-specific immunomodulators and suggest that CpG-ODN-HA-2kd might be a promising immune therapy for patients with influenza virus.