Conjugation of protein to immunostimulatory DNA results in a rapid, long-lasting and potent induction of cell-mediated and humoral immunity

Immunostimulatory DNA sequences (ISS) are a potent Th1 adjuvant. We hypothe sized that conjugation of ISS to protein antigens would strongly enhance th eir immunogenicity because both antigen and adjuvant (ISS) would be deliver ed to the same locale/antigen-presenting cell. To test this hypothesis, we conjugated a 22-mer immunostimulatory oligodeoxynucleotide (ISS-ODN) to two test antigens of differing intrinsic immunogenicity, namely Escherichia co li P-galactosidase and the HIV-1 envelope glycoprotein gp120. We show that the antigen-ISS conjugates rapidly induce Th1 cells secreting high levels o f IFN-gamma, strong CTL activity, and high titer IgG2a and HIV-neutralizing antibodies, exceeding gene and protein vaccination alone or immunization w ith mixtures of antigen and ISS-ODN. The data suggest that this procedure g enerates a novel and unique Vaccine that rapidly triggers strong humoral an d cell-mediated immunity.