A substantially pure or isolated oligodeoxynucleotide of at least 10 nucleotides is disclosed, wherein the oligodeoxynucleotide comprised a sequence represented by either formula: 5′N1N2N3T-CpG-WN4N5N63′ wherein the CpG motif is unmethylated, W is A or T, and N1, N2, N3, N4, N5, and N6 are nucleotides, or the formula: 5′RY-CpG-RY3′ wherein the central CpG motif is unmethylated, R is A or G, and Y is C or T, as well as an oligodeoxynucleotide delivery complex and a pharmacological composition comprising the present inventive oligodeoxynucleotide, and a method of inducing an immune response by administering the present inventive oligodeoxynucleotide to a host. In some embodiments, the oligodeoxynucleotide includes the nucleic acid sequences set forth as SEQ ID NO: 137.