Immunostimulatory CpG-modified plasmid DNA enhances IL-12, TNF-alpha, and NO production by bovine macrophages

The immunogenicity of DNA vaccines is partially attributable to the adjuvan t properties of bacterial plasmid DNA (pDNA) for B lymphocytes and professi onal antigen-presenting cells, In mice, modification of immunostimulatory s equences (ISSs), including CpG motifs, in pDNA vectors or oligodeoxynucleot ides can increase or decrease their adjuvant properties. ISSs that stimulat e optimal responses reportedly differ for murine and human leukocytes, We h ave previously characterized the mitogenic properties of oligodeoxynucleoti des containing one AACGTT motif for bovine B lymphocytes. We now define cyt okine responses by macrophages stimulated with pDNA engineered to contain a n ISS comprising two AACGTT motifs, Macrophages activated with CpG-modified pDNA secreted significantly more interleukin-12, tumor necrosis factor-alp ha, and nitric oxide than macrophages stimulated with unmodified pDNA or mo dified pDNA that contained nucleotides scrambled to remove CpG motifs, Engi neered CpG-pDNA or CpG-oligodeoxynucleotides should be useful as vaccines o r adjuvants to promote the enhanced type 1 responses important for protecti on against intracellular pathogens.