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

The immunogenicity of DNA vaccines is partially attributable to the adjuvant properties of bacterial plasmid DNA (pDNA) for B lympho- cytes and professional antigen-presenting cells. In mice, modification of immunostimulatory se- quences (ISSs), including CpG motifs, in pDNA vectors or oligodeoxynucleotides can increase or decrease their adjuvant properties. ISSs that stim- ulate optimal responses reportedly differ for mu- rine and human leukocytes. We have previously characterized the mitogenic properties of oligode- oxynucleotides containing one AACGTT motif for bovine B lymphocytes. We now define cytokine responses by macrophages stimulated with pDNA engineered to contain an ISS comprising two AACGTT motifs. Macrophages activated with CpG- modified pDNA secreted significantly more inter- leukin-12, tumor necrosis factor-a, and nitric ox- ide than macrophages stimulated with unmodified pDNA or modified pDNA that contained nucleo- tides scrambled to remove CpG motifs. Engineered CpG-pDNA or CpG-oligodeoxynucleotides should be useful as vaccines or adjuvants to promote the enhanced type 1 responses important for protec- tion against intracellular pathogens. J. Leukoc. Biol. 70: 103-112; 2001.