Immuno-stimulatory effects of bacterial-derived plasmids depend on the nature of the antigen in intramuscular DNA inoculations

Immunology. 1998 Jul;94(3):285-9. doi: 10.1046/j.1365-2567.1998.00557.x.


The CpG motifs of bacterial-derived plasmids augment antigen-specific immune responses and steer those responses towards the T helper 1 (Th1) type. In this study, we have addressed the immuno-stimulatory effect of intramuscular co-administration of CpG motifs containing vector DNA on the modulation of immune responses to the haemagglutinin (HA) and the nucleoprotein (NP) proteins of influenza virus. The co-administration of vector DNA with a HA-encoding plasmid DNA showed a significant enhancement in the total IgG response, the generation of cytotoxic T lymphocyte (CTL), and the T-cell proliferative response. In the case of NP-encoding plasmid DNA inoculations, the co-administration of vector DNA slightly decreased the total IgG response, although the IgG2a/IgG1 ratio and the CTL responses to NP were significantly increased. These observations suggest that the immuno-stimulatory effects of bacterial-derived plasmids depend upon the nature of the co-administered antigen.

MeSH terms

  • Animals
  • Antigens, Viral / administration & dosage*
  • Bacteria / genetics*
  • Female
  • Genetic Vectors
  • Hemagglutinins, Viral / genetics
  • Immunity, Cellular*
  • Immunization*
  • Immunoglobulin G / immunology
  • Influenza A virus / immunology*
  • Injections, Intramuscular
  • Lymphocyte Activation
  • Mice
  • Mice, Inbred BALB C
  • Nucleoproteins / genetics
  • Plasmids / immunology*
  • T-Lymphocytes, Cytotoxic / immunology
  • Vaccines, DNA / administration & dosage


  • Antigens, Viral
  • Hemagglutinins, Viral
  • Immunoglobulin G
  • Nucleoproteins
  • Vaccines, DNA