Protective immunity against heterologous challenge with encephalomyocarditis virus by VP1 DNA vaccination: effect of coinjection with a granulocyte-macrophage colony stimulating factor gene

For DNA vaccination studies, recombinant VP1 protein of encephalomyocarditis virus (EMCV) was produced from Escherichia coli, and eukaryotic VP1 expression vector pCT-Gs-VP1, was generated and used as a DNA vaccine, Mice were immunized intramuscularly (i.m.) with pCT-Gs-VP1 in the presence or absence of plasmid DNA expressing granulocyte-macrophage colony stimulating factor (GM-CSF), and were subsequently analyzed for their anti-VP1 immune responses with recombinant VPI in ELISA, Immunization of mice with pCT-Gs-VP1 resulted in I ipl-specific immune response and 43% protection from subsequent lethal heterologous challenge of EMCV. Coinjection of mice with pCT-Gs-VP1 and plasmid DNA encoding GM-CSF was shown to increase the seroconversion rate of the immunized mice with a single DNA injection, and enhanced to a higher degree VP1-specific immunity, which appeared to result in better protection (about 80%) from lethal virus challenge. Thus, our results provide evidence for the potential use of CM-CSF to induce better immune response and resistance against viral infection in DNA vaccination. (C) 1997 Elsevier Science Ltd.