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 encephalomyoca rditis virus (EMCV) was produced from Escherichia coli, and eukaryotic VP1 expression vector pCT-Gs-VP1, was generated and used as a DNA vac cine, Mice were immunized intramuscularly (i.m.) with pCT-Gs-VP1 in th e presence or absence of plasmid DNA expressing granulocyte-macrophage colony stimulating factor (GM-CSF), and were subsequently analyzed fo r their anti-VP1 immune responses with recombinant VPI in ELISA, Immun ization of mice with pCT-Gs-VP1 resulted in I ipl-specific immune resp onse 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 (abou t 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 Elsevi er Science Ltd.