IMMUNIZATION WITH DNA POLYNUCLEOTIDES PROTECTS MICE AGAINST LETHAL CHALLENGE WITH ST-LOUIS ENCEPHALITIS-VIRUS

In vivo transfection by intramuscular injection with plasmids expressi ng the immunogenic proteins of microbial pathogens has considerable po tential as a vaccination strategy against many pathogens of both man a nd animals. Here we report that weanling mice given a single intramusc ular injection of 50 mu g of a plasmid, pSLE1 expressing the St. Louis encephalitis virus (SLE) prM/E protein under the control of the cytom egalovirus immediate early protein promoter produced SLE-specific anti body and were protected against lethal challenge with the virulent vir us. Polynucleotide vaccine technology provides a unique opportunity to produce vaccines against flavivirus diseases of low incidence cheaply and rapidly, and to produce multivalent vaccines such as would be req uired for immunisation against dengue virus disease.