Needle-free jet injection of small doses of Japanese encephalitis DNA and inactivated vaccine mixture induces neutralizing antibodies in miniature pigs and protects against fetal death and mummification in pregnant sows

Japanese encephalitis (JE) virus causes abortion and stillbirth in swine and encephalitis in humans and horses We have previously reported that immunogenicity of a DNA vaccine against JE was synergistically enhanced in mice by co-immunization with a commercial inactivated JE vaccine (JEVAX) under a needle-free injection system Here we found that this immunization strategy was also effective in miniature pigs Because of the synergism miniature pigs immunized twice with a mixture of 10 mu g of DNA and a 1/100 dose of JEVAX developed a high neutralizing antibody titer (1 190 at 90% plague reduction assay) Even using 1 mu g of DNA 3 of 4 pigs developed neutralizing antibodies Following challenge all miniature pigs with detectable neutralizing antibodies were protected against viremia Pregnant sows inoculated with 10 or 1 mu g of DNA mixed with JEVAX (1/100 dose) developed antibody titers of 1 40-1 320 Following challenge fetal death and mummification were protected against in DNA/JEVAX-immunized sows (C) 2010 Elsevier Ltd All rights reserved