DNA VACCINES - PROTECTIVE IMMUNIZATIONS BY PARENTERAL, MUCOSAL, AND GENE-GUN INOCULATIONS

Plasmid DNAs expressing influenza virus hemagglutinin glycoproteins ha ve been tested for their ability to raise protective immunity against lethal influenza challenges of the same subtype. In trials using two i noculations of from 50 to 300 mug of purified DNA in saline, 67-95% of test mice and 25-63% of test chickens have been protected against a l ethal influenza challenge. Parenteral routes of inoculation that achie ved good protection included intramuscular and intravenous injections. Successful mucosal routes of vaccination included DNA drops administe red to the nares or trachea. By far the most efficient DNA immunizatio ns were achieved by using a gene gun to deliver DNA-coated gold beads to the epidermis. In mice, 95% protection was achieved by two immuniza tions with beads loaded with as little as 0.4 mug of DNA. The breadth of routes supporting successful DNA immunizations, coupled with the ve ry small amounts of DNA required for gene-gun immunizations, highlight the potential of this remarkably simple technique for the development of subunit vaccines.