PROTECTIVE IMMUNITY INDUCED BY ORAL IMMUNIZATION WITH A ROTAVIRUS DNAVACCINE ENCAPSULATED IN MICROPARTICLES

DNA vaccines are usually given by intramuscular injection or by gene g un delivery of DNA-coated particles into the epidermis. Induction of m ucosal immunity by targeting DNA vaccines to mucosal surfaces may offe r advantages, and an oral vaccine could be effective for controlling i nfections of the gut mucosa. In a murine model, we obtained protective immune responses after oral immunization with a rotavirus VP6 DNA vac cine encapsulated in poly(lactide-coglycolide) (PLG) microparticles. O ne dose of vaccine given to BALB/c mice elicited both rotavirus-specif ic serum antibodies and intestinal immunoglobulin A (IgA). After chall enge at 12 weeks postimmunization with homologous rotavirus, fecal rot avirus antigen was significantly reduced compared with controls. Earli er and higher fecal rotavirus-specific IgA responses were noted during the peak period of viral shedding, suggesting that protection was due to specific mucosal immune responses. The results that we obtained wi th PLG-encapsulated rotavirus VP6 DNA are the first to demonstrate pro tection against an infectious agent elicited after oral administration of a DNA vaccine.