THE LATEX ALLERGEN HEV-B-5 TRANSCRIPT IS WIDELY DISTRIBUTED AFTER SUBCUTANEOUS INJECTION IN BALB C MICE OF ITS DNA VACCINE/

Background: DNA vaccines reduce IgE responses to selected allergens, b ut severe reactions to the expressed antigen may limit the usefulness of the technique in allergen immunotherapy. Objective: We sought to de termine the extent of spread of an injected DNA vaccine in mice. Metho ds: We placed the gene encoding the potent Hevea latex allergen Hev b 5 in a mammalian expression vector and injected this DNA vaccine subcu taneously into BALB/c mice. At several times after injection, the pres ence of Hev b 5 transcript was determined in multiple tissues by RT-PC R, The identity of the amplification product was confirmed by Southern hybridization and restriction analyses. Results: Hev b 5 RNA appeared at the injection site and in the lymph nodes, spleen, and lungs withi n 1 day after injection and persisted for at least 14 days. Hev b 5 RN A was also identified in the blood and tongue 14 days after injection. Antibody and cell-mediated responses to Hev b 5 were also noted in th e immunized animals at later time points. As expected, animals injecte d with the identical plasmid containing the Hev b 5 DNA in the antisen se orientation mounted no immune response to Hev b 5. Conclusions: The rapid and widespread appearance of the Hev b 5 transcript in the inje cted mice confirms that DNA is translocated from the injection site, t ranscribed, and expressed in immune and nonimmune tissues after inject ion. Controlling the extent and degree of expression in specific targe t tissues may allow therapeutic DNA vaccination with plasmids that enc ode potentially toxic allergens.