Protection against respiratory syncytial virus (RSV) elicited in mice by plasmid DNA immunisation encoding a secreted RSV G protein-derived antigen

Plasmid vectors encoding two different variants, one cytoplasmic and one se creted version, of a candidate vaccine BBG2Na to respiratory syncytial viru s (RSV), were constructed and evaluated in a nucleic acid vaccination study . The two different vectors, which employed the Semliki Forest virus gene a mplification system, were found to express BBG2Na appropriately in in vitro cell cultures. Immunisation of mice with the plasmid vectors elicited sign ificant serum anti-BBG2Na IgG responses only in the mice receiving the plas mid encoding the secreted version of BBG2Na. Consistent with antibody induc tion data, sterilising lung protection against RSV-A challenge was also onl y observed in this group. These results indicate that the targeting of anti gen expression (intracellular versus secreted) would be an important factor to consider in the design of nucleic acid vaccines. (C) 2000 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.