SELF-REPLICATING SEMLIKI FOREST VIRUS-RNA AS RECOMBINANT VACCINE

Recombinant RNA based on the Semliki Forest virus (SFV) replicon was u sed to express the nucleoprotein of influenza virus in mice. Two strat egies were employed to deliver the RNA. In the first, recombinant RNA was packaged into infectious suicide SFV particles which were used dir ectly for immunization. The second approach involved injection of in v itro-synthesized RNA directly into the quadriceps muscle. Both approac hes resulted in the generation of humoral responses with high antibody titres. Immunization with suicide particles showed that a strong, cla ss I-restricted cytotoxic T-cell response can be obtained using only 1 00 infectious units. We conclude that the self-replicative recombinant SFV RNA may be quite useful as a nucleic acid vaccine.