PARTICULATE VACCINE CANDIDATE FOR JAPANESE ENCEPHALITIS INDUCES LONG-LASTING VIRUS-SPECIFIC MEMORY T-LYMPHOCYTES IN MICE

We previously reported that extracellular particles (EPs) composed of premembrane (prM) and envelope (E) proteins were released from cells i nfected with recombinant vaccinia viruses encoding Japanese encephalit is (JE) virus prM and E genes. In the present study, EPs were evaluate d for induction of JE virus-specific antibody, and specific T lymphocy tes in mice. Six- to 8-week-old male Balb/c mice were inoculated intra peritoneally once or twice (at a 3-week interval) with purified EPs co ntaining 1 mu g off without adjuvant. Neutralizing antibody, was detec ted and spleen cells proliferated against JE viral antigen 3 weeks aft er the second immunization with EPs, Neutralizing antibody and JE viru s-specific T Iymphocytes were also detected 10 months after immunizati on with EPs containing 2 mu g of E. Spleen cells obtained from EP-immu nized mice and stimulated in vitro with live JE virus, expressed JE vi rus-specific cytotoxic activity. The cytotoxic activity, was reduced b y treatment with anti-CD3 antibody and complement. These results indic ate that immunization with EPs induces long-lasting specific antibody and memory T cells in mice. (C) 1997 Elsevier Science Ltd.