Recently, GP has been used for viral vector-based or DNA vaccines that were shown to protect animals effectively. Replicationincompetent adenovirus expressing GP, a replication-competent vesicular stomatitis virus expressing GP, and a recombinant paramyxovirus expressing GP have been shown to protect nonhuman primates from lethal infections of filoviruses (Sullivan et al., , 2003 Jones et al., 2005; Bukreyev et al., 2007; Feldmann et al., 2007) . It should be noted that these vaccines potentially induce cytotoxic cellular response (i.e., CD8+ T lymphocytes) as well as antibody production, suggesting that activating cytotoxic T-cells is a key protective mechanism (Olinger et al., 2005; Sullivan et al., 2006; Reed and Mohamadzadeh, 2007) . Since cytotoxic T-cell response cannot be fully induced by immunization with non-replicative protein antigens such as inactivated virus and subunit vaccines, viral vector-based, or DNA vaccines may be promising in preventing filovirus infection.