Induction of potent Th1-type immune responses from a novel DNA vaccine forWest Nile virus New York isolate (WNV-NY1999)

West Nile virus (WNV) is a vectorborne pathogen that induces brain inflamma tion and death. Recently, confirmed cases of infection and deaths have occu rred in the United States Mid-Atlantic region. In this study, a DNA vaccine encoding the WNV capsid protein was constructed, and the in vivo immune re sponses generated were investigated in DNA vaccine-immunized mice. Antigen- specific humoral and cellular immune responses were observed, including a p otent induction of antigen-specific Th1 and cytotoxic, T lymphocyte respons es. Strong induction of Th1-type immune responses included high levels of a ntigen-specific elaboration of the Th1-type cytokines interferon-gamma and interleukin-2 and beta -chemokines RANTES (regulated upon activation, norma l T cell-expressed and secreted) and macrophage inflammatory protein-1 beta . Dramatic infiltration of CD4 and CD8 T cells and macrophages also was obs erved at the muscle injection site, These results support the potential uti lity of this method as a tool for developing immunization strategies for WN V and other emerging pathogens.