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

West Nile virus (WNV) is a vectorborne pathogen that induces brain inflammation and death. Recently, confirmed cases of infection and deaths have occurred 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 responses generated were investigated in DNA vaccine-immunized mice. Antigen-specific humoral and cellular immune responses were observed, including a potent induction of antigen-specific Th1 and cytotoxic T lymphocyte responses. Strong induction of Th1-type immune responses included high levels of antigen-specific elaboration of the Th1-type cytokines interferon-gamma and interleukin-2 and beta-chemokines RANTES (regulated upon activation, normal T cell-expressed and secreted) and macrophage inflammatory protein-1beta. Dramatic infiltration of CD4 and CD8 T cells and macrophages also was observed at the muscle injection site. These results support the potential utility of this method as a tool for developing immunization strategies for WNV and other emerging pathogens.