Fusion with extracellular domain of cytotoxic T-lymphocyte-associated-antigen 4 leads to enhancement of immunogenicity of Hantaan virus DNA vaccines in C57BL/6 mice oleh Wang Shiwen, Zhang Shuo, Li Chuan, Zhang Quanfu, Liu Qinzhi, Cao Shouchun, Liang Mifang, Liu Feng, Li Dexin