Dengue　fever　is　a　mosquito-borne　viral　disease　with　dramatically　increasing　morbidity　rate　worldwide　in　decades.　Since　there　is　no　specific　treatment　to　date,　early　diagnosis　is　important　for　providing　proper　timely　medical　care　to　minimize　mortality,　and　for　the　prompt　initiation　of　public　health　control　measures.　NS5　is　a　potential　biomarker　for　dengue　virus　infection　due　to　its　highly　conserved　and　immunogenic　properties.　In　this　study,　the　DENV　2　NS5　full-length　and　the　DENV　2　NS5　C-terminus　RNA-dependent　RNA　polymerase　domain　fragment　(NS5-C70)　expression　plasmids　were　constructed,　and　the　104　kDa　full-length　NS5　and　the　70　kDa　NS5-C70　were　respectively　expressed　in　Escherichia　coli.　These　two　purified　recombinant　products　were　found　to　react　with　the　sera　of　patients　infected　with　dengue　virus　when　analyzed　by　an　enzyme-linked　immunosorbent　assay　(ELISA),　which　resulted　in　significantly　higher　absorption　values　than　those　of　control　sera.　The　recombinant　DENV　2　NS5　exhibited　strong　reactivity　to　each　of　the　four　types　of　sera,　whereas　the　NS5-C70　showed　strong　reactivity　only　to　DENV　2　and　4.　In　comparison,　the　positive　agreement　value　of　recombinant　NS5-based　assay　with　either　MyBioSource　or　Panbio　assay　was　higher　than　that　of　the　two　commercially　available　IgG　indirect　ELISA　kits.　These　results　suggest　that　the　recombinant　DENV　2　NS5　be　an　effective　antigen　for　detection　of　dengue　virus　infection.　The　recombinant　NS5-C70　may　also　be　used　as　an　auxiliary　antigen　for　diagnostic　purposes.