Recombinant DENV 2 NS5: An effective antigen for diagnosis of DENV infection.

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.