The prevalence of NS1 Ab response in patients with
dengue viral infection and the potential of using recombinant NS1
protein as a diagnostic
antigen for
dengue viral infection were investigated. In this study, the full-length and C-terminal half of NS1
proteins (rNS1, rNS1-C) were highly expressed (10-30 mg/l) and further purified and refolded. The good antigenicity of the full-length rNS1
protein was confirmed by interaction with 19
dengue NS1-specific
monoclonal antibodies (MAbs) in ELISA; however, the antigenicity of rNS1-C was relatively lower. The full-length rNS1
antigen also differentiated reliably between sera from dengue virus-infected patients and sera from normal controls. When rNS1 was used as an
antigen to detect human anti-NS1
IgM and
IgG Ab, the anti-NS1 Ab response was found in 15 of 17 patients (88%) with primary
dengue infection and all 16 patients (100%) with secondary
dengue infection. These results indicated that using the full-length rNS1 whose antigenicity is restored as ELISA
antigen, a high anti-NS1 antibody prevalence could be detected in patients with either primary or secondary
dengue infection. This finding suggested that the anti-NS1 antibody appeared not only in secondary and
severe dengue virus infection and might not correlate the pathogenesis of
dengue hemorrhagic fever. The study also verified that our purified rNS1
protein showed similar immunological properties as native
dengue viral proteins. Genetic engineering production of recombinant NS1
antigen could provide a safe and valuable resource for dengue virus serodiagnosis.