【Objective】 To express the nonstructural protein 1 (NS1) of Dengue virus type 1 (DENV-1) and Dengue virus type 3 (DENV-3) in E.coli

and prepare polyclonal antibodies against the NS1 proteins in vivo and establish a high sensitivity and specificity ELISA of DENV NS1 antigen. 【Methods】 The full-length DENV-1 and DENV-3 NS1 genes were amplified by RT-PCR

and then cloned into pGEM-T vector. After the NS1 genes were cloned into expression plasmid PET30a(+) respectively

the recombinant plasmids were transformed into E. coli BL21. The recombinant NS1 proteins were expressed by induction with IPTG

and purified. For production of anti-NS1 polyclonal antibodies

we immunized mice with the purified recombinant proteins. The polyclonal antibodies were used to establish a double-antibody sandwich ELISA for detecting Dengue NS1 antigen. 【Results】 Successfully constructed highly efficient prokaryotic expression system which expressed DENV-1 or DENV-3 NS1 protein and obtained purified NS1 proteins. The recombinant proteins were used to immunize BALB/c mice. Polyclonal antibodies against NS1 of DENV-1 or DENV-3 with high titer (>1:30000) were finally obtained. With these polyclonal antibodies

we detected 1 ng/ml homo-typic DENV NS1 protein by using double-antibody sandwich ELISA. There was no cross-reactivity with other members of flavivirus

indicating a good specificity. 【Conclusion】 In this study

we succeeded in constructing highly efficient prokaryotic expression system of DENV-1 or DENV-3 NS1 protein

and demonstrated that the expressed NS1 proteins had good immunogenicity and immune reactivity. Established a double-antibody sandwich ELISA for detecting Dengue NS1 antigen

and proved the assay had high sensitivity and specificity

with a good application prospect.