Expression of NDV HN protein in rice and development of a semi-quantitative rapid method for detection of antibodies / 生物工程学报

The aim of this study was to develop a semi-quantitative immunochromatographic method for rapid detection of Newcastle disease virus (NDV) antibodies by expressing HN protein in rice endosperm bioreactor. The recombinant plasmid pUC57-HN was digested by MlyⅠ and XhoⅠ to retrieve the HN gene, while the intermediate vector pMP3 containing promoter, signal peptide and terminator was digested by NaeⅠ and XhoⅠ. The HN gene and the linearized pMP3 were purified and ligated to form a recombinant plasmid pMP3-HN1. Subsequently, pMP3-HN1 and plant vector pCAMBIA1300 were digested by EcoRⅠ and Hind Ⅲ, and the HN1 gene was cloned into pCAMBIA1300. The recombinant plasmid pCAMBIA1300-HN1 was introduced into Agrobacterium tumefaciens EHA105 by electrotransformation, and the pCAMBIA1300-HN1 was transferred into rice callus by agrobacterium-mediated method. After dark culture, callus screening, differentiation, rooting and transplanting, transgenic rice seeds were obtained 4 months later. PCR identified that the HN gene has been inserted into the rice genome. SDS-PAGE and Western blotting indicated that the HN protein was successfully expressed in the positive rice endosperm. The purity of the HN protein was more than 90% by SP cation exchange chromatography and gel filtration chromatography. According to the national standards for the diagnostic techniques of Newcastle disease HI test (HI≥4log2, positive antibody reaction), a colloidal gold labeled purified HN protein was used to prepare a semi-quantitative test strip by double-antibody sandwich method for rapid detection of NDV antibody. The results showed that the test strip did not cross-react with positive sera against other viruses, and the sensitivity of the test strip reached 1:102 400 for standard positive sera of Newcastle disease. Testing of a total of 308 clinical sera showed that the compliance rate of the test strip with HI test was 97.08%, and the Kappa value was 0.942. In conclusion, high purity recombinant HN protein was obtained from rice endosperm, and a simple, rapid, highly sensitive and highly specific semi-quantitative immunochromatographic strip was developed. The test strip could be used for immune evaluation of the Newcastle disease vaccine.

Development of Semi-quantitative Solid Sampling Mercury Analyzer for Cosmetics / 分析化学

On the basis of the chromogenic reaction between Hg and CuI, a semi-quantitative solid sampling Hg analyzer comprising the catalytic furance, Hg testing tube, air pump and smart cellphone was developed. White carrier 101 was chosen as the adsorbent for CuI to react with Hg from the catalytic furnace. The established Hg analyzer can not only visually recognize the coloration when Hg exceeding the limit standard, but also semi-quantitatively detect the Hg content in cosmetics fast using a smart cellphone and RGB analysis software, after direct solid sampling introduction of cosmetics sample. The instrumental detection limit ( LOD) of mercury was 50 ng, the linearity ranged from 50 ng to 2500 ng, the linear regression coefficient ( R2) was higher than 0. 97, and the RSD of the corresponding RGB values was 6% ( n=11 ) . Nine real cosmetics samples were measured by the established method, whose relative differences of Hg contents with that by the standard method (Safety Technical Specification for Cosmetics, 2015 edition) were less than 10% . The whole analytical time can be controlled within 5 min. The established instrumental method is simple, fast, accurate and visual, and extremely suitable to fast and on-site monitoring of Hg in cosmetics samples.