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    Study of Fluorescence Immunochromatography Based on Quantum Dots for the Detection of SARS-CoV-2 anti-N Protein IgG Antibody
    Renfeng YU, Xiaocang ZOU, Dayang ZOU, Linhao LI, Kehui WANG, Xiaoming HE, Yaqing XU, Rihui QIN, Dongdong MO, Jiahui Duan, Tao YU, Wei LIU, Jinpeng GUO
    Chinese General Practice    2022, 25 (14): 1741-1749.   DOI: 10.12114/j.issn.1007-9572.2022.0166
    Abstract806)   HTML13)    PDF(pc) (3967KB)(343)       Save
    Background

    Based on the current prevalence of Coronavirus Disease 2019 (COVID-19) , early diagnosis, isolation, and treatment are important methods to prevent and control infectious diseases. The establishment of convenient and efficient immunochromatographic detection techniques is essential for the prevention and control of COVID-19 epidemic.

    Objective

    To establish a method for the detection of SARS-CoV-2 anti-N protein IgG antibody by immun of luorescence chromatography method based on quantum dots labeling technology in August, 2020. In order to determine whether the detected persons had been infected with COVID-19 or been injected with SARS-CoV-2 inactivated vaccine.

    Methods

    The prepared rat anti-human secondary antibody and anti-N protein antibody were immobilized on a Nitrocellulose (NC) membrane as detection line (T) and quality control line (C) , respectively. Then the SARS-CoV-2 N protein labeled by quantum dots was evenly sprayed on glass fiber, which was assembled, cut and packaged into test strips after drying. The test strips were used to detect the clinical serum of 35 COVID-19 patients and 50 healthy individuals, the results of the initial screening of the ELISA kit were used as a control to calculate the detection specificity and sensitivity of quantum dots fluorescence immunochromatography. The sensitivity of the test strip was detected by using the N protein antibody standard.

    Results

    The specificity and sensitivity of the strip were 100.00%, 94.29%, and the susceptibility was 8.53-17.06 ng/ml antibody concentration.

    Conclusion

    The detection of anti-N protein IgG antibody in serum by quantum dots labeling is simple, fast, with strong sensitivity and specificity.

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    Research on Virus Morphology Recognition Method Based on Enhanced Graph Convolutional Network
    Yan HA, Weicheng YUAN, Xiangjie MENG, Junfeng TIAN
    Chinese General Practice    2022, 25 (14): 1749-1756.   DOI: 10.12114/j.issn.1007-9572.2022.0123
    Abstract692)   HTML12)    PDF(pc) (3384KB)(320)       Save
    Background

    Transmission electron microscope (TEM) is an important method to detect virus. TEM detection often relies on manual observation by experts, and the operation steps are cumbersome. Moreover, existing machine learning methods are easily affected by background and noise, resulting in poor virus detection methods, low efficiencyand time consuming.

    Objective

    In order to improve the efficiency of TEM virus detection, an Enhanced Graph Convolution Network (EGCN) is proposed to solve the problem of automatic identification of virus morphology in TEM images.

    Methods

    In this model, Convolutional Neural Network (CNN) was used to extract the local feature information between pixels, and GCN was used for graph feature learning combined with the nearest neighbor relationship between sample features. In the model optimization, the group super classification loss and classification cross entropy loss were introduced to improve the feature extraction ability of the model for virus category information, and further improve the robustness of TEM virus image features compared with convolution neural network.

    Results

    Experiments were carried out on 15 types of TEM virus image datasets through different methods, and EGCN achieved a top-1 error rate of 3.40%, a top-2 error rate of 1.88%, a precision of 96.65%, and a recall rate of 96.60%. A series of comparative experiments demonstrated that the EGCN can effectively solve the influence of background and noise in TEM virus recognition.

    Conclusion

    By using the enhanced graph convolutional neural network, the task of virus morphology recognition can be effectively solved, providing important reference value for virus diagnosis.

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