HW, XL, and SZ contributed to writing of the statement. test results of 633 non-SARS-COV-2 infected individuals, including pregnant women, individuals with other respiratory infections, and individuals with increased rheumatoid factor were all bad, with serum N protein concentration <10.00 pg/mL at 100% specificity. Using SPSS 19.0 to determine the receiver operating characteristic curve, the area under the curve was determined to be 0.9756 (95% confidence interval 0.94851.000,p< 0.0001), and level of sensitivity and specificity were 92% (95% confidence interval 81.1696.85%) and 96.84% (95% confidence interval 95.1797.15%), respectively. The best CUT-OFF value was 1.850 pg/mL. Summary:The measurement of serum SARS-COV-2 N protein has a high diagnostic value for infected individuals before the antibody appears and shortens the windowpane period of serological analysis. It is recommended that the manufacturer set up two different CUT-OFF ideals according to the purpose of the application. One CUT-OFF value is used for the analysis of medical SARS-COV-2 illness, and the additional is used to display out as many suspected cases as you can. Keywords:SARS-CoV-2, COVID-19, nucleocapsid protein, colloidal platinum immunochromatography, diagnostic value == Intro == As of July 10, 2020, there were more than 12.2 million people infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and more than 554,291 deaths (Johns Hopkins University or college CSSE,2020;https://gisanddata.Maps.Arcgis.Com/apps/opsdashboard/index.Html#/bda7594740fd40299423467b48e9ecf6), which has posed a serious threat to the health and economic existence of people globally. With the joint attempts of scientists worldwide, a variety Velneperit of diagnostic reagents have been developed to provide support for the medical analysis of SARS-COV-2 (Chan et al.,2020; Corman et al.,2020; Konrad et al.,2020; Reusken et al.,2020). At present, the analysis of SARS-COV-2 illness is mainly based on pharyngeal swab or sputum nucleic acid detection, and specific serum antibody detection is used as an auxiliary marker (To et al.,2020;http://www.nhc.gov.cn/yzygj/s7653p/202003/46c9294a7dfe4cef80dc7f5912eb1989.shtml). Nucleic acid screening is definitely greatly affected by specimen collection, transportation, and additional stages. The number of inconsistent positive and negative results is definitely high, and the overall rate of positivity is not high (Abduljalil,2020; Cheng et al.,2020; Xie et al.,2020), which causes great Velneperit misunderstandings during clinical analysis. The test for specific antibodies against SARS-COV-2 in Velneperit the serum will appear positive only about 7 days after illness or later CDC42 on in severe coronavirus disease 2019 (COVID-19) (Qu et al.,2020; Zainol Rashid et al.,2020). It is hard to detect the infection at an early stage, making it hard to block the source of illness, and this increases the difficulty of avoiding and controlling the spread of SARS-COV-2 illness. Given this scenario, this study analyzed the positivity rate of serum N protein before the generation of serum antibodies in individuals infected with SARS-COV-2, providing new diagnostic signals for Velneperit the early detection of SARS-COV-2 illness. == Materials and Methods == == Specimen Resource == == COVID-19 Individuals == Forty COVID-19 individuals were enrolled from your First Affiliated Hospital of Anhui Medical University or college, and 30 COVID-19 individuals were enrolled from your Anhui Provincial Center for Disease Prevention and Control. All COVID-19 individuals were diagnosed based on the results of nucleic acid Reverse Transcription-Polymerase Chain Reaction (RT-PCR) test, as well as pathological changes observed in computed tomography (CT) images, according to the seventh release of the pneumonia analysis and treatment program for the novel Coronavirus illness reported from the (National Health Commission of the People’s Republic of China,2020;http://www.Q13nhc.gov.cn/yzygj/s7653p/202003/46c9294a7dfe4cef80dc7f5912eb1989.shtml). Among the 40 COVID-19 patients enrolled from your First Affiliated Hospital of Anhui Medical University or college, 20 cases were unfavorable for serum SARS-COV-2 N protein antibody around the first day of admission; later, 37 cases tested positive for serum SARS-COV-2 N protein antibody within 9 days of admission. We categorized the 70 COVID-19 patients into a SARS-COV-2 N protein antibody-positive group and a SARS-COV-2 N protein antibody-negative group. Thus, 50 samples from patients with positive pharyngeal swab or sputum SARS-COV-2 nucleic acid and unfavorable serum SARS-COV-2 N protein antibody test results were collected from your First Affiliated Hospital of Anhui Medical University or college (20 cases) and the Anhui Provincial Center for Disease Prevention and Control (30 cases). Thirty-seven samples from patients with positive pharyngeal swab or sputum SARS-COV-2 nucleic acid and positive serum SARS-COV-2 N protein antibody test results were collected from your First Affiliated Hospital of Anhui Medical University or college. == Non-COVID-19 Patients == Six hundred thirty-three samples with unfavorable pharyngeal swab or sputum SARS-COV-2 nucleic acid result and unfavorable serum N protein antibody test results were obtained from the First Affiliated Hospital of Anhui Medical University or college, including 100 samples from pregnant women (serum of pregnant women at 1530 weeks), 369 serum samples from patients with other respiratory infections (non-COVID-19 patients with respiratory symptoms), 119 serum samples from individuals with increased rheumatoid factor (more than one time above the upper limit of the reference value; reference value: 014 IU/ml), and 45 hemolytic samples. All samples were tested for SARS-CoV-2 N protein by ELISA double antibody sandwich.