ABSTRACT
Objective To establish a sample panel for detection of severe acute respiratory symptom coronavirus 2 (SARS-CoV-2) antigen and apply to the development and quality evaluation of SARS-CoV-2 antigen colloidal gold test cassettes. Methods A sample panel for detection of SARS-CoV-2 antigen was established using 12 kinds of bulks of inactivated non-SARS-CoV-2 vaccine as negative controls, while two batches (Bl and B2) of bulks of inactivated SARS-CoV-2 vaccine (Bl, B2) and one batch (SI) of inactivated SARS-CoV-2 culture as positive controls. Bl was used as a positive control to evaluate the colloidal gold test cassettes from four manufacturers (A, B, C and D), and to monitor the development process of cassette from manufacturer A to improve its sensitivity. The negative sample panel was used to evaluate the specificity of colloidal gold test cassettes from five manufacturers (A, C, E, F and G), while positive sample panel (B2, SI and recombinant N protein) to evaluate the sensitivity. Inactivated SARS-CoV-2 culture SI was deter-mined with the commercial SARS-CoV-2 nucleic acid detection kit, and the result was compared with that by the colloidal gold test cassette from manufacturer A. Results N protein was determined as the main epitope of SARS-CoV-2 antigen by evaluation with positive control. The colloidal gold test cassettes from manufacturer A showed a sensitivity of 1 : 2 x 103to B1. The colloidal gold test cassettes from five manufacturers showed no cross reactions with inactivated non-SARS-CoV-2 vaccines, indicating a high specificity. The sensitivity of colloidal gold test cassette from manufacturer A was 106to B2 and 1 : 2 x 107to S1. However, the sensitivities of colloidal gold test cassettes from manufacturers E, F and were more than 1 : 103to B2 and 1 : 104- 1 : 105to SI, and that from manufacturer C was 1 : 104to B2 and 1 : 106to SI. The sensitivity of colloidal gold test cassette from manufacturer A was 100 pg/mL, while those from the other four manufacturers were 10 pg/mL, to recombinant N protein. The sensitivity of commercial nucleic acid detection kit to SI was 1 : 107, which was equal to that of colloidal gold test cassette from manufacturer A (1 : 2 x 107). Conclusion A sample panel for detection of SARS-CoV-2 antigen was successfully established, which showed high specificity and sensitivity, and might be used for the development and quality evaluation of SARS-CoV-2 antigen colloidal gold test cassettes. Copyright © 2022 Changchun Institute of Biological Products. All rights reserved.
ABSTRACT
BIRDS : The variety and widespread of coronavirus in natural reservoir animals is likely to cause epidemics via interspecific transmission, which has attracted much attention due to frequent coronavirus epidemics in recent decades. Birds are natural reservoir of various viruses, but the existence of coronaviruses in wild birds in central China has been barely studied. Some bird coronaviruses belong to the genus of Deltacoronavirus. To explore the diversity of bird deltacoronaviruses in central China, we tested faecal samples from 415 wild birds in Hunan Province, China. By RT-PCR detection, we identified eight samples positive for deltacoronaviruses which were all from common magpies, and in four of them, we successfully amplified complete deltacoronavirus genomes distinct from currently known deltacoronavirus, indicating four novel deltacoronavirus stains (HNU1-1, HNU1-2, HNU2 and HNU3). Comparative analysis on the four genomic sequences showed that these novel magpie deltacoronaviruses shared three different S genes among which the S genes of HNU1-1 and HNU1-2 showed 93.8% amino acid (aa) identity to that of thrush coronavirus HKU12, HNU2 S showed 71.9% aa identity to that of White-eye coronavirus HKU16, and HNU3 S showed 72.4% aa identity to that of sparrow coronavirus HKU17. Recombination analysis showed that frequent recombination events of the S genes occurred among these deltacoronavirus strains. Two novel putative cleavage sites separating the non-structural proteins in the HNU coronaviruses were found. Bayesian phylogeographic analysis showed that the south coast of China might be a potential origin of bird deltacoronaviruses existing in inland China. In summary, these results suggest that common magpie in China carries diverse deltacoronaviruses with novel genomic features, indicating an important source of environmental coronaviruses closed to human communities, which may provide key information for prevention and control of future coronavirus epidemics
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Objective To explore the application and safety of apheresis technology in collection of Coronavirus Disease 2019 (COVID-19) convalescent plasma (CP), and to analyze the quality characteristics of the plasma. Methods The general data of COVID-19 convalescent plasma (CP) donors, including gender, age, date of discharge or release from medical isolation, were collected based on informed consent. After physical examination, the CP was collected by apheresis technology with plasma separator, inactivated with methylene blue, and determined for severe acute respiratory symptom Coronavirus 2 (SARS-CoV-2) nucleic acid and specific antibody (RBD-IgG) against SARS-CoV-2. Results The collection process went well, and no serious adverse events related to plasma collection were reported during or after the collection. The average age of COVID-19 CP donors was 38 years (n = 933). The distributions of blood groups A, B, AB and 0 in RhD (+) COVID-19 CP were 33. 4%, 29. 2%, 10% and 27. 2% respectively. The plasma donation date was 18 d from the discharge date in average. All the test results of SARS-CoV-2 nucleic acid in CP were negative, while the proportion of plasma samples at SARS-CoV-2 antibody titer of more than 1: 160 was 92. 60%. Conclusion Apheresis technology was safe and reliable. The COVID-19 CP contained high titer antibody. Large-scale collection and preparation of inactivated plasma against SARS-CoV-2 played an important role in the treatment of COVID-19.
ABSTRACT
Objective: To compare the correlation between the results of SARS-CoV-2 neutralizing antibody colloidal gold test cards prepared by two different principles and the SARS-CoV-2 pseudovirus neutralization experiment, and to evaluate the feasibility of the neutralizing antibody colloidal gold test card for the SARS-CoV-2 neutralizing antibody detection in different populations. Methods: Two kinds of SARS-CoV-2 neutralizing antibody colloidal gold test cards using double antigen sandwich method (manufacturer A) and competitive blocking method (manufacturers B) were used to detect the samples with SARS-CoV-2 neutralizing antibody titers. Detection sensitivity and the correlation between the two methods and the neutralization experiment were compared. The intravenous human immunoglobulin and specific immunoglobulin prepared before the outbreak of COVID-19 epidemic were detected to investigate the specificity of the eligible test card. In order to determine whether there is a hook effect, individual immunized plasma samples of high ELISA titers were tested with series of dilutions and original dilution. Single post-immunized plasma samples were detected with different ELISA titers, the positive rates were determined and the color changes were observed. Single post-immunized plasma samples were screened in the low-dilution area of ELISA according to chromaticity of 120NT50 and 300NT50 on the colorimetric card to prepare pooled plasma. The results were compared with the currently used indirect ELISA method. Results: The detection limits of manufacturers A and B for the first-generation NIBSC international standard 20/136 (anti-SARS-CoV-2 human immunoglobulin international standard) were 0.612 5 and 5 IU•mL-1, respectively. The results of different titers of pooled plasma (both of post-immunization with SARS-CoV-2 vaccine and COVID-19 convalescence plasma) have a good correlation with the neutralizing antibody titer. The post-immunization plasma with high ELISA dilutions (above 10 000) did not show hook effect. The positive rate of individual plasma of different ELISA dilution levels reached 100% when the dilution was above 160, and the uniformity of the chromaticity was higher when the dilution level was above 640. The overall chromaticity became darker as the ELISA dilution increased. The chromaticities of Ppool 120NT50 and Ppool 300NT50 screened according to the colorimetric chart were close to the neutralizing antibody titers. Conclusion: The correlation between the results of the manufacturer A neutralizing antibody test card using the dual antigen sandwich method to detect SARS-CoV-2 neutralizing antibody in convalescent plasma and post-immunization plasma and the titer of the pseudovirus neutralization experiment is better than that of the manufacturer B product using the competitive inhibition method and indirect ELISA. And the color brightness of the detection line is positively correlated with the level of neutralizing antibody, which can be used for preliminary screening of neutralizing antibody in different populations.
ABSTRACT
Objective To establish a SARS-CoV-2 antibody sample panel and apply to the quality evaluation of test cassettes for colloidal gold lateral flow assay. Methods SARS-CoV-2 antibody sample panel was established with the convalescent plasma samples from patients with Corona Virus Disease 2019 (COVID-19) and optimized. Suggestions for modification were put forward on the sample panels from three manufacturers (S, L and H), and the test cassettes after modification were analyzed and compared. Results The accuracy, sensitivity, specificity and Youden index of cassette from manufacturer S were 92. 54%, 90. 78%, 100% and 0. 908 respectively, while the positive test region was light in color and not easy to be recognized. However, after modification, the accuracy, sensitivity, specificity and Youden index were 95. 35%, 98. 91%, 97. 19% and 0. 943 respectively, while the color of positive test region was developed obviously and easy to be recognized. The sensitivity of cassette from manufacturer L was only 14. 28% before modification, while the positive test region was unobvious in color, indicating a high missed detection rate. However, after modification, the sensitivity for IgM was 98. 63% , while the color of positive test region was developed obviously and rapidly. The sensitivity, specificity, accuracy and Youden index were 98. 08%, 100. 00%, 98. 90% and 0. 981 for IgG, while were 84. 50%, 86. 49%, 85. 71% and 0. 710 for IgM, respectively. Conclusion The developed sample panel may be used for the quality evaluation of SARS-CoV-2 antiobdy detection reagents. © 2021 Changchun Institute of Biological Products. All rights reserved.