Full
Outline
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.
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.
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.
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.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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