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@#Objective To prepare the second generation internal control reference(B2)for Ig G antibody against severe acute respiratory symptom coronavirus 2(SARS-CoV-2)and evaluate its applicability in ELISA detection method. Methods Among the volunteers vaccinated with SARS-CoV-2 inactivated vaccine(BBIBP-Cor V)produced by Beijing Institute of Biological Products Co.,Ltd.,19 Ig G antibody positive plasma samples with ELISA-Ig G dilution ratio of 20 ～ 60 were screened,and the Ig G antibody,IgM antibody and neutralizing antibody were detected by ELISA,B2 was prepared from nonlipid plasma with ELISA-Ig G dilution ratio of 32 ～ 45,IgM negative and similar neutralizing antibody inhibition rate. The neutralizing antibody potency of the first generation internal control reference(B1)and B2 detected by ELISA was calibrated with the first generation WHO international standard of anti-SARS-CoV-2 immunoglobulin(NIBSC 20/136),and the accelerated stability(storage at 2 ～ 8 ℃ for 5,8,14,20,and 30 d respectively),the service stability(storage at 18 ～25 ℃ for 1,2,and 3 h respectively),the freeze-thaw stability(1,2 and 3 times)and the long-term stability(storage at-25 ℃ for10 months)of B2 were tested. B2 was used as standard to detect plasma after single vaccine immunization and mixed plasma was prepared according to different ELISA-Ig G dilution ratio. The correlation and linear regression analysis between ELISA-Ig G dilution ratio and neutralizing antibody potency of pseudovirus in mixed plasma were carried out. Results Among 19 plasma samples,5 samples were non-lipid plasma with ELISA-Ig G dilution ratio of 32 ～ 45,IgM negative and similar neutralizing antibody inhibition rate. B2 was prepared by mixing every plasma in equal volume fraction,and the dilution ratio of ELISA-Ig G was assigned to 32. The neutralizing antibody potency of B1 calibrated with NIBSC 20/136 was 133. 38 EIU/m L and that of B2 was 122. 14 EIU/m L. The recovery rates of accelerated stability,service stability,freeze-thaw stability and long-term stability of B2 were all in the range of(100 ± 15)%. The ELISA-Ig G dilution ratio of the mixed plasma from the same source was significantly correlated with the neutralizing antibody potency of pseudovirus.(each R~2> 0. 99,each P < 0. 000 1).Conclusion B2 prepared from plasma immunized with SARS-CoV-2 inactivated vaccine can replace B1 prepared from plasma of COVID-19 convalescent patients.
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@#Objective To optimize and verify the ELISA method for quantitative detection of varicella-zoster virus(VZV)IgG antibody potency,and use it for the screening of plasma with high potency VZV-IgG in healthy donors.Methods The VZV-IgG indirect ELISA kit from Institut VirionSerion GmbH was selected,the first international standard for varicellazoster immunoglobulin(NIBSC code:W1044)was diluted to 2 IU/mL as the standard,and 4-parameter fitting curve was used to develop the quantitative ELISA method. The method was determined for the optimal linear range and verified for the precision and accuracy. VZV-IgG antibody potency of 1 962 human plasma samples and some batches of human immunoglobulin preparations from 10 plasma stations under Sinopharm Wuhan Plasma-derived Biotherapies Co.,Ltd.(SWPB)were detected by the developed method.Results The linear range of the standard curve was 16. 25 ～ 2 000 mIU/mL,the CV values of precision in intra-and inter-assays were 1. 3% ～ 10. 6% and 4. 270% ～ 7. 636%,and the accuracy in intra-and inter-assays were 92. 30% ～ 111. 02% and 98. 40% ～ 104. 88%,respectively;Sample-adding experiment showed that the measured value of the added sample was 95. 79% ～ 111. 03% of the theoretical value. The positive rate of 1 962 human plasma samples was 94. 29%,and the samples with potency greater than 3 000 mIU/mL accounted for 1. 02%. The potency of VZV-IgG antibody in different kinds of human immunoglobulin preparations was lower,while higher than that of intravenous human immunoglobulin(pH 4).Conclusion The optimized VZV-IgG quantitative detection method can be used for the screening of VZV-IgG in healthy people. The positive rate of VZV-IgG antibody in naturally infected healthy plasma donors is high,while the potency is low,thus,vaccine immunization is required to obtain qualified plasma with high potency.
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SARS-CoV-2;ELISA-IgG;Neutralizing antibody;Dilution multiple;Post-immunization plasma;Qualified rate of plasma collection@#Objective To determine the optimal plasma screening kit for raw materials by comparing the qualified rate of plasma collection and operation convenience of four SARS-CoV-2 ELISA-IgG and neutralizing antibody kits from three manufacturers.MethodsSingle plasma samples with different ELISA dilution multiples screened from existing plasma immunized with SARS-CoV-2 vaccine were used as raw materials,which were detected by using SARS-CoV-2 ELISA-IgG and neutralizing antibody kits from different manufacturers. Plasma samples were mixed according to the potency level of each manufacturer,and pseudovirus neutralization test was carried out on pooled plasma. According to the potency of neutralizing antibody,the plasma collection standard of different kits were determined,and the qualified rate of plasma collection was calculated respectively. The dilution method of single plasma sample screening was determined in regard of the plasma collection standard,and the operation convenience was compared;The applicability of the kits were evaluated comprehensively.ResultsThe qualified rate of ELISA-IgG antibody kit of manufacturer B in 1 108 WT > 16 plasma samples was 82. 1% with internal control reference B2 as the plasma collection standard,which was higher than that of the current ELISA-IgG antibody kit of manufacturer A(59. 8%). With the level of 50 IU/mL tested by neutralizing antibody kit of manufacturer B as the standard of plasma collection,the qualified rate of plasma collection of this kit in 387 WT16 ～64 samples was 66. 4%,higher than that of ELISA-IgG kit of manufacturer A(42. 1%). While with the level of 100 IU/mL tested by neutralizing antibody kit of manufacturer C as the standard of plasma collection,the qualified rate of plasma collection of this kit in 536 WT16 ～ 64 samples was 42. 5%,lower than that of ELISA-IgG kit of manufacturer A(50. 2%).Neutralizing antibody kit of manufacturer C had the most operation steps and the longest reaction time;ELISA-IgG kit of manufacturer B had the shortest reaction time,and required no out-of-hole dilution for samples of WT16 ～ 64,while the ELISA-IgG kit of manufacturer A required out-of-hole dilution in transition plate. The difference of qualified rate of plasma collection among the four kits mainly occurred in the samples of WT16 ～ 64. The order of the qualified rate of plasma collection in this range was:ELISA-IgG kit of manufacturer B > neutralizing antibody kit of manufacturer B > ELISA-IgG kit of manufacturer A > neutralizing antibody kit of manufacturer C. The order of operation convenience was:ELISA-IgG kit of manufacturer B > neutralizing antibody kit of manufacturer B > ELISA-IgG kit of manufacturer A > neutralizing antibody kit of manufacturer C.ConclusionIn view of the overall analysis of the applicability from qualified rate of plasma collection and operation convenience,ELISA-IgG kit of manufacturer B is the optimal.
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Objective@#To evaluate the status of dietary diversity and determinants among school age left behind children.@*Methods@#A total of 501 children aged 9-10 years in Sheyang Mini Cohort Study were enrolled from Sheyang City in Jiangsu Province during 2019. A questionnaires survey was administrated to collect left behind and socioeconomic information. Twenty four hour dietary recall survey was conducted, dietary diversity score (DDS 10 and DDS) and food variety score (FVS) were computed according to Food and Agriculture Organization (FAO). Weight and height of children were measured and sex and age standardized body mass index was used to define obesity. Multivariable regression models were preformed to explore the determinants of dietary diversity in school age left behind children.@*Results@#The proportion of left behind children was 40.9%. The mean value and standard deviation of three kinds of dietary diversity score (DDS 10 , DDS, FVS) in left behind children were (5.69±1.31)(6.55±1.44) and (13.48± 4.23 ), respectively. All of these were lower than that in non left behind children (DDS 10 :5.99±1.29; DDS:6.79±1.40; FVS:14.15±4.22). Significant difference in DDS 10 between left behind and non left behind children was observed ( P =0.01). The results of multivariable regression demonstrated that gender, passive smoking, family education level and family economic status were related to dietary diversity scores ( P <0.05).@*Conclusion@#Dietary diversity in school age left behind children was not optimistic and gender, passive smoking, parental education level, family economic status and left behind situation play a critical role in dietary diversity among these children.