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@#ObjectiveTo develop and apply a method for detecting the titer of varicella-zoster virus(VZV)neutralizing antibodies based on complement dependence,so as to improve the sensitivity of traditional plaque reduction neutralization assay for detection of the titer of VZV antibody.MethodsThe antigen(live attenuated varicella vaccine)and antibody(human VZV immunoglobulin)were mixed in different proportions and different incubation times. After neutralization,the antigen-antibody mixture was inoculated into human diploid cell 2BS strain cultured in a six-well plate. After 7 ～ 10 d of culture,the number of plaques was counted by Coomassie brilliant blue staining,and the 50% neutralizing antibody titer was calculated by Karber′s formula. Under the optimal neutralization conditions obtained,the effect of complement on the sensitivity of neutralization experiment was explored by changing the addition amount of complement(lyophilized guinea pig serum)to evaluate the optimal addition amount of complement. According to the determined neutralization test parameters,the neutralizing antibody titers of 12 anti-VZV mouse sera and 14 anti-VZV human sera were detected by using traditional plaque method and complement-dependent plaque method respectively.ResultsThe key parameters of the detection method were determined:the titer of VZV standard antigen was 500 ～ 1 000 PFU/mL;the proportion of complement added to the antigen-antibody neutralization system was 1∶10(v/v),and the neutralization condition was 37 ℃ for 1 h. Both the complement-dependent plaque method and the traditional plaque method were positive for anti-VZV mouse serum antibody,while the antibody titer detected by the traditional plaque method was generally lower,and the antibody level of mice inoculated with 2 doses of live attenuated varicella vaccine was significantly higher than that of mice inoculated with 1 dose(t = 0. 45,P < 0. 05);Both of the two methods were positive for anti-VZV human serum antibody.ConclusionA complement-dependent detection method for neutralizing antibody titer of VZV was established. The addition of complement significantly improved the sensitivity of neutralization detection. The evaluation of the titers of neutralizing antibodies in mouse serum with different immunization strategies by the method suggested that the immune effect of two doses of vaccine was better than that of one dose.
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@#ObjectiveTo develop and verify a double antibody sandwich ELISA for the quantitative detection of varicellazoster virus(VZV)glycoprotein E(gE).MethodsHybridoma cell lines secreting antibody against VZV-gE stably were screened by mouse hybridoma fusion technology,using VZV whole virus antigen as immunogen.The antibody titer in mouse ascites was detected by indirect ELISA.After purified by Hi Trap2=0.995 6,P=0.000 1)。结论 建立的双抗体夹心ELISA法具有良好的准确性、精密性和特异性，可用于VZV疫苗中g E抗原含量的快速检测。 ObjectiveTo develop and verify a double antibody sandwich ELISA for the quantitative detection of varicellazoster virus(VZV)glycoprotein E(gE).MethodsHybridoma cell lines secreting antibody against VZV-gE stably were screened by mouse hybridoma fusion technology,using VZV whole virus antigen as immunogen.The antibody titer in mouse ascites was detected by indirect ELISA.After purified by Hi Trap(TM)Mabselect(TM)Mabselect(TM)Su Re and Hi Trap(TM)Su Re and Hi Trap(TM)Desalting,monoclonal antibodies(m Abs)were analyzed for the purity by 12%SDS-PAGE,detected for the specificity by Western blot,and identified for the subtype by mouse monoclonal antibody typing kit.Capture antibody and enzyme-labeled antibody were screened by epitope superposition test,which were determined for the working concentrations by chessboard titration(capture antibody concentrations were 0.25,0.5,1,2,5 and 10μg/m L,enzyme-labeled antibody dilutions were 1∶500,1∶1 000,1∶2 000,1∶5 000 and 1∶10 000),and then a double antibody sandwich ELISA(DAS-ELISA)was developed for the detection of VZV-gE content.In addition,the linear range,accuracy,precision and specificity of the method were verified.The gE content in the supernatant of 3 batches of CHO-VZV-gE cells cultured in 7 L bioreactor for 1～14 d were detected by the developed method.ResultsFour positive hybridoma cell lines secreting specific antibodies against VZV-gE stably were obtained and named as m Ab-B2,m Ab-11,K9C7 and K9F4.The antibodies in mouse ascites showed titers of10(TM)Desalting,monoclonal antibodies(m Abs)were analyzed for the purity by 12%SDS-PAGE,detected for the specificity by Western blot,and identified for the subtype by mouse monoclonal antibody typing kit.Capture antibody and enzyme-labeled antibody were screened by epitope superposition test,which were determined for the working concentrations by chessboard titration(capture antibody concentrations were 0.25,0.5,1,2,5 and 10μg/m L,enzyme-labeled antibody dilutions were 1∶500,1∶1 000,1∶2 000,1∶5 000 and 1∶10 000),and then a double antibody sandwich ELISA(DAS-ELISA)was developed for the detection of VZV-gE content.In addition,the linear range,accuracy,precision and specificity of the method were verified.The gE content in the supernatant of 3 batches of CHO-VZV-gE cells cultured in 7 L bioreactor for 1～14 d were detected by the developed method.ResultsFour positive hybridoma cell lines secreting specific antibodies against VZV-gE stably were obtained and named as m Ab-B2,m Ab-11,K9C7 and K9F4.The antibodies in mouse ascites showed titers of106～106～107with purities of about 97%after purification,which all specifically bound to VZV whole virus protein with light chains ofκchain and heavy chains of Ig G_(2b),Ig G_1,Ig G_(2b)and Ig G_(2a)respectively.m Ab-B2 was determined as capture antibody and HPR-labeled m Ab-11 as enzyme-labeled antibody with the optimum working concentrations of 1.5μg/m L and 1∶5 000respectively.The internal reference concentration of gE antigen was in the range of 1.95～1 000 ng/m L,which showed a good linear relationship with A_(450).The four-parameter equation was Y=(0.15-3.99)/[1+(X/67.4)7with purities of about 97%after purification,which all specifically bound to VZV whole virus protein with light chains ofκchain and heavy chains of Ig G_(2b),Ig G_1,Ig G_(2b)and Ig G_(2a)respectively.m Ab-B2 was determined as capture antibody and HPR-labeled m Ab-11 as enzyme-labeled antibody with the optimum working concentrations of 1.5μg/m L and 1∶5 000respectively.The internal reference concentration of gE antigen was in the range of 1.95～1 000 ng/m L,which showed a good linear relationship with A_(450).The four-parameter equation was Y=(0.15-3.99)/[1+(X/67.4)(1.49)]+3.99,and R(1.49)]+3.99,and R2value was 0.999.The recoveries of accuracy verification were 94.9%～114.0%;The coefficients of variation(CVs)of precision verification were all less than 15%.Except CHO-VZV-gE cell culture supernatant,attenuated live varicella vaccine and attenuated live herpes zoster vaccine,the A_(450)of other samples were all less than 0.15 with no cross reaction.The content of gE in the supernatant of three batches CHO-VZV-gE cells increased gradually with the culture time,and was positively related with culture time within 14 days(R2value was 0.999.The recoveries of accuracy verification were 94.9%～114.0%;The coefficients of variation(CVs)of precision verification were all less than 15%.Except CHO-VZV-gE cell culture supernatant,attenuated live varicella vaccine and attenuated live herpes zoster vaccine,the A_(450)of other samples were all less than 0.15 with no cross reaction.The content of gE in the supernatant of three batches CHO-VZV-gE cells increased gradually with the culture time,and was positively related with culture time within 14 days(R2=0.995 6,P=0.000 1).ConclusionThe developed double antibody sandwich ELISA had good accuracy,precision and specificity,which might be used for rapid detection of gE antigen content in VZV vaccine.
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@#Abstract：Objective To carry out serological analysis of varicella⁃zoster virus（VZV）IgG antibody level in healthy people aged 1 ~ 30 years in Liaoning Province. Methods In October 2020，3～5 mL venous blood samples were collected from 617 healthy people aged 1～30 years selected from six counties and districts in Shenyang，Fuxin and Dandong of Liaoning Province by stratified random sampling method，of which serum samples were collected and determined for VZV IgG antibody level by ELISA. The positive rate of serum antibody and geometric mean concentration（GMC）of antibody were calculated and compared. Results Among 617 serum samples，302 samples were positive for VZV IgG antibody，the positive rate was 48. 947%，and the GMC was 112. 772 mIU／mL. The positive rate of VZV IgG antibody was 29. 670%～75. 789% and the GMC was 45. 508～366. 559 mIU／mL in healthy people of various ages. Both of the antibody positive rate（χ2 = 67. 104， P < 0. 001）and GMC（F = 20. 685，P < 0. 001）showed significant differences. The positive rates of VZV IgG antibody in male and female were 44. 817% and 53. 633% respectively，which showed significant difference（χ2 = 4. 779，P = 0. 029）， while the GMCs were 96. 983 and 133. 829 mIU／mL respectively（t = -1. 958，P = 0. 051）with no significant difference. The positive rates of VZV IgG antibody of healthy people in Shenyang，Fuxin and Dandong of Liaoning Province were 55. 224%，40. 201% and 51. 152% respectively with significant differences（χ2 = 9. 683，P = 0. 008），of which the positive rate of FuxinwassignificantlylowerthanthoseofShenyangandDandong（χ2 =9. 046and5. 013，P =0. 003and0. 025，respectively）； While the GMCs were 133. 523，85. 953 and 123. 713 mIU／mL respectively with no significant difference（F = 0. 514， P = 0. 598）. Among 617 serum samples，54 sampleswere suspicious，which remained within the criticalrange afterre⁃examina⁃ tion，while the gap between positive rate and the total percentage of positive and suspicious results gradually decreased with the increase of age，indicating that the immunity to varicella gradually increased with the increase of age. Conclusion The VZV⁃IgG antibody level of healthy people aged 1～30 years in Liaoning Province increased gradually with age，while the overall level was low. To control the spread of varicella virus，it is recommended to increase varicella vaccine coverage in vulnerable areas and susceptible population to build VZV immune barrier.
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@#Abstract：Objective To improve the replication level of varicella⁃zoster virus（VZV）in human diploid cell line MRC⁃5 and increase the yield of VZV vaccine by reducing the expression of interferon（IFN）related genes via optimizing the cell line MRC⁃5. Methods Interferon receptor 1（IFNAR1）silenced MRC⁃5 cell line（MRC⁃5IFNAR1⁃）was constructed by CRISPR／Cas9 gene editing technology，which was determined for the relative expression of IFNAR1 mRNA，and for those of mRNA of IFN related genes IFNβ and OAS1 after VZV infection by qRT⁃PCR to evaluate the effect of gene silencing. Gene mutation sequences were further identified by sequencing of the silenced sites. The replication of VZV in MRC⁃5 and MRC⁃5IFNAR1⁃ cell lines was compared 168 h after VZV infection by using qRT⁃PCR and plaque formation unit（PFU）assay， to evaluate the effect of MRC⁃5IFNAR1⁃cell line on VZV replication. Results The growth status of MRC⁃5IFNAR1⁃ cell line wasconsistent with that of MRC ⁃ 5 cells，and the relative expression of IFNAR1 mRNA decreased by 73%；The relative expressions of IFNβ and OAS1 mRNA in MRC⁃5IFNAR1⁃ cell line were 61% and 90% lower than those in MRC⁃ 5 cells respectively after VZV infection；In addition，168 h after VZV infection，the level of DNA replication and the titer of VZV increased by 5. 7 folds and 4 folds respectively. Conclusion The successful establishment of MRC⁃5IFNAR1⁃ cell line may be a potential scheme to increase the yield of vaccines based on human diploid cells，and provided a reference for expanding production of VZV vaccine.
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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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@#Objective To analyze the etiology of clinical cases of live attenuated varicella vaccine.Methods 64 samples of varicella vesicle fluid from 49 patients clinically diagnosed as varicella cases in phase Ⅲ clinical trial of live attenuated varicella vaccine in enterprises(the test site was Henan Province) were collected,extracted for DNA,and distinguished for wild-type strains and vaccine strains by PCR and restriction fragment length polymorphism(PCR-RFLP).Genotype was analyzed using the genotyping method recommended at the international(varicella-zoster virus,VZV) nomenclature meeting2008.Results 64 vesicle fluids were all wild-type strains(Pst Ⅰ~+Sma Ⅰ~-BssH Ⅱ~-Nae Ⅰ~-),and no vaccine-related cases occurred.All 49 isolates belonged to Clade 2.Additionally,compared with Clade 2,a synonymous mutation(T→C) in SNP18 082 was detected in all 49 isolates,and a mutation(C→A) in SNP790 was detected in one isolate.Conclusion In the clinical trial of live attenuated varicella vaccine in Henan Province,all the clinical cases were caused by infection of wild-type strain which belonged to Clade 2 genetic branch.
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【Objective】 To establish and evaluate a fluorescent antibody to membrane antigen (FAMA) method for detecting antibodies against varicella-zoster virus (VZV) based on Vero E6 cells. 【Methods】 Based on the adapted VZV-Oka-E6 strain that VZV-Oka live attenuated varicella vaccine strain grew in Vero E6 cells, Vero E6 cells were infected with VZV-Oka-E6 of three different doses (104.65, 104.95 and 105.25 TCID50), and the cytopathic effect was observed under a microscope to determine the optimal infection dose of VZV-Oka-E6 strain. Then the detectable sensitivity of the infected cell antigen slides prepared after fixing the infected cells with different fixatives was compared to determine the optimal fixative. As a result, the FAMA method based on Vero E6 cells for the determination of neutralizing anti-VZV has been developed. The established FAMA assay was used to detect the international standard for varicella zoster immunoglobulin with different titers to determine the sensitivity of the assay. The specificity of the assay was evaluated by detecting specific antibodies against human herpes simplex virus (HSV) type 1 and type 2. The neutralizing anti-VZV antibodies of the international standard for varicella zoster immunoglobulin were detected using VZV-infected cell antigen slides prepared in the same batch and four different batches, respectively, to determine the intra-assay repeatability and inter-assay repeatability. The international standard for varicella zoster immunoglobulin with three known titers was detected to evaluate the relative accuracy of this assay. The anti-VZV titers in 20 apheresis plasma samples were determined with the newly established FAMA test and ELISA test, respectively, and the detection results of the two methods were compared using Spearman’s correlation test. 【Results】 The optimal infection dose of the VZV-Oka-E6 strain in FAMA assay was determined to be 105.25 TCID50, and acetone precooled at -20℃ was used as the fixative. The FAMA test has a high sensitivity with a detecting limit of 31.25 mIU/mL for neutralizing anti-VZV titers. The negative result was observed when detecting herpes simplex virus (HSV) type 1 and 2 specific antibodies. The international standard for varicella zoster immunoglobulin was detected by VZV infected cell antigen slides prepared in the same batch and 4 different batches, with the coefficient of variation being 29.95% and 26.71%, respectively. The detection value of the international standard for varicella zoster immunoglobulin with three different titer levels was consistent with their theoretical value. The correlation coefficient of the detection results of 20 apheresis plasma samples by the FAMA test and ELISA test was 0.268. 【Conclusion】 The VZV FAMA assay has good sensitivity, specificity, repeatability, and relative accuracy in detecting neutralizing anti-VZV titers. It can be applied for detecting neutralizing anti-VZV titers in apheresis plasma samples as well as the varicella-zoster immunoglobulin (VZIG) preparations.