Objective To prepare neutralizing monoclonal antibodies (mAbs) against envelope protein domain III of the four dengue virus serotypes (DENV-EDIII) and identify its specificity. Methods BALB/c mice were immunized with recombinant EDIII protein (rDENV-EDIII) of the four DENV serotypes. Hybridoma cells secreting DENV-EDIII antibodies were screened by indirect ELISA. The specificity of positive hybridoma cells were further tested by indirect immunofluorescence assay (IFA). The neutralizing activities of DENV-EDIII mAbs in vitro were determined by the enzyme-linked immunospot microneutralization test (ELISPOT-MNT). Results 6 mAbs specific for the EDIII of the four DENV serotypes and 11 mAbs specific for only one serotype of DENV-EDIII protein were obtained, of which one monoclonal antibody had a balanced strong neutralizing activity against the four DENV serotypes in vitro, and its 50% inhibitory concentrations (IC50) for the four DENV serotypes was 0.05 μg/mL, 1.89 μg/mL, 0.02 μg/mL, 3.91 μg/mL, respectively. Conclusion A specific monoclonal antibody against DENV-EDIII is successfully screened and obtained to neutralize the four DENV serotypes.

Understanding the molecular basis of the neutralizing antibody response to dengue virus (DENV) is an essential component in the design and development of effective vaccines and immunotherapeutics. Here we present the structure of a cross-reactive, neutralizing antibody, 3E31, in complex with domain III (DIII) of the DENV envelope (E) protein and reveal a conserved, temperature-sensitive, cryptic epitope on DIII that is not available in any of the known conformations of E on the dengue virion. We observed that 3E31 inhibits E-mediated membrane fusion, suggesting that the antibody is able to neutralize virus through binding an as-yet uncharacterized intermediate conformation of DENV E and sterically block trimer formation. Finally, we show that, unlike cross-reactive fusion peptide-specific antibodies, 3E31 does not promote antibody-dependent enhancement of infection at sub-neutralizing concentrations. Our results highlight the 3E31 epitope on the E protein DIII as a promising target for immunotherapeutics or vaccine design.

目的 以西尼罗病毒非结构蛋白(nonstructural protein1,NS1)为免疫原制备西尼罗病毒NS1蛋白特异性单克隆抗体,并鉴定其特异性.方法 在表达具有良好抗原性的重组西尼罗病毒NS1蛋白基础上免疫Balb/c小鼠,取免疫小鼠的脾细胞与小鼠骨髓瘤细胞进行融合,用间接ELISA法筛选阳性的杂交瘤细胞,并结合免疫荧光(IFA)和免疫印迹对所获得单克隆抗体的特异性进行鉴定,通过竞争抑制试验对mAb识别的抗原位点进行分析.结果 获得39株特异性针对西尼罗病毒NS1蛋白的单克隆抗体,Ig亚类测定结果IgG3和IgG2a单抗各2株,IgG2b单抗5株,IgG单抗1株,另外29株均为IgG1.结论 成功获得了特异性针对西尼罗病毒NS1蛋白的单克隆抗体,将为进一步建立西尼罗病毒NS1抗原检测方法及探讨NS1蛋白及抗体在西尼罗病毒发病机制中提供依据.

目的 以Ⅰ型登革病毒(DENV)非结构蛋白1(NS1)为免疫原制备NS1特异性单克隆抗体,建立Ⅰ型登革病毒NS1抗原特异性检测方法,并应用于广东以Ⅰ型登革感染为主的临床血清标本检测.方法 用原核表达的重组登革病毒NS1蛋白和灭活的Ⅰ型登革病毒免疫Balb/c小鼠,通过细胞融合,间接ELISA、免疫荧光和免疫印迹鉴定,获得DENV1NS1特异性单克隆抗体并建立检测方法.结果 共获得26株Ⅰ型登革病毒NS1蛋白特异性结合的单抗.通过对26株1型登革病毒NS1蛋白特异性单抗进行多株抗体组合配对,最终筛选出最佳抗体组合.该组合检测DENV1病毒培养上清的检测限为1∶16 384(12.5 pfu/ml),且与其他3个血清型登革病毒、乙型脑炎病毒和黄热病毒均无交叉反应,对500份健康人血清标本检测中,阴性标本497例,临界3例,对发病0～13d的836份临床确诊的登革热患者血清检测的敏感性为85.6％,明显高于qRT-PCR检测体系(66.3％)(P＜0.001),亦明显高于病毒分离诊断率(P＜0.001).结论 成功获得了1组DENV1-NSl蛋白的特异性单克隆抗体,利用该组抗体建立了1种敏感性和特异性更好的只针对DENV1-NS1蛋白的双抗体夹心检测方法,且比其他方法能够覆盖更宽泛的时间范围,该方法可作为登革热早期诊断的工具.

Dengue virus (DENV) envelope [E] protein is the major surface protein of the virions that indued neutralizing antibodies. The domain III of envelope protein (EDIII) is an immunogenic region that holds potential for the development of vaccines; however, the epitopes of DENV EDIII, especially neutralizing B-cell linear epitopes, have not been comprehensively mapped. We mapped neutralizing B-cell linear epitopes on DENV-1 EDIII using 27 monoclonal antibodies against DENV-1 EDIII proteins from mice immunized with the DENV-1 EDIII. Epitope recognition analysis was performed using two set of sequential overlapping peptides (16m and 12m) that spanned the entire EDIII protein from DENV-1, respectively. This strategy identified a DENV-1 type- specific and a group-specific neutralizing epitope, which were highly conserved among isolates of DENV-1 and the four DENV serotypes and located at two regions from DENV-1 E, namely amino acid residues 309-320 and 381-392(aa 309-320 and 381-392), respectively. aa310 -319(310KEVAETQHGT319)was similar among the four DENV serotypes and contact residues on aa 309 -320 from E protein were defined and found that substitution of residues E309 , V312, A313 and V320 in DENV-2, -3, -4 isolates were antigenically silent. We also identified a DENV-1 type-specific strain-restricted neutralizing epitope, which was located at the region from DENV-1 E, namely amino acid residues 329-348 . These novel type- and group-specific B-cell epitopes of DENV EDIII may aid help us elucidate the dengue pathogenesis and accelerate vaccine design.

目的:利用慢病毒介导特异性短发夹状RNA(LV-shRNA) 靶向沉默生存素基因,观察其对子宫内膜异位症裸鼠模型异位病灶中caspase-3表达的影响.方法:建立人子宫内膜裸鼠皮下种植模型,将LV-shRNA、空载慢病毒及磷酸盐缓冲液分别注射至裸鼠皮下异位病灶,观察病灶生长情况.分别采用RT-PCR及免疫组化检测异位病灶中生存素、caspase-3 mRNA及蛋白的表达.结果:LV-shRNA处理组病灶体积、重量明显低于两对照组.与两对照组相比,LV-shRNA处理组生存素 mRNA及蛋白的表达量明显降低,caspase-3的表达量明显升高,而生存素及caspase-3的表达在两对照组之间相比,差异均无统计学意义.结论:LV-shRNA可明显抑制裸鼠异位子宫内膜病灶的生长,其机制可能与其通过下调生存素蛋白、激活下游的caspase-3诱导细胞凋亡有关.

Two label-free biosensor platforms, Resonance Waveguide Grating (RWG) and Surface Plasmon Resonance (SPR), were used to rank a large panel of anti-dengue virus NS1 antibodies. Dengue non-structural 1 (NS1) protein is an established serological marker for the early detection of dengue infection. A variety of commercial dengue NS1 antigen capture immunoassays are available in both ELISA and lateral flow format. However, there is a significant scope to improve both the sensitivity and the specificity of those tests. The interactions of antibody (Ab)-antigen (Ag) were profiled, with weak interactions (KD = 1–0.1 μM) able to be detected under static equilibrium conditions by RWG, but not observed to under more rigorous flow conditions using SPR. There were significant differences in the absolute affinities determined by the two technologies, and there was a poor correlation between antibodies best ranked by RWG and the lower limit of detection (LLOD) found by ELISA. Hence, whilst high-throughput RWG can be useful as preliminary screening for higher affinity antibodies, care should be exercised in the assignation of quantitative values for affinity between different assay formats.

Dengue virus (DENV) is a mosquito-borne virus that causes severe health problems. An effective tetravalent dengue vaccine candidate that can provide life-long protection simultaneously against all four DENV serotypes is highly anticipated. A better understanding of the antibody response to DENV envelope protein domain III (EDIII) may offer insights into vaccine development. Here, we identified 25 DENV cross-reactive mAbs from immunization with Pichia pastoris-expressed EDIII of a single or all four serotype(s) using a prime-boost protocol, and through pepscan analysis found that 60 % of them (15/25) specifically recognized the same highly conserved linear epitope aa 309-320 of EDIII. All 15 complex-reactive mAbs exhibited significant cross-reactivity with recombinant EDIII from all DENV serotypes and also with C6/36 cells infected with DENV-1, -2, -3 and -4. However, neutralization assays indicated that the majority of these 15 mAbs were either moderately or weakly neutralizing. Through further epitope mapping by yeast surface display, two residues in the AB loop, Q316 and H317, were discovered to be critical. Three-dimensional modelling analysis suggests that this epitope is surface exposed on EDIII but less accessible on the surface of the E protein dimer and trimer, especially on the surface of the mature virion. It is concluded that EDIII as an immunogen may elicit cross-reactive mAbs toward an epitope that is not exposed on the virion surface, therefore contributing inefficiently to the mAbs neutralization potency. Therefore, the prime-boost strategy of EDIII from a single serotype or four serotypes mainly elicited a poorly neutralizing, cross-reactive antibody response to the conserved AB loop of EDIII.

The risk of antibody-dependent enhancement (ADE) of dengue virus (DENV) infection is a major obstacle for the development of dengue vaccine candidates. Here, we described a novel approach for assessment of ADE by measuring DENV nonstructural protein 1 (NS1) production in culture supernatants with Fcγ receptor-expressing K562 cells in ELISA format (ELISA-ADE). Enhancing activities quantified by measurement of kinetics of NS1 production were in a good agreement with the results of the virus titration assay. In conjunction with the previously established enzyme-linked immunospot-based micro-neutralization test (ELISPOT-MNT) in 96-well format, the observable dose–response profiles of enhancing and neutralizing activities against all four DENV serotypes were produced with two flaviviral envelope cross-reactive monoclonal antibodies and four primary DENV-1-infected human sera. The simple high-throughput ELISA-ADE assay offers advantages for quantitative measurement of infection enhancement that can potentially be applied to large-scale seroepidemiological studies of DENV infection and vaccination.

OBJECTIVE:To establish a highly sensitive and specific assay to detect dengue virus (DENV) envelope protein domain III (EDIII) IgG antibody, and to explore its value in the diagnosis and seroepidemiological survey of dengue.METHODS:The DENV EDIII IgG antibody capture ELISA was developed using the recombinant full-length DENV EDIII, which was prepared by Pichia yeast expression system as the capture antigen. The serum samples were collected from the same group of 35 DENV-1 patients of primary infection during disease period in 2006 and their follow-up phase in 2010; and the sensitivity of the assay was compared to that of the commercial Panbio DENV IgG ELISA.RESULTS:The sensitivity of DENV EDIII IgG ELISA in detecting the serum samples from disease period and follow-up phase was 87% (20/23) and 94% (33/35), respectively; whereas the sensitivity of Panbio DENV IgG ELISA was 71% (25/35) and 0, respectively. The sensitivity of DENV EDIII IgG ELISA in detecting the serum samples from both periods was similar, without statistical significance (χ(2) = 0.946, P = 0.331). For serum samples from disease period, the sensitivity of DENV EDIII IgG ELISA was comparable with that of Panbio DENV IgG ELISA (χ(2) = 1.924, P = 0.165). However, DENV EDIII IgG ELISA demonstrated a significantly higher sensitivity than Panbio DENV IgG ELISA in detecting the serum samples from follow-up phase (χ(2) = 62.432, P = 0.000).CONCLUSION:DENV EDIII IgG capture ELISA is highly sensitive in detecting IgG in the serum samples from either disease period or follow-up phase. This method might be a promising alternative for diagnosis and seroepidemiologic survey of dengue.

The plaque reduction neutralization test (PRNT) is used widely to measure the neutralization activity of anti-dengue virus (DENV) antibodies, but it is time-consuming and labor-intensive and has low sample throughput. For fast and convenient measurement of neutralizing antibodies, especially in evaluating the efficiency of the DENV vaccines on a large scale, a new method is needed to replace PRNT. In recent decades, several microneutralization assays have been developed to overcome the limitations of PRNT. In the present study, we evaluated one of these, the enzyme-linked immunospot microneutralization test (ELISPOT-MNT), in comparison with PRNT. ELISPOT-MNT is performed in 96-well format, and the plaques are developed after 2 to 4 days using an ELISA to transform them into spots, which are detected automatically with an ELISPOT instrument. The assay is faster than PRNT, has a high throughput, and is more objective. We used 10 monoclonal antibodies (MAbs) against domain III of the DENV envelope protein (EDIII) to evaluate the two assays; all of these MAbs cross-react with all four serotypes of DENV as measured by immunofluorescence assay. The two neutralization assays were performed simultaneously to measure the 50% inhibitory concentration (IC(50)) of these MAbs. Using PRNT as the reference and treating IC(50) values higher than 50 μg/ml of MAbs as negative, ELISPOT-MNT showed a sensitivity of 95.6% and specificity of 88.24% when 10 MAbs were tested against four DENV serotype strains. A good correlation (R(2) = 0.672; P = 0.000) was observed between the two assays, making ELISPOT-MNT a potentially valuable method for measure of neutralizing antibodies against DENV.

OBJECTIVETo investigate the inhibitory effect of lentiviral vector-mediated short hairpin RNA targeting survivin (LV-survivin shRNA) on angiogenesis and growth of endometriosis-like lesions in chick en embryo chorioallantoic membrane.METHODSEutopic endometrium from women with endometriosis was transplanted onto the non-vascular region of (CAM), where LV-survivin shRNA was delivered subsequently. The angiogenesis and the growth of endometriosis-like lesions in the CAM model were evaluated.RESULTSThe angiogenesis and formation of endometriosis-like lesions were significantly suppressed in the CAM model by treatment with LV-survivin shRNA in comparison with those in the untreated CAM models and models treated with empty LV or DMEM (P<0.001). LV-survivin shRNA also caused a significantly higher cell apoptotic rate in the endometriosis-like lesions than the other treatments (P<0.001) and induced necrosis in the lesions.CONCLUSIONLV-survivin shRNA can effectively inhibit angiogenesis induced by the eutopic endometrium and markedly suppress the formation of endometriosis-like lesions in the CAM model.

Dysregulation of microRNAs (miRNAs) has been found to be associated with a variety of diseases, including epithelial ovarian cancer (EOC). Recently, miR-100 was reported to be downregulated in human ovarian carcinoma, however, the clinical significance and functional roles of miR-100 expression in human EOC are unclear. TaqMan real-time quantitative RT-PCR assay was performed to detect the expression of miR-100 in 98 EOC tissues and 15 adjacent normal epithelial tissues. The relationship between miR-100 expression and clinicopathological factors in 98 EOC patients was statistically analyzed. The effect of miR-100 expression on patient survival was determined. Finally, the role of miR-100 in EOC cell growth and its possible mechanisms were analyzed with miR-100 precursor or inhibitor-transfected cells. We showed that the level of miR-100 was significantly lower in EOC tissues compared to adjacent normal tissues. Low miR-100 expression was found to be closely correlated with advanced FIGO stage, higher serum CA125 expression level and lymph node involvement. Also, low miR-100 expression was correlated with shorter overall survival of EOC patients, and multivariate analysis showed that the status of miR-100 expression was an independent predictor of overall survival in EOC. Additionally, miR-100 could affect the growth of EOC cells by post-transcriptionally regulating polo-like kinase 1 (PLK1) expression. Together, these results suggest that low miR-100 expression may be an independent poor prognostic factor and miR-100 can function as a tumor suppressor by targeting PLK1 in human EOCs.

OBJECTIVE:To investigate the characteristics and dynamic changes of serum neutralizing antibody response in patients with primary infection of dengue virus type 1 (DENV-1).METHODS:Serum samples were obtained from the same patients with primary infection of DENV-1 within 2 weeks after symptom onset in 2006 and in 2010. A group-specific DENV NS1 capture ELISA-based micro-neutralizing test (ELISA-MNT) capable of detecting neutralizing antibodies against all the 4 serotypes of DENV was used to test the neutralizing antibody titers against DENV in the serum samples. The neutralizing antibody titers against a standard strain and 2 clinically isolated strains of DENV-1 were detected in serum samples collected in 2010.RESULTS:Cross-reactive neutralizing antibody response against all the 4 serotypes of DENV was found in both of the serum samples collected in 2006 and 2010, but the samples collected in 2006 showed stronger cross-reactive neutralizing antibody responses. The neutralizing antibody against DENV-2, rather than the anticipated DENV-1 antibody, had the highest titer in the samples collected in 2006, whereas the antibody against homologous DENV-1 had the highest titer in the samples obtained in 2010. The neutralizing antibody titers against the homologous DENV-1 was significantly higher in samples collected in 2010 (U=86.500, P=0.000), which also demonstrated significantly different neutralizing antibody titers against the 3 different strains of DENV-1 (Χ(2)=12.123, P=0.002).CONCLUSION:The production of cross-reactive neutralizing antibodies between the 4 serotypes of DENV is a characteristic of DENV infection, particularly during early infection, but only the homologous neutralizing antibody increases obviously over time. The titers of the neutralizing antibodies against different strains, even of the same serotype, may differ distinctly.

ABSTRACT Dengue virus (DENV), a member of the Flavivirus family, has four distinct serotypes (DENV serotype 1 [DENV1], DENV2, DENV3, and DENV4) that require differentiation for the effective prevention of morbid disease. Early and rapid differentiation between flaviviruses remains challenging. Full assays combining four individual, serotype-specific and one group-specific nonstructural protein 1 (NS1) antigen capture enzyme-linked immunosorbent assays (ELISAs) based on monoclonal antibodies (MAbs) against DENV NS1 were developed and validated. The sensitivities and specificities of the full NS1 ELISAs were evaluated with viral cultures and dengue acute-phase sera. Four serotype-specific NS1 ELISAs displayed high specificities for the detection and differentiation of appropriate serotypes. The group-specific NS1 ELISA was broadly reactive with the four dengue virus serotypes. None of the NS1 ELISAs displayed cross-reactivity with the other flaviviruses or samples from febrile patients with non-dengue virus infections. The full serotype- and group-specific MAb-based NS1 capture ELISAs may provide tools for the early detection and typing of dengue infection, which is preferable to reverse transcriptase PCR (RT-PCR) for the rapid differential diagnosis of dengue virus infection in the field.

A dengue nonstructural protein 1 (NS1) antigen capture enzyme-linked immunosorbent assay (ELISA)-based tissue culture infectious dose-50 (TCID(50)) test (TCID(50)-ELISA) was developed as an alternative to the standard plaque assay for titrating dengue virus. Virus titers obtained by TCID(50)-ELISA were comparable to those obtained by the plaque assay and by the traditional TCID(50)-cytopathic effect (CPE) test (TCID(50)-CPE), with a better reproducibility and a lower coefficient of variation. Quantitative comparison of TCID(50)-ELISA and TCID(50)-CPE resulted in a correlation coefficient of 0.976. Moreover, this new method showed a wider application to C6/36, Vero E6, BHK-21, and Vero cells compared with other titration methods. In summary, the novel TCID(50)-ELISA method described here provides a more reliable and more accurate alternative compared to the plaque assay and TCID(50)-CPE for titration of dengue virus.

Objective To precisely determine the antigenicity and immunogenicity on N-terminal regions of DENV NS1 and develope sero-diagnosis of DENV infection using an epitope-based peptide antigen.Methods The synthesis peptide sequences of N-terminal regions of DENV NS1 were derived from the four serotype DENV standard strains and named D-1 P1,D-2 P1,D-3 P1 and D-4 P1.ELISA was performed to analyze antibody responses to these peptides from monoclonal antibodies(MAbs) with dengue serotype specificity as well as antisera from mice immunized with the dengue virus serotypes.The specific reactivity of peptides with corresponding MAbs was further confirmed by competitive inhibition experiments.The degree of conservation and variability of N-terminal regions of DENV NS1 within DENV isolates which were reported in Pubmed were analyzed by Bioinformatics.Results Six DENV-1 serotype-specific MAbs(5A48A3,5A65A2,5B29A1,5B71A8,5C29A3,and 5E68A17) showed a strong reaction with D-1 P1.Six DENV-2 serotype-specific MAbs(5D21A1,5E19A5,5A62A12,5A70A4,5E30A5 and 5E48A15) showed a strong reaction with D-2 P1.D-1 P1 only reacted with all 3 sera from DENV-1-immunized mice.The other peptides were not different from sera from mice immunized with all four dengue virus serotypes.Alignment revealed that the conservation of 100% homology for N-terminal regions of DENV-1,2,3,4 NS1 was 98.96%,89.09%,83.58% and 57.81%,respectively.Conclusions N-terminal regions of Dengue virus-1 non-structural protein 1 contained an immunodominant serotype epitope and N-terminal regions of Dengue virus-2 non-structural protein 1 contained a serotype epitope.D-1 P1-based peptide antigen will be useful for serologic diagnosis of DENV-1 infection.These novel serotype B-cell epitopes of DENV NS1 may aid the development of new dengue vaccines and sero-diagnosis assays.

OBJECTIVE:To construct a lentiviral expression vector for short hairpin RNA (shRNA) of human survivin gene, and assess its gene silencing effect in human ectopic endometrial cells.METHODS:Human survivin gene shRNA sequence was designed using a software available on-line. The synthesized shRNA sequence was cloned into the pGCL-GFP vector to construct LV-survivin shRNA, which was confirmed by PCR and DNA sequence analysis. The packaging 293T cells were cotransfected with LV-survivin shRNA, pHelper 1.0 and pHelper 2.0, and the titer of the lentivirus was determined. The recombinant lentivirus was injected into human ectopic endometrial cells and the survivin mRNA expression was examined by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) in comparison with that in the non-transfected and blank vector-transfected human ectopic endometrial cells.RESULTS:PCR analysis and DNA sequencing confirmed correct insertion of the shRNA sequence into the lentiviral vector. The titer of virus after packaging was 8x10(8) U/ml. Survivin mRNA expression in human ectopic endometrial cells transfected by LV-survivin shRNA was significantly inhibited compared with those in the non-transfected and empty vector transfected human ectopic endometrial cells (P<0.01), and no significant difference was found between the latter two groups.CONCLUSION:The lentiviral shRNA vector of survivin gene constructed can effectively inhibit the expression of survivin gene in human ectopic endometrial cells in vitro. This vector provides a tool for investigating the role of survivin gene in the occurrence and progression of endometriosis and for searching new therapeutic targets.