BIOCHEMICAL AND IMMUNOLOGICAL CHARACTERIZATION OF THE 200kD SCHISTOSOMULUM SURFACE ANTIGEN COMMON TO SCHISTOSOMA MANSONI AND SCHISTOSOMA JAPONICUM

Objective To study the biochemecal and immunological characterization of the 200 kD schistosomulum surface antigen Method and results A very high molecular weight schistosomulum surface antigen of Mr>200kD was identified and characterized using monoclonal antibodies. Carbohydrate modification experiments followed by radioimmunobinding assays demonstrated that the epitope recognised by the mAbs on this antigen was carbohydrate in nature, while protein digestion experiments followed by SDS-PAGE indicated that this antigen also contained protein. Immunoprecipitation of ~(125)I-labelled cercarial, schistosomulum, adult worm and miracidial surface antigens followed by gel analysis showed the carbohydrate epitope to be present on 5 cercarial, 2 schistosomulum and 5 miracidial surface molecules, and suggested a possible ecological function involved in adapting the parasite to the aquatic free-living stages of its life cycle and possibly also in protecting the early schistosomula from host immune damage. The 5 cercarial surfacs antigens proved to be associated with the CHR, since all the mAbs which recognised those antigens could induce a strong CHR. A kinetic investigation of the carbohydrate epitope on schistosomula of different ages demonstrated a gradual and possibly irreversible loss during the culture period. The epitope completely disappeared from the surface of adult worms. Conclusion To demonstrate an epitope common to a number of surface molecules of various developmental stages of schistosome and therefore explains the immunological cross-reactivity among different stages at the molecular level.     

Cross－reactivity of hypervariable region 1 chimera of hepatitis C virus

AIM: To analyze the amino acid sequences of hypervariable region 1 (HVR1) of HCV isolates in China and to construct a combinatorial chimeric HVR1 protein having a very broad high cross-reactivity.METHODS: All of the published HVR1 sequences from China were collected and processed with a computer program.Several representative HVR1‘s sequences were formulated based on a consensus profile and homology within certain subdivision. A few reported HVR1 mimotope sequences were also included for a broader representation. All of them were cloned and expressed in E.coli. The cross-reactivity of the purified recombinant HVR1 antigens was tested by ELISA with a panel of sera from HCV infected patients in China.Some of them were further ligated together to form a combinatorial HVR1 chimera.RESULTS: Altogether 12 HVRls were selected and expressed in E.coli and purified to homogeneity. All of these purified antigens showed some cross-reactivity with sera in a 27 HCV positive panel. Recombinant HVRls of No. 1, 2, 4, and 8# showing broad cross-reactivities and complementarity with each other, were selected for the ligation elements. The chimera containing these 4 HVRls was highly expressed in E.coli. The purified chimeric antigen could react not only with all the HCV antibody positive sera in the panel but also with 90/91 sera of HCV-infected patients.CONCLUSION: The chimeric antigen was shown to have a broad cross-reactivity. It may be helpful for solving the problem caused by high variability of HCV, and in the efforts for a novel vaccine against the virus.     

Phage displaying peptides mimic schistosoma antigenic epitopes selected by rat natural antibodies and protective immunity induced by their immunization in mice

AIM: To obtain the short peptides mimic antigenic epitopes selected by rat natural antibodies to schistosomes, and to explore their immunoprotection against schistosomiasis in mice. METHODS: Adults worm antigens (AWA) were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and enzyme-linked transferred immunoblotting methods with normal SD rat sera (NRS). The killing effects on schistosomula with fresh and heat-inactivated sera from SD rats were observed. Then the purified IgG from sera of SD rats was used to biopan a phage random peptide library and 20 randomly selected positive clones were detected by ELISA and 2 of them were sequenced. Sixty female mice were immunized thrice with positive phage clones (0, 2nd, 4th wk). Each mouse was challenged with 40 cercariae, and all mice were killed 42 d after challenge. The worms and the liver eggs were counted. RESULTS: NRS could specifically react to the molecules of 75 000, 47 000, 34 500 and 23 000 of AWA. Sera from SD rats showed that the mortality rate of schistosomula was 76.2%, and when the sera were heat-inactivated in vitro, the mortality rate was decreased to 41.0% after being cultured for 48 h. The specific phages bound to IgG were enriched about 300-folds after three rounds of biopanning. Twenty clones were detected by ELISA, 19 of them bound to the specific IgG of rat sera. Immunization with these epitopes was carried out in mice. Compared with the control groups, the mixture of two mimic peptides could induce 34.9% (P = 0.000) worm reduction and 67.6% (P = 0.000) total liver egg reduction in mice. Two different mimic peptides could respectively induce 31.0% (P= 0.001), 14.5% (P= 0.074) worm reduction and 61.2% (P= 0.000), 35.7% (P = 0.000) total liver egg reduction. The specific antibody could be induced by immunization of the mimic peptides, and the antibody titer in immunized mice reached more than 1:6 400 as detected by ELISA. CONCLUSION: Specific peptides mimic antigenic molecules can be obtained by biopanning the phage random peptide library and a partially protective immunity against schistosome infection can be stimulated by these phage epitopes in mice.     

Establishment and identification of monoclonal antibodies against Brugia malayi adult worm ES antigen and Dot-ELISA to detect filarial circulating antigen.

A hybridoma cell line of monoclonal antibodies(McAb)against Brugia malayi adult worm excre-tory-secretory(E-S)antigen(AWES5)was established.The identification of immunoglobulin subclassshowed that MeAb AWES5 belongs to IgG3.We developed a Dot-enzyme linked immunosorbent assay(Dot-ELISA)to detect circulating parasite antigens in human lymphatic filariasis.2-4μ1 serum from     

Changes in indirect immunofluorescent antibody level in chronic schistosomiasis after effective chemotherapy.

The authors have assessed the feasibility of indirect fluorescent antibody test (IFA)with antigens of adult Schistosoma japonicum in cryostat section in the evaluation ofcure after chemotherapy. 3 groups of rabbits exposed to 8, 16 and 32 cercariae separately     

华支睾吸虫特异性富甘氨酸2a类抗原基因的克隆、表达和免疫学诊断价值评价

目的采取免疫学方法筛选华支睾吸虫成虫cDNA表达文库,寻找新的抗原基因。方法使用华支睾吸虫病人混合血清以及华支睾吸虫排泄分泌抗原的免疫小鼠血清,分别免疫学筛选华支睾吸虫成虫λ ZAP cDNA表达文库;将阳性噬菌体克隆、测序以及核苷酸序列比对分析;将目的基因的编码区克隆至原核表达质粒pET28a(+)中,采用制备不带N端融合标签的天然蛋白的策略表达融合蛋白,使用组氨酸标签亲和纯化柱（Ni NTA树脂）纯化融合蛋白;采用间接ELISA法,检测血清中的特异性抗体,共检测35例华支睾吸虫虫卵粪检阳性血清,36例正常人血清,15例日本血吸虫、15例卫氏并殖吸虫和13例猪囊尾蚴病人血清,评价重组蛋白的免疫学诊断价值。结果发现华支睾吸虫特异性富甘氨酸2a（GRA2a）类抗原基因家族,将其中的Cs4抗原基因植入重组表达质粒pET28a(+)的NcoI位点,成功实现融合蛋白的表达,并进一步纯化得到可溶性重组蛋白。采用间接ELISA法检测血清中的特异性抗体,该ELISA法的敏感性为80.0%,特异性为97.2%,总符合率为88.7%;日本血吸虫、卫氏并殖吸虫和猪囊尾蚴病人血清的假阳性率分别为6.7%、6.7%和7.7%。经核苷酸序列同源性比较,华支睾吸虫GRA2a类抗原是迄今为止尚未进行功能研究的华支睾吸虫特异性抗原。结论发现华支睾吸虫GRA2a类抗原基因家族;成功构建重组表达质粒,并表达、纯化出可溶性重组蛋白;该抗原具有较高的免疫学诊断价值。     

Relationship between the downregulation of HLA class Ⅰ antigen and clinicopathological significance in gastric cancer

AIM:To discuss the expression of human leukocyte antigen (HLA) class Ⅰ antigens in gastric cancer and correlate these with pathologic type and TNM stage. METHODS: The expression of HLA class Ⅰ antigen was detected by immunohistochemistry in 185 specimens of gastric cancer, 20 gastric cancer specimens with lymphatic metastasis and 22 controls of normal gastric mucosa using four monoclonal antibodies. RESULTS: The expression of HLA class Ⅰ antigen (B/C locus) was significantly downregulated in gastric cancer and in lymphatic metastasis than that in normal gastric mucosa (x2=7.712, P<0.05). The expression of other HLA class Ⅰ antigens was also downregulated, but the change was slight. There was no relationship between the downregulation of HLA class Ⅰ antigen and that of β2m and LMP2. The expression of HLA class Ⅰ (B/C locus) was statistically correlated with pathologic stage in gastric adenocarcinoma (x2=4.164,P<0.05). CONCLUSION: The expression of HLA class Ⅰ antigen (B/C locus) was obviously downregulated in gastric cancer and in lymphatic metastasis. This abnormal expression would provide the tumor cells with a way to avoid immunological recognition.     

Microsome antigen of Schistosoma japonicum II. Extraction, fractionation and chemical and immunological properties of microsome antigens of adult worm.

Microsome antigens were extracted from homogenate of adult S. japonicum by dif-ferential centrifugation and fractionated by Sepharose CL-2B chromatography. The crudemicrosome antigen (JAMAC), the urea soluble fraction (JMC) and the purified     

Relationship between the downregulation of HLA class I antigen and clinicopathological significance in gastric cancer

AIM: To discuss the expression of human leukocyte antigen(HLA) class I antigens in gastric cancer and correlate these with pathologic type and TNM stage. METHODS: The expression of HLA class I antigen was detected by immunohistochemistry in 185 specimens of gastric cancer, 20 gastric cancer specimens with lymphatic metastasis and 22 controls of normal gastric mucosa using four monoclonal antibodies. RESULTS: The expression of HLA class I antigen (B/C locus) was significantly downregulated in gastric cancer and in lymphatic metastasis than that in normal gastric mucosa (x^2=7.712, P&lt;0.05). The expression of other HLA class I antigens was also downregulated, but the change was slight. There was no relationship between the downregulation of HLA class I antigen and that of β2m and LMP2. The expression of HLA class I (B/C locus) was statistically correlated with pathologic stage in gastric adenocarcinoma (x^2=4.164, P&lt;0.05). CONCLUSION: The expression of HLA class I antigen (B/C locus) was obviously downregulated in gastric cancer and in lymphatic metastasis. This abnormal expression would provide the tumor cells with a way to avoid immunological recognition.     

An experimental study on the immunity to Ascaris suum in Guinea pigs.

The immunological activity induced in guinea pigs by two Ascaris suum antigensand the reaction of the immunized guinea pigs to A. suum infection were investigated.The animals were immunized with soluble antigen of whole adult worm intramuscularly     

华支睾吸虫未脱脂和脱脂成虫抗原的免疫印迹分析

目的 寻找华支睾吸虫成虫抗原中具有特异性诊断价值的抗原组分。方法 应用SDS—PAGE和Westernblot分析华支睾吸虫成虫未脱脂、脱脂的可溶性抗原蛋白组分的血清学反应特征。结果 未脱脂成虫抗原有14条蛋白带可与华支睾吸虫病病人血清反应，其中分子质量单位为180、170、100、67、41、37、35、32、26ku是主带，180、170、37、35ku条带还可与日本血吸虫病、卫氏并殖吸虫病病人血清发生交叉反应。脱脂成虫抗原有10条蛋白带可与华支睾吸虫病病人血清反应，其中分子质量单位为180、100、67、37、35、24、20ku是主带，此外，180ku带可与日本血吸虫病和卫氏并殖吸虫病病人血清发生交叉反应，78ku带可以与血吸虫病病人血清发生交叉反应。结论 华支睾吸虫成虫抗原经脱脂处理后可减少与日本血吸虫病和卫氏并殖吸虫病病人血清交叉反应的蛋白组分数量。华支睾吸虫未脱脂和脱脂成虫抗原中主要的特异性抗原组分分别是100、67、41、32、26ku和100、67、37、35、24、20ku，这些组分抗原可用于华支睾吸虫病的免疫诊断。     

三种抗原用于斑点免疫金银染色试验(Dot-IGSS)诊断华支睾吸虫病的研究

应用斑点免疫金银染色技术(Dot-IGSS),以华支睾吸虫成虫抗原(AWA)、尿素溶解性成虫抗原(CWU)和硫酸铵沉淀成虫抗原(AW)诊断华支睾吸虫病,60例血清抗体检出率均达100.0％,与正常人血清反应(60例)阴性符合率为93.3～96.6％,与日本血吸虫病人(60例)的交叉反应为0～5.0％,与囊虫病人(30例)和肝炎病人(15例)的交叉反应分别为3.3～6.7％和0。各抗原间未见显著性差异(P>0.05)。但与混合阳性血清反应,AW活性似较AWA和CWU强。     

华支睾吸虫成虫14～33 ku抗原诊断价值的研究

目的探讨纯化华支睾吸虫成虫14~33 ku抗原在华支睾吸虫病免疫诊断中的应用价值。方法使用SDS-PAGE和电洗提法,从可溶性华支睾吸虫成虫抗原中分离纯化14~33 ku抗原,用此抗原经ELISA方法检测华支睾吸虫病、卫氏并殖吸虫病、日本血吸虫病、姜片虫病患者血清及健康人血清特异性IgG抗体,并与粗制可溶性成虫抗原和可溶性成虫脱脂抗原ELISA结果相比较。结果检测63例华支睾吸虫病患者血清,纯化华支睾吸虫成虫14~33 ku抗原ELISA阳性率为76.2%,可溶性成虫抗原和可溶性成虫脱脂抗原ELISA阳性率均为100%;检测25例卫氏并殖吸虫病、85例日本血吸虫病、27例姜片虫病患者血清,14~33 ku抗原的ELISA交叉反应阳性率分别为8.0%、3.5%、0,而可溶性成虫抗原分别为80.0%、62.4%、14.8%,可溶性成虫脱脂抗原分别为64.0%、55.3%、7.4%;检测127例健康人血清,14~33 ku抗原的ELISA假阳性率为0,可溶性成虫抗原和可溶性成虫脱脂抗原的假阳性率分别为5.5%、3.1%。结论纯化华支睾吸虫成虫14~33 ku抗原用于华支睾吸虫病免疫诊断的特异性优于粗抗原,但敏感性较低。     

抗卫氏并殖吸虫单克隆抗体的筛选及其在诊断中的应用

本文报道测定16种抗卫氏并殖吸虫(Pw)囊蚴和成虫单克隆抗体(McAb)的同型及其交叉反应。其中,抗Pw成虫McAb A_3D_3为IgM,k型。应用Dot-ELISA方法,以McAb A_3D_3检测痰卵阳性患者21例和痰卵阴性疑似患者63例血清循环抗原(CAg)),结果痰卵阳性患者CAg阳性率为100％(21/21),痰卵阴性疑似患者CAg阳性率为85.7％(54/63);同法检测45例日本血吸虫病、55例华支睾吸虫病、24例丝虫病、49例肠线虫感染、31例肺结核患者以及93例健康人对照血清均为阴性。结果表明,McAb A_3D_3的特异性及敏感性强,因而在Pw活动性感染和Pw病的早期诊断上均具有应用和推广前景。     

亲和层析法纯化华支睾吸虫抗原的研究

目的探索华支睾吸虫特异性抗原的纯化方法。方法从华支睾吸虫病流行区的淡水鱼中分离华支睾吸虫囊蚴,接种动物,收集成虫,制备匀浆液(粗抗原),借助偶联华支睾吸虫病人血清抗体的Sepharose4B亲和层析柱,提取特异性抗原,用浓度梯度聚丙烯酰胺凝胶电泳(CG-PAGE)和免疫印迹方法鉴定纯化抗原的纯度和特异性。结果亲和层析法纯化抗原经CG-PAGE显示5条蛋白带,免疫印迹试验鉴定均有抗原性,强阳性带蛋白分子质量单位为31ku,各区带蛋白与并殖吸虫、血吸虫血清抗体无交叉反应。粗抗原有16条蛋白带。结论经亲和层析法纯化的华支睾吸虫抗原特异性高。亲合层析是获取华支睾吸虫诊断用抗原的较佳方法。     

Counterimmunoelectrophoresis test on human Clonorchis sinensis infection

A counterimmunoelectrophoresis test was used to detect antibodies against the adult worm antigen of Clonorchis sinensis in sera from 70 clonorchiasis patients, 20 uninfected healthy persons and 7 patients infected with other helminths. A constant voltage of 10 V/cm and a running time of 30 minutes was chosen in carrying out detection. Antibody titers of 1, 1:2 and 1:4 were obtained from 35, 21 and 14 clonorchiasis patients, respectively. Significant correlation was observed between worm burden in patients and antibody titer, the higher the antibody titer in patients, the more eggs per gram feces in their stool. Although cross reaction was observed with toxocariasis and angiostrongyliasis in this study, high (100%) sensitivity made it possible to screen the subjects in endemic areas to shorten the survey period.     

华支睾吸虫半胱氨酸蛋白酶的基因表达与在ELISA诊断上的应用研究

目的探讨重组华支睾吸虫半胱氨酸蛋白酶在华支睾吸虫病血清学诊断上的应用价值. 方法以成虫cDNA为模板PCR扩增GenBank中一个华支睾吸虫半胱氨酸蛋白酶(No. AF093242,简称CysB)的部分基因片段,亚克隆到pTrcHis表达载体,转化入大肠埃希菌DH5α.表达出的重组蛋白经亲合层析纯化后用于ELISA检测华支睾吸虫及其他寄生虫感染血清,评价其诊断应用价值. 结果成功克隆与表达CysB基因片段,纯化后的重组蛋白用于华支睾吸虫病诊断的敏感性达96.0%(48/50),与其他寄生虫病的总交叉反应为3.8%(1/26),而对比实验中可溶性粗抗原(CAA)用于检测的敏感性为88.0%(44/50),与其他寄生虫感染血清无交叉反应. 结论重组华支睾吸虫半胱氨酸蛋白酶(CysB)用于ELISA诊断技术具有较高的敏感性及特异性,有希望成为可溶性粗抗原的替代之一.     

旋毛虫、卫氏并殖吸虫及华支睾吸虫之间共同抗原的研究

目的鉴定旋毛虫、卫氏并殖吸虫及华支睾吸虫之间的共同抗原,避免血清学诊断这3种寄生虫病时的交叉反应。方法应用十二烷基硫酸钠-聚丙烯酸胺凝胶电泳(SDS-PAGE)和免疫印渍(Western blot)对旋毛虫肌幼虫、卫氏并殖吸虫成虫及华支睾吸虫成虫可溶性抗原中的蛋白组分进行研究。结果旋毛虫肌幼虫、卫氏并殖吸虫成虫及华文睾吸虫成虫3者相同蛋白带的分子量为108、65、53、43、42、31、25、16 kDa。免疫印渍结果表明,旋毛虫和卫氏并殖吸虫抗原中分子量为 65、58、53kDa的蛋白带均与旋毛虫感染的大鼠、小鼠及患者血清、肺吸虫感染的大鼠和患者血清发生反应;旋毛虫和华支睾吸虫抗原中分子量为108kDa的蛋白带均与旋毛虫感染的大鼠、小鼠及患者血清、肝吸虫病患者血清发生反应;而3种可溶性抗原中的53kDa与本实验中所有寄生虫感染的动物和患者均有交叉反应。结论 65、58、53 kDa蛋白为旋毛虫和卫氏并殖吸虫的共同抗原,108kDa蛋白为旋毛虫和华支睾吸虫的共同抗原,而53 kDa蛋白为这3种寄生虫的共同抗原。     

华支睾吸虫病金标诊断试剂盒的研制和现场初步实验

目的　研制华支睾吸虫病金标快速免疫诊断试剂盒 ,评价其敏感性、特异性和现场试用效果。　方法　以华支睾吸虫成虫水溶性抗原、分泌排泄抗原和重组抗原磷酸甘油酸激酶 (PGK)作为诊断试剂 ,制备胶体金免疫层析检测 (Im-munochromatography test,ICT)试剂盒 ,检测患者血清和唾液中抗华支睾吸虫 Ig G,并与常规 EL ISA血清学检测方法和粪便虫卵检查法相比较。　结果　实验室检测临床确诊的华支睾吸虫病人血清中特异的 Ig G,3种抗原的敏感性均为10 0 %。天然抗原除与慢性血吸虫病人血清有较强的交叉反应外 ,与囊虫、包虫、弓形虫病人血清没有交叉反应。重组PGK抗原同慢性血吸虫病人血清也没有交叉反应。用分泌排泄抗原制备的 ICT检测试剂盒在流行区现场检测被调查者的血清和唾液 ,总符合率为 92 .31% ;ICT与 EL ISA血清检测的总符合率为 81.5 4 %。现场获取了 9人的粪便样本 ,其中 4人检出华支睾吸虫卵 ,其血清 ICT和 EL ISA检测均呈强阳性 ,另外未检出虫卵的 5人中 ,1人血清 ICT和 EL ISA均呈阳性 ,另 1人仅血清 EL ISA呈弱阳性。　结论　诊断华支睾吸虫感染的 ICT抗体检测技术 ,尤其是无创性唾液检测技术 ,简便、快速、准确、安全 ,优于血清 EL ISA检测和粪便虫卵检测 ,适用于临床检验和现场大规模流行病