普氏立克次体120kDa表面抗原C段基因的克隆与表达

采用PCR方法 ,从普氏立克次体基因组中扩增出 1 2 0kDa表面抗原C段基因片断 ,并将其克隆于原核表达载体pQE30 ,构建重组质粒pQE30 6 7,将重组质粒转入大肠杆菌M1 5 ,用IPTG诱导大肠杆菌内的目的基因表达。SDS PAGE分析发现重组质粒转化菌产生了一 6 7kDa重组蛋白 ;在免疫印迹分析中 ,该 6 7kDa重组蛋白与普氏立克次体免疫血清发生特异反应 ,显示 6 7kDa重组蛋白具有普氏立克次体 1 2 0kDa表面抗原特性     

日本立克次体ompB蛋白基因的克隆及序列分析

参照立氏立克次体分子量为１２×１０４蛋白基因序列合成引物，分两段扩增日本立克次体的１２×１０~４蛋白基因，扩增ＤＮＡ的长度分别为２．５和２．６ｋｂ。含有启动子区的２．６ｋｂ片段在ｐＵＣ１９质粒中不稳定。从这段ＤＮＡ删去启动子及８５个氨基酸编码子区的扩增产物可被克隆。以这一重组质粒为载体克隆含终止密码子的２．５ｋｂ片段。序列分析表明开放阅读框架由４９５６核苷酸对组成，编码１６５２个氨基酸。日本立克次体与立氏立克次体ｏｍｐＢ基因的遗传同源性是９５．５％，表明分子量１２×１０~４可能被用于制备抗斑点热立克次体感染的亚单位疫苗。     

黑龙江立克次体外膜蛋白B基因表达及表达重组蛋白的抗原性分析

黑龙江立克次体为远东蜱传斑点热病原体,本文以黑龙江立克次体基因组为模板,扩增ompB的4段基因,利用原核表达载体构建重组表达质粒,IPTG诱导重组质粒转化的大肠杆菌表达重组目的蛋白,并对其抗原性进行分析.免疫印迹反应表明,重组表达的4个蛋白均与黑龙江立克次体感染小鼠血清反应.该4个重组蛋白分别免疫小鼠后,分析其血清的特...     

斑点热群立克次体HL-93株ompA蛋白基因片段的克隆及序列分析

以根据立氏立克次体（Ｒ．ｒｉｃｋｅｔｔｓｉｉ，Ｒｒ）分子量为１９０×１０~３蛋白抗原基因序列设计的一对引物Ｒｒ １９０．７０ｐ和Ｒｒ １９０．６０２ｎ，用聚合酶链反应技术从斑点热群立克次体ＨＬ－９３株染色体ＤＮＡ中扩增出了１９０×１０~３蛋白基因的部分片段。通过载体质粒ｐＧＥＭ－Ｔ将该部分基因片段克隆进入了大肠杆菌ＪＭ１０１，并进行了核苷酸序列分析。通过与已报道的立氏立克次体、日本立克次体１９０×１０~３蛋白基因该部分片段的ＤＮＡ序列进行比较发现：ＨＬ－９３株立克次体与立氏和日本立克次体该部分ＤＮＡ分别有３１和２４个核苷酸不同，与这两种立克次体该部分ＤＮＡ的同源性分别为９４％和９５．４％。根据改变的核苷酸推定的与这两种立克次体的氨基酸序列的同源性分别为８７％和８９％。序列分析表明ＨＬ－９３株立克次体属于斑点热群立克次体新成员。     

普氏立克次体14kD蛋白基因的扩增与克隆

根据普氏立克次体弱毒株－Ｅ株１４ｋＤ表面蛋白基因的ＤＮＡ序列设计合成了一对寡核苷酸引物，二引物的５＇端分别加上了限制性内切酶ＥｃｏＲＩ和ＨｉｎｄⅢ酶切位点。采用此引物对成功地扩增了普氏立克次体强毒株－－Ｂｒｅｉｎｌ株（国际标准株）的１４ｋＤ表面蛋白基因，基因的分子大小为０．７２ｋｂ。扩增获得的基因ＤＮＡ经限制性内切酶ＨｉｎｄⅢ和ＥｃｏＲＩ酶切后与经相同酶切的质粒载体ｐＵＣ１９连接，转化受体大肠杆菌工程菌ＪＭ１０３，经酶切和ＤＮＡ斑点杂交鉴定，成功地克隆了扩增的普氏立克次体强毒株（Ｂｒｅｉｎｌ株）的１４ｋＤ表面蛋白基因。     

疟疾传播阻断疫苗Pys25重组蛋白免疫活性的实验研究

为探讨约氏疟原虫传播阻断疫苗Pys25重组蛋白的免疫效果及其效应,我们以酵母菌表达的Pys25重组蛋白皮下免疫DBA/2小鼠,采用ELISA检测免疫后不同时间小鼠血清中的特异性抗体水平,并通过IFA观察免疫血清对有性阶段虫体发育的阻断效应。初次免疫后2周,小鼠血清中特异性IgG抗体水平开始升高,并于加强免疫后2周达到峰值;感染血液与免疫血清共同培养后,配子体向合子和动合子的发育明显受阻,并且其传播阻断效应与免疫血清呈剂量依赖性。实验表明,酵母菌表达的Pys25重组蛋白具有良好的免疫原性,其免疫血清可显著抑制有性阶段原虫的进一步发育。     

SARS病毒S1蛋白重组C端片段免疫效果的实验研究

为获得纯化的重组SARS病毒S1蛋白C端 ,研究其刺激机体产生针对SARS病毒免疫应答的规律和机制 ,将编码SARS病毒S1蛋白C端 311个氨基酸残基的基因克隆 ,并在原核表达系统中表达 ,纯化获得了的重组蛋白。利用SARS患者恢复期的血清 ,对纯化的重组S1蛋白进行血清学分析。结果表明 ,本研究中克隆表达的重组蛋白序列与公布的SARS病毒S1蛋白C端的序列相同 ,其编码的重组蛋白相对分子质量约为 5 90 0 0Mr。SARS患者恢复期的血清均与重组蛋白反应 ,在5 9 0 0 0Mr处形成特异性的反应条带 ,而来自SARS流行前的正常人对照血清则不能与重组蛋白反应。在本研究中获得的重组蛋白可以为研究SARS病毒识别宿主细胞受体的过程及其机制提供条件。     

朊蛋白N端和C端多肽特异性抗体的制备及ELISA检测技术的研究

目的 制备朊蛋白N端和C端多肽特异性抗体，并对ELISA方法在朊病毒病检测中的应用进行研究。方法构建人朊蛋白N端和C端多肽原核表达重组质粒，分别表达纯化融合蛋白。以此为抗原制备朊蛋白N端和C端多肽特异性抗体。ELISA和Western Blot检测所制备抗体与重组和天然的PrP蛋白的免疫反应性。初步建立间接ELISA检测技术。结果 所制备的N端和C端抗体可特异性识别重组全长PrP蛋白和相应的PrP片段，无明显交叉反应。C端抗体还可有效地识别感染羊瘙痒因子263K的仓鼠脑组织中经PK消化后的prp^Se，其Western Blot反应带型与PrP单抗3174相似。5000r／min离心处理脑组织悬液可有效保留上清中PrP^Se成分而不影响ELISA检测。蛋白酶K虽经灭活处理，但可明显抑制重组和天然PrP在液相中与相应抗体的结合。间接ELISA方法可根据反应A值区分正常或感染动物样本。结论 所制备的朊蛋白N端和C端抗体具有良好的特异性，C端抗体可用于实验性朊病毒病的检测。建立的间接ELISA方法可试用于朊病毒病的初步筛查。     

人巨细胞病毒PP150蛋白C端多肽与gp52蛋白片段的融合表达

目的：将人巨细胞病毒PP150蛋白C端多肽与gp52蛋白片段融合,构建表达该融合蛋白的工程菌。方法：合成PP150蛋白C端25个氨基酸的基因片段,并选有细菌偏爱的密码子。用PCR方法扩增gp52蛋白基因片段。将这2个基因片段分别克隆至同一质粒pET28a( )内的NcoI/BamHI和BamHI/EcoRI位点,使两者串联在一起,并且翻译框架一致,可表达1个融合蛋白。将重组质粒转化大肠杆菌,用酶切及SDS－PAGE等方法筛选表达融合蛋白的工程菌。结果：构建成功了高效表达PP150C端多肽与pg52蛋白片段的融合蛋白工程菌,表达量为35％左右。初步纯化获得了表达的融合蛋白。结论:初步纯化的融合蛋白能与已知的抗gp52-IgM阳性血清和抗PP150－IgM阳性血清反应,说明融合蛋白C端的gp52蛋白保持较好的抗原性,融合蛋白N端的PP150C端多肽也显示有抗原性。     

恙虫病东方体58kDa热休克蛋白与47kDa外膜蛋白的基因嵌合及58-47嵌合基因在大肠杆菌中的表达

采用PCR方法 ,从恙虫病东方体Karp株基因组DNA中扩增 5 8kDa热休克蛋白的基因 ,将该基因分别与原核表达载体pQE30及 4 7kDa外膜蛋白的基因重组质粒 (pQE30 4 7)连接 ,构建pQE30 5 8及pQE30 5 8 4 7重组质粒 ,用重组质粒转化大肠杆菌。SDS PAGE显示 ,pQE30 5 8和pQE30 5 8 4 7转化的大肠杆菌分别产生一 5 8kDa重组蛋白和一 90kDa的双抗原 (5 8- 4 7)融合蛋白。免疫印迹分析显示Karp株免疫血清能特异识别 5 8kDa重组蛋白和 90kDa融合蛋白 ,90kDa融合蛋白既与 4 7kDa重组蛋白也与 5 8kDa重组蛋白的免疫血清特异反应 ,5 8kDa与 4 7kDa重组蛋白也被 90kDa融合蛋白免疫血清所识别。研究结果证明 5 8 4 7融合蛋白具有恙虫病东方体Karp株 4 7kDa外膜蛋白和 5 8kDa热休克蛋白的抗原特性     

Surface proteins of typhus and spotted fever group rickettsiae.

Six proteins, previously established as major constituents of intact organisms, were identified in cell envelopes obtained from intrinsically radiolabeled Rickettsia prowazekii. Extrinsic radioiodination of intact organisms conducted at 0.5 micronM iodide indicated that protein 4 was the most peripheral, although protein 1 also had reactive groups exposed on the surface of the organisms. A 10-fold increase in iodide concentration resulted in labeling of protein 2, and at 50 micronM iodide, all six major proteins were radiolabeled. Similar selective labeling was not achieved with R. conorii. Analysis of both typhus and spotted fever group organisms radiolabeled with galactose suggested that carbohydrate was associated with proteins 1, 3, and 4. Typhus soluble antigen included all major proteins except protein 2, which remained attached to particulate rickettsiae after ether extraction. Protein 4 appeared to be prominent in the surface topography of R. prowazekii, was a component of soluble antigen and may have an important role in rickettsiae-host interactions.     

Evidence for proteolytic cleavage of the 120-kilodalton outer membrane protein of rickettsiae: identification of an avirulent mutant deficient in processing.

The 120-kDa rickettsial outer membrane protein (rOmpB) is encoded by a gene with the capacity to encode a protein of approximately 168 kDa. The carboxy-terminal end of the molecule is apparently cleaved to yield 120- and 32-kDa products. Both polypeptides are surface exposed and remain associated with the outer membrane of intact rickettsiae. All species of rickettsiae examined display similar cleavage of rOmpB. Comparison of diverse species of rickettsiae demonstrate a conserved N terminus of the 32-kDa fragment, with a predicted procaryotic secretory signal peptide immediately upstream of the proposed cleavage site. Coprecipitation of the 120-kDa rOmpB protein and the 32-kDa peptide by monoclonal antibodies specific for the 120-kDa portion of the molecule suggests that the two fragments remain noncovalently associated on the surface of rickettsiae. Analysis of an avirulent mutant of Rickettsia rickettsii revealed reduced amounts of the 120- and 32-kDa fragments, but with a correspondingly larger rOmpB protein that displayed properties expected of the putative precursor. This avirulent mutant grows intracellularly but fails to cause the lysis of infected cells that is typical of R. rickettsii. DNA sequence analysis of the region of the gene encoding the cleavage site of the avirulent strain revealed no difference from the sequence obtained from virulent R. rickettsii. The 168-kDa putative precursor of the avirulent strain of R. rickettsii was not extracted from the surface by dilute buffers, as is the 120-kDa protein of virulent R. rickettsii or R. prowazekii. These latter results suggest that the 32-kDa C-terminal region of the molecule may serve as a membrane anchor domain.     

Comparison of properties of virulent, avirulent, and interferon-resistant Rickettsia prowazekii strains.

Several properties of virulent, avirulent, and interferon-resistant Rickettsia prowazekii strains were compared. All of the interferon-resistant rickettsial strains (which were derived from the avirulent Madrid E strain) resembled the virulent Breinl strain in that they grew well in untreated mouse macrophagelike RAW264.7 cells. In contrast, the avirulent Madrid E strain grew poorly in untreated RAW264.7 cells. Pretreatment of interferon-resistant rickettsiae or R. prowazekii Breinl with antirickettsial serum or immunoglobulin G suppressed the ability of the rickettsiae to grow in untreated RAW264.7 cells. Interferon-resistant R. prowazekii strains, like the Madrid E and Breinl strains, rapidly killed a substantial proportion of RAW264.7 cells that had been treated with gamma interferon or very high concentrations of alpha/beta interferon. Untreated infected RAW264.7 cells and interferon-treated mock-infected RAW264.7 cells were not killed during the same period. In cultures of RAW264.7 cells treated with either alpha/beta interferon (120 to 1,200 U/ml) or a subsaturating concentration of gamma interferon (0.5 U/ml), R. prowazekii Breinl organisms killed a higher percentage of the cells than did comparable numbers of R. prowazekii Madrid E organisms or interferon-resistant rickettsiae. Although R. prowazekii Breinl (like R. prowazekii Madrid E) was quite sensitive to gamma interferon in mouse L929 cells, the Breinl strain was resistant to murine alpha/beta interferon compared with the Madrid E strain and the two strains selected for resistance to murine gamma interferon. One of the interferon-resistant strains (strain 60P, which was selected for resistance to murine alpha/beta interferon) differed from the other R. prowazekii strains in that it induced little or no detectable interferon in L929 cell cultures.     

Detection of Rickettsia prowazekii in body lice and their feces by using monoclonal antibodies

In order to identify Rickettsia prowazekii in lice, we developed a panel of 29 representative monoclonal antibodies selected from 187 positive hybridomas made by fusing splenocytes of immunized mice with SP2/0-Ag14 myeloma cells. Immunoblotting revealed that 15 monoclonal antibodies reacted with the lipopolysaccharide-like (LPS-L) antigen and 14 reacted with the epitopes of a 120-kDa protein. Only typhus group rickettsiae reacted with the monoclonal antibodies against LPS-L. R. felis, a recently identified rickettsial species, did not react with these monoclonal antibodies, confirming that it is not antigenically related to the typhus group. Monoclonal antibodies against the 120-kDa protein were highly specific for R. prowazekii. We successfully applied a selected monoclonal antibody against the 120-kDa protein to detect by immunofluorescence assay R. prowazekii in smears from 56 wild and laboratory lice, as well as in 10 samples of louse feces infected or not infected with the organism. We have developed a simple, practical, and specific diagnostic assay for clinical specimens and large-scale epidemiological surveys with a sensitivity of 91%. These monoclonal antibodies could be added to the rickettsial diagnostic panel and be used to differentiate R. prowazekii from other rickettsial species.     

犬蠕形螨病诊断抗原制备研究

通过刮取重症病犬蠕形螨发病部位的皮屑 ,用 5 %NaOH消化 2h后进行虫体浓集 ,将浓集的虫体冻融、研磨、超声破碎 ,经 80 0 0r min离心 2 0min ,取上清为蠕形螨盐溶性粗抗原 ;将沉渣用尿素混匀 ,再次超声 ,经 80 0 0r min离心 2 0min ,取上清为蠕形螨尿素溶性粗抗原。所得抗原用Bradford法进行蛋白浓度检测 ,浓度分别为 1 4mg mL和 1 1mg mL。经过葡聚糖凝胶层析 (G 10 0 ) ,分别得到两个层析峰。经SDS 聚丙烯酰胺凝胶电泳 ,盐溶性粗抗原显示 2条主蛋白带 ,分子量约为 4 5 7kDa和 2 7 5kDa ;尿素溶性粗抗原显示2条主蛋白带 ,分子量约为 4 6 8kDa和 2 7 5kDa ,用正常犬皮处理的对照抗原却出现至少 9条蛋白带 ,分子量范围为 :2 7kDa～ 110kDa。将抗原稀释至 1∶30 0 ,血清按 1∶30 0稀释 ,酶标SPA (葡萄球菌A蛋白 )作为二抗 ,通过ELISA检测 ,尿素溶性粗抗原层析峰第一峰具有较好抗原性 ,实际检测 12例临床检查发现蠕形螨的临床病犬和 19例未发现蠕形螨的临床健康犬 ,阳性符合率和阴性符合率分别为 91 6 7%和 78 95 %。经与其他皮肤病犬进行检测发现该抗原能较好地与其他皮肤病进行鉴别 ,与猪蠕形螨阳性血清有一定的交叉反应。获得了敏感性和特异性较高的犬蠕形螨病诊断抗原     

Mapping of monoclonal antibody binding sites on CNBr fragments of the S-layer protein antigens of Rickettsia typhi and Rickettsia prowazekii.

The 120 kDa surface protein antigens (SPAs) of typhus rickettsiae lie external to the outer membrane in regular arrays and chemically resemble the S-layer proteins of other bacteria. These proteins elicit protective immune responses against the rickettsiae. In order to study the immunochemistry of these proteins, purified SPAs from Rickettsia typhi and Rickettsia prowazekii were fragmented with CNBr. The fragments were separated by SDS-PAGE and were recovered on PVDF membrane following electroblotting. The origin of eight major fragments from R. prowazekii and seven major fragments from R. typhi was determined by automated N-terminal amino acid sequencing and by comparison with the DNA sequence encoding R. prowazekii SPA. The cleavage patterns and protein sequences of the two proteins differed significantly. CNBr fragments corresponding to the C-terminus (amino acid 1372-1612 of the deduced sequence from encoding gene spaP) were not present in both SPAs. This suggests that the corresponding C-terminal region was not synthesized or was removed during SPA translocation to the cell surface. Modified amino acids were detected in each protein. Eighteen monoclonal antibodies selected for varied reactivity with both native and denatured SPA proteins could be classified into eight different types based on western blot analysis of the CNBr fragments. Six of the monoclonal antibody types reacted predominantly with a single region of the SPAs. Two types of antibodies bound to several CNBr fragments which contained both limited sequence similarity and modified amino acids either of which might account for the multisite binding of these antibodies.     

Detection and characterization of mouse monoclonal antibodies to epidemic typhus rickettsiae.

A solid-phase immunofluorometric assay was used to detect mouse monoclonal antibodies to epidemic typhus rickettsiae, Rickettsia prowazekii (the immunizing antigen), and to murine typhus rickettsiae, Rickettsia typhi, a related antigen. Of the 649 hybridoma cultures obtained, 628 contained antibodies either to R. prowazekii or to both R. prowazekii and R. typhi. A total of 72 cultures were cloned by limiting dilution and yielded 137 antibody-producing clones. Of these, 104 produced antibodies specific for R. prowazekii, 22 produced antibodies that reacted with R. prowazekii and R. typhi, and 11 produced antibodies that reacted with R. prowazekii, R. typhi, and R. canada. The immunoglobulin isotypes of the mouse monoclonal antibodies produced were identified by a related indirect immunofluorometric assay technique with fluorescein isothiocyanate-conjugated antisera specific for each isotype. Antibodies were also evaluated by indirect fluorescent antibody tests, and antibodies from selected clones were found to neutralize rickettsial toxic activity in mice.     

Characterization of the Madrid E strain of Rickettsia prowazekii purified by renografin density gradient centrifugation.

The avirulent Madrid E strain of Rickettsia prowazekii cultivated in chicken yolk sacs could be purified successfully with a Renografin density gradient method developed previously for Rickettsia typhi. Recovery during purification, viability, and lack of contamination with host cell components were similar for the two species, although yields of R. prowazekii per yolk sac were lower. Purified typhus rickettsiae provided satisfactory antigens in the complement fixation, Ouchterlony double-diffusion, and microagglutination tests. The retention of the typhus soluble group antigen during purification was readily demonstrated by complement fixation tests. However, removal of the soluble group antigen by ether treatment was not always adequate for the demonstration of type-specific particulate antigens. Heat-killed R. prowazekii cells gave higher serum microagglutination titers than untreated or formalized cells, a difference was noted for R. typhi cells. Although the protein profiles of whole cells and extracts of R. typhi and R. prowazekii on sodium dodecyl sulfate-polyacrylamide gels were relatively similar, a small but reproducible, difference in the electrophoretic mobilities of their malate dehydrogenases was detected. Purification of typhus rickettsiae on Renografin gradients has no apparent adverse effects on their metabolic or antigenic properties.     

Heterogeneity of CD4-positive human T-cell clones which recognize the surface protein antigen of Rickettsia typhi

Immunity to the typhus group of rickettsiae is largely dependent on the effector function of several classes of T lymphocytes, including those which produce gamma interferon. Since the surface protein antigen (SPA) derived from typhus group rickettsiae has been shown to be an effective immunogen in animal models, human T-cell clones specific for the SPA of Rickettsia typhi were isolated and tested for their antigenic specificity, as well as for their ability to produce gamma interferon. Eighteen CD4-positive clones specific for the SPA of R. typhi exhibited considerable diversity in their response to the SPAs derived from two strains of Rickettsia prowazekii and from Rickettsia canada. The vast majority of clones also recognized the SPAs from R. prowazekii but not from R. canada. Two heteroclitic clones demonstrated significantly higher proliferative responses to the SPAs derived from one or both of the R. prowazekii strains than to the SPA of R. typhi, and one clone demonstrated a significantly higher response to the SPA of R. typhi than to the other SPAs. All 18 clones produced gamma interferon in response to SPA stimulation. We conclude that the SPAs from typhus group rickettsiae can elicit both a diverse T-cell response in humans and the efficient stimulation of gamma interferon-mediated immunity.