人白细胞介素4的原核表达、复性、纯化及生物学活性鉴定

用PCR方法从pORF-hIL4质粒中扩增重组人白细胞介素4(hIL-4)的基因,构建PQE60原核表达载体并诱导其目的蛋白的表达。对表达的目的蛋白的可溶性进行鉴定,发现hIL-4基因表达产物在大肠杆菌中主要以不溶性包涵体形式存在,经过超声波破细菌、包涵体提取、洗涤处理后,用5mol/L盐酸胍变性溶解包涵体沉淀,上清稀释复性后透析,再经镍亲和层析进行纯化。纯化后的hIL-4进行TF-1细胞体外增生实验检测其生物学活性后,可用于人外周血树突状细胞的体外诱导培养。     

抗人HAb18G分子单链抗体基因的构建及在大肠杆菌中的分泌表达

目的 :构建抗人HAb18G分子单链抗体基因 ,并在大肠杆菌中进行分泌表达。方法 :通过连接肽 (Gly4Ser) 3基因序列将已成功克隆的抗人肝癌单抗HAb18轻、重链可变区基因拼接成单链抗体 (ScFv)基因 ,并在 5′和 3′端引入相应的酶切位点 ,克隆至改造的分泌性表达载体pCANTAB 5His之中 ,转化到E coliHB2 15 1中进行诱导表达。亲和层析纯化表达蛋白后 ,以SDS PAGE电泳、Westernblot及ELISA等方法分析检测表达产物。结果 :经限制性酶切鉴定及DNA测序分析 ,证实基因构建正确。SDS PAGE电泳和Westernblot分析表明ScFv基因在大肠杆菌中成功表达。表达产物的相对分子质量 (Mr)为 31kD ,与理论预期值相符 ,并且可与相应的抗原特异结合。结论 :成功实现了抗人HAb18G分子单链抗体的原核分泌表达 ,为其在人肝癌诊治中的进一步应用奠定了基础。     

戊型肝炎病毒结构区基因在大肠杆菌中的表达

目的获得可用于研制戊型肝炎疫苗的基因工程抗原。方法用非融合蛋白表达载体ｐＥＴ１１ａ,表达戊型肝炎病毒（ＨＥＶ）第二读码框区（ＯＲＦ２）２２４６６０ａａ段蛋白。结果得到分子量为５００００的表达产物,经Ｗｅｓｔｅｒｎｂｌｏｔ证实,表达产物具有ＨＥＶ特异抗原性。结论该基因工程抗原可能具有制备戊型肝炎疫苗的前景。     

IFN-gamma enhances immune responses to E. coli infection in the chicken.

Escherichia coli infection of the respiratory system in chickens occurs as a sequel to a variety of environmental stressors or microbial infections, culminating as chronic respiratory disease (CRD) syndrome or colibacillosis. These diseases cause significant production losses in poultry. With the growing concerns about the use of antibiotics in animal production, for diseases such as CRD, alternative natural agents, like cytokines, may be considered for enhancing health by stimulating the immune system. The current study was aimed at understanding the in vivo effects of recombinant chicken interferon-gamma (ChIFN-gamma) treatment on a variety of immunologic parameters during E. coli infection in chickens. Administration of ChIFN-gamma to chickens increased the percentage of phagocytes in lung and blood of E. coli-infected birds. At the phenotypic level, there was an increase in the percentage of cells expressing MHC II in the air sac, with a concomitant reduction in the proportion of these cells in blood. Furthermore, the blood plasma from ChIFN-gamma-treated infected birds showed an increased level of interleukin-6 (IL-6) activity. Cumulatively, these findings are indicative of in vivo enhancement of immune responses due to ChIFN-gamma. However, administration of ChIFN-gamma protein did not mitigate the development of air sac lesions following E. coli infection.     

Intestinal immune response to E. coli antigens in the germ-free chicken.

The secretory intestinal immune response to live and heat-inactivated E. coli 02 has been studied in young germ-free chicks. A response to live organisms was evident from an infiltration of the intestinal mucosa with IgA and IgM immunoglobulin-producing cells (IPC). Antibody associated with both immunoglobulin classes which was specific for E. coli 02 was demonstrated in saline extracts of contents from the small intestine. Repeated oral immunization with heat-killed E. coli 02 failed to stimulate serum or intestinal antibody. This finding reflected the complete absence of IPC within the intestinal mucosa of these birds. The IPC profile of unimmunized germ-free chicks was identical to that seen in chicks orally immunized with inactivated E. coli. An interesting feature of all gnotobiotic birds was a considerable elevation of serum IgM levels, compared to those of conventional birds, which was unassociated with immunization procedures. Serum IgG and IgA levels in gnotobiotes were much lower than those in the serum of conventional birds of comparable age. Studies on the fate of orally administered antigen using radiolabelled E. coli endotoxin indicated that a proportion remained intact as far down the intestinal tract as the caecum. However, unaccountably high levels of low mol. wt antigen in the faeces suggested degradation, intestinal absorption and subsequent excretion of endotoxin fragments in the urine. The differences between the avian response and that observed in mammals are discussed in relation to the comparative roles of Peyer's patches and the bursa of Fabricius in initiating intestinal immununity.     

人Ⅱ型免疫缺陷病毒gag基因在大肠杆菌中的表达

目的：表达ＨＩＶ－２基因工程ｇａｇ抗原。方法：将编码ＨＩＶ－２型ｇａｇ的部分和全部ｐ５５ｇａｇ１／２基因,克隆到载体ｐＥＴ－１７ｂ后,分别在Ｅ．Ｃｏｌｉ ＢＩ２１中表达。结果;表达产物为５１和６１ｋＤ融合蛋白,并可与ＨＩＶ－２病人血清发生特异性反应。     

The Escherichia coli K-12 gntP gene allows E. coli F-18 to occupy a distinct nutritional niche in the streptomycin-treated mouse large intestine.

Escherichia coli F-18 is a human fecal isolate that makes type 1 fimbriae, encoded by the fim gene cluster, and is an excellent colonizer of the streptomycin-treated mouse intestine. E. coli F-18 fimA::tet, lacking type 1 fimbriae, was constructed by bacteriophage P1 transduction of the fim region of the E. coli K-12 strain ORN151, containing the tetracycline resistance gene from Tn10 inserted in the fimA gene, into E. coli F-18. E. coli F-18 fimA::tet was found to occupy a distinct niche in the streptomycin-treated mouse intestine when fed in small numbers (10(4) CFU) to mice, along with large numbers (10(10) CFU) of E. coli F-18, as defined by the ability of the E. coli F-18 fimA::tet strain to grow and colonize only 1 order of magnitude below E. coli F-18. The same effect was observed when mice already colonized with E. coli F-18 were fed small numbers of E. coli F-18 fimA::tet. Experiments which show that the E. coli K-12 gene responsible for this effect is not fim::tet but gntP, which maps immediately downstream of the fim gene cluster, are presented. gntP encodes a high-affinity gluconate permease, suggesting that the distinct niche in the mouse large intestine is defined by the presence of gluconate. The data presented here support the idea that small numbers of an ingested microorganism can colonize the intestine as long as it can utilize an available nutrient better than any of the other resident species can.     

Optimization of Dengue-3 recombinant NS1 protein expression in E. coli and in vitro refolding for diagnostic applications

Dengue non-structural protein (NS1) is known to be protective antigen and also has immense application for serodiagnosis. Several serodiagnostic assays available for dengue viral infection are dependent on tissue culture-grown viral proteins. This task is unsafe, laborious, more expensive that makes it unsuitable for routine large-scale production. Although bacterial expression is relatively simple and easy for recombinant protein expression, it is more challenging to make NS1 protein with native structural and immunological features using bacterial expression system. We have successfully developed a method leading to the purification and refolding of recombinant dengue virus type 3 (DENV3) NS1. The gene encoding NS1 was amplified and cloned in pET28a (+) vector. In order to increase the purity of the recombinant NS1, the transgene was engineered to carry 6× Histidine tags at both N and C-terminal ends. The recombinant construct (pETNS1) was transformed into E. coli Rosetta-gami cells and the expression conditions viz IPTG concentration, media type, temperature, and harvest time were optimized. The size of the expressed protein was found to be ~45 kDa and the authenticity of the expressed protein was confirmed using anti-His and anti-NS1 monoclonal antibodies. The NS1 protein was purified under denaturing conditions, to attain the native conformation, NS1 protein was in vitro refolded and dialyzed. The refolded NS1 protein was detected by commercial Immuno chromatographic strip and NS1 specific monoclonal antibodies. IgM antibody capture ELISA was performed using refolded recombinant NS1 protein which recognized the IgM antibodies in dengue-positive samples of acute phase of infection. Our result suggests that rNS1 protein has immense diagnostic potential and can be used in developing point of care diagnostic assays.     

Molecular typing of avian pathogenic Escherichia coli colonies originating from outbreaks of E. coli peritonitis syndrome in chicken flocks

Escherichia coli colonies isolated from the bone marrow of fresh dead hens of laying flocks with the E. coli peritonitis syndrome (EPS) were genotyped using pulsed-field gel electrophoresis (PFGE). Typing is important from an epidemiological point of view and also if the use of autogenous (auto)vaccines is considered. Birds with EPS originated from one house of each of three layer farms and one broiler breeder farm. Farms were considered as separate epidemiological units. In total, six flocks were examined including two successive flocks of one layer farm and the broiler breeder farm. E. coli colonies (one per bird) from nine to 16 hens of each flock were genotyped. The clonality of E. coli within birds was studied using five colonies of each of nine to 14 birds per flock. E. coli genotypes, which totalled 15, differed between farms and flocks except for two successive layer flocks that shared three genotypes. One to five genotypes were found per flock with one or two genotypes dominating each outbreak. Within hens, E. coli bacteria were always clonal. Colonies of the same PFGE type always had the same multilocus sequence type. However, four PFGE types shared sequence type 95. Neither PFGE types nor multilocus sequence types were unambiguously related to avian pathogenic E. coli from EPS. In cases where persistence of E. coli strains associated with EPS is found to occur frequently, routine genotyping to select strains for autovaccines should be considered.     

幽门螺杆菌全长hpaA基因克隆和在大肠杆菌中高效表达

为了构建幽门螺杆菌（H.pylori)全长hpaA基因表达质粒,在大肠杆菌中表达重组HpaA(reHpaA)蛋白,我们用PCR扩增全长hpaA基因,经适当的酶切－连接反应将其连入原核表达质粒pTrc99A,反应产物转化大肠杆菌JM105,用Amp( )培养基筛选,提取重组菌质粒,PCR和酶切鉴定,筛选阳性克隆,并用重组菌质粒进行hpaA基因测序。阳性克隆经IPTG诱导培养,用SDS－PAGE电泳和Western blot进行reHpaA表达分析和鉴定,用薄层扫描分析reHpaA含量。结果显示,重组质粒pTrc99A-hpaA经PCR和酶切后均产生783bp hpaA基因。重组菌能表达约30kD reHpaA蛋白,含量占全菌体蛋白量的51．99％,Western blot证实其有免疫反应性。重组H.pylori HpaA表达质粒的成功构建及在大肠杆菌中高效表达的实现,为探索制备H.pylori疫苗奠定了一定基础。     

Interleukin-18 facilitates the early antimicrobial host response to Escherichia coli peritonitis

To determine the role of endogenous interleukin-18 (IL-18) during peritonitis, IL-18 gene-deficient (IL-18 KO) mice and wild-type mice were intraperitoneally (i.p.) infected with Escherichia coli, the most common causative agent found in septic peritonitis. Peritonitis was associated with a bacterial dose-dependent increase in IL-18 concentrations in peritoneal fluid and plasma. After infection, IL-18 KO mice had significantly more bacteria in the peritoneal lavage fluid and were more susceptible for progression to systemic infection at 6 and 20 h postinoculation than wild-type mice. The relative inability of IL-18 KO mice to clear E. coli from the abdominal cavity was not due to an intrinsic defect in the phagocytosing capacity of their peritoneal macrophages or neutrophils. IL-18 KO mice displayed an increased neutrophil influx into the peritoneal cavity, but these migratory neutrophils were less activate, as reflected by a reduced CD11b surface expression. These data suggest that endogenous IL-18 plays an important role in the early antibacterial host response during E. coli-induced peritonitis.