Safety and immunogenicity of Escherichia coli O18 O-specific polysaccharide (O-PS)-toxin A and O-PS-cholera toxin conjugate vaccines in humans.

O-specific polysaccharide (O-PS) isolated from serotype 18 Escherichia coli lipopolysaccharide (LPS) was covalently coupled to either Pseudomonas aeruginosa toxin A (TA) or or cholera toxin (CT). The conjugates were nontoxic and nonpyrogenic. The conjugates were well tolerated on parenteral administration to human volunteers, with only mild, transient local reactions reported. Immunization engendered an IgG antibody response to both the O-PS and carrier protein. Anti-LPS antibody promoted the uptake and killing of an E. coli O18 strain bearing the K1 capsule by human polymorphonuclear leukocytes, which was complement dependent. Antibody to carrier protein neutralized the activity of native TA or CT in cell culture assays. Passively transferred IgG isolated from the serum of immunized donors provided a significant (P less than .01) degree of protection against fatal experimental E. coli O18 sepsis in mice. This study illustrates the potential use of such conjugates as vaccines against E. coli extraintestinal infections.     

Engineering N-linked protein glycosylation with diverse O antigen lipopolysaccharide structures in Escherichia coli

Campylobacter jejuni has a general N-linked protein glycosylation system that can be functionally transferred to Escherichia coli. In this study, we engineered E. coli cells in a way that two different pathways, protein N-glycosylation and lipopolysaccharide (LPS) biosynthesis, converge at the step in which PglB, the key enzyme of the C. jejuni N-glycosylation system, transfers O polysaccharide from a lipid carrier (undecaprenyl pyrophosphate) to an acceptor protein. PglB was the only protein of the bacterial N-glycosylation machinery both necessary and sufficient for the transfer. The relaxed specificity of the PglB oligosaccharyltransferase toward the glycan structure was exploited to create novel N-glycan structures containing two distinct E. coli or Pseudomonas aeruginosa O antigens. PglB-mediated transfer of polysaccharides might be valuable for in vivo production of O polysaccharides-protein conjugates for use as antibacterial vaccines.     

Intranasal immunization with heterologously expressed polysaccharide protects against multiple Pseudomonas aeruginosa infections

Surface-expressed bacterial polysaccharides are often immunodominant, protective antigens. However, these antigens are chemically and serologically highly heterogeneous, and conjugation to protein carriers is often necessary to enhance their immunogenicity. Here we show the efficacy of intranasal immunization of mice with attenuated Salmonella enterica serovar Typhimurium expressing the O antigen portion of Pseudomonas aeruginosa lipopolysaccharide. P. aeruginosa is an ideal model system because it can cause a myriad of localized and systemic infections. In particular, this bacterium is a leading cause of hospital-acquired pneumonia and is responsible for infections after burns and after eye injury. In addition, there are mouse models of infection that mimic the clinical manifestations of P. aeruginosa infections. Immunized mice were highly protected against infection, with long-lasting immunity to acute P. aeruginosa pneumonia, whereas mice immunized with Salmonella containing only the cloning vector or PBS were not. Prophylactic and therapeutic administration of sera from vaccinated animals protected naive mice. Intranasal vaccination also provided complete protection from infections after burns and reduced pathology after corneal abrasions. These results indicate that intranasal delivery of heterologously expressed polysaccharide antigens provides protection at distinct sites of infection. This approach for the expression and delivery of polysaccharide antigens as recombinant immunogens could be easily adapted to develop vaccines for many infectious agents, without the need for complicated purification and conjugation procedures.     

Safety and immunogenicity of Escherichia coli O157 O-specific polysaccharide conjugate vaccine in 2-5-year-old children

BACKGROUND: Escherichia coli O157:H7 causes severe enteritis and hemolytic-uremic syndrome, mostly in young children and older adults. Similar to the case with Shigella, serum IgG against the O-specific polysaccharide of E. coli O157:H7 may confer immunity by lysing the inoculum in the intestine. A phase 1 trial in adults showed that a vaccine of E. coli O157:H7 O-specific polysaccharide conjugated to recombinant exotoxin A of Pseudomonas aeruginosa (O157-rEPA) was safe and immunogenic. METHODS: A phase 2 trial of the O157-rEPA vaccine was conducted in 49 children 2-5 years old who were divided randomly into groups receiving 1 or 2 doses of vaccine. Adverse reactions were monitored. Serum IgG lipopolysaccharide (LPS) antibodies were determined. RESULTS: No significant adverse reactions were observed. At 1 week after the first dose was administered, most children (81%) responded with a >4-fold increase in serum IgG LPS antibodies. At 6 weeks after the first dose was administered, all children responded with a >8-fold increase; a second dose did not elicit a booster response. At 26 weeks after the first dose was administered, the geometric mean titer of serum IgG LPS antibodies was ~20-fold higher than was the prevaccination titer. These serum samples had high titers of bactericidal activity that were correlated roughly with serum IgG LPS antibody titers (r = .78). CONCLUSIONS: The O157-rEPA vaccine was safe and immunogenic in young children. A phase 3 trial of the administration of this conjugate vaccine concurrently with routine immunization in infants is planned.     

Characterization of the human immune response to a polysaccharide vaccine from Pseudomonas aeruginosa

Sera from humans vaccinated with a high-molecular-weight polysaccharide vaccine to Pseudomonas aeruginosa immunotype 1 (IT-1) were analyzed for duration of the immune response, specificity for the IT-1 determinant, and by assessing the immunoglobulin classes elicited. The ability of purified IgG, IgM, and IgA to interact with peripheral blood leukocytes, as well as purified polymorphonuclear neutrophils or mononuclear cells, was also examined in an opsonophagocytosis assay. Levels of antibody to IT-1 remained significantly (P less than 0.001) elevated 21 months after immunization. Responses were generally specific to the IT-1 serotype determinant. Some vaccinees also responded to immunotype 2 and immunotype 5 determinants. IgG, IgM, and IgA serum antibodies were all elicited by vaccination. IgG and IgA were effective opsonins for P aeruginosa. IgM-mediated opsonophagocytosis required complement. Serum IgA was highly effective in conjunction with mononuclear cells in opsonophagocytosis of P aeruginosa, suggesting that these immune components may be capable of protecting neutropenic hosts.     

肝硬化并发自发性细菌性腹膜炎患者临床特点、病原学和药敏结果分析*

目的 探讨肝硬化并发自发性细菌性腹膜炎（SBP）患者的临床特点、病原学分布和药敏情况。方法 经细菌培养阳性的60例乙型肝炎肝硬化并发SBP患者,使用德国德灵诊断产品有限公司生产的细菌自动鉴定仪进行细菌鉴定,并采用纸片扩散(K-B)法或MIC法测定细菌对抗菌药物的敏感性。结果 在60例SBP患者中,分离出大肠埃希菌8株（7.1%）、肺炎克雷伯菌7株（11.7%）、鲍曼不动杆菌10株（16.7%）、铜绿假单胞菌6株（10.0%）、阴沟肠杆菌4株（6.7%）、产气肠杆菌3株（5.0%）、葡萄球菌14株（23.3%）和肠球菌8株（13.3%）;对头孢西丁耐药的细菌有大肠埃希菌2株、肺炎克雷伯菌2株、鲍曼不动杆菌1株、铜绿假单胞菌2株、阴沟肠杆菌1株和产气肠杆菌1株;对头孢曲松耐药的细菌有大肠埃希菌1株,肺炎克雷伯菌1株,鲍曼不动杆菌3株,铜绿假单胞菌1株,阴沟肠杆菌2株和产气肠杆菌2株;对亚胺培南耐药的细菌有大肠埃希菌3株,肺炎克雷伯菌3株,鲍曼不动杆菌2株,铜绿假单胞菌1株,产气肠杆菌3株;对克林霉素耐药的细菌有凝固酶阴性葡萄球菌8株,肠球菌2株;对万古霉素耐药的细菌有葡萄球菌1株。结论 肝硬化并发 SBP 患者细菌培养阳性率不高,但在成功分离得到的阳性细菌中以革兰阴性杆菌居多,对亚胺培南的敏感性在降低,而大多数革兰阳性菌仍对万古霉素敏感。     

Live oral Salmonella vaccines: potential use of attenuated strains as carriers of heterologous antigens to the immune system

Live attenuated strains of salmonellae are showing promise as live oral vaccines against human typhoid fever and other Salmonella infections of man and animals. Attenuation can be achieved by introducing genetically defined, non-reverting mutations into specific genes on the Salmonella chromosome. Mutations in the gal E or aroA genes of Salmonella inhibit the ability of the bacteria to grow in vivo, and strains carrying such lesions are effective vaccines against salmonellosis. Genetic determinants encoding for the expression of potentially protective antigens from heterologous, non-Salmonella pathogens can be readily introduced into these attenuated Salmonella strains. Expression of the heterologous antigen does not affect the ability of the Salmonella host to be used as a Salmonella vaccine. Mice infected orally with a Salmonella typhimurium aroA vaccine expressing the Escherichia coli heat-labile toxin B subunit developed both a secretory and serum antibody response to this antigen. These serum antibodies were able to neutralise the activity of E. coli heat-labile toxin in tissue culture assays. A humoral and cell-mediated (DTH) immune response was detected against beta galactosidase, an intracellular antigen, in mice infected with an aroA vaccine expressing this cloned antigen. The prospects for the development of live Salmonella vaccines as a method for delivering heterologous antigens derived from bacteria, viruses and parasites is discussed.     

Effects of Lipopolysaccharide from Porphyromonas gingivalis and Escherichia coli on Gene Expression Levels of Toll-like Receptors and Inflammatory Cytokines in Human Dental Pulp Stem Cells

Background: Periodontal diseases originate from a group of oral inflammatory infections initiated by oral pathogens. Among these pathogens, Gram-negative bacteria such as p. gingivalis play a major role in chronic periodontitis. P. gingivalis harbours lipopolysaccharide (LPS) which enables it to attach to TLR2.Objectives: Evaluating the effects of P. gingivalis and E. coli LPS on the gene expression of TLRs and inflammatory cytokines in human dental pulp stem cells (hDPSCs).Methods: We evaluated the expression level of TLR2, TLR4, IL-6, IL-10, and 1L-18 in hDPSCs treated with 1μg/mL of P. gingivalis lipopolysaccharide and E. coli LPS at three different exposure times using Real-time RT-PCR.Result: The test group treated with P. gingivalis LPS showed a high level of TLR4 expression in 24 hours exposure period and the lowest expression in 48 hours of exposure time. In the case of IL-10, the lowest expression was in the 24 hours exposure period. Although in the E.coli LPS treated group, IL-10 showed the highest expression in 24 and lowest in 48 hours exposure period. Moreover, IL-18 in P. gingivalis LPS treated group showed a significant difference between 6, 24, and 48-time periods of exposure, but not in the E. coli LPS treated group.Conclusion: Both types of LPS stimulate inflammation through TLR4 expression. P. gingivalis LPS performs more potentially than E. coli in terms of stimulating inflammation at the first 24 hours of exposure. Nevertheless, our study confirmed that increasing P. gingivalis and/or the E.coli LPS exposure time, despite acting as an inflammatory stimulator, apparently showed anti-inflammatory properties.     

Serum sensitivity of Pseudomonas aeruginosa isolated from sputum as a virulence factor in the lower respiratory tract

To elucidate the clinical significance of serum-sensitivity of respiratory pathogenic Pseudomonas aeruginosa (P. aeruginosa) strains, we examined serum-sensitivity of P. aeruginosa isolated from 16 patients with lower respiratory tract infections and clinical backgrounds of these patients. We also evaluated the virulence of four serum-resistant and four serum-sensitive P. aeruginosa strains in murine pneumonia model induced by intratracheal challenge, and the silver-stained profiles of purified lipopolysaccharide (LPS) from these strains. Serum-sensitive strains were isolated only from patients with chronic bronchitis, bronchiectasis, and diffuse panbronchiolitis colonized with P. aeruginosa, and rarely caused pneumonias, while serum-resistant strains caused pneumonias in some cases. Intratracheal challenge of mice with 5 x 10(7) cfu per mouse of a serum resistant strain caused fatal hemorrhagic pneumonia with bacteremia. In contrast, the same dose of a serum-sensitive strain provided non-fatal pneumonia without bacteremia. LD50 of serum-sensitive strains in a murine model of P. aeruginosa pneumonia were at least 2-10 times higher than those of serum-resistant strain. The LPS profiles of two serum-resistant strains and one serum-sensitive strain showed ladder-like patterns. The similar analysis demonstrated that one serum-sensitive strain was lack of ladder-like patterns. These data support that serum-sensitive P. aeruginosa strains are less virulent than serum-resistant P. aeruginosa strains in the lower respiratory tract, and serum sensitivity of P. aeruginosa strains is determined by the structure of the O-side chain of LPS; either lack of the O-side chain or the presence of sparse O-side chain.     

Induction of the early hypotensive phase by Escherichia coli: role of bacterial surface structures and inflammatory mediators

An early hypotensive phase was induced in rats by different strains of Escherichia coli and cell wall fractions to study the role of the bacterial surface structure, the complement system, histamine, and serotonin in induction of hypotension. E. coli strains with only core glycolipid (E. coli strain J5) or with intact lipopolysaccharide O antigens on their surface induced hypotension and thrombopenia within 5 min after intravenous administration. This response was reduced by prior decomplementation of the rats and by methysergide, a serotonin antagonist. Two K antigen-positive strains induced no hypotension except after removal of K antigen. The isolated lipopolysaccharide fractions and the lipid A subfractions, but not the polysaccharide subfractions, were also able to induce hypotension. Thus the core glycolipid structure, by interactions that involve platelets and the complement system, is mainly responsible for induction of an early hypotensive phase in rats, and K antigens interfere with this response.     

Staphylococcus aureus strains lacking D-alanine modifications of teichoic acids are highly susceptible to human neutrophil killing and are virulence attenuated in mice

P1 and ABO antigens and bacterial stx genotypes might influence the risk of developing hemolytic uremic syndrome (HUS) after Escherichia coli O157:H7 infections. We determined ABO status and P1 antigen expression in 130 infected and 17 uninfected children, and we determined the stx genotype of the infecting isolate. P1 expression was weakly and directly related to HUS risk (P=.04), but this risk did not extend to the group with the greatest P1 expression. P1 expression remained constant as HUS evolved. The ABO frequency was similar in all groups. These associations were not affected by the stx genotype. stx1(-)/stx2(+) E. coli O157:H7 strains were more commonly associated with HUS than were stx1(+)/stx2(+) strains (P=.21), and 1 child with HUS was infected with a rare stx1(+)/stx2(-) isolate. In the present study, ABO antigens and stx genotypes were not major determinants of the outcome of E. coli O157:H7 infections, and P1 expression did not protect against the development of HUS.     

大肠杆菌O157VT2 B亚基基因的克隆与表达

目的对大肠杆菌O157VT2毒素B亚基基因进行克隆、表达与鉴定,为VT2毒素的抗原、抗体大规模制备及疾病的预防、诊断和疫苗研究打下基础。方法设计寡核苷酸引物,利用PCR技术从出血性大肠杆菌O157的染色体基因组中扩增出VT2毒素B亚基基因,连接到表达载体pET-28a以构建重组质粒。将重组质粒转入表达宿主菌BL21感受态细胞,通过IPTG诱导进行表达,对表达蛋白进行SDSPAGE电泳分析和Western检测。结果用PCR方法扩增出了预期大小的VT2B亚基基因,克隆得到重组质粒pET28aVT2B,转化后宿主菌成功表达分子量为8kD的目的蛋白,用特异抗体经Western检测该条带为阳性反应。结论目的基因成功克隆到宿主菌内,目的蛋白得到高效表达,最佳诱导时间为4h,目的蛋白表达量可达总蛋白量45.72%。     

马链球菌兽疫亚种中国株的类M蛋白基因抗原表位片段的克隆与表达

目的　构建马链球菌兽疫亚种 (Streptococcusequisubsp zooepidemicus)中国株的类M蛋白基因抗原表位片段的重组表达质粒 (pET -Szp) ,并检测表达产物的免疫反应性。 方法　根据GenBank登录的马链球菌兽疫亚种纽约分离株w6 0类M蛋白基因序列设计和合成引物 ,以该菌中国分离株ATCC35 2 4 6的基因组DNA为模板 ,扩增类M蛋白基因 5’端第 5 83～ 10 6 8bp片段 ,并按正确的阅读框架定向克隆到表达载体pET - 32a(+)中 ,将重组质粒转化大肠杆菌BL2 1株 ,用IPTG诱导表达 ,并通过SDS -PAGE和免疫印迹对表达蛋白进行初步分析。结果　扩增出 4 86bp的马链球菌兽疫亚种ATCC35 2 4 6的类M蛋白基因片段 ,该基因在大肠杆菌表达系统中经诱导 ,得到分子量为 5 0 0 0 0的表达产物 ,免疫印迹表明该产物具有特异的免疫反应性。结论　成功构建了表达马链球菌兽疫亚种中国株类M蛋白片段的重组表达质粒 ,并实现在大肠杆菌中表达 ,为重组类M蛋白亚单位疫苗的研制奠定了基础。     

Refinement of a therapeutic Shiga toxin-binding probiotic for human trials

We have previously constructed a recombinant bacterium expressing a modified lipopolysaccharide (LPS) mimicking the Shiga toxin receptor, which binds toxin with high avidity. This involved cloning Neisseria galactosyl transferase genes (lgtC and lgtE) in pK184 in a derivative of Escherichia coli R1 (CWG308). Such constructs have considerable potential for prevention of disease caused by Shiga toxin-producing E. coli (STEC). However, neither the E. coli host strain nor the expression plasmid is suitable for human use, because the former is derived from a clinical isolate and the latter contains a kanamycin-resistance gene. We have constructed, as a prelude to human trials, a nonpathogenic E. coli K-12 C600 derivative with deletions in waaO and waaB, such that it has the same LPS core structure as CWG308. We also deleted the thyA gene from this strain, rendering it thymine dependent. The kanamycin-resistance gene was also deleted from pK184 and was replaced with Salmonella typhimurium thyA. Neisseria lgtCE was then cloned into this plasmid and transformed into C600 Delta waaOB Delta thyA. The plasmid was stably maintained, and the construct produced a modified LPS and neutralized Stx1 and Stx2c. Moreover, mice challenged with an otherwise fatal dose of STEC were completely protected by oral administration of the novel construct.     

铜绿假单胞菌LexA蛋白在大肠杆菌中的表达与纯化

目的克隆铜绿假单胞菌PAO1株的LexA蛋白编码区，在大肠杆菌中表达并纯化表达蛋白。方法提取铜绿假单胞菌PAO1株基因组DNA，PCR扩增LexA蛋白编码区，A—T克隆于质粒pMD18-T载体中。阳性重组子经酶切后，回收目的片段连接至相应线性化的表达型载体pET-28a（＋）中，重组质粒经测序鉴定后，转化大肠杆菌BL21感受态，筛选高效表达株，表达产物经SDS-PAGE初步鉴定后，用镍珠吸附一步法纯化，表达蛋白转印PVDF膜后，经N-端测序证实。结果本研究成功克隆到PAO1株的LexA蛋白编码区并在大肠杆菌中获得表达，纯化表达蛋白经N-端测序证实确为PAO1的LexA蛋白。结论研究结果为铜绿假单胞菌PAO1株基因组中SOS盒的实验鉴定及LexA蛋白调控基因的筛选奠定了基础。     

Molecular epidemiological study on Escherichia coli O114 by DNA analyses]

Four strains of Escherichia coli O114:non-motile (NM) were isolated from patients supposed to have endemic diarrhea in 1989. The plasmid DNA profiles and restriction fragment patterns of chromosomal DNA digested with Not I analysed by pulsed-field gel electrophoresis (PFGE) of E. coli O114:NM strains were compared with those of other 9 strains of E. coli O114 isolated elsewhere (O114:H2, 1 strain; O114:H4, 2 strains; O114:H9, 2 strains; O114:H10, 1 strain; O114:H11, 1 strain; O114:H21, 1 strain; O114:H32, 1 strain). All of E. coli O114:NM strains showed the same plasmid DNA profile and chromosomal DNA fragment patterns. The strains of E. coli O114:NM and O114:H11, and O114:H21 and O114:H32 showed the same plasmid DNA profiles, respectively. On the other hand, these strains could be differentiated by the chromosomal DNA fingerprint patterns. The chromosomal DNA fragment pattern of all E. coli O114:NM strains is completely different from those of the other 9 control strains. We suggest that chromosomal DNA fingerprinting is useful for the epidemiological study of E. coli O114 associated endemic diarrhea.     

Extension of bacteriophage lambda host range: selection, cloning, and characterization of a constitutive lambda receptor gene.

A set of plasmids has been constructed that carry a constitutive lamB gene (LamBc phenotype) from Escherichia coli and that confer functional phage lambda receptors to bacteria other than E. coli. This E. coli LamBc strain has been selected to escape both maltose-inducible and glucose-repressible control. Constitutivity results from an IS-3 insertion, carrying a mobile promoter, proximal to lamB. The LamBc DNA has been cloned into both broad and narrow host-range plasmids, and the resulting pTROY plasmids have been transferred to diverse bacteria. Both Salmonella typhimurium/pTROY and Klebsiella pneumoniae/pTROY strains efficiently adsorb phage lambda; Pseudomonas aeruginosa/pTROY strains do not. Introduction of a functional E. coli LamB protein into foreign bacterial will allow these bacteria carrying pTROY plasmids to be infected by phage lambda recombinant DNA libraries, phage lambda::Tn insertion mutagenesis vectors, and in vivo lambda-packaged cosmids.     

编码弓形虫表面抗原P30基因的克隆及在E.coli中的表达

目的　构建编码弓形虫RH株表面抗原P30基因重组表达质粒 ,初步观察P30基因在E coli表达。方法　将P30基因定向克隆到分支杆菌 -大肠杆菌穿梭表达质粒热休克蛋白 70 (hsp70 )起动基因的下游的多克隆位点 ,构建重组表达质粒pBCG -P30 ;采用亚克隆技术 ,将含P30和hsp70起动基因的复合片段 ,插入表达载体 pBK -CMV质粒 ,转化大肠杆菌DH5α ,在卡那霉素阳性LB培养基平板筛选阳性重组子 ,并经双酶切及PCR扩增鉴定。重组质粒 pBK -P30转化大肠杆菌 ,IPTG诱导表达后进行SDS -PAGE和Westernboltting分析。 结果　 1)阳性重组质粒 pBCG -P30、pBK -P30经酶切和PCR鉴定 ,与预期的结果相符合。 2 )序列测定证实克隆的基因为编码P30抗原的基因。 3)P30基因在大肠杆菌诱导表达后获得4 5kDa融合蛋白 ,此抗原未被弓形虫高免兔血清识别。结论　成功构建编码弓形虫表面抗原P30重组表达质粒 ,并在大肠杆菌中获得表达 ,为弓形虫DNA疫苗的研制奠定基础     

Development of O-serogroup serodiagnosis for patients with hemolytic uremic syndrome by Ec-LPS array

We extracted lipopolysaccharides from 58 O-serogroup strains of Escherichia coli with phenol-water for use as antigens for an Ec-LPS array. The Ec-LPS array was made by dot-blotting of E. coli LPS on PVDF membrane. Commercial anti-E. coli O-serogroup antisera reacted with homologous O-serogroup LPS in Ec-LPS arrays. Convalescent sera of 6 patients with hemolytic uremic syndrome reacted strongly with O157 LPS when IgM and IgA antibodies in patient sera analyzed by Ec-LPS arrays. When IgG antibody was analyzed in this array, it was difficult to diagnose the O-serogroup because of the reactivity of patient sera against many O-serogroup LPS. These results match those by ELISA and western blotting. Compared to these serological techniques, Ec-LPS array appears superior to ELISA and western blotting in cost performance, time performance, and technical complexity.     

The current status of cholera vaccine development and experience with cholera vaccine trials in volunteers

In recent years notable advances have been made in the development of improved vaccines to prevent cholera. These new vaccines are administered orally to maximally stimulate intestinal secretory immunity. Killed vibrios, given in conjunction with purified B subunit or administered alone, in three spaced doses, caused no adverse reactions and have conferred significant protection in volunteer challenge studies and in field trials. Two attenuated mutants of V. cholerae, prepared by recombinant DNA techniques, CVD 103 and CVD 103-HgR are well-tolerated and elicit prominent immune responses and protective immunity after ingestion of a single oral dose. Other modern approaches being pursued include the development of auxotrophic strains and of modifying attenuated S. typhi strain Ty21a to express V. cholerae Inaba and Ogawa LPS antigens.