幽门螺杆菌相关保护性抗原

幽门螺杆菌(Hp)是人类上消化道疾病的重要致病菌,为慢性胃炎、胃溃疡和十二指肠溃疡的主要病因。1994年国际癌症研究所将Hp认定为第一类致癌因子。幽门螺杆菌疫苗的研究近年来取得了很大的进展,本文对幽门螺杆菌主要保护性抗原的研究及其特征作了概述,并对未来抗原和疫苗的研究方向进行展望。     

幽门螺杆菌疫苗常用抗原的研究进展

幽门螺杆菌(Helicobacter pylori,H.pylori)属于Ⅰ类致癌因子,是慢性胃炎、消化性溃疡、胃癌等的首要病原菌。目前临床疗法存在诸多不足,而疫苗接种被认为是对抗大多数细菌感染的有效手段,也是当前防治H.pylori感染的研究热点,可作为抗生素疗法的补充。目前尚未研发出高效、安全的H.pylori疫苗,选择合适的抗原是研制疫苗成功的重要因素。本文总结了H.pylori疫苗研发领域经典抗原的研究进展,从分泌型毒力蛋白抗原、菌体表面抗原和胞内蛋白抗原三方面作一综述,为H.pylori感染预防的新策略提供更多依据。     

幽门螺杆菌疫苗的研究进展

幽门螺杆菌疫苗是预防和治疗幽门螺杆菌感染引起的上消化道疾病的有效途径。而疫苗的研制是关键和基础。一种好的疫苗完全可结束人与幽门螺杆菌共存的现象。本文综述了幽门螺杆菌疫苗的研究现状及前景。     

幽门螺杆菌疫苗研究进展

幽门螺杆菌由于在人群中具有较高的感染率及被WHO确认为Ⅰ类致癌因子而受到重视,近年来对它的疫苗研究进展迅速,本文对幽门螺杆菌的全菌体疫苗,亚单位疫苗,重组减毒疫苗,微球疫苗及临床实验的情况进行了综述。     

幽门螺杆菌动物模型研究进展

幽门螺杆菌动物模型用于HP相关疾病和HP疫苗作用的研究。常规实验动物包括悉生猪、悉生狗、非人类灵长动物、猫、雪貂、小鼠、大鼠、沙鼠等。猫螺杆菌和雪貂螺杆菌感染也被用于模型研究。最近,转基因小鼠和基因敲除小鼠也被用作幽门螺杆菌动物模型研究。     

改良幽门螺杆菌抗原检测试剂盒检测粪便幽门螺杆菌抗原的临床评价

目的 评估改良幽门螺杆菌抗原检测试剂盒检测粪便幽门螺杆菌抗原（Helicobacter pylori stool antigen,HpSA）的准确性以及临床应用价值。方法 采用随机、双盲、双验证和与13C呼气试验（13C-UBT）对比的方法,对门诊175例接受13C-UBT检测的患者,采用最新研制出的一种改良幽门螺杆菌抗原检测试剂盒（胶体金法）检测粪便幽门螺杆菌抗原,以13C-UBT检测结果为诊断H. pylori感染的“金标准”,并将两者进行对比研究,所有检测结果均拍照存档,采用随机、双盲和双验证法,以期客观真实地评价改良幽门螺杆菌抗原检测试剂盒检测粪便幽门螺杆菌的效果。结果 改良幽门螺杆菌抗原检测试剂盒检测HpSA敏感度为90.48%,特异度为90.00%,Youden指数为80.48%,Kappa值为0.799;HpSA检测ROC曲线下面积为0.902±0.027,与完全无诊断价值的机会线下面积0.50相比,差异有统计学意义（P=0.000）;Spearman相关系数r=0.800,P=0.000。结论 改良幽门螺杆菌抗原检测试剂盒能准确检测H. pylori感染,其操作简便,可作为非侵入性诊断H. pylori感染筛查以及流行病调查的一种方法,将来有望成为患者家庭自查幽门螺杆菌的一种方法     

幽门螺杆菌球状体的研究进展

幽门螺杆菌在体内外各种不利因素的作用下可转变为球状体。该菌球状体是一种有活力但不能培养成活的幽门螺杆菌形态变异体,可能在幽门螺杆菌感染的传播途径及其相关性消化系统疾病的复发中发挥重要作用。本文拟对幽门螺杆菌球状体的诱变因素、超微结合、分子生物学特征、毒力以及与疾病的关系、与原生质球的区别等方面作一综述。     

应用生物信息学方法筛选幽门螺杆菌疫苗候选抗原

目的：应用生物信息学分析方法筛选幽门螺杆菌新的疫苗候选抗原。方法：从TIGRCMR下载幽门螺杆菌26695和J99株全基因组序列,应用生物信息学SignalP、PredTMBB、LipoP、TMHMM、Phobius、PSORT-B和SubLoc等分析软件,筛选幽门螺杆菌新的外膜蛋白和分泌蛋白疫苗候选抗原。结果：从幽门螺杆菌26695株筛选得到54个编码β-桶型跨膜蛋白、脂蛋白或分泌表达蛋白的疫苗候选蛋白抗原,从幽门螺杆菌J99株得到61个呈现上述表达方式的疫苗候选蛋白抗原;且这2株细菌的疫苗候选蛋白呈现良好的交集状况,即有43个候选疫苗蛋白是相同的。结论：用生物信息学分析方法可以从全基因组范围内快速筛选到保守的分泌或表面暴露的疫苗候选抗原,为疫苗抗原的快速筛选与鉴定奠定了基础。     

幽门螺杆菌耐药机制研究进展

幽门螺杆菌耐药是一个全球性问题,由于耐药株的增多,给幽门螺杆菌感染的治疗带来困难,本文就该菌对常用抗生素的耐药机制作一综述。     

Helicobacter pylori stool antigen test in patients with bleeding peptic ulcers

BACKGROUND: Helicobacter pylori has been linked to chronic gastritis, peptic ulcers, gastric cancer and mucosa-associated lymphoid tissue lymphoma. Invasive tests are less sensitive than noninvasive tests in diagnosing H. pylori infection in patients with bleeding peptic ulcers. The H. pylori stool antigen test has been useful in diagnosing H. pylori in patients with peptic ulcers before and after eradication of H. pylori. The aim of this study was to evaluate the H. pylori stool antigen test in patients with bleeding peptic ulcers. METHODS: Patients with bleeding and nonbleeding peptic ulcers underwent a rapid urease test, histology, bacterial culture and H. pylori stool antigen test. Positive H. pylori infection was defined as a positive culture or both a positive histology and a positive rapid urease test. Helicobacter pylori stool antigen was assessed with a commercial kit (Diagnostec H. pylori antigen EIA Kit, Hong Kong). RESULTS: Between October 2000 and April 2002, 93 patients with bleeding peptic ulcers (men/women: 78/15, gastric ulcer/duodenal ulcer: 58/35) and 59 patients with nonbleeding peptic ulcers (men/women: 47/12, gastric ulcer/duodenal ulcer: 30/29) were enrolled in this study. Forty-seven (50.5%) patients with bleeding peptic ulcers and 30 (50.8%) patients with nonbleeding peptic ulcers, were found to be infected with H. pylori (p > .1). Helicobacter pylori stool antigen tests were positive in 54 (58.1%) and 30 (50.8%) patients with bleeding peptic ulcers and nonbleeding peptic ulcers, respectively (p > .1). The sensitivity (82% vs. 93%), specificity (68% vs. 93%), positive predictive value (74% vs. 93%), negative predictive value (77% vs. 93%) and diagnostic accuracy (75% vs. 93%) were all lower in patients with bleeding vs. nonbleeding peptic ulcers. The specificity, positive predictive value, and diagnostic accuracy of the H. pylori stool antigen test in patients with bleeding peptic ulcers were significantly lower than those in patients with nonbleeding peptic ulcers (p = .01, p = .02 and p = .003, respectively). CONCLUSION: The H. pylori stool antigen test is not reliable for diagnosing H. pylori infection in patients with bleeding peptic ulcers.     

Protection against Helicobacter pylori infection by intestinal immunisation with a 50/52-kDa subunit protein

A mouse model of Helicobacter pylori infection was used to evaluate the vaccine antigen potential of the citrate synthase homologue protein purified from the H. pylori NCTC 11637 strain. Mice were immunised with the protein by intra-Peyer's patch immunisation. This route gives maximal intestinal immunisation and was used to screen oral vaccine candidate antigens without the added complication of simultaneously testing oral delivery systems. Two weeks post-immunisation mice were infected with Sydney strain H. pylori and 4 weeks after infection the mice were killed and the level of H. pylori infection in the stomach determined. Pre-immunisation with the 50/52-kDa protein led to a 84-91% reduction in H. pylori infection compared to unimmunised controls.     

Comparison of stool antigen immunoassay and serology for screening for Helicobacter pylori infection in intellectually disabled children

Diagnosis of active Helicobacter pylori infection in intellectually disabled (ID) children is problematic because they are unable to cooperate with performance of invasive tests. In this study, the non‐invasive methods of measuring serum IgG antibody concentrations and performing stool antigen tests were used to screen for H. pylori infection in ID children. Eighty‐seven children with intellectual disabilities were studied. The amount of serum IgG antibody against H. pylori was measured by the ELISA method. Stool samples were examined using an amplified IDEIA HpStAR kit. To assess categorical variables, X², Fisher's exact and Kappa tests were used. The stool antigen tests showed that 93.1% of the children had H. pylori antigen and the serology test that 85.1% of children were positive for H. pylori IgG antibodies. Agreement between results of H. pylori stool antigen (HpSA) testing and IgG antibody serology was 82.8%; however, according to the kappa measure of agreement this agreement is not statistically significant (value, 0.128; P = 0.19). Discordant results were observed for 15 children (17.2%): 11 (12.6%) who were positive on HpSA test but negative by serology and 4 (4.6%) who were IgG seropositive but had negative HpSA tests. This study showed a notably higher rate of H. pylori infection in ID children than has been reported by others for non‐ID children from the same geographical area. The HpSA test is a valid method for primary screening for H. pylori infection in ID children; it detects the specific antigens shed during active infections and has less cross‐reactivity than serological tests that detect antibodies. HpSA is a sensitive non‐invasive method for detecting infection in ID children and may serve as an accurate alternative to serology.     

Effectiveness of vaccination with recombinant HpaA from Helicobacter pylori is influenced by host genetic background

Several studies have explored the production and immunogenicity of HpaA as a potential protective antigen against Helicobacter pylori but little is known regarding its protective capabilities. We therefore evaluated the protective efficacy of recombinant HpaA (rHpaA) as a candidate vaccine antigen against H. pylori. To explore the impact of genetic diversity, inbred and outbred mice were prophylactically and therapeutically immunized with rHpaA adjuvanted with cholera toxin (CT). Prophylactic immunization induced a reduction in bacterial colonization in BALB/c and QS mice, but was ineffective in C57BL/6 mice, despite induction of antigen-specific antibodies. By contrast, therapeutic immunization was effective in all three strains of mice. Prophylactic immunization with CT-adjuvanted rHpaA was more effective when delivered via the nasal route than following intragastric delivery in BALB/c mice. However, HpaA-mediated protection was inferior to that induced by bacterial lysate. Hence, protective efficacy is inducible with vaccines containing HpaA, most relevantly shown in an outbred population of mice. The effectiveness of protection induced by HpaA antigen was influenced by host genetics and was less effective than lysate. HpaA therefore has potential for the development of effective immunization against H. pylori but this would probably entail the antigen to be one component of a multiantigenic vaccine.     

Comparison of two different stool antigen tests for the primary diagnosis of Helicobacter pylori infection in turkish patients with dyspepsia

AIM: To assess the reliability of two different enzyme immunoassays in detecting the Helicobacter pylori status in stool specimens of Turkish patients with dyspepsia. MATERIALS AND METHODS: One hundred and fifty-one patients [74 with nonulcer dyspepsia (NUD), 64 with duodenal ulcer (DU) and 13 with gastric cancer] who were admitted to the endoscopy unit of Istanbul University, Cerrahpasa Medical Faculty for upper gastrointestinal endoscopy because of dyspepsia were enrolled in the study. Helicobacter pylori infection was confirmed in all patients by histology, rapid urease test and culture. A patient was classified as being H. pylori-positive if the culture alone or both the histology and the rapid urease test were positive and as negative only if all of these tests remained negative. Stool samples were obtained from patients to assess the reliability of a monoclonal (FemtoLab H. pylori) and a polyclonal (Premier Platinum HpSA) stool antigen test and to compare the diagnostic accuracies of these two tests. A chi2 test was used for statistical comparisons. RESULTS: Using cut-off values of 0.19 for FemtoLab H. pylori and 0.16 for Premier Platinum HpSA, the sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy were 93%, 90%, 98%, 68% and 93% for the monoclonal test and 84%, 67%, 94%, 40% and 81% for the polyclonal test, respectively. The sensitivity, specificity, negative predictive value and diagnostic accuracy of the monoclonal test were significantly greater than those of the polyclonal test (chi2 = 3.98; p < .05 for sensitivity and chi2 = 15.67; p = .000 for specificity, chi2 = 15.78; p = .000 for negative predictive value and chi2 = 6.37; p = .012 for diagnostic accuracy). The bacterial load did not affect the sensitivity of either test. CONCLUSIONS: The monoclonal FemtoLab H pylori test, using a cut-off 0.19, is a very sensitive, specific and easy to perform diagnostic tool for the primary diagnosis of H. pylori infection in Turkish patients with dyspepsia.     

Helicobacter pylori flagella: antigenic profile and protective immunity

Reproducible induction of sterilizing immunity, essential for an effective Helicobacter pylori vaccine, remains elusive. As motility is essential for gastric colonization by Helicobacter, we evaluated whether a vaccine targeting flagella induces improved protection. Mice immunized with a vaccine enriched for H. pylori flagella sheath proteins exhibited significantly reduced colonization, equivalent to that observed in mice immunized with whole-cell lysate. Two-dimensional profiles indicated that flagella contain proteins not evident in whole-cell lysate. Moreover, comparison of Western blot profiles using whole-cell lysate antisera revealed striking differences in antigenicity.     

Potential antigen candidates for subunit vaccine development against Helicobacter pylori infection

Helicobacter pylori (H. pylori) is a resident bacterium in the stomach that accounts for 75% cases of gastric cancer. In this review, we comprehensively studied published papers on H. pylori vaccines using Google Scholar and NCBI databases to gather information about vaccines against H. pylori. Considering the pivotal roles of the enzyme urease (in production of NH₃ and neutralization of the acidic medium of the stomach), cytotoxin-associated gene A, and vacuolating cytotoxin A proteins in H. pylori infection, they could be the best candidates for the construction of recombinant vaccines. The outer membrane porins (Hop), blood group antigen-binding adhesin (BabA), sialic acid-binding adhesin (SabA), and outer inflammatory protein A, play significant roles in binding of bacterium to human gastric tissues, and because binding is the first step in bacterial fixation and colonization, these antigens also can be considered as suitable candidates for designing vaccines. Likely, other significant bacterial antigens, such as NapA (chemotactic factor for recruitment of human neutrophils and monocytes to the site of infection), duodenal ulcer promoting protein A (to promote duodenal ulcer), and Hsp60 (as a molecular chaperon for activation of urease enzyme), can be used in the construction of subunit vaccines. New vaccines in use currently, such as DNA vaccines and subunit vaccines, can efficiently replace the dead and attenuated vaccines. Nonetheless, the results show that urease enzyme is most used compared with bacterial components in the designing and construction of recombinant vaccines. The BabA and SabA antigens belong to the outer membrane porins family in H. pylori and are required for binding and fixation of the bacterium to the human gastric tissues.