无细胞百日咳疫苗全球孕期接种的现状

近年来百日咳(pertussis)再现引起了广泛关注,其中婴幼儿是主要的高风险群体,感染后可导致严重后果。孕期接种无细胞百日咳疫苗被认为是预防婴幼儿感染百日咳最经济有效的办法,其安全性已得到充分认可。有些国家已将其纳入免疫规划,但在中国目前仍未实施。迄今为止无细胞百日咳疫苗的最佳孕期接种时间及孕期接种是否会影响婴儿主动免疫应答仍需进一步研究并加以明确。现就无细胞百日咳疫苗(acellular pertussis vaccine, aPV)全球孕期接种的现状作一概述。     

百日咳免疫保护相关机制及评价指标的研究进展

百日咳是目前世界上普遍采用疫苗可进行免疫预防策略的疾病之一。近十年来包括中国在内的许多国家出现的百日咳发病率上升的现象已引起了全球极大关注。其主要原因可能与疫苗接种尤其是无细胞百日咳疫苗(acellular pertussis vaccine, APV)诱导产生的免疫力不断衰减有关。血清中的抗百日咳毒素特异性IgG抗体检测是最重要的免疫力评价方法之一,但到目前为止,感染百日咳菌或接种百日咳疫苗后的免疫力保护相关机制及评价指标尚无统一的标准。现就国内外百日咳相关研究进展作一概述。     

百日咳呼吸道感染模型的研究进展

百日咳呼吸道感染模型是研究百日咳鲍特菌(Bordetella pertussis)致病机制及百日咳疫苗评价的重要手段。人是百日咳鲍特菌的唯一自然宿主,由于受伦理学限制及志愿者重症感染等风险,使人百日咳呼吸道感染模型研究受限。近年来,百日咳呼吸道感染动物模型取得了明显进展。目前,应用于百日咳研究的动物模型主要包括小鼠、小型猪和狒狒等。现就百日咳呼吸道感染模型在百日咳疫苗临床前研究及有效性评价的进展作一概述。     

溶液环境对百日咳疫苗分离纯化的影响

针对百日咳疫苗在低盐条件下不稳定, 容易聚集而导致层析过程收率低、分离度低的难题, 实验中选择脲作为稳定剂来改善百日咳疫苗所处的溶液环境, 并采用离子交换层析和凝胶过滤层析进行百日咳疫苗的分离纯化, 通过ELISA抗原活性测定和还原性SDS-PAGE等方法研究了脲对百日咳疫苗分离纯化的影响。结果表明, 在流动相中加入 2 mol/L脲作为稳定剂, 能显著提高离子交换层析和凝胶过滤层析中的PT和FHA活性回收率、凝胶过滤层析的分离度、PT和FHA的纯度。这些结果对百日咳疫苗的分离纯化和层析工艺优化提供了重要的依据和参考。     

婴幼儿及学龄前儿童百日咳初免对4岁儿童记忆B细胞免疫应答的影响

<正>由博特百日咳杆菌引起的百日咳疾病在接种过百日咳疫苗的人群中再度发生。接种了全细胞百日咳疫苗(wP)和无细胞百日咳疫苗(aP)之后机体内百日咳抗体会迅速衰退,免疫力则主要来自于B细胞和T细胞的长期保护。荷兰根据计划免疫程序,给2、3、4和11月龄的婴幼儿分别接种wP和aP,4     

第二代百日咳疫苗毒性国家标准品的建立

目的建立第二代百日咳疫苗毒性国家标准品(简称二代毒性标准品)。方法选用百日咳疫苗生产菌株(编号CS株CMCC58003)进行发酵罐培养,将收获的百日咳菌液灭活后分装冻干后,作为第二代百日咳国家毒性标准品的候选品(简称候选毒性标准品)。以第一代百日咳疫苗毒性国家标准品为标准(简称一代毒性标准品),由4个单位协作标定候选毒性标准品,采用热加速法考察候选毒性标准品的稳定性。结果共获得检定合格的候选毒性标准品1 800支;经4个实验室协作标定,每支二代毒性标准品LPU为21,HSU为41;且稳定性良好。结论候选毒性标准品各项指标均符合要求,可作为第二代百日咳疫苗毒性国家标准品使用。     

056全球百日咳协作组推荐的新百日咳疫苗接种方案

百日咳是由百日咳鲍特菌感染引起的急性呼吸道传染病，呈现地方性特征。在未免疫接种和免疫接种不彻底的地区，百日咳仍是严重威胁幼儿的疾病。全球百日咳协作组（The Global Pertussis Initiative，GPI）是一个科学论坛，其目的是通过百日咳疫苗的接种加强对疾病的控制以及为其他百日咳相关研究提供建议。该协作组的主要研究内容是：百日咳病的流行病学、诊断、预防和治疗及其带来的卫生经济负担；     

美国用基因操作改进百日咳疫苗

美国国立卫生研究所(NIH)的Camille L.和Jerry M.K.鉴定了百日咳毒素基因的克隆和碱基序列。这一结果向开发安全的百日咳疫苗迈进了重要的一步。详文请参考“Science”第232卷1258—1259页。百日咳毒素是由百日咳病原菌百日咳博德特氏菌(Bordatclla pcrtussis)产生的。给儿童注射百日咳疫苗之所以常有副作用,推测其原因就是此毒素引起的。     

无细胞百日咳疫苗的质量控制及其标准化

无细胞百日咳疫苗在全世界范围内已逐渐用于婴幼儿的计划免疫和加强注射中,但到目前为止没有完全令人满意的效力试验方法。小鼠保护试验不适合对无细胞百日咳疫苗进行效力评估,免疫原性试验在衡量制品一致性方面是有用的,但与临床保护之间缺乏相关性,最近建立的气雾攻击主动保护试验为功能性效力试验开创了美好的前景。用生物学结合物理化学方法对疫苗抗原含量,纯度,安全性和免疫原性的研究,对新开发的尚无有效效力试验方法的同类疫苗质量控制及标准化问题提供了指导。     

一株减毒百日咳鲍特菌的构建及生物学特性分析

百日咳是传染性强、感染率高的急性呼吸道传染病,主要感染婴幼儿,是婴儿死亡的主要原因之一。百日咳鲍特菌（Bordetella pertussis）是引起百日咳的最主要病原菌。近年来世界各地多次出现百日咳暴发,迫切需研制更加有效的新型百日咳疫苗。本研究构建了一株减毒百日咳活疫苗BPTM1,利用同源重组方法敲除编码百日咳鲍特菌主要毒力因子百日咳毒素（pertussis toxin,PTX）和皮肤坏死毒素（dermonecrotic toxin,DNT）的基因,并用大肠埃希菌的同源基因置换了负责气管细胞毒素（tracheal cytotoxin,TCT）转运的基因ampG。通过聚合酶链反应验证了毒素及相关基因的敲除和置换,蛋白免疫印迹法检测表明PTX的S1亚基未表达。体外生长曲线和体内定植曲线均表明,相比于野生型百日咳鲍特菌BPMM,减毒BPTM1的生长和定植能力未受影响,其所致肺部病理效应减轻,而所诱导的百日咳鲍特菌特异性IgG、IgG1、IgG2a抗体保持高水平。本研究表明,减毒百日咳鲍特菌BPTM1有可能成为百日咳疫苗的候选疫苗。     

Specificity and detection limit of a dermal temperature histamine sensitization test for absence of residual pertussis toxin in vaccines

Currently, an assay based on fatal sensitization of mice to histamine challenge is widely used for testing absence of residual pertussis toxin in acellular pertussis containing vaccines. For replacement of this lethal end-point assay, an alternative method based on body temperature measurement in mice has been presented, and in this study the specificity and detection limit of a dermal temperature-based assay were assessed. Test preparations containing pertussis toxin were prepared in aluminum-adjuvanted pertussis toxoid vaccine and injected intraperitoneally in histamine sensitive mice. Later the mice were challenged with histamine and the pertussis toxin-induced decrease in dermal temperature recorded. By comparison of mice treated with pertussis toxoid vaccine spiked with pertussis toxin with mice treated with pertussis toxoid vaccine alone, the assay gave a response that specifically could detect presence of pertussis toxin. The acellular pertussis containing vaccine did not interfere with the pertussis toxin-induced temperature response recorded. In tests for presence of pertussis toxin in the pertussis vaccine preparation, the detection limit of the assay was estimated to approximately 5 ng pertussis toxin per human dose of pertussis toxoid. The dermal temperature-based assay was found to be a valid method to be applied in routine quality control of vaccines.     

An international collaborative study of the effect of active pertussis toxin on the modified Kendrick test for acellular pertussis vaccines

Speculation that the Japanese modified intra-cerebral challenge assay, which is used in several countries for control of acellular pertussis vaccines, depends on the presence of small amounts of active pertussis toxin led to an assumption that it may not be appropriate for highly toxoided or genetically detoxified vaccines. Consequently, at the recommendation of a World Health Organisation AD Hoc Working Group on mouse protection models for testing and control of acellular pertussis vaccine, the effect of pertussis toxin on the modified intra-cerebral challenge assay (modified Kendrick, MICA) was evaluated in an international collaborative study. Results of this study showed that for genetically detoxified vaccines both with and without active pertussis toxin the MICA clearly distinguished mice vaccinated with acellular vaccines from unvaccinated mice and gave a significant dose–response relationship. However, vaccine samples containing active pertussis toxin (5 or 50 ng/single human dose) appeared to be more potent than the equivalent sample without active pertussis toxin. Similar results were also given by two respiratory infection models (intranasal and aerosol) included in the study. The results also indicated that the effect of pertussis toxin may vary depending on mouse strain.     

Importance of the degree of antigen polymerization by detoxification in modulating the immunogenicity of acellular pertussis vaccine

For the acellular pertussis vaccine with a high immunogenicity, the concentration, composition and characteristics of acellular pertussis antigens are the crucial points to be considered. Nevertheless, it has not been proved yet whether or not the polymerization degree, one of the characteristics of formalin-detoxified acellular pertussis antigens, has an influence on vaccine potency. Thus, in the present study, the correlations among detoxification conditions of acellular pertussis bulks, their polymerization degrees and their immunogenicities were examined. In addition, the relative importance of pertussis toxoid in vaccine immunogenicity was also investigated. Results show that a lower lysine concentration during detoxification induces highly-polymerized antigens, the immunogenicity has a great dependency on the polymerization degree of antigens, and also pertussis toxoid has a relatively stronger influence on the immunogenicity than other antigens. Accordingly, in the aspect of the potency of detoxified acellular pertussis vaccine, it can be demonstrated that the polymerization of antigens and its degree are the major factors affecting the immunogenicity along with a relatively high content of pertussis toxoid.     

百日咳、白喉、破伤风、乙型肝炎联合疫苗的实验研究

对制备无细胞百日咳菌苗、白喉、破伤风、乙型肝炎联合疫苗的实验室条件进行了初步探索,实验结果表明,联合疫苗的配方以每毫升无细胞百日咳组分１５－１８μｇ．ＰＮ、白喉类毒素３０ｌｆ、破伤风类毒素７－１０ｌｆ和基因工程乙肝表面抗原２０μｇ为宜,稀释缓冲液选用０．８５％ＮａＣｌ溶液吸附效果较好,动物实验证明联合疫苗中各组分均安全有效。     

百日咳杆菌69KDa外膜蛋白的分离纯化及生物学特性研究

本文发展了一种从百日咳杆菌Ⅰ相菌株中纯化６９ＫＤａ外膜蛋白的简易方法,将细菌体经加热浸提、乙醇沉淀蛋白、ＤＥＡＥ－Ｓｅｐｈａｄｅｘ Ａ５０柱层析精制而成。用ＳＤＳ－ＰＡＧＥ、免疫印迹、光密度仪扫描分析,证明纯化制剂为均一的、特异性的６９ＫＤａ外膜蛋白,其收率为５４．２％,纯度达９９．２％,每微克６９ＫＤａ蛋白制剂中的内毒素含量低于０．８５ＥＵ;ＰＴ残留量小于０．１０５ｎｇ。抗６９ＫＤａ蛋白抗血清能     

The Bordetella type III secretion system: its application to vaccine development

B. pertussis is a causative agent of whooping cough (pertussis) in humans. Despite wide-scale vaccination in many countries, there is serious concern about pertussis as a re-emerging disease. Re-emergence of pertussis may be explained by several factors: the short duration of protection by the currently available acellular pertussis vaccine, an increase in asymptomatic adult carriers and expansion of strains with certain antigenic variations which are not covered by currently available vaccines. To develop safer and more efficacious vaccines which confer more prolonged protection, researchers are focusing on identification and characterization of new virulence factors. One candidate for protective antigens is the type III secretion system and its secreted proteins.     

Protective effects of in vivo‐expressed autotransporters against Bordetella pertussis infection

Bordetella pertussis causes whooping cough, a severe and prolonged respiratory disease that results inhas high morbidity and mortality rates, particularly in developing countries. The number incidence of whooping cough cases is increasing in many countries despite high vaccine coverage. Causes for the re‐emergence of the disease include the limited duration of protection conferred by the acellular pertussis vaccines (aP)s and pathogenic adaptations that involve antigenic divergence from vaccine strains. Therefore, current vaccines therefore need to be improved. In the present study, we focused on five autotransporters: namely SphB1, BatB, SphB2, Phg, and Vag8, which were previously found to be expressed by B. bronchiseptica during the course of infection in rats and examined their protective efficiencies as vaccine antigens. The passenger domains of these proteins were produced in recombinant forms and used as antigens. An intranasal murine challenge assay showed that immunization with a mixture of SphB1 and Vag8 (SV) significantly reduced bacterial load in the lower respiratory tract and a combination of aP and SV acts synergistically in effects of conferring protection against B. pertussis infection, implying that these antigens have potential as components to for improvinge th the currently available acellular pertussis vaccine.

     

Consistency of Bordetella pertussis vaccine seed strains and potency of whole-cell pertussis vaccine still in use in Poland

In Poland, where the wP vaccine has been used since 1960, pertussis rates increased in the mid-1990s. In 2012, the rate of pertussis recognised by surveillance was unexpectedly found to be two-fold higher than in the previous decade. Quality measures on potency and vaccine working seeds were introduced, to confirm the possible impact of manufacturing inconsistency or potency lowering on the observed increase in pertussis. Shewhart charts on potency values for lots released between 2001 and 2013 did not reveal any significant fluctuations. Working seeds of three vaccine strains used within last decade for wP manufacturing belong to the PFGE group III and were highly related. According to PFGE and SDS-PAGE data, all vaccine strains were found consistent according profiling on the genomic and protein levels. According to the sequencing data, they harboured ptxA2, ptxC1, prn1, fim2-1, fim3-1, tcfA2, ptxP1 and were assigned as MLST-2 type. Other factors apart from vaccine manufacturing inconsistency might be responsible for the increase in pertussis noted in 2012 in Poland.     

Evaluation of Fourth International Standard for Whole Cell Pertussis Vaccine

Whole cell pertussis vaccine is still widely used in many countries. An International Standard is needed for its potency control. The Third International Standard for Pertussis Vaccine was prepared about 40 years ago and its replacement was recommended by the Expert Committee for Biological Standardisation (ECBS) of the WHO. Material in ampoules coded 94/532 was prepared as a candidate replacement and has been evaluated in international collaborative studies which consisted of two parts. The first part, to assess the suitability of the candidate standard by comparing it with the Second International Standard for Pertussis Vaccine (IS2) involved 14 laboratories in 11 countries. The second part to compare the candidate standard with the Third International Standard for Pertussis Vaccine (IS3) involved 16 laboratories in 14 countries. Since 1995 various other studies have included the international standards and the results of these are also considered in assessing likely continuity of the IU for potency of whole cell pertussis vaccine. The preparation in ampoules coded 94/532 was adopted by the WHO ECBS in October 2006 as the 4th International Standard for whole cell pertussis vaccine and assigned an activity of 40 IU per ampoule on the basis of the studies reported here.     

不同减毒方法对无细胞百日咳菌苗减毒效果的比较研究

采用５种不同的化学减毒方法对无细胞百日咳菌苗的ＰＴ组分减毒效果进行了比较研究,选择出对菌苗的抗原性破坏小、减毒效果确切、减毒时不产生变性蛋白凝块的改进的甲醛减毒方法。