Tuberculosis vaccines: current status and future prospects

There is an urgent need to develop more effective tuberculosis vaccines as chemotherapy and Bacille Calmette-Guérin (BCG) have failed to control the current epidemic. BCG does have some protective effect in childhood, so using a second vaccine to boost BCG would be the most ethical and logistically feasible strategy. The cost of tuberculosis efficacy trials will be high and return on investment into the development of a tuberculosis vaccine will be low. Incentives such as orphan drug status could encourage industrial interest. As more vaccines enter into early clinical trials, there is an urgent need for the identification of correlates of protection to aid decisions about which vaccines should go forward into efficacy testing. Research efforts that focus on reducing the cost and risk of conducting clinical trials will be of direct benefit to tuberculosis vaccine development.     

Tuberculosis vaccines: progress and challenges

An effective tuberculosis (TB) vaccine could have a significant impact on the current TB pandemic. The past decade has seen sustained global investment into reaching this goal; currently there are several promising vaccines in clinical trials. Current strategies include the development of an improved bacille Calmette-Guerin (BCG) vaccine to be given at birth and a booster vaccine to be administered after BCG. Here, we describe the current vaccination strategy and review the main issues in novel TB vaccine development. Potential vaccine candidates are evaluated in pre-clinical animal models, and the most promising go into clinical testing; a vaccine candidate is evaluated in at least one model before progressing to early clinical trials. The main challenge in early trials is the lack of a defined correlate of vaccine-induced immune protection. Following this, large efficacy trials are undertaken, which face the daunting challenges of cost, logistics and trial site capacity.     

mpt64-卡介苗重组疫苗对结核病预防作用的研究

目的评价mpt64-卡介苗重组疫苗对结核病预防效果。方法观察mpt64-卡介苗重组疫苗对结核分支杆菌感染的预防试验中实验动物半数死亡时间、一定时间内的死亡率、大体病变、T细胞及B细胞免疫功能等指标评价mpt64-卡介苗重组疫苗对结核分支杆菌的预防效果。结果用mpt64-卡介苗重组疫苗对分支杆菌感染进行预防,mpt64-卡介苗重组疫苗组及卡介苗组与生理盐水对照组比较都能延长结核分支杆菌感染小鼠的半数死亡时间,降低2个月的死亡率。结核分支杆菌攻击后2个月,处死小鼠时,mpt64-卡介苗重组疫苗组小鼠脏器与其他各组之间差异无统计学意义。各组小鼠脏器研磨、消化后稀释为不同梯度进行培养,mpt64-卡介苗重组疫苗小鼠肺结核分支杆菌生长的最低稀释度主要集中在10-5,肝、脾结核分支杆菌生长的最低稀释度主要集中在10-4。抗体检测结果及淋巴细胞增殖实验各组间差异无统计学意义。结论初步实验表明:mpt64-卡介苗重组疫苗对结核分支杆菌感染的预防作用与卡介苗差异无统计学意义。     

结核病疫苗研究进展

目前结核病疫情非常严峻,而唯一可用的疫苗卡介苗效果并不理想.因此,需要研发更安全有效和实用价廉的新型疫苗.此文综述了目前正在研发的新型结核病疫苗的研究进展,这些疫苗包括重组卡介苗、减毒活疫苗、亚单位疫苗、DNA疫苗和病毒载体疫苗.     

BCG新应用研究进展

近年来人们围绕BCG开展了新应用研究.此文对重组BCG抗结核病、抗寄生虫病和抗肿瘤,BCG多糖核酸与临床药物联合应用以及BCG作为佐剂的研究进展做一综述.     

乙型肝炎卡介苗联合疫苗的制备

在常规制备乙型肝炎疫苗和卡介苗技术基础上制备联合疫苗,建立了联合疫苗制备及冻干工艺,对冻干工艺的稳定性及其对抗原的影响进行了研究,采用动物实验进行免疫效果比较、安全性、局部毒性、过敏试验。结果表明冻干对两种抗原无影响;两种抗原具有良好的相容性;联合疫苗与同批卡介苗相比,效力无显著性差异(P>0.05);联合疫苗组与同批乙肝疫苗组全程免疫相比,统计学无显著性差异(P>0.05);安全性试验联合疫苗组与卡介苗组反应一致,均未见结核性病变。联合疫苗组与卡介苗组病变性质和病理演变过程相似,HBsAg并不增强卡介苗引起的炎症反应;未见全身过敏反应。连续9批成品检定全部合格,证明冻干工艺稳定,技术可行。     

结核病疫苗研发面临的挑战

结核病（tuberculosis ,TB）是由结核杆菌（Mycobacterium tuberculosis ,M tb）引起的传染病,每年有近1000万例 TB 新发病例,150万人死于 TB 。卡介苗是唯一能够为婴幼儿提供保护作用的疫苗,但它却不能预防成年人 TB 以及控制 TB 流行。随着耐多药 TB 的播散和 M tb／HIV 双重感染人数的不断上升,在世界范围内控制 TB 的形势变得愈发严峻。新疫苗的研发是 TB 防治的重要内容之一,目前全世界已有至少15种 TB 候选疫苗进入临床试验。此外,适宜的动物模型也将对新型疫苗研发以及宿主抗 TB 免疫机制研究起重要作用。     

Doctor Albert Calmette 1863-1933: founder of antivenomous serotherapy and of antituberculous BCG vaccination.

In 1891 in Saigon (now Ho Chi Minh City), Dr. Albert Calmette established the first daughter Pasteur Institute for the protection of the local population against rabies and smallpox. Inspired by the discovery of diphtheria antitoxin by Behring, Calmette studied ways of raising serum against cobra venom. In 1895, now in Lille at the second daughter institute that he established, Calmette produced anticobra serum for therapeutic use that was to revolutionize the treatment of snakebite worldwide. The incidence of tuberculosis in the working class of the industrial north shocked Calmette. In response, firstly he organized an antituberculous dispensary to provide assistance to the sick and help limit the spread of the disease by improving social hygiene and secondly he devoted himself, with the assistance of Camille Guérin, to obtaining an attenuated live strain of tubercle bacilli with fixed biological characteristics for use as a vaccine. Such a strain developed during repeated passage of a culture of Mycobacterium bovis grown on a bile potato medium. In 1919, Dr. Albert Calmette took up the appointment of Sub-Director of the Pasteur Institute of Paris. Prolonged trials of BCG (Bacille Calmette-Guérin) vaccine showed it to be safe and vaccination of very young infants born of tuberculous mothers commenced in 1921. The use of BCG vaccine as a prophylactic against tuberculosis spread world-wide and has remained important in combatting this scourge.     

卡介苗抗肿瘤治疗研究进展

卡介苗（Bacillus Calmette-Guerin,BCG）是用牛型结核分枝杆菌培育而成的减毒活疫苗,广泛用于结核病预防。近年来研究发现,BCG具有抗肿瘤活性,可作为膀胱癌、黑素瘤、肺癌、肾癌等恶性肿瘤的治疗制剂。此文就BCG抗肿廇治疗的作用机制和应用作一综述。     

结核病疫苗研究新进展

摘 要 本文综述了近年结核病疫苗的研究进展,涵盖了BCG相关研究、基因（DNA）疫苗、亚单位疫苗、全菌体灭活疫苗与减毒活疫苗、活载体疫苗等,重点讲述了一些具有应用前景的微卡、AdHu5等有望应用于结核病防治领域结核病疫苗。     

卡介苗各亚株间Rv1985c和Rv1986基因缺失的研究

目的明确卡介苗群体内在Rv1985c和Rv1986两个位点上的遗传差异。方法基于结核分枝杆菌设计引物,针对21株卡介苗标准株和临床株进行Rv1985c和Rv1986两个位点的PCR鉴定,鉴定基因的缺失情况。结果 21株卡介苗中10株缺失Rv1985c基因,11株缺失Rv1986基因。结论卡介苗中部分菌株中两个基因位点的缺失,为今后的疫苗改造提供了备选位点,同时本研究中所建立的PCR方法也可以在临床上用于部分卡介苗菌株与结核分枝杆菌的快速鉴别。     

Tuberculosis vaccines: current progress

Tuberculosis continues to be a major cause of disease and death throughout the developing world. Chemotherapy is the current method of control but with the continuing emergence of drug resistance, coupled with the reticence of major drug companies to invest in drug discovery, the identification of new vaccines to combat tuberculosis is a pressing need. Rational vaccine design requires knowledge of the protective immune response and, while this is not fully understood, it is clear that induction of a T-helper-1 type of immunity is critical to host resistance. A variety of animal models, but especially the mouse and guinea pig, can be used to determine the protective efficacy of new vaccines. These mostly consist of relatively short-term prophylactic models in which animals are vaccinated and then challenged by the aerosol infection route to determine their capacity to reduce the lung bacterial load. Several promising vaccine types have emerged, including subunit vaccines, DNA vaccines and vaccines based upon living vectors, such as recombinant bacillus Calmette-Guérin (BCG) vaccines and auxotrophic or gene disrupted mutants of Mycobacterium tuberculosis. A few of these have already entered early stage clinical trials.     

BCG-loaded chitosan microparticles: interaction with macrophages and preliminary in vivo studies

The aim of this study was to develop a novel BCG-loaded chitosan vaccine with high association efficiency which can afford efficient interaction with APC and elicit local and Th1-type-specific immune response after intranasal administration. Chitosan-suspended BCG and BCG-loaded chitosan-alginate microparticles were prepared by ionotropic gelation. Interaction with APC was evaluated by fluorescence microscopy using rBCG-GFP. Specific immune responses were evaluated following intranasal immunisation of mice. Cellular uptake was approximately two-fold higher for chitosan-suspended BCG. A single dose of BCG-loaded microparticles or chitosan-suspended BCG by intranasal route improved Th1-type response compared with subcutaneous BCG. Chitosan-suspended BCG originated the highest mucosal response in the lungs by intranasal route. These positive results indicate that the proposed approach of whole live BCG microencapsulation in chitosan-alginate for intranasal immunisation was successful in allowing efficient interaction with APC, while improving the cellular immune response, which is of interest for local immunisation against tuberculosis.     

Biotechnology in the development of new vaccines and diagnostic reagents against tuberculosis

Tuberculosis (TB) is a disease of global concern. About one third of the world population is infected with Mycobacterium tuberculosis. Every year, approximately 8 million people get the disease and 2 million die of TB. The currently available vaccine against TB is the attenuated strain of Mycobacterium bovis, Bacillus Calmette Guerin (BCG), which has failed to provide consistent protection in different parts of the world. The commonly used diagnostic reagent for TB is the purified protein derivative (PPD) of M. tuberculosis, which is nonspecific because of the presence of antigens crossreactive with BCG and environmental mycobacteria. Thus there is a need to identify M. tuberculosis antigens as candidates for new protective vaccines and specific diagnostic reagents against TB. By using the techniques of recombinant DNA, synthetic peptides, antigen-specific antibodies and T cells etc., several major antigens of M. tuberculosis have been identified, e.g. heat shock protein (hsp)60, hsp70, Ag85, ESAT-6 and CFP10 etc. These antigens have shown promise as new candidate vaccines and/or diagnostic reagents against TB. In addition, recent comparisons of the genome sequence of M. tuberculosis with BCG and other mycobacteria have unraveled M. tuberculosis specific regions and genes. Expression and immunological evaluation of these regions and genes can potentially identify most of the antigens of M. tuberculosis important for developing new vaccines and specific diagnostic reagents against TB. Moreover, advances in identification of proper adjuvant and delivery systems can potentially overcome the problem of poor immunogenicity/short-lived immunity associated with protein and peptide based vaccines. In conclusion, the advances in biotechnology are contributing significantly in the process of developing new protective vaccines and diagnostic reagents against TB.     

Comparative genomics in the fight against tuberculosis: diagnostics,epidemiology, and BCG vaccination

Although the causative agent of tuberculosis, Mycobacterium tuberculosis, has been known for some 120 years, the disease continues to plague humanity. In 1998, the sequencing of M. tuberculosis H37Rv enabled tuberculosis researchers to draw comparisons between it and other species of the closely-related M. tuberculosis complex, including bacillus Calmette-Guerin (BCG), the vaccine administered to prevent human tuberculosis. These efforts have uncovered genomic variability that potentially encodes the discrepant phenotypes displayed by species. Due to the infrequency of single nucleotide polymorphisms (SNPs) and other modes of genomic change, large sequence polymorphisms (LSPs) have presented themselves as the most obvious form of genomic variability among species. This review discusses genomic polymorphism among species of the M. tuberculosis complex as revealed through comparative genomics. Attention is drawn towards the impact of comparative genomics in generating several exciting hypotheses towards diagnosis, epidemiology, and prevention of tuberculosis disease.     

Drug treatment for tuberculosis during pregnancy: safety considerations.

Untreated tuberculosis in pregnancy poses a significant threat to the mother, fetus and family. Adherence to treatment is especially difficult in pregnancy because of the general fear of any medication and pregnancy-related nausea. Supervised treatment is especially helpful in encouraging adherence. All 4 first line drugs [isoniazid, rifampicin (rifampin), ethambutol and pyrazinamide] have an excellent safety record in pregnancy and are not associated with human fetal malformations. Drug-induced hepatitis, especially with isoniazid, is a significant problem in treating tuberculosis, not peculiar to pregnancy; close monitoring of liver function is recommended. Liver enzyme induction by rifampicin alters the metabolism of other drugs, e.g. methadone doses will need to be increased. Streptomycin should not be used in pregnancy, as perhaps 1 in 6 babies will have problems with hearing and/or balance. Ciprofloxacin has the best safety profile of second line drugs in the treatment of drug-resistant tuberculosis. Preventive treatment with isoniazid can be undertaken safely during pregnancy. Pyridoxine (vitamin B6) should be added to the drug treatment of tuberculosis in all pregnant women taking isoniazid. Neither tuberculin nor the bacille Calmette Guérin (BCG) vaccine are treatments for tuberculosis, but they play an important role in the management of the disease. Tuberculin testing is safe, but BCG vaccination should be avoided in pregnancy and instead given earlier in life.     

New drug candidates and therapeutic targets for tuberculosis therapy

Despite advances in chemotherapy and the BCG (Bacillus Calmette-Guérin) vaccine, tuberculosis remains a significant infectious disease. Although it can be cured, the therapy takes at least 6-9 months, and the laborious and lengthy treatment brings with it dangers of noncompliance, significant toxicity and drug resistance. The increasing emergence of drug resistance and the problem of mycobacterial persistence highlight the need to develop novel TB drugs that are active against drug resistant bacteria but, more importantly, kill persistent bacteria and shorten the length of treatment. Recent new and exciting developments in tuberculosis drug discovery show good promise of a possible revolution in the chemotherapy of tuberculosis.     

抗结核药物的作用机制及结核分枝杆菌的耐药机理

结核病是一个严重的全球性疾病,随着艾滋病病毒及耐药结核菌的出现及播散成为结核病控制的又一个威胁。虽然我们有结核疫苗及抗结核药物,但控制结核病仍是一件很棘手的事情。多重耐药结核菌的不断出现给结核病的治疗带来很大的困难。为有效控制耐药结核病,我们必须了解结核菌的耐药机理。本文讨论了抗结核药物的作用机制及结核菌的耐药机理。结核菌耐药机理的阐明对耐药菌的快速分子诊断及新药的开发有重要的意义。     

Influence of T-2 toxin on BCG vaccine efficacy against murine pulmonary tuberculosis

Unvaccinated mice were treated with T-2 toxin either 6 days before or 1 day after exposure to aerosols of virulent Mycobacterium tuberculosis. Mice were also treated with T-2 toxin 6 days before vaccination with Mycobacterium bovis (BCG). There was a T-2 toxin mediated increase in the number of viable vaccine organisms recovered from the spleens of toxin-treated mice at 3 weeks after vaccination, and splenomegaly at post-vaccine weeks 3 through 5. At the seventh week after vaccination, toxin-treated vaccinated, toxin-treated non-vaccinated, vaccinated, and untreated mice were exposed to aerosols of viable M tuberculosis. The number of viable mycobacteria in the lungs was determined at weeks 3, 5, 7, and 9 after pulmonary infection. The number of viable tubercle bacilli recovered from the lungs of vaccinated mice was significantly lower than from unvaccinated mice. However, T-2 toxin-treatment did not alter the vaccine efficacy.