Current concepts in cancer vaccine strategies

Cancer vaccines are entering a new phase of popularity, in part because of the recognition of when a therapeutic vaccine is most effective and the identification of appropriate target antigens. New technologies, most notably gene transfection into dendritic cell and DNA vaccination approaches, have spurred further clinical evaluations. While many researchers consider humoral responses as not being viable for large tumors, these responses may play a role in regulating micrometastases (i.e., adjuvant setting). The recent approval of antibodies as therapeutics for cancer treatment has lent to the viability of this therapy concept. The success of carbohydrate-conjugate vaccines in bacterial systems has also renewed interest in developing such vaccines for cancer immunotherapy. Carbohydrates can be further converted into peptide/protein mimetics with several of these mimetics in clinical trials. These mimetic forms can be manipulated into DNA vaccine types that may be combined into DNA cassettes that contain CTL-associated epitopes to further define a novel strategy for future vaccine development.     

Overview of vaccines

This article lists the vaccines current available for the control of both viral and bacterial infections. They may be attenuated live or inactivated whole microorganisms, or subunit preparations. Many more are in the pipeline and increasing attention is being given to establishing their safety before registration. Following the earlier eradication of smallpox, good progress is now being made toward the global eradication of poliomyelitis and a new program to eliminate measles from the Americas has begun. A variety of new approaches to vaccine development is now available. The hepatitis B virus surface antigen, made by DNA-transfected yeast or mammalian cells, is the basis of the first genetically engineered vaccine. Early in the 21st century, new vaccines based on oligopeptides, recombinant live viral or bacterial vectors (often existing live vaccines), or recombinant DNA plasmids are likely to be registered for human use. The efficacy of vaccines depends on the immune responses generated, and the recent substantial increase in our understanding of the mammalian immune system now offers great opportunities for manipulation to best obtain desired responses. These include mixing vaccine formulations to maximize immune responses, and combining vaccines to simplify their administration. Despite these advances, some persisting infections, such as those caused by HIV, plasmodia, and mycobacteria, still pose a great challenge to vaccine developers.     

New approaches towards the identification of antibiotic and vaccine targets in Streptococcus pneumoniae

Streptococcus pneumoniae causes more than one million deaths every year, mostly of young children in developing countries, due to pneumonia, bacteremia and meningitis. The emergence and dissemination of drug-resistant pneumococcal strains, coupled to changing patterns of virulence and the inadequacy of available vaccines, calls for an aggressive search for novel targets for antibiotic and vaccine development. Microbial genomics techniques allow genetic and biochemical tools to be employed to tackle discovery, design and development of new anti-infective agents based on the identification of hundreds of new targets. In this review, novel approaches employed to identify potential antibiotic and vaccine targets in S. pneumoniae are highlighted. Recently identified virulence factors, as well as molecules essential for bacterial viability, cell wall integrity and infectivity, are discussed.     

Pre-absorbed immunoproteomics: a novel method for the detection of Streptococcus suis surface proteins

Streptococcus suis serotype 2 (SS2) is a zoonotic pathogen that can cause infections in pigs and humans. Bacterial surface proteins are often investigated as potential vaccine candidates and biomarkers of virulence. In this study, a novel method for identifying bacterial surface proteins is presented, which combines immunoproteomic and immunoserologic techniques. Critical to the success of this new method is an improved procedure for generating two-dimensional electrophoresis gel profiles of S. suis proteins. The S. suis surface proteins identified in this study include muramidase-released protein precursor (MRP) and an ABC transporter protein, while MRP is thought to be one of the main virulence factors in SS2 located on the bacterial surface. Herein, we demonstrate that the ABC transporter protein can bind to HEp-2 cells, which strongly suggests that this protein is located on the bacterial cell surface and may be involved in pathogenesis. An immunofluorescence assay confirmed that the ABC transporter is localized to the bacterial outer surface. This new method may prove to be a useful tool for identifying surface proteins, and aid in the development of new vaccine subunits and disease diagnostics.     

Monophosphoryl lipid A (MPL) formulations for the next generation of vaccines.

Many of the latest trends in vaccine development are dependent on immunological adjuvants that mediate and promote a wide variety of immune responses. One promising adjuvant candidate, monophosphoryl lipid A (MPL) immunostimulant, is being investigated with many of these new vaccine approaches in either preclinical or clinical trials. This is possible because different vehicle formulations can significantly influence the type of immunological response MPL promotes. Procedures are provided for formulating MPL in an aqueous vehicle or an oil-in-water emulsion. These two MPL formulations can be beneficial for most vaccine approaches being investigated today.     

The genome revolution in vaccine research

The conventional approach to vaccine development is based on dissection of the pathogen using biochemical, immunological and microbiological methods. Although successful in several cases, this approach has failed to provide a solution to prevent several major bacterial infections. The availability of complete genome sequences in combination with novel advanced technologies, such as bioinformatics, microarrays and proteomics, have revolutionized the approach to vaccine development and provided a new impulse to microbial research. The genomic revolution allows the design of vaccines starting from the prediction of all antigens in silico, independently of their abundance and without the need to grow the pathogen in vitro. This new genome-based approach, which we have named "Reverse Vaccinology", has been successfully applied for Neisseria meningitidis serogroup B for which conventional strategies have failed to provide an efficacious vaccine. The concept of "Reverse Vaccinology" can be easily applied to all the pathogens for which vaccines are not yet available and can be extended to parasites and viruses.     

Biotechnology and vaccines: application of functional genomics to Neisseria meningitidis and other bacterial pathogens

Since its introduction, vaccinology has been very effective in preventing infectious diseases. However, in several cases, the conventional approach to identify protective antigens, based on biochemical, immunological and microbiological methods, has failed to deliver successful vaccine candidates against major bacterial pathogens. The recent development of powerful biotechnological tools applied to genome-based approaches has revolutionized vaccine development, biological research and clinical diagnostics. The availability of a genome provides an inclusive virtual catalogue of all the potential antigens from which it is possible to select the molecules that are likely to be more effective. Here, we describe the use of "reverse vaccinology", which has been successful in the identification of potential vaccines candidates against Neisseria meningitidis serogroup B and review the use of functional genomics approaches as DNA microarrays, proteomics and comparative genome analysis for the identification of virulence factors and novel vaccine candidates. In addition, we describe the potential of these powerful technologies in understanding the pathogenesis of various bacteria.     

Quo vadis en vacunas: desde la aproximación empírica a la nueva oleada tecnológica

The development of vaccines is a multifactorial process that has evolved and expanded, particularly over the last decades. The search for immunogenic vaccines that are also acceptably safe and tolerable enacted continuous technological advances in this field. In this regard, the technology applied to vaccines can historically be divided into 3 approaches: the empirical approach, the modern approach, and the new technological wave. The empirical approach for vaccine development includes whole micro-organisms, attenuation, inactivation, cell cultures and sub-unit vaccines. The modern approach contributed to leaps and bounds to vaccine development using chemical conjugation, as well as recombinant protein DNA technology and reverse vaccinology. Lastly, the new technological wave includes, among others, bioconjugation, viral vectors, synthetic biology, self-amplification of messenger RNA, generalized modules for membrane antigens, structural vaccinology and the new adjuvants.     

The analysis of Neisseria meningitidis proteomes: Reference maps and their applications

Neisseria meningitidis is an encapsulated Gram-negative bacterium responsible for significant morbidity and mortality worldwide. The availability of meningococcal genome sequences in combination with the rapid growth of proteomic techniques and other high-throughput methods, provided new approaches to the analysis of bacterial system biology. This review considers the meningococcal reference maps so far published as a starting point aimed to elucidate bacterial physiology and pathogenicity, paying particular attention to proteins with potential vaccine and diagnostic applications.     

作为疫苗和疫苗载体的减毒细菌

减毒细菌不但能作为疫苗,而且已被证实是理想的疫苗载体,尤其是在研制基因工程疫苗方面显现了独特的优越性,减毒细菌作为载体可激发强烈的体液免疫、细胞免疫和黏膜免疫。主要就沙门氏菌、志贺氏菌、李斯特菌和BCG等细菌作为疫苗和疫苗载体的研究进展进行综述,以期为新型疫苗的研制奠定基础。     

Live bacterial vaccines – a review and identification of potential hazards

The use of live bacteria to induce an immune response to itself or to a carried vaccine component is an attractive vaccine strategy. Advantages of live bacterial vaccines include their mimicry of a natural infection, intrinsic adjuvant properties and their possibility to be administered orally. Derivatives of pathogenic and non-pathogenic food related bacteria are currently being evaluated as live vaccines. However, pathogenic bacteria demands for attenuation to weaken its virulence. The use of bacteria as vaccine delivery vehicles implies construction of recombinant strains that contain the gene cassette encoding the antigen. With the increased knowledge of mucosal immunity and the availability of genetic tools for heterologous gene expression the concept of live vaccine vehicles gains renewed interest. However, administration of live bacterial vaccines poses some risks. In addition, vaccination using recombinant bacteria results in the release of live recombinant organisms into nature. This places these vaccines in the debate on application of genetically modified organisms. In this review we give an overview of live bacterial vaccines on the market and describe the development of new live vaccines with a focus on attenuated bacteria and food-related lactic acid bacteria. Furthermore, we outline the safety concerns and identify the hazards associated with live bacterial vaccines and try to give some suggestions of what to consider during their development.     

Vaccines against Tuberculosis: Where Are We and Where Do We Need to Go?

In this review we discuss recent progress in the development, testing, and clinical evaluation of new vaccines against tuberculosis (TB). Over the last 20 years, tremendous progress has been made in TB vaccine research and development: from a pipeline virtually empty of new TB candidate vaccines in the early 1990s, to an era in which a dozen novel TB vaccine candidates have been and are being evaluated in human clinical trials. In addition, innovative approaches are being pursued to further improve existing vaccines, as well as discover new ones. Thus, there is good reason for optimism in the field of TB vaccines that it will be possible to develop better vaccines than BCG, which is still the only vaccine available against TB.     

Malaria vaccine development: current status

The development of an effective malaria vaccine represents one of the most important approaches that would provide a cost-effective intervention for addition to currently available malaria control strategies. Here, Howard Engers and Tore Godal review recent advances. Over the past decade there has been considerable progress in the understanding of immune mechanisms involved in conferring protection to malaria and in the identification of vaccine candidate antigens and their genes. Several new vaccines have entered Phase I/II trials recently, new adjuvants have been developed for human use and new approaches, such as DNA vaccines and structural modification of antigens to circumvent some of the strategies the parasite uses to avoid the immune response, are being applied. Thus, from the TDR perspective, global malaria vaccine development is entering a crucial period with unprecedented opportunities.     

Publics and vaccinomics: beyond public understanding of science

Vaccines have been among the most effective tools for addressing global public health challenges. With the advent of genomics, novel approaches for vaccine discovery are opening up new opportunities for vaccine development and applications, particularly with the expectation of personalized vaccines and the possibility of addressing a broader range of infectious diseases. In this context, it is useful to reflect on the social contexts of vaccine development as these have been influenced by social, ethical, political challenges. This article discusses the historical context of vaccine controversies and factors that help explain public acceptance and resistance, illustrating that these challenges go well beyond simple public misunderstandings. The broader vaccine challenges evident along the innovation trajectory, from development to commercialization and implementation include problems in research and development, organizational issues, and legal and regulatory challenges that may collectively contribute to public resistance or confidence. The recent history of genomics provides further lessons that the developing field of vaccinomics can learn from.     

Biotechnology approaches to produce potent,self-adjuvanting antigen-adjuvant fusion protein subunit vaccines

Traditional vaccination approaches (e.g. live attenuated or killed microorganisms) are among the most effective means to prevent the spread of infectious diseases. These approaches, nevertheless, have failed to yield successful vaccines against many important pathogens. To overcome this problem, methods have been developed to identify microbial components, against which protective immune responses can be elicited. Subunit antigens identified by these approaches enable the production of defined vaccines, with improved safety profiles. However, they are generally poorly immunogenic, necessitating their administration with potent immunostimulatory adjuvants. Since few safe and effective adjuvants are currently used in vaccines approved for human use, with those available displaying poor potency, or an inability to stimulate the types of immune responses required for vaccines against specific diseases (e.g. cytotoxic lymphocytes (CTLs) to treat cancers), the development of new vaccines will be aided by the availability of characterized platforms of new adjuvants, improving our capacity to rationally select adjuvants for different applications. One such approach, involves the addition of microbial components (pathogen-associated molecular patterns; PAMPs), that can stimulate strong immune responses, into subunit vaccine formulations. The conjugation of PAMPs to subunit antigens provides a means to greatly increase vaccine potency, by targeting immunostimulation and antigen to the same antigen presenting cell. Thus, methods that enable the efficient, and inexpensive production of antigen-adjuvant fusions represent an exciting mean to improve immunity towards subunit antigens. Herein we review four protein-based adjuvants (flagellin, bacterial lipoproteins, the extra domain A of fibronectin (EDA), and heat shock proteins (Hsps)), which can be genetically fused to antigens to enable recombinant production of antigen-adjuvant fusion proteins, with a focus on their mechanisms of action, structural or sequence requirements for activity, sequence modifications to enhance their activity or simplify production, adverse effects, and examples of vaccines in preclinical or human clinical trials.     

细菌菌影作为新型疫苗和递送载体的研究进展

细菌菌影（bacterial ghost,BG）是革兰阴性菌在噬菌体PhiX174的裂解基因E的作用下形成不含核酸、核糖体等胞质内容物的细菌空壳。这种细菌空壳保留了与天然细菌一样的完整外膜结构,且不具有活菌样的致病作用,可作为疫苗无需佐剂就能诱导机体产生体液免疫应答和细胞免疫应答。菌影内部及外膜上可装载DNA、抗原和药物等异源物质,易被机体免疫细胞识别捕获,使其成为一种新型的生物递送载体。另外,菌影具有制备简单,易于保存等优点。细菌菌影在疾病预防和治疗方面具有广阔的应用前景。     

金黄色葡萄球菌组分疫苗研究进展

临床上,耐药性的金黄色葡萄球菌日益增多,极其耐药的菌株甚至获得了超级耐药细菌的称谓,难以找到有效的抗菌素控制其感染,因而研制有效的疫苗来防治金黄色葡萄球菌感染显得更加重要。对研制开发的金黄色葡萄球菌荚膜多糖疫苗、纤维粘连结合蛋白疫苗、RNAⅢ激活蛋白疫苗以及核酸疫苗等进行了综述。     

Accelerating vaccine development and deployment: report of a Royal Society satellite meeting

The Royal Society convened a meeting on the 17th and 18th November 2010 to review the current ways in which vaccines are developed and deployed, and to make recommendations as to how each of these processes might be accelerated. The meeting brought together academics, industry representatives, research sponsors, regulators, government advisors and representatives of international public health agencies from a broad geographical background. Discussions were held under Chatham House rules. High-throughput screening of new vaccine antigens and candidates was seen as a driving force for vaccine discovery. Multi-stakeholder, small-scale manufacturing facilities capable of rapid production of clinical grade vaccines are currently too few and need to be expanded. In both the human and veterinary areas, there is a need for tiered regulatory standards, differentially tailored for experimental and commercial vaccines, to allow accelerated vaccine efficacy testing. Improved cross-fertilization of knowledge between industry and academia, and between human and veterinary vaccine developers, could lead to more rapid application of promising approaches and technologies to new product development. Identification of best-practices and development of checklists for product development plans and implementation programmes were seen as low-cost opportunities to shorten the timeline for vaccine progression from the laboratory bench to the people who need it.     

Genes to genetic immunization: identification of bacterial vaccine candidates

Pathogenic bacteria still represent a major threat to human health worldwide and the need for new vaccines is great. Virulence factors, particularly surface-located molecules, often make good vaccine targets because they are essential for access to their niche within the host. The advent of whole-genome sequencing of bacterial pathogens has revolutionized the methods by which these organisms are studied and provides us with the possibility of identifying potential targets for vaccines by sequence scanning alone. Other developments in molecular biology, such as whole genome expression and mass mutagenesis, are also contributing to the identification of potential vaccine targets. In this chapter, we review approaches that exploit whole genome sequence data to identify potential virulence determinants and vaccine antigens.