key: cord-0008679-x48mutwm authors: Boraschi, Diana; Tagliabue, Aldo; Martin, Michael U.; Rappuoli, Rino title: INNAMORA, a European Workshop focussed on the mechanisms of innate immunity in pathogen–host interaction and their exploitation in novel mucosal immunisation strategies date: 2003-06-01 journal: Vaccine DOI: 10.1016/s0264-410x(03)00194-4 sha: d98ae703c83275a4f9df7f62cc707629949ae87b doc_id: 8679 cord_uid: x48mutwm nan The Euroconference/Workshop "Novel Strategies of Mucosal Immunisation through Exploitation of Mechanisms of Innate Immunity in Pathogen-Host Interaction" (acronym INNAMORA) was held in Siena, [6] [7] [8] [9] November 2002, at the Research Centre of Chiron Vaccines. The aim of the meeting was the implementation of European efforts towards novel vaccination strategies within a global vision, with many objectives: 1. To gather the co-ordinators of the most relevant EU-funded projects on vaccine strategies, mucosal immunisation, and innate immunity, in order to establish the state of the art of the European research in this field. 2. To be updated on the newest trends and directions of research on the mechanisms of innate immunity and their exploitation in the design of new vaccination strategies, with a series of high-level overviews and lectures from top scientists and opinion leaders. The use of vaccines has been generally introduced at the beginning of last century and has greatly contributed to abating the incidence of a series of infectious disease that had previously caused great part of the mortality of the human population [1] . Vaccines are among the most effective types of medical intervention [2] and it is generally agreed that their use caused and will cause the disappearance from the globe of many of the great killers of the past, such as smallpox and plague. At the present time, the rapid progress in research and a continuously increasing public awareness of the social value of vaccination are setting the bases for an unprecedented favourable situation for implementing vaccination strategies world-wide. In this context, the concept set forth in 1983 by the World Bank that absence of health is the main obstacle to economic development in poor countries has placed vaccination as the first action for the economic improvement of less-developed countries [3] . Likewise, the World Health Organisation (WHO) together with UNICEF (United Nations Children's Fund) launched in 1981 a global campaign of immunisation (Expanded Programme of Immunisation, EPI) to vaccinate 80% of children world-wide with five basic vaccines (against polio, diphtheria, measles, pertussis, tetanus). The Global Alliance for Vaccines and Immunisation (GAVI) was founded in January 2000, to unify public and private efforts towards enlarging vaccine availability particularly in less-developed countries. The financial body of GAVI, the Vaccine Fund, has received excellent support through private donations (up to US$ 1.1 billion), including a contribution of US$ 750 million from the Bill and Melinda Gates Foundation. Furthermore, during the World Economic Forum held in Davos in January 2003, the Bill and Melinda Gates Foundation has announced a further contribution of US$ 200 million to establish the "Grand Challenges in Global Health" initiative, to support and accelerate research and vaccine development for AIDS, malaria, diarrhoeal diseases and other infections affecting the most impoverished countries. The main problem faced in the practical implementation of all these enthusiastic public and private initiatives is the progressive disinterest of vaccine industries, with the consequent risk of inadequate vaccine supplies. In fact, the economic value of vaccines is negligible from the industrial viewpoint, where its potential business amounts to only about 2% of the global pharmaceutical market [4] . Other problems that make the vaccine business unattractive for companies include the high risk of liability actions, the pressing requests from humanitarian organisations for decreasing vaccine prices, the recalcitrant attitude of some public health administrations to meet the vaccine costs to the full coverage of the population. As a consequence, the number of industries producing and manufacturing vaccines has dramatically dropped in recent years. In the USA, vaccine companies have decreased from 37 in 1967 to 10, bringing about a significant shortage in vaccine supply that would expose the population to the risks of uncontrolled outbreaks of vaccine-preventable diseases [2, 5, 6] . Even more dramatic would be the situation in less-developed countries, where vaccine coverage is most needed. A comprehensive organisation of the global efforts towards vaccine implementation is clearly needed at multiple levels. The programmes of GAVI and other similar programmes need to be paralleled by a clear policy towards encouraging industrial involvement in vaccine research, development and manufacturing. Incentives for industrial research and investments in the vaccine field should be devised, such as de-taxation policies, insurances against liability risks, more attractive patent coverage, waiving the pressure of public-sector agencies (the principal buyers of vaccines) for lowering the vaccine price. Without genuine involvement of vaccine companies, no social or humanitarian effort towards vaccination in less-developed countries could be hoped to be successful. Generally, the need of vaccines in developing countries involves vaccines already available and vaccines still to be developed, which are directed to diseases that do not affect developed countries and are not of interest to industry. In the case of vaccines that are already available, the recent effort for global vaccination coverage (e.g. EPI, GAVI) is facing an increasing shortage in vaccine supply caused by lack of industrial interest. If the problem is true for developed countries, it is greatly exacerbated in the poorest countries that do not have the financial capacity of meeting the cost of vaccines. However, decreasing vaccine price for these countries does not offer a reasonable solution, as price could always be too high for them, and companies are increasingly discouraged in maintaining the vaccine business. Moreover, vaccines developed and tested in developed countries might need to be adapted to the widely different geographical conditions and infrastructure present in other countries. To make some simple examples, vaccines that need to be conserved at +4 • C may pose insurmountable difficulties of distribution in sub-equatorial countries, vaccines that need multiple administrations will face problems of compliance, injectable vaccines will pose the problem of supply of sterile syringes and or their safe disposal to avoid spreading of infections, oral or nasal vaccines will face problems of proper absorption in populations stricken by diarrhoeal and lung diseases with generalised mucosal inflammation and abundant mucus secretion. Development of new vaccines is progressing slowly. From the point of view of more basic research, the enthusiastic availability of funding from charities and private organisations makes possible to invest also in areas considered of low priority in developed countries. This is the case of the International Vaccine Institute (IVI), an international organisation located in South Korea, that relies upon a substantial funding received from GAVI for running top-level basic research and epidemiological studies on vaccines for diarrhoeal diseases (e.g. Shigella, rotaviruses), and for running a large training programme for Asian countries such as Bangladesh, China, India, Pakistan, Philippines, Thailand, Vietnam [7] . Again, the main problem is not that of devising an effective new vaccine, but that of adequate vaccine manufacturing and of proper vaccine distribution and administration. From this point of view, there is a tendency by international organisations of supporting the independent development of vaccine production and distribution in each country. This is an issue that further bothers vaccine companies, as they fear unforeseen competition risks with little possibility of enforcing their patent rights without raising strong public reaction and risking a generalised damage to their business. However, this does not appear as a consistent or imminent risk for companies. Indeed, implementation of independent vaccine production in less-developed countries will need a more basic and long-term strategy in supporting the social and economic development of the country. Social and economic development is necessary before industrial initiatives such as independent vaccine manufacturing could be safely established. Organisations such as the Human Frontier Science Programme Organisation (HF-SPO), the Wellcome Trust, the Third-World Academy of Sciences (TWAS), and European Molecular Biology Organisation (EMBO) are actively tackling the issue of higher education and basic research in life sciences in less-developed countries. Although apparently of little immediate practical outcome, the establishment of higher education programmes in these countries and the formation of a class of young independent scientists is the basis for any future social and economic development. Specific training and technology transfer will be needed in order to implement independent vaccine manufacturing and distribution. In this sense, the involvement of vaccine companies, on the basis of international cooperation and licensing agreements, would be of great importance. Other initiatives, as that of IVI, are moving in this direction by establishing facilities for small-scale vaccine production devoted to training of third-world personnel and technology transfer. Co-ordination of international policies and forging of new treaties for implementing development in poor countries is at the basis of the successful outcome of global vaccination and health improvement. USA policies on vaccination have undergone major change in direction after 11 September, due to the threat of bioterrorism. Large financial resources have been contracted to vaccine companies for resuming/increasing the production of old vaccines (e.g. anthrax and smallpox) in spite of their inadequate safety profile. In addition, large financial support for research is being made available to scientists world-wide. Three areas of biodefence vaccine research will be tackled: innate and adaptive immunity, human immunology, unusually susceptible civilian populations (children, elderly, immunosuppressed people). The EU Commission, on the other hand, has focussed efforts in the vaccine field of the new 6th Framework Programme almost exclusively on dealing with three major poverty-related diseases: a viral one (HIV/AIDS), a bacterial one (tuberculosis, TB), and a protozoan one (malaria). The programme promotes international collaboration with direct involvement of third-world scientists, a major involvement of vaccine companies in the R&D activities, and strong training programmes for young investigators of developing countries. A wealth of other initiatives are taken by individual countries, e.g. countries of northern Europe such as Sweden and Denmark. Furthermore, international organisations have vaccine programmes in poverty-stricken countries (WHO, UNICEF, IVI). Large and small initiatives world-wide are flourishing, given the excellent social perception of vaccines as tools for improving human health and advancing social and economic development. As a consequence, private foundations and charities are sustaining many of these initiatives, as is the case of the Vaccine Fund of GAVI. However, the progress in basic research and in vaccination strategies needs to be pursued in parallel by a concomitant progress in the industrial development and manufacturing activities. No practical progress can take place if the current shortage in vaccine supplies due to the lack of industrial interest is not overcome and if industrial investment into new vaccine development is not implemented (Table 1) . Within the new 6th Framework Programme (2002-2006) , the EU Commission specifically aims at poverty-related diseases, and this follows the concept that improving health is the way of fighting poverty [8] . A specific line of research will be funded, entitled "Confronting the major communicable diseases linked to poverty". The strategic objective for this action is to develop new vaccines, drugs and other innovative interventions to fight the three major infectious diseases linked to poverty: HIV/AIDS, malaria and tuberculosis. These three diseases are both the cause and consequence of poverty in many developing countries, in particular in Sub-Saharan Africa. In its programme for action "Accelerated action on HIV/AIDS, malaria and tuberculosis in the context of poverty reduction" [9] , the EU Commission provided a broad policy framework for a comprehensive global and multidisciplinary approach against the three poverty-linked diseases. Concerning research, the overall strategy is to develop new effective interventions against these three diseases. In order to realise this goal, the action is organised in two major components: (i) developing new promising candidates up to the pre-clinical and early human testing (phase I clinical trials), and (ii) establishing a clinical trial programme to support phases II and III clinical trials [10] . It is planned to develop new effective interventions harnessing the full spectrum of basic molecular research through to pre-clinical and proof-of-principle testing (early human testing, safety trials) using the integration of different disciplines and approaches, while pursuing rational and systematic concepts and comparative evaluation procedures. The emphasis will be in translating new knowledge effectively into the development of promising new candidate vaccines, drugs or microbicides. The involvement of relevant research groups from developing countries is highly encouraged. The second component of this action is the implementation of the European and Developing Countries Clinical Trials Partnership (EDCTP) [10] . One of the main goals of the EDCTP is to support phases II and III clinical trials of promising candidates in developing countries. Within EU policies, the EDCTP is part of the overall strategy of the FP6 but is an independent legal and financial entity, specifically dedicated to supporting clinical trials in developing countries. Thus, the most relevant effort of the EU Commission not only puts the emphasis on basic research, but it strongly encourages transfer of scientific results into practice, which needs an important industrial involvement. Advanced training activities are emphasised as an essential component of these projects and should be specifically directed at the professional development of third-world fellows for implementing their formation as researchers in basic science and clinical research, as research managers and as industrial executives or users of the knowledge produced within the project. The first approach in the strategies for designing innovative vaccines is that of understanding the paths of interaction of the pathogen with host cells. This interaction is dynamic, in that both the pathogen and the host cell upon encounter change their physiological features in the attempt to survive. Escape mechanisms of pathogen and the host's mechanisms of defence have evolved concomitantly in an astonishingly dynamic relationship of co-evolution and reciprocal adaptation. Knowing the mechanisms of escape built by the pathogen, and the mechanisms of defence used by the host is the basis for designing effective and better targeted interventions of protection. The innate mechanisms used by host cells to fight and neutralise the pathogen invasion, and the mechanisms used by micro-organisms to escape host surveillance, are comprehensively described in the excellent review of Basset et al. [11] . The first interaction between a pathogen and the host usually takes place at the mucosal level, since mucosal linings represent the mechanical barrier between external environment and internal space. Thus, the first defensive activities take place at the mucosal surfaces, to avoid adhesion of micro-organisms to the cell surface (cilial movement, mucus secretion). The epithelial cells also express defence receptors (e.g. the Toll-like receptors, TLR) that recognise and bind specific pathogen associated molecular patterns (PAMP) and initiate defensive cell activation. Epithelial cells can synthesise and secrete a wide array of anti-microbial peptides (including defensins, cathelicidins and histatins) that contribute to the host defence. Cell activation leads to the production of chemokines, cytokines and other agents signalling cell injury [12] . Chemokines have the role of attracting immune cells (neutrophils, macrophages, NK cells and lymphocytes) to the infection site. There, phagocytic cells (neutrophils, macrophages) can ingest and kill the micro-organisms into phagolysosomes. Other cytokines produced at the infection site, together with TLR triggering by microbial or endogenous agents, can activate immune cells to better effect their inflammatory defence action and to initiate the triggering of specific acquired immunity [13] [14] [15] . Factors with a potent anti-microbial role produced during the inflammatory reaction include cytokines and chemokines, acute phase proteins and long pentraxins, complement components [16, 17] . Dendritic cells and NK cells are also involved in pathogen recognition, antigen uptake and presentation, and cytocidal activities, contributing both to the innate defence response and to the initiation of the subsequent acquired type of specific immunity and establishment of immunological memory [18] [19] [20] . Micro-organisms can attach to the epithelial cells through specialised surface structures (adhesins) or through other receptors. To avoid recognition by TLR and anti-microbial peptide action, several pathogens have evolved modifications in their surface components, and have devised inhibitory molecules against defensins. To pass the epithelial barrier, micro-organisms can either damage (induction of cell necrosis or apoptosis or degradation of the extracellular matrix) or invade the mucosal cells. After entering the cell, micro-organisms can survive in membrane-linked vacuoles and spread to the underlying and surrounding tissue. To survive the innate immunity surveillance, some micro-organisms have devised systems to inhibit phagocyte-mediated killing through different mechanisms of avoidance, e.g. by interfering with uptake or by inhibition of phagolysosome formation. Other infective agents, e.g. some viruses, are able to produce anti-cytokine proteins (such as mimics of soluble cytokine receptors) that can capture and neutralise cytokines, thus avoiding activation of the immune response. In the last two decades, it has been thought that vaccines administered via oral, nasal, vaginal and rectal routes (i.e. mucosal vaccines) could solve many of the problems related to parenteral vaccination. The interest in developing mucosal vaccines is based on a series of considerations [21] . In the first place, establishment of protective immunity at the mucosal sites would greatly increase vaccine effectiveness, in light of the fact that the vast majority of infections occur or begin at the mucosal surface. Moreover, mucosal immunisation could overcome the problems of vaccine efficacy in immunosuppressed people (e.g. HIV-infected), in people previously vaccinated with parenteral vaccines and in young children with circulating maternal antibodies [22] . Other more practical reasons are the easy administration, and the highly reduced risk of transmitting infections (as with syringes in the case of injectable vaccines). Since in the experimental models mucosal vaccines showed promising results it was expected that within a shorttime mucosal vaccines could be developed for human use. However, this was not the case. In the last few years, the most important oral vaccine, the attenuated anti-polio vaccine developed by Sabin in the 1950s, has been progressively abandoned in developed countries to avoid the few cases of disease caused by the vaccine. Furthermore, two recently developed mucosal vaccines for human use, against rotavirus diarrhoea and influenza, were withdrawn after a short period in the market because of adverse reactions among the vaccinees. However, the first evidence that a nasal vaccine against flu with LTK63 mucosal adjuvant could be safe and effective in humans was presented at this meeting [23] . It is extremely important to further develop mucosal vaccination, as it would be of paramount importance in eradicat-ing diseases in developing countries. At first, the paradigm of immunity versus tolerance (particularly important at the gastro-intestinal level) must be solved. Gastro-intestinal tolerance allows us to co-exist with our normal flora and to ingest large amounts of foreign food proteins without inducing harmful systemic immune responses. If we want to immunise at the mucosal level we have to invent new delivery systems and effective mucosal adjuvants. The characteristics of the mucosal immune system are different from those of the systemic immune response, and can be exploited to design effective mucosal vaccines [24] . The mucosal immune system (mucosal associated lymphoid system (MALT)) has been well defined in terms of inductive and effector sites in the gastro-intestinal tract (GALT), and in the nasal tract (NALT). Less known is the corresponding genito-rectal associated lymphoid system (GERALT). Inductive sites are the regional lymph nodes and aggregates of lymphoid tissue (e.g. Peyer's patches in the gut) where immunisation occurs and from which lymphocytes migrate to the effector sites (e.g. mucosal lamina propria). MALT is a common, communicating system as, for instance, genital mucosal immunity can be induced by nasal or oral immunisation [25] . Defence at the mucosal level includes both mechanical and innate mechanisms effected by epithelial cells, and innate and adaptive immunity involving leukocytes, dendritic cells, and lymphocytes. Secretory IgA, produced at the mucosal surface, participate both in killing invading micro-organisms (by opsonisation and neutrophil activation, and by arming intestinal lymphocytes in an antibody-dependent cellular cytotoxicity mechanism) [26] , and in inhibiting microbial adhesion. The route and features of antigen interaction with immune cells at the mucosal surface can determine the type of immune response elicited. Whereas mucosal delivery of microbial antigens (e.g. cholera) can elicit significant response also in immunosuppressed patients, a particular characteristic of the mucosal system is the induction of tolerance (especially to T-dependent antigens able to elicit delayed type hypersensitivity reactions, DTH). The phenomenon of oral tolerance (or ignorance) is a very important physiological mechanism to avoid development of DTH and other allergic reactions to ingested food proteins and other antigens. Oral tolerance and induction of mucosal immunity usually involve different types of antigens, oral tolerance being difficult or impossible to induce with strong immunogens, while the reverse is true for the mucosal immune response. However, the two phenomena are not mutually exclusive and sometimes the same mucosal immunisation procedure may concomitantly give rise both to a local significant IgA antibody formation and to tolerance or suppressed peripheral immune response. Therefore, mucosal immunisation and induction of oral tolerance may represent promising approaches to induce protection against mucosal infectious agents and against systemic inflammatory autoimmune disorders, respectively. However, in practice it has been very difficult to elicit strong protective immune response and IgA production by oral administration of soluble antigens. The successful oral vaccines for human use are therefore very few: the Sabin polio vaccine, two cholera vaccines (one killed, one attenuated), an adenovirus vaccine, and the Ty21a thypoid vaccine. To overcome the difficulties in inducing effective and protective immunity by mucosal administration of antigen, different vectors are being studied for appropriate delivery at the mucosal sites [21] . Several live bacterial vectors have been developed to target and deliver relevant antigens at the mucosal sites. These are either based on attenuated or mutated pathogens (e.g. Salmonella, Shigella, BCG, Bordetella) or on commensal bacteria (lactobacilli, certain streptococci and staphylococci). The tropism of these bacteria for the human gut or respiratory mucosa is essential for adequate delivery to the mucosal sites. The system using Bacillus spores expressing recombinant foreign antigens is proving very effective and safe in inducing mucosal immunity and protection in experimental models [27] . The use of attenuated bacterial vectors is being tested in severe infections, such as that of the intracellular pathogen Listeria monocytogenes, exploiting the same pathways of infection followed by the virulent bacterium [28] . Among viral vectors, the early vaccinia vector is being replaced by other poxviruses (e.g. canary poxvirus) and by adenoviruses. Psudoviruses appear rather promising, as do virus-like particles (VLP), recombinant self-assembling non-replicating viral core structures from non-enveloped viruses. Their high immunogenicity, together with the possibility of expressing recombinant antigens on their surface, make VLP excellent candidates for mucosal vaccine delivery. In addition, VLP prepared from pathogenic viruses can be used safely when administered by the natural route of infection to elicit mucosal immunity and IgA antibodies. These vectors, besides actual antigen delivery, serve also the function of adjuvants, as they usually elicit strong activation of innate response mechanisms and of immunostimulatory cytokine production. In experimental systems, the most effective and well studied mucosal adjuvants are cholera toxin (CT) and the closely related E. coli heat labile enterotoxin (LT). Both toxins are pentamers of cell-binding B subunits, associated with a single toxic A subunit. CT and LT can potently enhance im-munogenicity at the mucosal level, by increasing antigen uptake and presentation, and inducing B cell maturation and immunostimulatory cytokine production [21] . Moreover, CT and LT fail to induce tolerance and can even abrogate tolerance induction. However, their toxicity has prevented the possibility of human use [29] . Development of non-toxic CT and LT derivatives was at first based on isolated B subunits (CTB and LTB), which however worked only when physically coupled to the antigen and delivered intranasally. Non-toxic recombinant mutated forms of CT and LT retain partial adjuvant capacity as compared to the native toxins. Mutants and modifications of the A subunit of CT (CTA) are also being tested with some promising results, although in general adjuvanticity decreases with toxicity [30] . Agents stimulating innate immunity and triggering Toll-like receptors are excellent adjuvants, in that they induce production of cytokines and co-stimulatory molecules, contributing not only to the non-specific amplification of the immune response but also to the induction of the specific adaptive immunity [31] . These agents are essentially microbial products able to induce strong inflammation (e.g. bacterial LPS). However, of particular interest as potential adjuvants are synthetic oligodeoxynucleotides containing non-methylated cytosine-phosphate-guanosine (CpG) motifs, which are particularly abundant in bacterial DNA. CpG motifs bind to TLR9 and trigger strong, predominantly Th1 immune response and cytokine production [32] . CpG oligodeoxynucleotides, besides good systemic adjuvants, are quite effective also as mucosal adjuvants in several experimental systems. Intranasal, oral, or vaginal administration of CpG oligodeoxynucleotides together with the antigen can induce mucosal IgA production, systemic Th1 response, cytokine production, cytotoxic T lymphocyte (CTL) induction, and effective protection from subsequent infectious challenge [21] . Since a significant part of the effect of many adjuvants is due to induction of inflammatory cytokines, combinations of cytokines have been tested to obtain an adjuvant effect in the absence of toxicity. IL-1 is well known for its potent adjuvant activity and, in combination with Th1-stimulating cytokines (in particular IL-18), it can elicit a mucosal immune response (CTL, IFN-␥, IgA) against the antigen as potent as that obtained with CT [33] . Use of chemokines has also proven useful in stimulating effective mucosal immunity after mucosal administration with antigens in experimental models, although a thorough study on the efficacy of chemokines as mucosal adjuvants is not available. One of the great advantages of mucosal vaccination against pathogens is the exploitation of the same routes used by pathogens for entering and invading the body. Mucosal vaccines therefore can take advantage of the mucosal route for eliciting the same type of defensive reactions that are mounted against the pathogen (both innate local reactions and subsequent specific local and systemic immunity and generation of memory), i.e. the optimal response against the pathogen. This, together with the peculiar features of communication in the mucosal associated lymphoid system, makes mucosal vaccination the choice vaccination for all infections occurring or beginning at mucosal surfaces, which account for the majority of infectious diseases. The notion that health is necessary for the economic and social progress of a nation has given rise to numerous private and public initiatives world-wide to improve health conditions in developing countries. Vaccination is the first objective to be tackled and it needs a renewed effort to develop novel vaccines and to make old vaccines available. To this end, a global strategy of support of the vaccine business should be designed, in order to attract the interest of industries. This would not only ensure the adequate supply of vaccines (both for developed and developing countries) but it would also encourage new investments and research in the vaccine field [34] . Special emphasis should also be devoted to supporting higher education and training, and research in basic science in developing countries. This will pose the basis for future independent development, thus allowing implementation of technology transfer and independent vaccine production, manufacturing and distribution. The need for vaccines in developed countries should be implemented through several parallel strategies: (1) re-establish the production of old vaccines and implement national policies of vaccination; (2) support research and development of new vaccines (e.g. AIDS); (3) optimise old vaccines (to increase their efficacy and safety, e.g. new routes of administration). The need for vaccines in developing countries has to be dealt with by different objectives: (1) immediate use of old vaccines, even if their efficacy is not complete, to reduce disease burden; (2) research to develop "tailored" vaccines adapted to the different conditions of the population, such as health state (considering ongoing infections and/or mucosal inflammation, e.g. diarrhoea or respiratory infections), immunodepression (in conditions of starvation and disease), age (newborn, young children, elderly people), geographical considerations (climate, genetic factors). Mucosal vaccines are one of the most promising avenues for future vaccination. Their advantages include high efficacy due to exploitation of the same routes/mechanisms of immune activation as infective micro-organisms, effectiveness also in immunosuppressed people and in the presence of interfering immunity, easy administration, low crossinfection risk. Despite the limited success obtained so far in developing mucosal vaccines for human use, the ongoing and future research effort in this direction are bound to yield important results in the fight against disease and poverty. The intangible value of vaccination Provisional cases of selected notifiable diseases, United States, weeks ending The health and wealth of nations The future of vaccines: an industrial perspective Update: supply of diphtheria and tetanus toxoids and acellular pertussis vaccine Shortage of varicella and measles, mumps and rubella vaccines and interim recommendations from the Advisory Committee on Immunisation Practices Thinking downstream to accelerate the introduction of new vaccines for developing countries The European research effort for HIV/AIDS, malaria and tuberculosis Programme for action: accelerated action on HIV/AIDS, malaria and tuberculosis in the context of poverty reduction. 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An overview Novel human vaccine strategies and the 5FP: pushing the envelope. Vaccine Innate and adaptive mucosal immunity in protection against HIV infection Evidence for a common mucosal system. I. Migration of B immunoblasts into intestinal, respiratory and genital tissues Antibody-dependent cell-mediated antibacterial activity of intestinal lymphocytes with secretory IgA Bacillus spores for vaccine delivery Induction of immune responses by attenuated isogenic mutant strains of Listeria monocytogenes The mechanism of cholera toxin adjuvanticity Mucosal vaccines: non toxic derivatives of LT and CT as mucosal adjuvants The toll receptor family and microbial recognition CpG motifs in bacterial DNA and their immune effects Cytokine requirements for induction of systemic and mucosal CTL after nasal immunization The value of vaccines This work was supported by EU contracts QLK2-2002-30189 (INNAMORA), QLK2-1999-00228 (MUCIMM) and QLK2-1999-00070 (MUCADJ). DB was also supported by a grant from AIRC (Associazione Italiana Ricerca sul Cancro), Milan, Italy; and by the EU contract QLK4-2001-00147 (NANO-PATHOLOGY). MUM was supported by EU contract QLK2-1999-02072 (CYTOKINES DESTR OA). Chiron Vaccines S.r.l. contributed to the publication of these proceedings.