Apart from better diagnostics and new anti-microbial drugs, an effective vaccine for tuberculosis is urgently needed to halt this poverty-related disease, afflicting millions of people worldwide.
After a general introduction on the global threat of tuberculosis, the pros and cons of the existing M. bovis BCG vaccine are discussed. As the correlates of protection against tuberculosis remain largely unknown, new findings in biomarker research are described. Next, an update on the ongoing Phase I and Phase II clinical trials is given. Finally, some of the most promising novel pre-clinical developments using live attenuated vaccines, sub-unit vaccines, prime-boost strategies, and new vaccination routes are discussed. The field has made considerable progress and 12 vaccine candidates have now actually entered Phase I or Phase IIa and IIb clinical trials.
It is argued that the variable protection conferred by the existing BCG vaccine against reactivation of latent TB is caused not only by waning of its efficacy with time but also by its weak induction of MHC class I restricted responses. Prime-boost strategies based on the actual BCG vaccine may not be sufficient to overcome this hurdle. The use of plasmid DNA vaccination might offer a solution.
"Hence, attempts at manually creating these deletions are on. Recombinant BCG vaccines co-expressing other antigens from pathogens are also in clinical trials (35, 36). For cholera too, many endogenously produced live attenuated vaccines (Peru15 and Bengal15) are available as a traveler’s vaccine in different countries (37–39). "
[Show abstract][Hide abstract] ABSTRACT: Vaccination is the most effective method of preventing infectious diseases. Since the eradication of small pox in 1976, many other potentially life compromising if not threatening diseases have been dealt with subsequently. This event was a major leap not only in the scientific world already burdened with many diseases but also in the mindset of the common man who became more receptive to novel treatment options. Among the many protozoan diseases, the leishmaniases have emerged as one of the largest parasite killers of the world, second only to malaria. There are three types of leishmaniasis namely cutaneous (CL), mucocutaneous (ML), and visceral (VL), caused by a group of more than 20 species of Leishmania parasites. Visceral leishmaniasis, also known as kala-azar is the most severe form and almost fatal if untreated. Since the first attempts at leishmanization, we have killed parasite vaccines, subunit protein, or DNA vaccines, and now we have live recombinant carrier vaccines and live attenuated parasite vaccines under various stages of development. Although some research has shown promising results, many more potential genes need to be evaluated as live attenuated vaccine candidates. This mini-review attempts to summarize the success and failures of genetically modified organisms used in vaccination against some of major parasitic diseases for their application in leishmaniasis.
Frontiers in Immunology 05/2014; 5:213. DOI:10.3389/fimmu.2014.00213
"Healthy donors may be carriers for S. aureus or C. albicans, but in some instances these agents may be the cause of human disease (e.g., in immunologically compromised individuals) (Gow et al., 2012; Otto, 2009). BCG is used as a vaccine in order to protect humans from childhood tuberculosis and is the standard of care for treatment of bladder cancer (NB: all donors received BCG vaccination) (Kawai et al., 2013; Romano and Huygen, 2012). L. rhamnosus is considered to be a transient inhabitant of humans and is present in some yogurt preparations (Borriello et al., 2003). "
[Show abstract][Hide abstract] ABSTRACT: Standardization of immunophenotyping procedures has become a high priority. We have developed a suite of whole-blood, syringe-based assay systems that can be used to reproducibly assess induced innate or adaptive immune responses. By eliminating preanalytical errors associated with immune monitoring, we have defined the protein signatures induced by (1) medically relevant bacteria, fungi, and viruses; (2) agonists specific for defined host sensors; (3) clinically employed cytokines; and (4) activators of T cell immunity. Our results provide an initial assessment of healthy donor reference values for induced cytokines and chemokines and we report the failure to release interleukin-1α as a common immunological phenotype. The observed naturally occurring variation of the immune response may help to explain differential susceptibility to disease or response to therapeutic intervention. The implementation of a general solution for assessment of functional immune responses will help support harmonization of clinical studies and data sharing.
"These leading vaccines are all designed as preventive vaccines and have been demonstrated in preclinical animal models to give varying levels of protection against M.tb. challenge [2,6,7]. This includes the MVA85A vaccine that recently failed to confer protection in a phase 2B efficacy trial in BCG vaccinated infants , a target population where it is clear in hindsight that the animal data supporting the performance of MVA85A are very limited . "
[Show abstract][Hide abstract] ABSTRACT: The ESX systems from Mycobacterium tuberculosis are responsible for the secretion of highly immunogenic proteins of key importance for bacterial survival and growth. The two prototypic proteins, ESAT-6 (EsxA from ESX-1) and TB10.4 (EsxH from ESX-3) share a lot of characteristics regarding genome organization, size, antigenic properties, and vaccine potential but the two molecules clearly have very different roles in bacterial physiology. To further investigate the role of ESAT-6 and TB10.4 as preventive and post-exposure tuberculosis vaccines, we evaluated four different fusion-protein vaccines; H1, H4, H56 and H28, that differ only in these two components. We found that all of these vaccines give rise to protection in a conventional prophylactic vaccination model. In contrast, only the ESAT-6-containing vaccines resulted in significant protection against reactivation, when administered post-exposure. This difference in post-exposure activity did not correlate with a difference in gene expression during infection or a differential magnitude or quality of the vaccine-specific CD4 T cells induced by ESAT-6 versus TB10.4-containing vaccines. The post-exposure effect of the ESAT-6 based vaccines was found to be influenced by the infectious load at the time-point of vaccination and was abolished in chronically infected animals with high bacterial loads at the onset of vaccination. Our data demonstrate that there are specific requirements for the immune system to target an already established tuberculosis infection and that ESAT-6 has a unique potential in post-exposure vaccination strategies.
PLoS ONE 12/2013; 8(12):e80579. DOI:10.1371/journal.pone.0080579 · 3.23 Impact Factor
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