Exchanging ESAT6 with TB10.4 in an Ag85B fusion molecule-based tuberculosis subunit vaccine: efficient protection and ESAT6-based sensitive monitoring of vaccine efficacy.
ABSTRACT Previously we have shown that Ag85B-ESAT-6 is a highly efficient vaccine against tuberculosis. However, because the ESAT-6 Ag is also an extremely valuable diagnostic reagent, finding a vaccine as effective as Ag85B-ESAT-6 that does not contain ESAT-6 is a high priority. Recently, we identified a novel protein expressed by Mycobacterium tuberculosis designated TB10.4. In most infected humans, TB10.4 is strongly recognized, raising interest in TB10.4 as a potential vaccine candidate and substitute for ESAT-6. We have now examined the vaccine potential of this protein and found that vaccination with TB10.4 induced a significant protection against tuberculosis. Fusing Ag85B to TB10.4 produced an even more effective vaccine, which induced protection against tuberculosis comparable to bacillus Calmette-Guerin vaccination and superior to the individual Ag components. Thus, Ag85B-TB10 represents a new promising vaccine candidate against tuberculosis. Furthermore, having now exchanged ESAT-6 for TB10.4, we show that ESAT-6, apart from being an excellent diagnostic reagent, can also be used as a reagent for monitoring vaccine efficacy. This may open a new way for monitoring vaccine efficacy in clinical trials.
Full-textDOI: · Available from: Timothy Mark Doherty, May 26, 2015
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ABSTRACT: TB remains a very significant global health burden. There is an urgent need for better tools for TB control, which include an effective vaccine. Bacillus Calmette-Guérin (BCG), the currently licensed vaccine, confers highly variable protection against pulmonary TB, the main source of TB transmission. Replacing BCG completely or boosting BCG with another vaccine are the two current strategies for TB vaccine development. Delivering a vaccine by aerosol represents a way to match the route of vaccination to the route of infection. This route of immunisation offers not only the scientific advantage of delivering the vaccine directly to the respiratory mucosa, but also practical and logistical advantages. This review summarises the state of current TB vaccine candidates in the pipeline, reviews current progress in aerosol administration of vaccines in general and evaluates the potential for TB vaccine candidates to be administered by the aerosol route. © The Author 2015. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene.Transactions of the Royal Society of Tropical Medicine and Hygiene 01/2015; DOI:10.1093/trstmh/tru206 · 1.93 Impact Factor
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ABSTRACT: Unlike most pathogens, many of the immunodominant epitopes from Mycobacterium tuberculosis are under purifying selection. This startling finding suggests that M. tuberculosis may gain an evolutionary advantage by focusing the human immune response against selected proteins. Although the implications of this to vaccine development are incompletely understood, it has been suggested that inducing strong Th1 responses against Ags that are only weakly recognized during natural infection may circumvent this evasion strategy and increase vaccine efficacy. To test the hypothesis that subdominant and/or weak M. tuberculosis Ags are viable vaccine candidates and to avoid complications because of differential immunodominance hierarchies in humans and experimental animals, we defined the immunodominance hierarchy of 84 recombinant M. tuberculosis proteins in experimentally infected mice. We then combined a subset of these dominant or subdominant Ags with a Th1 augmenting adjuvant, glucopyranosyl lipid adjuvant in stable emulsion, to assess their immunogenicity in M. tuberculosis-naive animals and protective efficacy as measured by a reduction in lung M. tuberculosis burden of infected animals after prophylactic vaccination. We observed little correlation between immunodominance during primary M. tuberculosis infection and vaccine efficacy, confirming the hypothesis that subdominant and weakly antigenic M. tuberculosis proteins are viable vaccine candidates. Finally, we developed two fusion proteins based on strongly protective subdominant fusion proteins. When paired with the glucopyranosyl lipid adjuvant in stable emulsion, these fusion proteins elicited robust Th1 responses and limited pulmonary M. tuberculosis for at least 6 wk postinfection with a single immunization. These findings expand the potential pool of M. tuberculosis proteins that can be considered as vaccine Ag candidates.The Journal of Immunology 08/2014; 193(6). DOI:10.4049/jimmunol.1401103 · 5.36 Impact Factor
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ABSTRACT: TB10.4 protein is a member of the ESX family that is necessary for Mycobacterium tuberculosis survival and plays a vital role in mycobacterial pathogenesis. In this study, the gene encoding TB10.4 was cloned into prokaryotic expression vecters pET-30(a) and pGEX-6p-1. The two recombinant proteins His-TB10.4 and GST-TB10.4 were then expressed in vitro in prokaryotic expression systems to develop monoclonal antibodies (MAbs) against TB10.4 protein. The purified rHis-TB10.4 protein was used to immunize BALB/c mice, and eight MAbs were produced. An immunoblotting analysis indicated that all these MAbs specifically recognize the TB10.4 protein. These new MAbs provide powerful reagents for further functional research into TB10.4 protein.12/2014; 33(6):444-7. DOI:10.1089/mab.2014.0039