Development of novel carrier(s) mediated tuberculosis vaccine: more than a tour de force

Mucosal vaccines for viral diseases: Status and prospects

Virus-associated infectious diseases are highly detrimental to human health and animal husbandry. Among all countermeasures against infectious diseases, prophylactic vaccines, which developed through traditional or novel approaches, offer potential benefits. More recently, mucosal vaccines attract attention for their extraordinary characteristics compared to conventional parenteral vaccines, particularly for mucosal-related pathogens. Representatively, coronavirus disease 2019 (COVID-19), a respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), further accelerated the research and development efforts for mucosal vaccines by thoroughly investigating existing strategies or involving novel techniques. While several vaccine candidates achieved positive progresses, thus far, part of the current COVID-19 mucosal vaccines have shown poor performance, which underline the need for next-generation mucosal vaccines and corresponding platforms. In this review, we summarized the typical mucosal vaccines approved for humans or animals and sought to elucidate the underlying mechanisms of these successful cases. In addition, mucosal vaccines against COVID-19 that are in human clinical trials were reviewed in detail since this public health event mobilized all advanced technologies for possible solutions. Finally, the gaps in developing mucosal vaccines, potential solutions and prospects were discussed. Overall, rational application of mucosal vaccines would facilitate the establishing of mucosal immunity and block the transmission of viral diseases.

Enhancing TB Vaccine Efficacy: Current Progress on Vaccines, Adjuvants and Immunization Strategies

Tuberculosis (TB) remains a global infectious disease primarily transmitted via respiratory tract infection. Presently, vaccination stands as the primary method for TB prevention, predominantly reliant on the Bacillus Calmette-Guérin (BCG) vaccine. Although it is effective in preventing disseminated diseases in children, its impact on adults is limited. To broaden vaccine protection, efforts are underway to accelerate the development of new TB vaccines. However, challenges arise due to the limited immunogenicity and safety of these vaccines, necessitating adjuvants to bolster their ability to elicit a robust immune response for improved and safer immunization. These adjuvants function by augmenting cellular and humoral immunity against M. tuberculosis antigens via different delivery systems, ultimately enhancing vaccine efficacy. Therefore, this paper reviews and summarizes the current research progress on M. tuberculosis vaccines and their associated adjuvants, aiming to provide a valuable reference for the development of novel TB vaccines and the screening of adjuvants.

Advanced drug delivery and therapeutic strategies for tuberculosis treatment

Tuberculosis (TB) remains a significant global health challenge, necessitating innovative approaches for effective treatment. Conventional TB therapy encounters several limitations, including extended treatment duration, drug resistance, patient noncompliance, poor bioavailability, and suboptimal targeting. Advanced drug delivery strategies have emerged as a promising approach to address these challenges. They have the potential to enhance therapeutic outcomes and improve TB patient compliance by providing benefits such as multiple drug encapsulation, sustained release, targeted delivery, reduced dosing frequency, and minimal side effects. This review examines the current landscape of drug delivery strategies for effective TB management, specifically highlighting lipid nanoparticles, polymer nanoparticles, inorganic nanoparticles, emulsion-based systems, carbon nanotubes, graphene, and hydrogels as promising approaches. Furthermore, emerging therapeutic strategies like targeted therapy, long-acting therapeutics, extrapulmonary therapy, phototherapy, and immunotherapy are emphasized. The review also discusses the future trajectory and challenges of developing drug delivery systems for TB. In conclusion, nanomedicine has made substantial progress in addressing the challenges posed by conventional TB drugs. Moreover, by harnessing the unique targeting abilities, extended duration of action, and specificity of advanced therapeutics, innovative solutions are offered that have the potential to revolutionize TB therapy, thereby enhancing treatment outcomes and patient compliance.

Towards the development of subunit vaccines against tuberculosis: The key role of adjuvant

According to the World Health Organization (WHO), tuberculosis (TB) is the leading cause of death triggered by a single infectious agent, worldwide. Bacillus Calmette-Guerin (BCG) is the only currently licensed anti-TB vaccine. However, other strategies, including modification of recombinant BCG vaccine, attenuated Mycobacterium tuberculosis (Mtb) mutant constructs, DNA and protein subunit vaccines, are under extensive investigation. As whole pathogen vaccines can trigger serious adverse reactions, most current strategies are focused on the development of safe anti-TB subunit vaccines; this is especially important given the rising TB infection rate in immunocompromised HIV patients. The whole Mtb genome has been mapped and major antigens have been identified; however, optimal vaccine delivery mode is still to be established. Isolated protein antigens are typically poorly immunogenic so adjuvants are required to induce strong and long-lasting immune responses. This article aims to review the developmental status of anti-TB subunit vaccine adjuvants.

Prime Vaccination with Chitosan-Coated Phipps BCG and Boosting with CFP-PLGA against Tuberculosis in a Goat Model

Simple Summary

Bovine tuberculosis is a disease that affects cattle and other animal species worldwide and represents a risk to public health. Even though there is a vaccine that has been used to control tuberculosis in humans for almost 100 years, up to now, it has not been used in animals. The reason is that vaccination interferes with the tuberculin test, the current test to diagnose tuberculosis in the field, and shows an inconsistent efficacy in animals. Recent studies report that prime vaccinating with BCG and boosting with proteins vaccinations perform better. In addition, there are reports that some polymers increase the immune response against various infectious diseases; therefore, testing a vaccine formula with polymers sounds like a wise thing to do. In this study, we showed that priming with BCG and boosting with a culture filtrate protein, alone or in combination with a polymer, the number of animals with lesions, the number of lesions per animal, and the size of the lesions in vaccinated animals, compared with those not vaccinated or those vaccinated with BCG alone, are significantly reduced. Our results mean that a vaccination used as a complement of actual tuberculosis control programs in animal populations can be useful to reduce tuberculosis dissemination.

Abstract

Attempts to improve the immune response and efficacy of vaccines against tuberculosis in cattle, goats, and other animal species have been the focus of research in this field during the last two decades. Improving the vaccine efficacy is essential prior to running long-lasting and expensive field trials. Studies have shown that vaccine protocols utilizing boosting with proteins improve the vaccine efficacy. The use of polymers such as chitosan and PolyLactic-co-Glycolic Acid (PLGA) improves the immune response against different diseases by improving the interaction of antigens with the cellular immune system and modulating the host immune response. This study shows that the prime BCG vaccination, boosted with a culture filtrate protein (CFP), alone or in combination with chitosan and PolyLactic-co-Glycolic Acid (PLGA), have the potential to reduce tuberculosis (TB) dissemination by reducing the number of animals with lesions, the number of lesions per animal, and the size of the lesions in vaccinated animals, compared with those not vaccinated or those vaccinated with BCG alone. The vaccinated groups showed significantly higher Interferon-γ levels in the blood compared to the control, nonvaccinated group after vaccination, after boosting, and after the challenge with the wild-type Mycobacterium bovis strain.

Immunogenicity of HspX/EsxS fusion protein of Mycobacterium tuberculosis along with ISCOMATRIX and PLUSCOM nano-adjuvants after subcutaneous administration in animal model

BACKGROUND

Tuberculosis (TB), caused by Mycobacterium tuberculosis (M. tuberculosis), is one of the most common and dangerous infectious diseases in the world. Despite vaccination with BCG, it is still considered as a major health problem. Therefore, design and production of an effective novel vaccine against TB is necessary. Our aim was to evaluate immunogenicity of HspX/EsxS fusion protein of M. tuberculosis along with ISCOMATRIX, PLUSCOM nano-adjuvants and MPLA through the subcutaneous route in mice model.

METHODS

HspX/EsxS fused protein of M. tuberculosis was cloned, expressed and purified in the prokaryotic system. ISCOMATRIX and PLUSCOM nano-adjuvants were prepared by film hydration method. Subcutaneous immunization of BALB/c mice was performed by different formulations. IFN-γ, IL-4, IL-17 and TGF-β cytokines levels as well as serum IgG1, IgG2a.

RESULTS

Our results showed that subcutaneous administration of mice with HspX/EsxS along with three adjuvants, ISCOMATRIX, PLUSCOM and MPLA increased immunogenicity of multi-stage fusion protein of M. tuberculosis. Additionally, HspX/EsxS protein + ISCOMATRIX or + PLUSCOM nano-adjuvants induced stronger Th1, IgG2a and IgG1 immune responses compared to MPLA adjuvant. Totally, HspX/EsxS/ISCOMATRIX/MPLA, HspX/EsxS/PLUSCOM/MPLA and two BCG booster groups could significantly induce higher Th1 and IgG2a immune responses.

CONCLUSION

With regard to ability of ISCOMATRIX, PLUSCOM and MPLA adjuvants to increase immunogenicity of HspX/EsxS protein through induction of IFN-γ and IgG2a immune responses, it seems that these adjuvants and especially ISCOMATRIX and PLUSCOM, could also improve BCG efficacy as a BCG booster.

7-oxo-DHEA enhances impaired M. tuberculosis-specific T cell responses during HIV-TB coinfection

BACKGROUND

Mycobacterium tuberculosis (Mtb) is the causative agent of tuberculosis (TB), affecting approximately one third of the world's population. Development of an adequate immune response will determine disease progression or progress to chronic infection. Risk of developing TB among human immunodeficiency virus (HIV)-coinfected patients (HIV-TB) is 20-30 times higher than those without HIV infection, and a synergistic interplay between these two pathogens accelerates the decline in immunological functions. TB treatment in HIV-TB coinfected persons is challenging and it has a prolonged duration, mainly due to the immune system failure to provide an adequate support for the therapy. Therefore, we aimed to study the role of the hormone 7-oxo-dehydroepiandrosterone (7-OD) as a modulator of anti-tuberculosis immune responses in the context of HIV-TB coinfection.

METHODS

A cross-sectional study was conducted among HIV-TB patients and healthy donors (HD). We characterized the ex vivo phenotype of CD4 + T cells and also evaluated in vitro antigen-specific responses by Mtb stimulation of peripheral blood mononuclear cells (PBMCs) in the presence or absence of 7-OD. We assessed lymphoproliferative activity, cytokine production and master transcription factor profiles.

RESULTS

Our results show that HIV-TB patients were not able to generate successful anti-tubercular responses in vitro compared to HD, as reduced IFN-γ/IL-10 and IFN-γ/IL-17A ratios were observed. Interestingly, treatment with 7-OD enhanced Th1 responses by increasing Mtb-induced proliferation and the production of IFN-γ and TNF-α over IL-10 levels. Additionally, in vitro Mtb stimulation augmented the frequency of cells with a regulatory phenotype, while 7-OD reduced the proportion of these subsets and induced an increase in CD4 + T-bet+ (Th1) subpopulation, which is associated with clinical data linked to an improved disease outcome.

CONCLUSIONS

We conclude that 7-OD modifies the cytokine balance and the phenotype of CD4 + T cells towards a more favorable profile for mycobacteria control. These results provide new data to delineate novel treatment approaches as co-adjuvant for the treatment of TB.

Mucosal vaccines: Strategies and challenges

Mucosal immunization has potential benefits over conventional parenteral immunization, eliciting immune defense in both mucosal and systemic tissue for protecting from pathogen invasion at mucosal surfaces. To provide a first line of protection at these entry ports, mucosal vaccines have been developed and hold a significant promise for reducing the burden of infectious diseases. However, until very recently, only limited mucosal vaccines are available. This review summarizes recent advances in selected aspects regarding mucosal vaccination, including appropriate administration routes, reasonable formulations, antigen-sampling and immune responses of mucosal immunity, and the strategies used to improve mucosal vaccine efficacy. Finally, the challenges of developing successful mucosal vaccines and the potential solutions are discussed.

A Promising Listeria-Vectored Vaccine Induces Th1-Type Immune Responses and Confers Protection Against Tuberculosis

Deaths associated with tuberculosis (TB) is rising and accounted for 1.4 million deaths in 2015 many of which were due to drug-resistant bacteria. Vaccines represent an important medical intervention, but the current Bacilli Calmette-Guerin (BCG) vaccine is not ideal for the protection of teenagers and adults. Therefore, a safe and effective vaccine is urgently needed. In this study, we designed a novel vaccine using an attenuated Listeria monocytogenes strain carrying fusion antigen FbpB-ESAT-6 (rLM) and characterized its safety and protective efficacy against Mycobacterium tuberculosis (M.tb) infection in mice. Compared to the wild type strain yzuLM4 and parental strain LMΔactA/plcB (LM1-2), the virulence of rLM was significantly reduced as judged by its infectious kinetics and LD₅₀ dose. Further characterization of intravenous immunization showed that prime-boost vaccination significantly increased the levels of Th1 cytokines (IFN-γ, IL-17, and IL-6), and enhanced cytotoxic T lymphocyte (CTL) CTLs activity, suggesting that rLM could elicit potent Th1/Th17 responses. More importantly, rLM significantly conferred the protection against M.tb H37Rv challenge. Collectively, our findings indicated that rLM is a novel and useful tool to prevent M.tb infection, and can be potentially be used to boost BCG-primed immunity.