Tuberculosis Vaccine Research Articles

Influence of Heterologous and Homologous Vaccines, and Their Components, on the Host Immune Response and Protection Against Experimental Caprine Paratuberculosis.

Vaccination against paratuberculosis, a chronic disease of ruminants caused by Mycobacterium avium subsp. paratuberculosis (Map), has been considered as the most effective control method. However, protection is incomplete, and the mechanisms operating in the response of the animals to vaccination are not fully understood. Therefore, this study analyzed the immune response and the effects on protection against Map infection, elicited by paratuberculosis (Silirum®) and tuberculosis (heat-inactivated M. bovis [HIMB]) vaccines and their components in a caprine experimental model. Fifty goat kids were divided into 10 groups (n = 5) according to their vaccination (Silirum®, HIMB and nonvaccinated), immunization (inactivated bacteria or adjuvant), and/or infection. Oral challenge with Map was performed 45 days postvaccination/immunization (dpv), and animals were euthanized at 190 dpv. Peripheral immune response and proportion of lymphocyte subpopulations were assessed monthly by enzyme-linked immunosorbent assay and flow cytometry analysis, respectively. Local immune response, proportion of tissue lymphocyte subpopulations, Map detection (polymerase chain reaction), and histological examination were conducted in gut-associated lymphoid tissues. All infected groups developed paratuberculosis granulomatous lesions despite vaccination or immunization. The Silirum® and HIMB-vaccinated groups showed a considerable lesion reduction consistent with a significant peripheral cellular and humoral immune response. Besides, a lower number of granulomas were observed in groups immunized with inactivated bacteria and adjuvants in comparison to nonvaccinated and infected group. However, despite not being significant, this reduction was even higher in adjuvant immunized groups, which developed milder granulomatous lesion with no detectable peripheral immune responses associated with immunization. No changes in the peripheral and local proportion of lymphocyte subsets or local immune response were detected in relation to either vaccination/immunization or infection. Despite that paratuberculosis and tuberculosis vaccination showed a partial and cross-protection against Map infection, respectively, only histological examination could assess the progression of infection in these animals. In addition, the pattern observed in the reduction of the lesions in adjuvant immunized groups suggests the possible involvement of a nonspecific immune response that reduces the development of granulomatous lesions.

Candidate Vaccines against Tuberculosis and the Future of Novel TB Vaccine Research

Introduction: Tuberculosis (TB) continues to be a global health challenge and currently only one licensed vaccine is available. For nearly 100 years, the Bacillus Calmette-Guérin (BCG) vaccine has been in use. While it provides protection against disseminated TB in infants, its protection against adult and adolescent pulmonary tuberculosis (PTB) is variable. This literature review will provide an overview of the clinical status of candidate TB vaccines and discuss the challenges and future development trends of novel TB vaccine research, in combination with a general overview of the Tuberculosis (TB) disease and Mycobacterium tuberculosis itself. Methods: Bibliographic searches were carried out on medical journal databases, publishers, and aggregators. The most used databases were PubMed, NCBI and MDPI. Publications in English on these and other databases relating to novel TB vaccines were included in this review. Results: Currently, there are 12 main vaccine candidates in various phases of clinical trials, they include four protein or adjuvant vaccines, three viral-vectored vaccines, three mycobacterial whole cells or extract vaccines, and one each of the recombinant life and the attenuated Mycobacterium tuberculosis vaccine. Currently, the most likely candidate vaccines are the M72 + AS01E and Vaccae vaccines. M72 + AS01E is a recombinant fusion protein vaccine candidate, clinical trials showed that administering two doses of M72/AS01E was successful in reducing the development of active TB disease with 50% efficacy. Studies have also proven the efficacy of Vaccae (which is currently in phase III clinical trials) as an adjunctive therapy, with it being curative in conjunction with current therapy. Conclusion: Given the morbidity and mortality suffered globally by M. tuberculosis, it is time to realize the seriousness of the situation and accelerate our commitment and investment to the eradication of this infectious disease. With the number of vaccine candidates currently in clinical trials having promising results, it is imperative to continue these studies and accelerate towards phase III licensure trials if we are to achieve the milestone of “End TB Strategy” by 2035. Today, we are witnessing immense progress in both preclinical and clinical TB vaccine research despite disappointing results from some of the clinical efficacy trials like that of MVA85A. We can revisit the design of vaccines and learn from them. It is important not only to recognize and give credit to those that have tested well in human trials, such as M72 + AS01E, but to expedite and improve its efficacy through funding of its research.

Challenges in Developing a Controlled Human Tuberculosis Challenge Model.

Controlled human infection models (CHIMs) have provided pivotal scientific advancements, contributing to the licensure of new vaccines for many pathogens. Despite being one of the world's oldest known pathogens, there are still significant gaps in our knowledge surrounding the immunobiology of Mycobacterium tuberculosis (M. tb). Furthermore, the only licensed vaccine, BCG, is a century old and demonstrates limited efficacy in adults from endemic areas. Despite good global uptake of BCG, tuberculosis (TB) remains a silent epidemic killing 1.4 million in 2019 (WHO, Global tuberculosis report 2020). A mycobacterial CHIM could expedite the development pipeline of novel TB vaccines and provide critical understanding on the immune response to TB. However, developing a CHIM for such a complex organism is a challenging process. The first hurdle to address is which challenge agent to use, as it would not be ethical to use virulent M. tb. This chapter describes the current progress and outstanding issues in the development of a TB CHIM. Previous and current human studies include both aerosol and intradermal models using either BCG or purified protein derivative (PPD) as a surrogate agent. Future work investigating the use of attenuated M. tb is underway.

Insufficient vaccine coverage for vaccines included in the National Program of Immunization

Vaccine coverage for vaccines provided through the Natio­nal Immunization Program is an element that is evaluated annually, including in Romania. Unfortunately, with the exception of the tuberculosis vaccine which has an optimal vaccine coverage (over 95%) both in total and in areas of residence (urban and rural), thus ensuring effective pro­tec­tion, for other types of vaccines this desideratum does not reach. Vaccine coverage of less than 95% does not provide effective cohort protection. This is the case for all types of pediatric vaccines administered in our coun­try, other than the tuberculosis vaccine. Comparing the na­tio­nal data with those determined by World Health Orga­ni­za­tion worldwide, we notice that in Romania, although the per­­cen­­tages are not very low, their amount does not offer sufficient protection. Real tests and measures with an impact on the immunization process are needed to in­crease the level of vaccine coverage.

Uticaj Covid-19 pandemije na obuhvat imunizacijom dece obaveznim vakcinama u Republici Srbiji

Objective. Infectious diseases have always been a challenge for medicine and healthcare workers. In addition to the enormous progress of medicine, they still represent a major public health problem. The pandemic caused by Covid-19 shows that. Due to the pandemic itself, the overload of the health care system, the fear of infection, the reallocation of health resources to respond to the pandemic, and other measures to control and suppress the infection, routine immunization services for children have been disrupted around the world. The aim of the work is to examine the impact of Covid-19 on the frequency of immunization of children with mandatory vaccines. Methods. Through retrospective analysis of data from the annual reports of the WHO and the Institute for Public Health of the Republic of Serbia "Dr. Milan Jovanović Batut", comparative data on coverage of required vaccination against infectious diseases in the Republic of Serbia was provided. Results. The results of a five-year analysis in the Republic of Serbia indicate that coverage of more than 95% was met only with immunization against tuberculosis, while against diphtheria, tetanus and whooping cough, coverage of 95% was until 2019, only to record a decline later. In 2021, a percentage decrease can be seen for all vaccines except the tuberculosis vaccine, and the lowest coverage is for the MMR vaccine (74.8%). In Serbia, in 2020 compared to 2019, the percentage of people vaccinated with the MMR vaccine decreased by 9.9%, i.e. by 3.3% in 2021 compared to 2020, and the data for central Serbia show a decrease of 11.6% in time period from 2019 to 2021. Conclusion. The trend of decline in immunization coverage of mandatory vaccines in Serbia follows the global trend, with the exception of the MMR vaccine, where a significantly greater decline is recorded in Serbia.

Liposomes as immunological adjuvants and delivery systems in the development of tuberculosis vaccine: A review

Liposomes are phospholipid bilayer vesicles, which are biocompatible, biodegradable and nontoxic vehicles suitable for numerous drug and gene delivery applications. In this review, we discuss the prospect of using liposome technology in the development of a vaccine for tuberculosis. Tuberculosis remains an important health problem that requires the development of an effective vaccine, especially since the only approved vaccine for it continues to be the Bacille Calmette-Geurin (BCG) one developed 100 years ago. This review focuses on the different applications of liposomes toward achieving this goal. Numerous liposomal formulations showing prospect in the research stage and in clinical trials are discussed.

Safety and Immunogenicity of a Candidate Tuberculosis Vaccine ChAdOx1-85A Delivered by Aerosol Versus Intramuscular Route in Healthy Adults in a Phase 1, Double-Blind Randomized Controlled Trial

Safety and Immunogenicity of a Candidate Tuberculosis Vaccine ChAdOx1-85A Delivered by Aerosol Versus Intramuscular Route in Healthy Adults in a Phase 1, Double-Blind Randomized Controlled Trial

Review on microbial genetics and virulence factors of mycobacterium bovis

Bovine tuberculosis is a disease caused by Mycobacterium bovis that affects cattle and other species, including humans. Mycobacterium bovis resides mainly in macrophages, so bacilli survival within macrophages is related to virulence. The role of bacterial genetic variability in the infection’s outcome remains uncertain. Until the early 1990s, when DNA fingerprints were introduced, it was believed that the M. tuberculosis complex was a group of highly genetically conserved bacteria, with limited phenotypic differences that influenced pathogenesis. However, epidemiological data suggest that differences in transmissibility and virulence between strains are related to their genotypes. Bovine tuberculosis is a chronic, debilitating infection that infects a wide range of hosts including domesticated and wild animals. Unlike M. tuberculosis, M. bovis has an unusually extensive host range including humans as recognized by the World Health Organization4 with a greater zoonotic potential in developing countries. M. bovis is also the progenitor of the Bacillus Calmette–Guérin (BCG), the only licensed tuberculosis vaccine and the gold standard for protection against childhood disseminated tuberculosis. Isolation and strain identification are important for disease control. However, little is known about virulence factors of the circulating strains in cattle populations. Therefore, the aim of this paper is to review the genetics and virulence factors of intracellular Mycobacterium bovis strains in pathogenicity and pathogenesis of the disease.

SARS-COV-2 Infection and Anti-Tuberculosis Immunity: Temporal Association or Real Protective Role?

Introduction: According to the literature consulted to date, there is epidemiological heterogeneity of Covid-19 between countries depending on their vaccination policy, in particular BCG vaccination. These findings have led to several hypotheses, including the protective role of immunity induced by the BCG tuberculosis vaccine against Covid-19 infection. The immunity induced by the BCG vaccine significantly increases the secretion of pro-inflammatory cytokines, in particular IL-1B, which has been shown to play an essential role in antiviral immunity. This cross-immunity, although not specific, if highlighted, is a real providence that must be taken advantage of in the face of this pandemic. The main objective of this study is to rule out or confirm that anti-tuberculosis immunity protects against SARS-COV-2 in our context. Material and Methods: Two groups will be compared: cases infected with the virus and controls who have never been infected with the virus. Both case and control groups will undergo a tuberculin skin test: the intra dermal tuberculin reaction (IDR). Results: We found that our control group had a high IDR immunity value, with an IDR tuberculin positive percentage of 67.2%. This suggests that immunity to IDR is a protective factor against coronavirus disease. Conclusion: The hypothesis of nonspecific anti-tuberculosis protection deserves further verification studies; it would have large positive repercussions for developing countries.

An Update on Tuberculosis Vaccines.

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), is a leading cause of mortality and morbidity due to a single infectious agent. Aerosol infection with Mtb can result in a range of responses from elimination, active, incipient, subclinical, and latent Mtb infections (LTBI), depending on the host's immune response and the dose and nature of infecting bacilli. Currently, BCG is the only vaccine approved to prevent TB. Although BCG confers protection against severe forms of childhood TB, its use in adults and those with comorbid conditions, such as HIV infection, is questionable. Novel vaccines, including recombinant BCG (rBCG), were developed to improve BCG's efficacy and use as an alternative to BCG in a vulnerable population. The first-generation rBCG vaccines had different Mtb antigens and were tested as a prime, prime-boost, or immunotherapeutic intervention. The novel vaccines target one or more of the following requirements, namely prevention of infection (POI), prevention of disease (POD), prevention of recurrence (POR), and therapeutic vaccines to treat a TB disease. Several vaccine candidates currently in development are classified into four primary categories: live attenuated whole-cell vaccine, inactivated whole-cell vaccine, adjuvanted protein subunit vaccine, and viral-vectored vaccine. Each vaccine's immunogenicity, safety, and efficacy are tested in preclinical animal models and further validated through various phases of clinical trials. This chapter summarizes the various TB vaccine candidates under different clinical trial stages and promises better protection against TB.

Considering human challenge trials for tuberculosis vaccine development

Human challenge trials provide a promising route to cut down on the high, sometimes prohibitive, costs of vaccine development. By requiring fewer participants than a conventional clinical trial and reducing the time required for a trial, human challenge trials improve economic feasibility and reduce the risk of vaccine development. Tuberculosis is one disease where challenge trials could be very impactful, given that it is a widespread and dangerous disease that is nonetheless difficult to track in a standard clinical vaccine trial. Various attenuated strains of Mycobacterium tuberculosis are in development and can be used in a challenge trial in order to reduce the risk to challenge trial participants and their surrounding communities.

Quantitative Rapid Test for Detection and Monitoring of Active Pulmonary Tuberculosis in Nonhuman Primates.

Simple SummaryTuberculosis (TB), caused by Mycobacterium tuberculosis (MTB), is the most lethal infectious disease from a single pathogen for which there is no effective vaccine available. Rhesus macaques are extremely susceptible to MTB and therefore represent relevant models to study the pathogenesis of TB and assess the potential of TB drugs and vaccines. However, there are no diagnostic tools currently available that allow rapid, user-friendly detection of TB for either TB research purposes or monitoring nonhuman primate colonies. To develop a rapid diagnostic test, we investigated whether low complexity lateral flow assays (LFAs) that we recently developed for rapid and quantitative detection of human serum proteins are applicable to detect and monitor active pulmonary TB in NHPs. We found that serum levels of SAA1, IP-10, and IL-6 detected by LFAs were significantly increased after MTB infection in rhesus macaques. Moreover, levels of these biomarkers correlated with disease severity as determined by pathology scoring and allowed detection of the effect of vaccination and drug treatment in experimentally MTB infected macaques. These UCP-LFAs thus offer a low-cost, convenient, and minimally invasive diagnostic tool that can be used to assess new therapeutic and prophylactic treatment methods in macaques to tackle TB.Nonhuman primates (NHPs) are relevant models to study the pathogenesis of tuberculosis (TB) and evaluate the potential of TB therapies, but rapid tools allowing diagnosis of active pulmonary TB in NHPs are lacking. This study investigates whether low complexity lateral flow assays utilizing upconverting reporter particles (UCP-LFAs) developed for rapid detection of human serum proteins can be applied to detect and monitor active pulmonary TB in NHPs. UCP-LFAs were used to assess serum proteins levels and changes in relation to the MTB challenge dosage, lung pathology, treatment, and disease outcome in experimentally MTB-infected macaques. Serum levels of SAA1, IP-10, and IL-6 showed a significant increase after MTB infection in rhesus macaques and correlated with disease severity as determined by pathology scoring. Moreover, these biomarkers could sensitively detect the reduction of bacterial levels in the lungs of macaques due to BCG vaccination or drug treatment. Quantitative measurements by rapid UCP-LFAs specific for SAA1, IP-10, and IL-6 in serum can be utilized to detect active progressive pulmonary TB in macaques. The UCP-LFAs thus offer a low-cost, convenient, and minimally invasive diagnostic tool that can be applied in studies on TB vaccine and drug development involving macaques.

Guinea Pig Model of Mycobacterium tuberculosis Infection.

Guinea pigs have been used as a model for Mycobacterium tuberculosis infection for many years and have been more recently adopted as a model for testing new tuberculosis (TB) vaccines. From the time of Robert Koch, who used guinea pigs to test theories about the newly discovered pathogen, the guinea pig has modeled active human infections, as it is susceptible to infection with low numbers of organisms. This article describes the modern use of the guinea pig to examine the pathology of the disease and the protocols used to examine specific outcomes associated with aerosol infection with virulent M. tuberculosis. The guinea pig is used extensively to investigate the ability of new TB vaccines to reduce TB disease, and two models have been employed. The first is the long-term disease model, in which vaccinated guinea pigs are monitored for disease after infection, and the second is the short-term assessment of mycobacterial burden model, which can determine the ability of a vaccine to reduce organism burden. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Preparation of virulent Mycobacterium tuberculosis seed stocks for animal infections Basic Protocol 2: Preparation of virulent Mycobacterium tuberculosis working stocks for animal infections Basic Protocol 3: Preparation of M. tuberculosis for aerosol infection of guinea pigs Basic Protocol 4: Injection of guinea pigs Basic Protocol 5: Blood collection from live guinea pigs Basic Protocol 6: Guinea pig euthanasia.

Evaluation of Tuberculosis Vaccine Candidate, pcDNA3.1-rpfD using Mycobacterial Growth Inhibition Assay (MGIA)

Resuscitation-promoting factor D (RpfD) is a protein involved in the resuscitation of dormant bacteria. A new tuberculosis vaccine carrying the rpfD gene has been successfully constructed, pcDNA3.1-rpfD. It was demonstrated that this vaccine exhibits cellular and humoral immune responses. Therefore, within this study, the efficacy of this new vaccine candidate was evaluated using mycobacterial growth inhibition assay (MGIA). MGIA is a functional assay that measures the complex host immune response, peripheral blood mononuclear cell (PBMC) and splenocyte from BALB/c mice against mycobacteria. With BACTECTM MGITTM 960 automated system, the effect of vaccination on bacterial growth was reported as a time to positivity (TTP) in hours. The mean of TTP from the vaccinated group (both pcDNA3.1-rpfD and BCG) was higher than the negative control group. These results suggest that pcDNA3.1-rpfD may be effective in controlling tuberculosis growth and may provide a clue for the development of the tuberculosis vaccine. In addition, despite previous evidence that IFNγ was essential for tuberculosis immunity, IFNγ (interferon gamma) production was found not to be correlated with mycobacterial inhibition. Therefore, these findings offer an alternative method to evaluate vaccine candidates than the assessment using IFNγ only.

A single dose, BCG-adjuvanted COVID-19 vaccine provides sterilising immunity against SARS-CoV-2 infection

Global control of COVID-19 requires broadly accessible vaccines that are effective against SARS-CoV-2 variants. In this report, we exploit the immunostimulatory properties of bacille Calmette-Guérin (BCG), the existing tuberculosis vaccine, to deliver a vaccination regimen with potent SARS-CoV-2-specific protective immunity. Combination of BCG with a stabilised, trimeric form of SARS-CoV-2 spike antigen promoted rapid development of virus-specific IgG antibodies in the blood of vaccinated mice, that was further augmented by the addition of alum. This vaccine formulation, BCG:CoVac, induced high-titre SARS-CoV-2 neutralising antibodies (NAbs) and Th1-biased cytokine release by vaccine-specific T cells, which correlated with the early emergence of T follicular helper cells in local lymph nodes and heightened levels of antigen-specific plasma B cells after vaccination. Vaccination of K18-hACE2 mice with a single dose of BCG:CoVac almost completely abrogated disease after SARS-CoV-2 challenge, with minimal inflammation and no detectable virus in the lungs of infected animals. Boosting BCG:CoVac-primed mice with a heterologous vaccine further increased SARS-CoV-2-specific antibody responses, which effectively neutralised B.1.1.7 and B.1.351 SARS-CoV-2 variants of concern. These findings demonstrate the potential for BCG-based vaccination to protect against major SARS-CoV-2 variants circulating globally.

Rapidly Growing Mycobacterium Species: The Long and Winding Road from Tuberculosis Vaccines to Potent Stress-Resilience Agents

Inflammatory diseases and stressor-related psychiatric disorders, for which inflammation is a risk factor, are increasing in modern Western societies. Recent studies suggest that immunoregulatory approaches are a promising tool in reducing the risk of suffering from such disorders. Specifically, the environmental saprophyte Mycobacterium vaccae National Collection of Type Cultures (NCTC) 11659 has recently gained attention for the prevention and treatment of stress-related psychiatric disorders. However, effective use requires a sophisticated understanding of the effects of M. vaccae NCTC 11659 and related rapidly growing mycobacteria (RGMs) on microbiome–gut–immune–brain interactions. This historical narrative review is intended as a first step in exploring these mechanisms and provides an overview of preclinical and clinical studies on M. vaccae NCTC 11659 and related RGMs. The overall objective of this review article is to increase the comprehension of, and interest in, the mechanisms through which M. vaccae NCTC 11659 and related RGMs promote stress resilience, with the intention of fostering novel clinical strategies for the prevention and treatment of stressor-related disorders.

Robust IgM responses following intravenous vaccination with Bacille Calmette\u2013Gu\xe9rin associate with prevention of Mycobacterium tuberculosis infection in macaques

Development of an effective tuberculosis (TB) vaccine has suffered from an incomplete understanding of the correlates of protection against Mycobacterium tuberculosis (Mtb). Intravenous (i.v.) vaccination with Bacille Calmette–Guérin (BCG) provides nearly complete protection against TB in rhesus macaques, but the antibody response it elicits remains incompletely defined. Here we show that i.v. BCG drives superior antibody responses in the plasma and the lungs of rhesus macaques compared to traditional intradermal BCG administration. While i.v. BCG broadly expands antibody titers and functions, IgM titers in the plasma and lungs of immunized macaques are among the strongest markers of reduced bacterial burden. IgM was also enriched in macaques that received protective vaccination with an attenuated strain of Mtb. Finally, an Mtb-specific IgM monoclonal antibody reduced Mtb survival in vitro. Collectively, these data highlight the potential importance of IgM responses as a marker and mediator of protection against TB.

Boosting BCG with recombinant influenza A virus tuberculosis vaccines increases pulmonary T cell responses but not protection against Mycobacterium tuberculosis infection.

The current Mycobacterium bovis BCG vaccine provides inconsistent protection against pulmonary infection with Mycobacterium tuberculosis. Immunity induced by subcutaneous immunization with BCG wanes and does not promote early recruitment of T cell to the lungs after M. tuberculosis infection. Delivery of Tuberculosis (TB) vaccines to the lungs may increase and prolong immunity at the primary site of M. tuberculosis infection. Pulmonary immunization with recombinant influenza A viruses (rIAVs) expressing an immune-dominant M. tuberculosis CD4+ T cell epitope (PR8-p25 and X31-p25) stimulates protective immunity against lung TB infection. Here, we investigated the potential use of rIAVs to improve the efficacy of BCG using simultaneous immunization (SIM) and prime-boost strategies. SIM with parenteral BCG and intranasal PR8-p25 resulted in equivalent protection to BCG alone against early, acute and chronic M. tuberculosis infection. Boosting BCG with rIAVs increased the frequency of IFN-γ-secreting specific T cells (p<0.001) and polyfunctional CD4+ T cells (p<0.05) in the lungs compared to the BCG alone, however, this did not result in a significant increase in protection against M. tuberculosis compared to BCG alone. Therefore, sequential pulmonary immunization with these rIAVs after BCG increased M. tuberculosis-specific memory T cell responses in the lung, but not protection against M. tuberculosis infection.

Design of a peptide-based vaccine from late stage specific immunogenic cross-reactive antigens of PE/PPE proteins of Mycobacterium tuberculosis

Since decades now, Tuberculosis (TB) is among the leading cause of death globally. Innovative and extensive research strategies are necessary to lower TB incidence and achieve the End TB Strategy milestone. Epitope-based vaccine designing and development provides a promising solution with high efficacy and effectiveness. Mining of less studied genes of Mycobacterium tuberculosis (Mtb) is crucial for recognizing potential antigenic peptide epitopes which can mount protective immune response in host. Many proteins from ESX associated Proline-Glutamate (PE)/ Proline-Proline-Glutamate (PPE) family are virulence factors and alter host mediated immune response against the pathogen.In the present study, we have targeted 34 late stage expressing (being expressed at 90 days) PE/PPE proteins of Mtb for prediction and identification of promiscuous, immunogenic and cross-reactive CD4+ T cell specific epitopes. We found a total of 149 promiscuous and cross-reactive epitopes out of which 42 were antigenic as well. Further, we shortlisted top 10 Promiscuous, Cross-reactive CD4+ T cell specific, Antigenic Peptide Epitopes (PCAPEs) which were characterized to be non-allergenic and pro-inflammatory cytokine inducing in nature. These epitopes also showed strong binding affinity for CD8+ T cell restricted Major Histo-compatibility Complex (MHC) class I alleles. Additionally, these PCAPEs showed wide population coverage of 99.6% globally for both MHC class I and class II alleles. Molecular docking studies were conducted to confirm the affinity of these shortlisted peptides for widely occurring MHC alleles. Additionally, we performed codon adaptation and in silico cloning of the recombinant vaccine construct incorporating EsxA (ESAT-6) as an adjuvant and the 10 selected PCAPEs joined by linkers. The recombinant vaccine construct showed strong affinity for Toll-like receptor2 (TLR2) immune receptor in docking studies. In silico prediction based study using C-ImmSim server shows significant population of Th1 type immune cells with memory cells lasting for months in response to our vaccine administration.Since, majority of TB vaccines under clinical trials are antigens expressed at early stages; a combinatorial approach inclusive of peptide epitopes derived from proteins being expressed at all stages could be a promising strategy to design and develop effective TB vaccine. Synthesis and experimental validation of this multi-epitopic recombinant TB vaccine construct may result in an effective vaccine to confer protection against Mtb.

Immunotherapy With 5, 15-DPP Mediates Macrophage M1 Polarization and Modulates Subsequent Mycobacterium tuberculosis Infectivity in rBCG30 Immunized Mice

Tuberculosis (TB) is a significant and continuing problem worldwide, with a death toll of around 1.5 million human lives annually. BCG, the only vaccine against TB, offers a varied degree of protection among human subjects in different regions and races of the world. The majority of the population living near the tropics carries a varying degree of tolerance against BCG due to the widespread prevalence of non-tuberculous mycobacteria (NTM). Interestingly, ≈90% of the Mycobacterium tuberculosis (Mtb) infected population restrain the bacilli on its own, which strengthens the notion of empowering the host immune system to advance the protective efficacy of existing mycobacterial vaccines. In general, Mtb modulates IL-10/STAT3 signaling to skew host mononuclear phagocytes toward an alternatively activated, anti-inflammatory state that helps it thrive against hostile immune advances. We hypothesized that modulating the IL-10/STAT3 driven anti-inflammatory effects in mononuclear cells may improve the prophylactic ability of TB vaccines. This study investigated the immunotherapeutic ability of a porphyrin based small molecule inhibitor of IL-10/STAT3 axis, 5, 15-diphenyl porphyrin (DPP), in improving anti-TB immunity offered by second generation recombinant BCG30 (rBCG30-ARMF-II®) vaccine in mice. The DPP therapy potentiated vaccine induced anti-TB immunity by down-modulating anti-inflammatory responses, while simultaneously up-regulating pro-inflammatory immune effector responses in the immunized host. The employed DPP based immunotherapy led to the predominant activation/proliferation of pro-inflammatory monocytes/macrophages/DCs, the concerted expansion of CD4+/CD8+ effector and central memory T cells, alongside balanced Th17 and Treg cell amplification, and conferred augmented resistance to aerosol Mtb challenge in rBCG30 immunized BALB/c mice.