Immunotherapy with plasmid DNA encoding mycobacterial hsp65 in association with chemotherapy is a more rapid and efficient form of treatment for tuberculosis in mice

Safety and Immunogenicity of an In Vivo Muscle Electroporation Delivery System for DNA-hsp65 Tuberculosis Vaccine in Cynomolgus Monkeys

A Bacille Calmette-Guérin (BCG) is still the only licensed vaccine for the prevention of tuberculosis, providing limited protection against Mycobacterium tuberculosis infection in adulthood. New advances in the delivery of DNA vaccines by electroporation have been made in the past decade. We evaluated the safety and immunogenicity of the DNA-hsp65 vaccine administered by intramuscular electroporation (EP) in cynomolgus macaques. Animals received three doses of DNA-hsp65 at 30-day intervals. We demonstrated that intramuscular electroporated DNA-hsp65 vaccine immunization of cynomolgus macaques was safe, and there were no vaccine-related effects on hematological, renal, or hepatic profiles, compared to the pre-vaccination parameters. No tuberculin skin test conversion nor lung X-ray alteration was identified. Further, low and transient peripheral cellular immune response and cytokine expression were observed, primarily after the third dose of the DNA-hsp65 vaccine. Electroporated DNA-hsp65 vaccination is safe but provides limited enhancement of peripheral cellular immune responses. Preclinical vaccine trials with DNA-hsp65 delivered via EP may include a combination of plasmid cytokine adjuvant and/or protein prime-boost regimen, to help the induction of a stronger cellular immune response.

Recent Advances in Genomics-Based Approaches for the Development of Intracellular Bacterial Pathogen Vaccines

Infectious diseases continue to be a leading cause of morbidity and mortality worldwide. The majority of infectious diseases are caused by intracellular pathogenic bacteria (IPB). Historically, conventional vaccination drives have helped control the pathogenesis of intracellular bacteria and the emergence of antimicrobial resistance, saving millions of lives. However, in light of various limitations, many diseases that involve IPB still do not have adequate vaccines. In response to increasing demand for novel vaccine development strategies, a new area of vaccine research emerged following the advent of genomics technology, which changed the paradigm of vaccine development by utilizing the complete genomic data of microorganisms against them. It became possible to identify genes related to disease virulence, genetic patterns linked to disease virulence, as well as the genetic components that supported immunity and favorable vaccine responses. Complete genomic databases, and advancements in transcriptomics, metabolomics, structural genomics, proteomics, immunomics, pan-genomics, synthetic genomics, and population biology have allowed researchers to identify potential vaccine candidates and predict their effects in patients. New vaccines have been created against diseases for which previously there were no vaccines available, and existing vaccines have been improved. This review highlights the key issues and explores the evolution of vaccines. The increasing volume of IPB genomic data, and their application in novel genome-based techniques for vaccine development, were also examined, along with their characteristics, and the opportunities and obstacles involved. Critically, the application of genomics technology has helped researchers rapidly select and evaluate candidate antigens. Novel vaccines capable of addressing the limitations associated with conventional vaccines have been developed and pressing healthcare issues are being addressed.

Vaccination against Bacterial Infections: Challenges, Progress, and New Approaches with a Focus on Intracellular Bacteria

Many bacterial infections are major health problems worldwide, and treatment of many of these infectious diseases is becoming increasingly difficult due to the development of antibiotic resistance, which is a major threat. Prophylactic vaccines against these bacterial pathogens are urgently needed. This is also true for bacterial infections that are still neglected, even though they affect a large part of the world’s population, especially under poor hygienic conditions. One example is typhus, a life-threatening disease also known as “war plague” caused by Rickettsia prowazekii, which could potentially come back in a war situation such as the one in Ukraine. However, vaccination against bacterial infections is a challenge. In general, bacteria are much more complex organisms than viruses and as such are more difficult targets. Unlike comparatively simple viruses, bacteria possess a variety of antigens whose immunogenic potential is often unknown, and it is unclear which antigen can elicit a protective and long-lasting immune response. Several vaccines against extracellular bacteria have been developed in the past and are still used successfully today, e.g., vaccines against tetanus, pertussis, and diphtheria. However, while induction of antibody production is usually sufficient for protection against extracellular bacteria, vaccination against intracellular bacteria is much more difficult because effective defense against these pathogens requires T cell-mediated responses, particularly the activation of cytotoxic CD8+ T cells. These responses are usually not efficiently elicited by immunization with non-living whole cell antigens or subunit vaccines, so that other antigen delivery strategies are required. This review provides an overview of existing antibacterial vaccines and novel approaches to vaccination with a focus on immunization against intracellular bacteria.

Immunotherapeutic Activities of a DNA Plasmid Carrying the Mycobacterial hsp65 Gene (DNAhsp65)

DNA vaccines have become relevant subject matter, and efforts for their development have been increasing due to their potential as technology platforms applicable for prophylactic and therapeutic approaches for infectious diseases and for cancer treatment, allergies, and autoimmune diseases. This review aimed to summarize current knowledge about the plasmid DNA vaccine carrying the mycobacterial hsp65 gene (DNAhsp65), which demonstrates immunomodulatory and immunoregulatory properties of both the innate and adaptive immune systems. The possible mechanisms associated with the modulation and regulatory role of DNAhsp65 in the control of various conditions is also discussed.

Antibiotic Treatment Shapes the Antigenic Environment During Chronic TB Infection, Offering Novel Targets for Therapeutic Vaccination

The lengthy and complicated current regimen required to treat drug-susceptible tuberculosis (TB) reflects the ability of Mycobacterium tuberculosis (Mtb) to persist in host tissues. The stringent response pathway, governed by the dual (p)ppGpp synthetase/hydrolase, Rel_Mtb, is a major mechanism underlying Mtb persistence and antibiotic tolerance. In the current study, we addressed the hypothesis that Rel_Mtb is a “persistence antigen” presented during TB chemotherapy and that enhanced immunity to Rel_Mtb can enhance the tuberculocidal activity of the first-line anti-TB drug, isoniazid, which has reduced efficacy against Mtb persisters. C57BL/6 mice and Hartley guinea pigs were aerosol-infected with M. tuberculosis (Mtb) and, 4 weeks later, received either human-equivalent daily doses of isoniazid alone, or isoniazid in combination with a DNA vaccine targeting rel_Mtb. After isoniazid treatment, there was a significant reduction in dominant antigen ESAT6-reactive CD4⁺ or TB10.4-reactive CD8⁺ T cells in the lungs and spleens of mice. However, the total number of Rel_Mtb-reactive CD4⁺ T cells remained stable in mouse lungs and spleens, as did the number of Rel_Mtb-reactive CD8⁺T cells. Therapeutic vaccination with rel_Mtb DNA vaccine enhanced the activity of isoniazid in Mtb-infected C57BL/6 mice and guinea pigs. When treatment with isoniazid was discontinued, mice immunized with the rel_Mtb DNA vaccine showed a lower mean lung bacterial burden at relapse compared to the control group. Our work shows that antitubercular treatment shapes the antigenic environment, and that therapeutic vaccination targeting the Mtb stringent response may represent a novel approach to enhance immunity against Mtb persisters, with the ultimate goal of shortening curative TB treatment.

Immunotherapeutic potential of an N-formylated peptide of Listeria monocytogenes in experimental tuberculosis

Objective: The current therapeutic regimens for tuberculosis (TB) are complex and involve the prolonged use of multiple antibiotics with diverse side effects that lead to therapeutic failure and bacterial resistance. The standard appliance of immunotherapy may aid as a powerful tool to combat the ensuing threat of TB. We have earlier reported the immunotherapeutic potential of N-formylated peptides of two secretory proteins of Mycobacterium tuberculosis H₃₇Rv. Here, we investigated the immunotherapeutic effect of an N-formylated peptide from Listeria monocytogenes in experimental TB. Methods: The N-terminally formylated listerial peptide with amino acid sequence 'f-MIGWII' was tested for its adjunctive therapeutic efficacy in combination with anti-tuberculosis drugs (ATDs) in the mouse model of TB. In addition, its potential to generate reactive oxygen species (ROS) in murine neutrophils was also evaluated. Results: The LemA peptide (f-MIGWII) induced a significant increase in the intracellular ROS levels of mouse neutrophils (p ≤ .05). The ATD treatment reduced the colony forming units (CFU) in lungs and spleen of infected mice by 2.39 and 1.67 log₁₀ units, respectively (p < .001). Treatment of the infected mice with combination of ATDs and LemA peptide elicited higher therapeutic efficacy over ATDs alone. The histopathological changes in the lungs of infected mice also correlated well with the CFU data. Conclusions: Our results clearly indicate that LemA peptide conferred an additional therapeutic effect when given in combination with the ATDss (p < .01) and hence can be used as adjunct to the conventional chemotherapy against TB.

Nanoparticle Vaccines Against Infectious Diseases

Due to emergence of new variants of pathogenic micro-organisms the treatment and immunization of infectious diseases have become a great challenge in the past few years. In the context of vaccine development remarkable efforts have been made to develop new vaccines and also to improve the efficacy of existing vaccines against specific diseases. To date, some vaccines are developed from protein subunits or killed pathogens, whilst several vaccines are based on live-attenuated organisms, which carry the risk of regaining their pathogenicity under certain immunocompromised conditions. To avoid this, the development of risk-free effective vaccines in conjunction with adequate delivery systems are considered as an imperative need to obtain desired humoral and cell-mediated immunity against infectious diseases. In the last several years, the use of nanoparticle-based vaccines has received a great attention to improve vaccine efficacy, immunization strategies, and targeted delivery to achieve desired immune responses at the cellular level. To improve vaccine efficacy, these nanocarriers should protect the antigens from premature proteolytic degradation, facilitate antigen uptake and processing by antigen presenting cells, control release, and should be safe for human use. Nanocarriers composed of lipids, proteins, metals or polymers have already been used to attain some of these attributes. In this context, several physico-chemical properties of nanoparticles play an important role in the determination of vaccine efficacy. This review article focuses on the applications of nanocarrier-based vaccine formulations and the strategies used for the functionalization of nanoparticles to accomplish efficient delivery of vaccines in order to induce desired host immunity against infectious diseases.

Mycobacterium tuberculosis GroEL2 Modulates Dendritic Cell Responses

Mycobacterium tuberculosis successfully subverts the host immune response to promote disease progression. In addition to its known intracellular niche in macrophages, M. tuberculosis interferes with the functions of dendritic cells (DCs), which are the primary antigen-presenting cells of the immune system. We previously showed that M. tuberculosis dampens proinflammatory responses and impairs DC functions through the cell envelope-associated serine protease Hip1. Here we present data showing that M. tuberculosis GroEL2, a substrate of Hip1, modulates DC functions. The full-length GroEL2 protein elicited robust proinflammatory responses from DCs and promoted DC maturation and antigen presentation to T cells. In contrast, the cleaved form of GroEL2, which predominates in M. tuberculosis, was poorly immunostimulatory and was unable to promote DC maturation and antigen presentation. Moreover, DCs exposed to full-length, but not cleaved, GroEL2 induced strong antigen-specific gamma interferon (IFN-γ), interleukin-2 (IL-2), and IL-17A cytokine responses from CD4⁺ T cells. Moreover, the expression of cleaved GroEL2 in the hip1 mutant restored the robust T cell responses to wild-type levels, suggesting that proteolytic cleavage of GroEL2 allows M. tuberculosis to prevent optimal DC-T cell cross talk during M. tuberculosis infection.

No Evidence of Pathological Autoimmunity following Mycobacterium Leprae Heat-Shock Protein 65-Dna Vaccination in Mice

Heat-shock proteins (HSPs) are currently one of the most promising targets for the development of immunotherapy against tumours and autoimmune disorders. This protein family has the capacity to activate or modulate the function of different immune system cells. They induce the activation of monocytes, macrophages and dendritic cells, and contribute to cross-priming, an important mechanism of presentation of exogenous antigen in the context of MHC class I molecules. These various immunological properties of HSP have encouraged their use in several clinical trials. Nevertheless, an important issue regarding these proteins is whether the high homology among HSPs across different species may trigger the breakdown of immune tolerance and induce autoimmune diseases. We have developed a DNA vaccine codifying the Mycobacterium leprae Hsp65 (DNAhsp65), which showed to be highly immunogenic and protective against experimental tuberculosis. Here, we address the question of whether DNAhsp65 immunization could induce pathological autoimmunity in mice. Our results show that DNAhsp65 vaccination induced antibodies that can recognize the human Hsp60 but did not induce harmful effects in 16 different organs analysed by histopathology up to 210 days after vaccination. We also showed that anti-DNA antibodies were not elicited after DNA vaccination. The results are important for the development of both HSP and DNA-based immunomodulatory agents.

Efficacy and Safety of Mycobacterium indicus pranii as an adjunct therapy in Category II pulmonary tuberculosis in a randomized trial

Prolonged treatment of tuberculosis (TB) often leads to poor compliance, default and relapse, converting primary TB patients into category II TB (Cat IITB) cases, many of whom may convert to multi-drug resistant TB (MDR-TB). We have evaluated the immunotherapeutic potential of Mycobacterium indicus pranii (MIP) as an adjunct to Anti-Tubercular Treatment (ATT) in Cat II pulmonary TB (PTB) patients in a prospective, randomized, double blind, placebo controlled, multicentric clinical trial. 890 sputum smear positive Cat II PTB patients were randomized to receive either six intra-dermal injections (2 + 4) of heat-killed MIP at a dose of 5 × 10⁸ bacilli or placebo once in 2 weeks for 2 months. Sputum smear and culture examinations were performed at different time points. MIP was safe with no adverse effects. While sputum smear conversion did not show any statistically significant difference, significantly higher number of patients (67.1%) in the MIP group achieved sputum culture conversion at fourth week compared to the placebo (57%) group (p = 0.0002), suggesting a role of MIP in clearance of the bacilli. Since live bacteria are the major contributors for sustained incidence of TB, the potential of MIP in clearance of the bacilli has far reaching implications in controlling the spread of the disease.

Stringent Response Factors PPX1 and PPK2 Play an Important Role in Mycobacterium tuberculosis Metabolism, Biofilm Formation, and Sensitivity to Isoniazid In Vivo

Mycobacterium tuberculosis remains a global health threat largely due to the lengthy duration of curative antibiotic treatment, contributing to medical nonadherence and the emergence of drug resistance. This prolonged therapy is likely due to the presence of M. tuberculosis persisters, which exhibit antibiotic tolerance. Inorganic polyphosphate [poly(P)] is a key regulatory molecule in the M. tuberculosis stringent response mediating antibiotic tolerance. The polyphosphate kinase PPK1 is responsible for poly(P) synthesis in M. tuberculosis, while the exopolyphosphatases PPX1 and PPX2 and the GTP synthase PPK2 are responsible for poly(P) hydrolysis. In the present study, we show by liquid chromatography-tandem mass spectrometry that poly(P)-accumulating M. tuberculosis mutant strains deficient in ppx1 or ppk2 had significantly lower intracellular levels of glycerol-3-phosphate (G3P) and 1-deoxy-xylulose-5-phosphate. Real-time PCR revealed decreased expression of genes in the G3P synthesis pathway in each mutant. The ppx1-deficient mutant also showed a significant accumulation of metabolites in the tricarboxylic acid cycle, as well as altered arginine and NADH metabolism. Each poly(P)-accumulating strain showed defective biofilm formation, while deficiency of ppk2 was associated with increased sensitivity to plumbagin and meropenem and deficiency of ppx1 led to enhanced susceptibility to clofazimine. A DNA vaccine expressing ppx1 and ppk2, together with two other members of the M. tuberculosis stringent response, M. tuberculosis rel and sigE, did not show protective activity against aerosol challenge with M. tuberculosis, but vaccine-induced immunity enhanced the killing activity of isoniazid in a murine model of chronic tuberculosis. In summary, poly(P)-regulating factors of the M. tuberculosis stringent response play an important role in M. tuberculosis metabolism, biofilm formation, and antibiotic sensitivity in vivo.

Ag85A/ESAT-6 chimeric DNA vaccine induces an adverse response in tuberculosis-infected mice

The Mycobacterium tuberculosis (M. tb) antigens encoded by the 6 kDa early secretory antigenic target (esat-6) and antigen 85A (ag85a) genes are known to exert protective effects against tuberculosis in animal models. In addition, these antigens represent vaccine components that were tested in early human clinical trials. In the present study, a chimeric DNA vaccine was constructed that contained two copies of the esat-6 gene inserted into the ag85a gene from M. tb. BALB/c mice were treated with this chimeric vaccine following infection with either M. tb H37Rv or a clinical multi drug resistant tuberculosis isolate. Treatment of both groups of mice with the chimeric vaccine resulted in accelerated mortality. These findings are in contrast with previous results, which indicated that DNA vaccines expressing the individual antigens were either beneficial or at least not harmful. The results of the present study suggested that the ESAT-6 antigen is not suitable for inclusion in therapeutic vaccines.

Immunogenicity without Efficacy of an Adenoviral Tuberculosis Vaccine in a Stringent Mouse Model for Immunotherapy during Treatment

To investigate if bacterial persistence during TB drug treatment could be overcome by modulation of host immunity, we adapted a clinically-relevant model developed for the evaluation of new drugs and examined if immunotherapy with two adenoviral vaccines, Ad35-TBS (AERAS-402) and Ad26-TBS, could shorten therapy in mice. Even though immunotherapy resulted in strong splenic IFN-γ responses, no effect on bacterial replication in the lungs was seen. Multiplex assay analysis of lung samples revealed the absence of cytokine augmentation such as IFN-γ, TNF-α and IL-2, suggesting that immunization failed to induce immunity in the lungs. In this model, we show that IFN-γ levels were not associated with protection against disease relapse. The results obtained from our study raise questions regarding the traits of protective TB immunity that are relevant for the development of future immunotherapeutic and post-exposure vaccination strategies.

Synergy of chemotherapy and immunotherapy revealed by a genome-scale analysis of murine tuberculosis

OBJECTIVES

Although TB immunotherapy improves the results of conventional drug treatment, the effects of combining chemotherapy and immunotherapy have never been systematically evaluated. We used a comprehensive lung transcriptome analysis to directly compare the activity of combined chemotherapy and immunotherapy with that of single treatments in a mouse model of TB.

METHODS

Mycobacterium tuberculosis-infected mice in the chronic phase of the disease (day 30) received: (i) isoniazid and rifampicin (drugs) daily for 30 days; (ii) DNA immunotherapy (DNA), consisting of four 100 μg injections at 10 day intervals; (iii) both therapies (DNA + drugs); or (iv) saline. The effects were evaluated 10 days after the end of treatment (day 70 post-infection).

RESULTS

In all groups a systemic reduction in the load of bacilli was observed, bacilli became undetectable in the drugs and DNA + drugs groups, but the whole lung transcriptome analysis showed 867 genes exclusively modulated by the DNA + drugs combination. Gene enrichment analysis indicated that DNA + drugs treatment provided synergistic effects, including the down-regulation of proinflammatory cytokines and mediators of fibrosis, as confirmed by real-time PCR, ELISA, histopathology and hydroxyproline assay.

CONCLUSIONS

Our results provide a molecular basis for the advantages of TB treatment using combined chemotherapy and DNA immunotherapy and demonstrate the synergistic effects obtained with this strategy.

Adjunctive immunotherapy with α-crystallin based DNA vaccination reduces Tuberculosis chemotherapy period in chronically infected mice

By employing modified Cornell model, we have evaluated the potential of adjunctive immunotherapy with DNA vaccines to shorten the tuberculosis chemotherapy period and reduce disease reactivation. We demonstrate that α-crystallin based DNA vaccine (DNAacr) significantly reduced the chemotherapy period from 12 weeks to 8 weeks when compared with the chemotherapy alone. Immunotherapy with SodA based DNA vaccine (DNAsod) reduced the pulmonary bacilli only as much as DNAvec. Both DNAacr and DNAsod, although significantly delayed the reactivation in comparison to the chemotherapy alone, this delay was associated with the immunostimulatory sequences present in the vector backbone and was not antigen specific. Both DNA vaccines resulted in the production of significantly higher number of T_EM cells than the chemotherapy alone, however, only in the case of DNAsod, this enhancement was significant over the DNAvec treatment. Overall, our findings emphasize the immunotherapeutic potential of DNAacr in shortening the duration of TB chemotherapy.

Combined immunization using DNA-Sm14 and DNA-Hsp65 increases CD8+ memory T cells, reduces chronic pathology and decreases egg viability during Schistosoma mansoni infection

BACKGROUND

Schistosomiasis is one of the most important neglected diseases found in developing countries and affects 249 million people worldwide. The development of an efficient vaccination strategy is essential for the control of this disease. Previous work showed partial protection induced by DNA-Sm14 against Schistosoma mansoni infection, whereas DNA-Hsp65 showed immunostimulatory properties against infectious diseases, autoimmune diseases, cancer and antifibrotic properties in an egg-induced granuloma model.

METHODS

C57BL/6 mice received 4 doses of DNA-Sm14 (100 μg/dose) and DNA-Hsp65 (100 μg/dose), simultaneously administrated, or DNA-Sm14 alone, once a week, during four weeks. Three groups were included: 1- Control (no immunization); 2- DNA-Sm14; 3- DNA-Sm14/DNA-Hsp65. Two weeks following last immunization, animals were challenged subcutaneously with 30 cercariae. Fifteen, 48 and 69 days after infection splenocytes were collected to evaluate the number of CD8+ memory T cells (CD44(high)CD62(low)) using flow cytometry. Forty-eight days after challenge adult worms were collected by portal veins perfusion and intestines were collected to analyze the intestinal egg viability. Histological, immunohistochemical and soluble quantification of collagen and α-SMA accumulation were performed on the liver.

RESULTS

In the current work, we tested a new vaccination strategy using DNA-Sm14 with DNA-Hsp65 to potentiate the protection against schistosomiasis. Combined vaccination increased the number of CD8+ memory T cells and decreased egg viability on the intestinal wall of infected mice. In addition, simultaneous vaccination with DNA-Sm14/DNA-Hsp65 reduced collagen and α-SMA accumulation during the chronic phase of granuloma formation.

CONCLUSION

Simultaneous vaccination with DNA-Sm14/DNA-Hsp65 showed an immunostimulatory potential and antifibrotic property that is associated with the reduction of tissue damage on Schistosoma mansoni experimental infection.

Downmodulation of peripheral MOG-specific immunity by pVAXhsp65 treatment during EAE does not reach the CNS

Most of the therapeutic strategies to control multiple sclerosis are directed to immune modulation and inflammation control. As heat shock proteins are able to induce immunoregulatory T cells, we investigated the therapeutic effect of a genetic vaccine containing the mycobacterial hsp65 gene on experimental autoimmune encephalomyelitis (EAE). Although pVAXhsp65 was immunogenic for mice with EAE and downmodulated specific cytokine induction by MOG, therapy was not able to decrease clinical severity nor to modify immunologic parameters in the CNS. These results indicate that hsp65, administered as a DNA vaccine, was not therapeutic for EAE.

Immunotherapeutic potential of recombinant ESAT-6 protein in mouse model of experimental tuberculosis

Recent understanding of the pathogenesis of tuberculosis allows the possible application of immunotherapy for the treatment of tuberculosis. Therapies that would upregulate the host antimycobacterial immune response and/or attenuate T-cell suppressive and macrophage-deactivating cytokines may prove to be useful in the treatment of tuberculosis. ESAT6, 6-kDa early secreted antigenic target, is a potent protective antigen and is considered as major target for long-lived memory cells. In the present study the immunotherapeutic potential of ESAT-6 has been evaluated in mouse model of experimental tuberculosis. In the present study the ESAT-6 protein was cloned in Escherichia coli using pET23a(+) plasmid and purified by Ni(2+)-NTA chromatography. Further, the immunotherapeutic potential of the recombinant ESAT-6 (in terms of CFU enumeration in the target organs and histopathological analysis of lungs) was evaluated against experimental tuberculosis. The recombinant ESAT-6 with C-terminal histidine-tag and free N-terminus mimics the natural form of ESAT-6 has been successfully cloned and purified. The recombinant ESAT-6 protein adjuvanted with dimethyl dioctadecylammonium bromide (DDA) moderately reduced the bacterial load in the target organs of infected mice. Further, the formulation (ESAT-6-DDA) was able to act synergistically when given in combination with antituberculosis drugs. This recombinant ESAT-6 showed good immunotherapeutic potential against experimental tuberculosis and can be used as an adjunct to the conventional antituberculosis chemotherapy.

Immunotherapeutic efficacy of recombinant Mycobacterium smegmatis expressing Ag85B-ESAT6 fusion protein against persistent tuberculosis infection in mice

The application of immunotherapy in combination with chemotherapy is considered an effective treatment strategy against persistent Mycobacterium tuberculosis (Mtb) infection. In this study, we constructed a novel recombinant Mycobacterium smegmatis (rMS) strain that expresses Ag85B and ESAT6 fusion protein (AE-rMS). Immunization of C57BL/6 mice with AE-rMS generated mainly Th1-type immune responses by strongly stimulating IFN-γ- and IL-2-producing splenocytes and increasing antigen-specific cytotoxic T lymphocyte (CTL) activity. To test the immunotherapeutic efficacy of AE-rMS, a persistent tuberculosis infection (PTBI) model was established via tail-vein injection of C57BL/6 mice with 1×10(4) colony forming units (CFU) of Mtb strain H37Rv in combination with concurrent chemotherapy drugs isoniazid (INH) and pyrazinamide (PZA). PTBI mice immunized with AE-rMS showed high levels of IFN-γ secreted by splenocytes and decreased bacteria loads in lung. Treatment with only the anti-tuberculosis (anti-TB) drugs RFP and INH (RI), decreased bacteria loads to low levels, with the Th1-type immune response further attenuated. Moreover, AE-rMS, when combined with RI treatment, further reduced the bacteria load as well as the pathological tissue damage in lung. Together, these results demonstrated the essential roles of AE-rMS-induced Th1-type responses, providing an effective treatment strategy by combining AE-rMS and RI for persistent TB.

Heat shock proteins: stimulators of innate and acquired immunity

Adjuvants were reintroduced into modern immunology as the dirty little secret of immunologists by Janeway and thus began the molecular definition of innate immunity. It is now clear that the binding of pathogen-associated molecular patterns (PAMPs) by pattern recognition receptors (PRRs) on antigen presenting cells (APCs) activates the innate immune response and provides the host with a rapid mechanism for detecting infection by pathogens and initiates adaptive immunity. Ironically, in addition to advancing the basic science of immunology, Janeway's revelation on induction of the adaptive system has also spurred an era of rational vaccine design that exploits PRRs. Thus, defined PAMPs that bind to known PRRs are being specifically coupled to antigens to improve their immunogenicity. However, while PAMPs efficiently activate the innate immune response, they do not mediate the capture of antigen that is required to elicit the specific responses of the acquired immune system. Heat shock proteins (HSPs) are molecular chaperones that are found complexed to client polypeptides and have been studied as potential cancer vaccines. In addition to binding PRRs and activating the innate immune response, HSPs have been shown to both induce the maturation of APCs and provide chaperoned polypeptides for specific triggering of the acquired immune response.

DNA-hsp65 vaccine as therapeutic strategy to treat experimental chromoblastomycosis caused by Fonsecaea pedrosoi

Chromoblastomycosis (CBM) is a chronic subcutaneous mycosis, caused by several dimorphic, pigmented dematiaceous fungi. Patients with the disease are still considered a therapeutic challenge, mainly due to its recalcitrant nature. There is no "gold standard" treatment for this neglected mycosis, but rather there are several treatment options. Chemotherapy alternatives include 5-flucytosine, itraconazole, terbinafine, fluconazole, thiabendazole, ketoconazole and amphotericin B, although the healing of severe cases is still uncommon. However, several studies have reported the DNA vaccine to be promising in the treatment for fungal infections; this vaccine allows the host to restore depressed cellular immunity, minimizing the toxic effects from conventional antifungal therapies. This work was therefore carried out aiming to establish a suitable model for experimental CBM, suggesting also new therapies, including DNA-hsp65 vaccine. By analyzing the morphometrical and histopathological aspects and by quantifying the fungal burden, the results showed the establishment of a chronic, although transitory, experimental CBM model with lesions similar to those presented in humans. A treatment regimen using intralesional itraconazole or amphotericin B was effective in treating experimental CBM, as was a therapy using naked DNA-hsp65 vaccine. It has also been shown that chemotherapy associated with DNA-hsp65 vaccine is promising in the treatment for CBM.

Efficacy of Mycobacterium indicus pranii immunotherapy as an adjunct to chemotherapy for tuberculosis and underlying immune responses in the lung

BACKGROUND

The 9-month-long chemotherapy of tuberculosis often results in poor compliance and emergence of drug-resistant strains. So, improved therapeutic strategy is urgently needed. Immunotherapy could be beneficial for the effective management of the disease. Previously we showed the protective efficacy of Mycobacterium indicus pranii (MIP) when given as prophylactic vaccine in animal models of tuberculosis.

METHODS

We sought to investigate whether MIP can be used as an adjunct to the chemotherapy in guinea pig models of tuberculosis. Efficacy of MIP was evaluated when given subcutaneously or by aerosol.

RESULTS

MIP-therapy as an adjunct to the chemotherapy was found to be effective in accelerating bacterial killing and improving organ pathology. MIP-immunotherapy resulted in higher numbers of activated antigen-presenting cells and lymphocytes in the infected lungs and also modulated the granulomatous response. Early increase in protective Th1 immune response was observed in the immunotherapy group. Following subsequent doses of MIP, decrease in the inflammatory response and increase in the immunosuppressive response was observed, which resulted in the improvement of lung pathology.

CONCLUSION

MIP immunotherapy is a valuable adjunct to chemotherapy for tuberculosis. Aerosol route of immunotherapy can play a crucial role for inducing immediate local immune response in the lung.

Immunotherapy for TB

Mycobacterium tuberculosis was one of the first human pathogens to be identified as the cause of a specific disease – TB. TB was also one of the first specific diseases for which immunotherapy was attempted. In more than a century since, multiple different immunotherapies have been attempted, alongside vaccination and antibiotic treatment, with varying degrees of success. Despite this, TB remains a major worldwide health problem that causes nearly 2 million deaths annually and has infected an estimated 2 billion people. A major reason for this is that M. tuberculosis is an ancient human pathogen that has evolved complex strategies for persistence in the human host. It has thus been long understood that, to effectively control TB, we will need to address the ability of the pathogen to establish a persistent, latent infection in most infected individuals. This review discusses what is presently known about the interaction of M. tuberculosis with the immune system, and how this knowledge has been used to design immunotherapeutic strategies.

Attempted immunotherapy for Mycobacterium tuberculosis with viral and protein vaccines based on Ag85B-ESAT6 in a mouse model

The increasing threat of drug-resistant strains of Mycobacterium tuberculosis (M. tb) and co-infection with human immunodeficiency virus (HIV) has worsened the international public health crisis and challenged conventional chemotherapy. Therapeutic vaccines, which possess the capacity to stimulate the immune system and affect the disease progression, deserve reconsideration to aid chemotherapy. Vaccines based on Ag85B-ESAT6 fusion protein were tested as potential immunotherapeutic vaccines against ongoing intravenous infection in a mouse model. Therapeutic efficacy was evaluated by enumeration of bacilli in infected tissues and by histological examination of the lungs. Ag85B-ESAT6 with the adjuvant dimethyl dioctadecylammonium bromide (DDA) - monophosphoryl lipid A (MPL) did not reduce bacterial load, however induced a sharp weight loss and worsened pathology. Recombinant virus-based vaccines failed to protect mice against tuberculosis either. More efforts should be taken to search for protective candidates and elucidate the mechanism for immunotherapy.

Protective and therapeutic efficacy of Mycobacterium smegmatis expressing HBHA-hIL12 fusion protein against Mycobacterium tuberculosis in mice

Tuberculosis (TB) remains a major worldwide health problem. The only vaccine against TB, Mycobacterium bovis Bacille Calmette-Guerin (BCG), has demonstrated relatively low efficacy and does not provide satisfactory protection against the disease. More efficient vaccines and improved therapies are urgently needed to decrease the worldwide spread and burden of TB, and use of a viable, metabolizing mycobacteria vaccine may be a promising strategy against the disease. Here, we constructed a recombinant Mycobacterium smegmatis (rMS) strain expressing a fusion protein of heparin-binding hemagglutinin (HBHA) and human interleukin 12 (hIL-12). Immune responses induced by the rMS in mice and protection against Mycobacterium tuberculosis (MTB) were investigated. Administration of this novel rMS enhanced Th1-type cellular responses (IFN-γ and IL-2) in mice and reduced bacterial burden in lungs as well as that achieved by BCG vaccination. Meanwhile, the bacteria load in M. tuberculosis infected mice treated with the rMS vaccine also was significantly reduced. In conclusion, the rMS strain expressing the HBHA and human IL-12 fusion protein enhanced immunogencity by improving the Th1-type response against TB, and the protective effect was equivalent to that of the conventional BCG vaccine in mice. Furthermore, it could decrease bacterial load and alleviate histopathological damage in lungs of M. tuberculosis infected mice.

Molecular characterization of the Corynebacterium pseudotuberculosis hsp60-hsp10 operon, and evaluation of the immune response and protective efficacy induced by hsp60 DNA vaccination in mice

Background

Heat shock proteins (HSPs) are important candidates for the development of vaccines because they are usually able to promote both humoral and cellular immune responses in mammals. We identified and characterized the hsp60-hsp10 bicistronic operon of the animal pathogen Corynebacterium pseudotuberculosis, a Gram-positive bacterium of the class Actinobacteria, which causes caseous lymphadenitis (CLA) in small ruminants.

Findings

To construct the DNA vaccine, the hsp60 gene of C. pseudotuberculosis was cloned in a mammalian expression vector. BALB/c mice were immunized by intramuscular injection with the recombinant plasmid (pVAX1/hsp60).

Conclusion

This vaccination induced significant anti-hsp60 IgG, IgG1 and IgG2a isotype production. However, immunization with this DNA vaccine did not confer protective immunity.

Immunotherapeutic role of Ag85B as an adjunct to antituberculous chemotherapy

BACKGROUND

Immunotherapy to enhance the efficiency of the immune response in tuberculosis patients and to eliminate the persisters could be an additional valuable strategy to complement anti-mycobacterial chemotherapy. This study was designed to assess the immunotherapeutic potential of Ag85B as an adjunct to chemotherapy and its effect against active and persister bacteria left after therapy in mouse model of tuberculosis.

METHODS

6-8 week old female Balb/c mice were infected with Mycobacterium tuberculosis and treated with chemotherapy or immunotherapy. Protective efficacy was measured in terms of bacterial counts in lungs and spleen. Immune correlates of protection in terms of Th1 and Th2 cytokines were measured by ELISA.

RESULTS

Therapeutic effect of Ag85B was found to be comparable to that of short term dosage of antituberculous drugs (ATDs). The therapeutic effect of ATDs was augmented by the simultaneous treatment with rAg85B and moreover therapy with this protein allowed us to reduce ATD dosage. This therapy was found to be effective even in case of drug persisters. The levels of antigen specific IFNγ and IL-12 were significantly increased after immunotherapy as compared to the basal levels; moreover antigen specific IL-4 levels were depressed on immunotherapy with Ag85B.

CONCLUSION

We demonstrated in this study that the new combination approach using immunotherapy and concurrent chemotherapy should offer several improvements over the existing regimens to treat tuberculosis. The therapeutic effect is associated not only with initiating a Th1 response but also with switching the insufficient Th2 immune status to the more protective Th1 response.

Therapeutic DNA vaccine reduces schistosoma mansoni-induced tissue damage through cytokine balance and decreased migration of myofibroblasts

Helminths are known to elicit a wide range of immunomodulation characterized by dominant Th2-type immune responses. Our group previously showed that a DNA vaccine encoding the mycobacterial 65-kDa heat shock protein (DNA-hsp65) showed immunomodulatory properties. We also showed, using a helminth-tuberculosis (TB) co-infection model, that the DNA-hsp65 vaccine protected mice against TB. We next investigated the mechanistic role of the vaccine during helminth-TB co-infection. Clinically, helminth infection causes type 2 granulomas in the lung. Mice were immunized with DNA-hsp65 while they were submitted to the type 2 granuloma induction protocol by Schistosoma mansoni eggs infusion. In this work we investigated the effects of DNA-hsp65 on the pathology and immune response during the development of type 2 granuloma induced by S. mansoni eggs. Histologic analyses of lung parenchyma showed that the DNA-hsp65 vaccine protected mice against exacerbated fibrosis induced by Schistosoma eggs, and decreased the size of the granulomas. These changes were correlated with a reduction in the number of T cells specific for the egg antigens in the lung and also with modulation of Th2 cytokine expression. Taken together, our results showed that the adjuvant properties of the DNA-hsp65 vaccine regulated the immune response in this Th2 model, and resulted in a preserved lung parenchyma.

Adjunct immunotherapy with Ag85 complex proteins based subunit vaccine in a murine model of Mycobacterium tuberculosis infection

This study was designed to evaluate the immunotherapeutic potential of Mycobacterium tuberculosis Ag85AB emulsified with unmethylated CpG motif-containing oligonucleotide (CpG-ODN) and dimethyldioctadecylammonium bromide (DDA) adjuvants (Ag85AB-CpG-DDA) in conjunction with antituberculous drugs. Ag85 complex proteins of M. tuberculosis purified from total culture filtrate and purified proteins were emulsified with CpG-ODN and DDA adjuvants. Mice were infected with M. tuberculosis H37 Rv and left for 30 days to establish infection. These mice were named 'tuberculous mice'. Tuberculous mice were treated with Ag85AB-CpG-DDA alone or in conjunction with antituberculous drugs. Treatment of tuberculous mice with Ag85AB-CpG-DDA in conjunction with antituberculous drugs reduced significant bacilli burden in lung and spleen. Moreover, treatment of tuberculous mice with Ag85AB-CpG-DDA induced higher production of type-I cytokines, generated more CD44-positive T cells and suppresses secretion of IL-4 as compared with untreated animals. In conclusion, this study shows that Ag85AB-CpG-DDA formulation may act as a potential future therapeutic regimen in conjunction with antituberculous drugs.

CCL2, CCL18 and sIL-4R in renal, meningeal and pulmonary TB; a 2 year study of patients and contacts

The role of Th2 cytokines and Th2-associated chemokines in tuberculosis (TB) remains controversial, though in Mexico a polymorphism causing increased production of CCL2 is a risk factor. We studied levels of the Th2-associated chemokines CCL2 and CCL18, circulating soluble IL-4 receptors (sIL-4R), IL-4 and the inhibitory splice variant of IL-4 (IL-4δ2) in a cohort of patients with pulmonary TB and their healthy contacts. These were followed for 2 years during which time 10 contacts developed pulmonary TB. Results were compared with measurements made in renal and meningeal TB, and in disease controls with bacterial pneumonias or Dengue fever that have large Th2 components. In these disease controls both chemokines were significantly raised. They were also very significantly raised in all forms of TB, irrespective of age or disease site. Levels of CCL18 were raised least in meningeal TB, and most in pulmonary patients with long histories, when levels were similar to those in disease controls. Levels of CCL2, although also raised in all three forms of TB, were negatively correlated with CCL18. We found that levels of sIL-4R were strikingly reduced in all forms of TB, particularly meningeal. Contacts who progressed could not be distinguished from contacts who remained healthy at 2 years in terms of IL-4, sIL-4R, CCL2 or CCL18. However contacts had raised expression of IL-4δ2 as previously found. These results indicate vigorous and previously unrecorded activity within the Th2 axis, and further investigation is warranted.

The impact of transcriptomics on the fight against tuberculosis: focus on biomarkers, BCG vaccination, and immunotherapy

In 1882 Robert Koch identified Mycobacterium tuberculosis as the causative agent of tuberculosis (TB), a disease as ancient as humanity. Although there has been more than 125 years of scientific effort aimed at understanding the disease, serious problems in TB persist that contribute to the estimated 1/3 of the world population infected with this pathogen. Nonetheless, during the first decade of the 21st century, there were new advances in the fight against TB. The development of high-throughput technologies is one of the major contributors to this advance, because it allows for a global vision of the biological phenomenon. This paper analyzes how transcriptomics are supporting the translation of basic research into therapies by resolving three key issues in the fight against TB: (a) the discovery of biomarkers, (b) the explanation of the variability of protection conferred by BCG vaccination, and (c) the development of new immunotherapeutic strategies to treat TB.

Intranasal vaccination with messenger RNA as a new approach in gene therapy: use against tuberculosis

BACKGROUND

mRNAs are highly versatile, non-toxic molecules that are easy to produce and store, which can allow transient protein expression in all cell types. The safety aspects of mRNA-based treatments in gene therapy make this molecule one of the most promising active components of therapeutic or prophylactic methods. The use of mRNA as strategy for the stimulation of the immune system has been used mainly in current strategies for the cancer treatment but until now no one tested this molecule as vaccine for infectious disease.

RESULTS

We produce messenger RNA of Hsp65 protein from Mycobacterium leprae and show that vaccination of mice with a single dose of 10 μg of naked mRNA-Hsp65 through intranasal route was able to induce protection against subsequent challenge with virulent strain of Mycobacterium tuberculosis. Moreover it was shown that this immunization was associated with specific production of IL-10 and TNF-alpha in spleen. In order to determine if antigen presenting cells (APCs) present in the lung are capable of capture the mRNA, labeled mRNA-Hsp65 was administered by intranasal route and lung APCs were analyzed by flow cytometry. These experiments showed that after 30 minutes until 8 hours the populations of CD11c+, CD11b+ and CD19+ cells were able to capture the mRNA. We also demonstrated in vitro that mRNA-Hsp65 leads nitric oxide (NO) production through Toll-like receptor 7 (TLR7).

CONCLUSIONS

Taken together, our results showed a novel and efficient strategy to control experimental tuberculosis, besides opening novel perspectives for the use of mRNA in vaccines against infectious diseases and clarifying the mechanisms involved in the disease protection we noticed as well.

Helminth coinfection does not affect therapeutic effect of a DNA vaccine in mice harboring tuberculosis

Background

Helminthiasis and tuberculosis (TB) coincide geographically and there is much interest in exploring how concurrent worm infections might alter immune responses against bacilli and might necessitate altered therapeutic approaches. A DNA vaccine that codifies heat shock protein Hsp65 from M. leprae (DNAhsp65) has been used in therapy during experimental tuberculosis. This study focused on the impact of the co-existence of worms and TB on the therapeutic effects of DNAhsp65.

Methodology/Principal Findings

Mice were infected with Toxocara canis or with Schistosoma mansoni, followed by coinfection with M. tuberculosis and treatment with DNAhsp65. While T. canis infection did not increase vulnerability to pulmonary TB, S. mansoni enhanced susceptibility to TB as shown by higher numbers of bacteria in the lungs and spleen, which was associated with an increase in Th2 and regulatory cytokines. However, in coinfected mice, the therapeutic effect of DNAhsp65 was not abrogated, as indicated by colony forming units and analysis of histopathological changes. In vitro studies indicated that Hsp65-specific IFN-γ production was correlated with vaccine-induced protection in coinfected mice. Moreover, in S. mansoni-coinfected mice, DNA treatment inhibited in vivo TGF-β and IL-10 production, which could be associated with long-term protection.

Conclusions/Significance

We have demonstrated that the therapeutic effects of DNAhsp65 in experimental TB infection are persistent in the presence of an unrelated Th2 immune response induced by helminth infections.

From 14 diseases considered by WHO as Neglected Tropical Diseases, four involve helminth infections, such as schistosomiasis and soil-transmitted helminthiasis. Toxocariasis is a soil-transmitted worm highly prevalent in many developing countries, while schistosomiasis causes an annual mortality of 14,000 deaths per year, with 200–300 million infected people and 10% at risk of infection worldwide. Additionally, tuberculosis (TB) remains one of the leading causes of morbidity and mortality in many settings, particularly in the world's poorest countries. Mycobacteria and helminths are co-endemic and induce opposing patterns of immune responses in the host, recognized as Th1 and Th2 respectively. These co-existing patterns could be associated with the failure of TB vaccines. In this sense, we investigated the inflammatory and immune response in a coinfection model with T. canis or S. mansoni and M. tuberculosis analyzing the effects of an immunotherapy that has previously shown efficacy in experimental TB. This immunotherapy is based on a DNA vaccine that codifies a mycobacterial heat shock protein (hsp65), which can prevent TB in a prophylactic and also therapeutic setting. In this work, we show that helminth coinfection does not abrogate the therapeutic effects of DNAhsp65 vaccine against TB.

Evaluation of environmental mycobacteria contamination in a specific pathogen free animal facility from a tropical country

With the evidence showing the protection variability of bacille Calmette-Guérin, new potential vaccines for tuberculosis have been tested around the world. One of the general concerns in tuberculosis vaccine development is the possibility of priming the host immune system with prior exposure to environmental mycobacteria antigens, which can change the efficacy of subsequent vaccination. As there is a great homology between the species from Mycobacterium genera, the previous contact of experimental animals with environmental mycobacteria could sensitize the mice and, in this way, could influence subsequent vaccine research. The aim of our study was to investigate critical points in an animal facility to search for environmental mycobacteria that eventually could be in direct or indirect contact with the experimental animals. Samples were collected from surfaces of walls, floor, animal cages and shelves and analysed using the Ogawa-Kudoh decontamination method. Samples of drinking water, food and sawdust were collected for analysis by the NALC/NaOH decontamination method. Also, the samples were cultivated directly in broth medium, without any method for decontamination. After decontamination methods, we observed bacterial colony growth in 4.31% of the total of samples analysed. These samples were stained with Ziehl-Neelsen and we did not detect any acid-fast bacilli, suggesting that the animal facility analysed is free from contamination by environmental mycobacteria and is not a source of mycobacterial antigens. Furthermore, our study showed a new paradigm in tuberculosis vaccine development: concern about the animal facility environment in terms of immune system priming of experimental animals by nascent bacterial contaminants.

Comprehensive gene expression profiling in lungs of mice infected with Mycobacterium tuberculosis following DNAhsp65 immunotherapy

BACKGROUND

The continued increase in tuberculosis (TB) rates and the appearance of extremely resistant Mycobacterium tuberculosis strains (XDR-TB) worldwide are some of the great problems of public health. In this context, DNA immunotherapy has been proposed as an effective alternative that could circumvent the limitations of conventional drugs. Nonetheless, the molecular events underlying these therapeutic effects are poorly understood.

METHODS

We characterized the transcriptional signature of lungs from mice infected with M. tuberculosis and treated with heat shock protein 65 as a genetic vaccine (DNAhsp65) combining microarray and real-time polymerase chain reaction analysis. The gene expression data were correlated with the histopathological analysis of lungs.

RESULTS

The differential modulation of a high number of genes allowed us to distinguish DNAhsp65-treated from nontreated animals (saline and vector-injected mice). Functional analysis of this group of genes suggests that DNAhsp65 therapy could not only boost the T helper (Th)1 immune response, but also could inhibit Th2 cytokines and regulate the intensity of inflammation through fine tuning of gene expression of various genes, including those of interleukin-17, lymphotoxin A, tumour necrosis factor-alpha, interleukin-6, transforming growth factor-beta, inducible nitric oxide synthase and Foxp3. In addition, a large number of genes and expressed sequence tags previously unrelated to DNA-therapy were identified. All these findings were well correlated with the histopathological lesions presented in the lungs.

CONCLUSIONS

The effects of DNA therapy are reflected in gene expression modulation; therefore, the genes identified as differentially expressed could be considered as transcriptional biomarkers of DNAhsp65 immunotherapy against TB. The data have important implications for achieving a better understanding of gene-based therapies.

Influência do biofármaco DNA-hsp65 na lesão pulmonar induzida por bleomicina

OBJETIVO: Avaliar a influência do biofármaco DNA-hsp65 em um modelo de distúrbio fibrosante pulmonar experimental. MÉTODOS: Foram estudados 120 camundongos machos C57BL/6, divididos em quatro grupos: grupo SS, animais tratados com salina (placebo) e injetados com salina intratraqueal (IT); grupo SB, tratados com salina (placebo) e injetados com bleomicina IT; grupo PB, tratados com plasmídeo, sem gene bacteriano, e injetados com bleomicina IT; e grupo BB, tratados com DNA-hsp65 e injetados com bleomicina IT. A bleomicina foi injetada 15 dias após a última imunização, e os animais sacrificados seis semanas após o uso da droga IT. O pulmão esquerdo retirado foi utilizado para análise morfológica, e o pulmão direito para dosagens de hidroxiprolina. RESULTADOS: A proporção de camundongos que apresentaram morte não-programada depois de 48 h da injeção IT foi maior no grupo SB em comparação ao grupo SS (57,7% vs. 11,1%). A área percentual média de interstício septal foi maior nos grupos SB e PB (53,1 ± 8,6% e 53,6 ± 9,3%, respectivamente) em comparação aos grupos SS e BB (32,9 ± 2,7% e 34,3 ± 6,1%, respectivamente). Os grupos SB, PB e BB mostraram aumentos nos valores médios da área de interstício septal corada por picrosirius em comparação ao grupo SS (SS: 2,0 ± 1,4%; SB: 8,2 ± 4,9%; PB: 7,2 ± 4,2%; e BB:6,6±4,1%).O conteúdo pulmonar de hidroxiprolina no grupo SS foi inferior ao dos demais grupos (SS: 104,9 ± 20,9 pg/pulmão; SB: 160,4 ±47,8 pg/pulmão; PB:170,0 ± 72,0 pg/pulmão; e BB: 162,5 ± 39,7 pg/pulmão). CONCLUSÕES: A imunização com o biofármaco DNA-hsp65 interferiu na deposição de matriz não-colágena em um modelo de lesão pulmonar induzida por bleomicina.

Protection against tuberculosis by a single intranasal administration of DNA-hsp65 vaccine complexed with cationic liposomes

Background

The greatest challenges in vaccine development include optimization of DNA vaccines for use in humans, creation of effective single-dose vaccines, development of delivery systems that do not involve live viruses, and the identification of effective new adjuvants. Herein, we describe a novel, simple technique for efficiently vaccinating mice against tuberculosis (TB). Our technique consists of a single-dose, genetic vaccine formulation of DNA-hsp65 complexed with cationic liposomes and administered intranasally.

Results

We developed a novel and non-toxic formulation of cationic liposomes, in which the DNA-hsp65 vaccine was entrapped (ENTR-hsp65) or complexed (COMP-hsp65), and used to immunize mice by intramuscular or intranasal routes. Although both liposome formulations induced a typical Th1 pattern of immune response, the intramuscular route of delivery did not reduce the number of bacilli. However, a single intranasal immunization with COMP-hsp65, carrying as few as 25 μg of plasmid DNA, leads to a remarkable reduction of the amount of bacilli in lungs. These effects were accompanied by increasing levels of IFN-γ and lung parenchyma preservation, results similar to those found in mice vaccinated intramuscularly four times with naked DNA-hsp65 (total of 400 μg).

Conclusion

Our objective was to overcome the significant obstacles currently facing DNA vaccine development. Our results in the mouse TB model showed that a single intranasal dose of COMP-hsp65 elicited a cellular immune response that was as strong as that induced by four intramuscular doses of naked-DNA. This formulation allowed a 16-fold reduction in the amount of DNA administered. Moreover, we demonstrated that this vaccine is safe, biocompatible, stable, and easily manufactured at a low cost. We believe that this strategy can be applied to human vaccines to TB in a single dose or in prime-boost protocols, leading to a tremendous impact on the control of this infectious disease.