Prime-boost vaccination with Bacillus Calmette Guerin and a recombinant adenovirus co-expressing CFP10, ESAT6, Ag85A and Ag85B of Mycobacterium tuberculosis induces robust antigen-specific immune responses in mice

Inhaled aerosol viral-vectored vaccines against tuberculosis

Bacille Calmette-Guérin (BCG) remains the sole licensed vaccine against tuberculosis (TB), despite its variable efficacy in protecting against pulmonary TB. The development of effective TB vaccines faces significant challenges, marked by the absence of validated correlates of protection and predictive animal models. Strategic approaches to enhance TB vaccines and augment BCG efficacy include utilising prime-boost strategies with viral-vectored vaccines and exploring innovative delivery techniques, such as mucosal vaccine administration. Viral vectors offer numerous advantages, including the capacity to accommodate genes encoding extensive antigenic fragments and the induction of robust immune responses. Aerosol delivery aligns with the route of Mycobacterium tuberculosis infection and holds the potential to enhance protective mucosal immunity. Aerosolised viral-vectored vaccines overcome anti-vector immunity, facilitating repeated aerosol deliveries.

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.

Nano-Sized Chimeric Human Papillomavirus-16 L1 Virus-like Particles Displaying Mycobacterium tuberculosis Antigen Ag85B Enhance Ag85B-Specific Immune Responses in Female C57BL/c Mice

Bacillus Calmette-Guerin (BCG), the only current vaccine against tuberculosis (TB) that is licensed in clinics, successfully protects infants and young children against several TB types, such as TB meningitis and miliary TB, but it is ineffective in protecting adolescents and adults against pulmonary TB. Thus, it is a matter of the utmost urgency to develop an improved and efficient TB vaccine. In this milieu, virus-like particles (VLPs) exhibit excellent characteristics in the field of vaccine development due to their numerous characteristics, including but not limited to their good safety without the risk of infection, their ability to mimic the size and structure of original viruses, and their ability to display foreign antigens on their surface to enhance the immune response. In this study, the HPV16 L1 capsid protein (HPV16L1) acted as a structural vaccine scaffold, and the extracellular domain of Ag85B was selected as the M. tb immunogen and inserted into the FG loop of the HPV16 L1 protein to construct chimeric HPV16L1/Ag85B VLPs. The chimeric HPV16L1/Ag85B VLPs were produced via the Pichia pastoris expression system and purified via discontinuous Optiprep density gradient centrifugation. The humoral and T cell-mediated immune response induced by the chimeric HPV16L1/Ag85B VLP was studied in female C57BL/c mice. We demonstrated that the insertion of the extracellular domain of Ag85B into the FG loop of HPV16L1 did not affect the in vitro stability and self-assembly of the chimeric HPV16L1/Ag85B VLPs. Importantly, it did not interfere with the immunogenicity of Ag85B. We observed that the chimeric HPV16L1/Ag85B VLPs induced higher Ag85B-specific antibody responses and elicited significant Ag85B-specific T cell immune responses in female C57BL/c mice compared with recombinant Ag85B. Our findings provide new insights into the development of novel chimeric HPV16L1/TB VLP-based vaccine platforms for controlling TB infection, which are urgently required in low-income and developing countries.

An overview of the BCG vaccine and its future scope

Despite intense elimination efforts, tuberculosis (TB) still poses a threat to world health, disproportionately affecting less developed and poorer countries. The Bacillus Calmette-Guérin (BCG) vaccine, the only anti-TB authorized vaccine can partially stop TB infection and transmission, however, its effectiveness ranges from 0 to 80%. As a result, there is an urgent need for a more potent TB vaccination given the widespread incidence of the disease. Enhancing BCG's effectiveness is also important due to the lack of other licensed vaccinations. Recently, fascinating research into BCG revaccination techniques by modulating its mode of action i.e., intravenous (IV) BCG delivery has yielded good clinical outcomes showing it still has a place in current vaccination regimens. We must thus go over the recent evidence that suggests trained immunity, and BCG vaccination techniques and describe how the vaccination confers protection against bacteria that cause both TB and non-tuberculosis. This review of the literature offers an updated summary and viewpoints on BCG-based TB immunization regimens (how it affects granulocytes at the epigenetic and hematopoietic stem cell levels which may be related to its efficacy), and also examines how the existing vaccine is being modified to be more effective, which may serve as an inspiration for future studies on the development of TB vaccines.

Immunoinformatic-Based Multi-Epitope Vaccine Design for Co-Infection of Mycobacterium tuberculosis and SARS-CoV-2

(1) Background: Many co-infections of Mycobacterium tuberculosis (MTB) and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) have emerged since the occurrence of the SARS-CoV-2 pandemic. This study aims to design an effective preventive multi-epitope vaccine against the co-infection of MTB and SARS-CoV-2. (2) Methods: The three selected proteins (spike protein, diacylglycerol acyltransferase, and low molecular weight T-cell antigen TB8.4) were predicted using bioinformatics, and 16 epitopes with the highest ranks (10 helper T lymphocyte epitopes, 2 CD8⁺ T lymphocytes epitopes, and 4 B-cell epitopes) were selected and assembled into the candidate vaccine referred to as S7D5L4. The toxicity, sensitization, stability, solubility, antigenicity, and immunogenicity of the S7D5L4 vaccine were evaluated using bioinformatics tools. Subsequently, toll-like receptor 4 docking simulation and discontinuous B-cell epitope prediction were performed. Immune simulation and codon optimization were carried out using immunoinformatics and molecular biology tools. (3) Results: The S7D5L4 vaccine showed good physical properties, such as solubility, stability, non-sensitization, and non-toxicity. This vaccine had excellent antigenicity and immunogenicity and could successfully simulate immune responses in silico. Furthermore, the normal mode analysis of the S7D5L4 vaccine and toll-like receptor 4 docking simulation demonstrated that the vaccine had docking potential and a stable reaction. (4) Conclusions: The S7D5L4 vaccine designed to fight against the co-infection of MTB and SARS-CoV-2 may be safe and effective. The protective efficacy of this promising vaccine should be further verified using in vitro and in vivo experiments.

The use of adenoviral vectors in gene therapy and vaccine approaches

Adenovirus was first identified in the 1950s and since then this pathogenic group of viruses has been explored and transformed into a genetic transfer vehicle. Modification or deletion of few genes are necessary to transform it into a conditionally or non-replicative vector, creating a versatile tool capable of transducing different tissues and inducing high levels of transgene expression. In the early years of vector development, the application in monogenic diseases faced several hurdles, including short-term gene expression and even a fatality. On the other hand, an adenoviral delivery strategy for treatment of cancer was the first approved gene therapy product. There is an increasing interest in expressing transgenes with therapeutic potential targeting the cancer hallmarks, inhibiting metastasis, inducing cancer cell death or modulating the immune system to attack the tumor cells. Replicative adenovirus as vaccines may be even older and date to a few years of its discovery, application of non-replicative adenovirus for vaccination against different microorganisms has been investigated, but only recently, it demonstrated its full potential being one of the leading vaccination tools for COVID-19. This is not a new vector nor a new technology, but the result of decades of careful and intense work in this field.

Towards Reverse Vaccinology for Bovine TB: High Throughput Expression of Full Length Recombinant Mycobacterium bovis Proteins

Bovine tuberculosis caused by Mycobacterium bovis, is a significant global pathogen causing economic loss in livestock and zoonotic TB in man. Several vaccine approaches are in development including reverse vaccinology which uses an unbiased approach to select open reading frames (ORF) of potential vaccine candidates, produce them as recombinant proteins and assesses their immunogenicity by direct immunization. To provide feasibility data for this approach we have cloned and expressed 123 ORFs from the M. bovis genome, using a mixture of E. coli and insect cell expression. We used a concatenated open reading frames design to reduce the number of clones required and single chain fusion proteins for protein pairs known to interact, such as the members of the PPE-PE family. Over 60% of clones showed soluble expression in one or the other host and most allowed rapid purification of the tagged bTB protein from the host cell background. The catalogue of recombinant proteins represents a resource that may be suitable for test immunisations in the development of an effective bTB vaccine.

CFP10-loaded PLGA nanoparticles as a booster vaccine confer protective immunity against Mycobacterium bovis

Introduction: The limited efficacy of BCG (bacillus Calmette-Guérin) urgently requires new effective vaccination approaches for the control of tuberculosis. Poly lactic-co-glycolic acid (PLGA) is a prevalent drug delivery system. However, the effect of PLGA-based nanoparticles (NPs) against tuberculosis for the induction of mucosal immune response is no fully elucidated. In this study, we hypothesized that intranasal immunization with culture filtrate protein-10 (CFP10)-loaded PLGA NPs (CFP10-NPs) could boost the protective immunity of BCG against Mycobacterium bovis in mice. Methods: The recombinant protein CFP10 was encapsulated with PLGA NPs to prepare CFP10-NPs by the classical water-oil-water solvent-evaporation method. Then, the immunoregulatory effects of CFP10-NPs on macrophages in vitro and on BCG-immunized mice in vivo were investigated. Results: We used spherical CFP10-NPs with a negatively charged surface (zeta-potential -28.5 ± 1.7 mV) having a particle size of 281.7 ± 28.5 nm in diameter. Notably, CFP10-NPs significantly enhanced the secretion of tumor necrosis factor α (TNF-α) and interleukin (IL)-1β in J774A.1 macrophages. Moreover, mucosal immunization with CFP10-NPs significantly increased TNF-α and IL-1β production in serum, and immunoglobulin A (IgA) secretion in bronchoalveolar lavage fluid (BALF), and promoted the secretion of CFP10-specific interferon-γ (IFN-γ) in splenocytes of mice. Furthermore, CFP10-NPs immunization significantly reduced the inflammatory area and bacterial load in lung tissues at 3-week post-M. bovis challenge. Conclusion: CFP10-NPs markedly improve the immunogenicity and protective efficacy of BCG. Our findings explore the potential of the airway mucosal vaccine based on PLGA NPs as a vehicle for targeted lung delivery.

Chitosan nanoparticles containing fusion protein (Hspx–PPE44–EsxV) and resiquimod adjuvant (HPERC) as a novel booster vaccine for Mycobacterium tuberculosis

This study attempted to explore the immunogenicity of chitosan nanoparticles containing fusion protein (Hspx–PPE44–EsxV; HPE) and resiquimod adjuvant (HPERC) in BALB/c mice. HPE was initially expressed in E. coli BL21 cells. HPE and resiquimod adjuvant were then encapsulated in chitosan nanoparticles (HPERC). One group of mice were subcutaneously vaccinated on days 0, 14, and 28 with HPERC, and the other group was primed with bacilli Calmette-Guérin (BCG) on day 0 and then boosted with HPERC on days 14 and 28. Two weeks after the last injection, IFN-γ, IL-4, and IL-17 in spleen cell culture supernatants, and IgG2a and IgG1 titers in sera were measured. HPERC size was 130.84 ± 12.08 nm ( n = 5). Zeta potential of HPERC was 29 ± 4 mv. The highest IFN-γ concentration was detected in BCG-primed mice that were boosted with HPERC. In addition, IL-17 production was significantly increased in all groups compared with that of control, except in those that received nanoparticle (NP), adjuvant (ADJ), NP/ADJ, and fusion protein (Hspx–PPE44–EsxV) (HPE). Comparison of IFN-γ and IL-4 concentration determined that Th1 was activated in BCG-primed and HPERC-boosted group in comparison to the other groups. No significant difference in concentration of IL-4 was observed between groups receiving HPERC and BCG-primed and HPERC-boosted group in comparison to group BCG. Concentrations of IgG2a and IgG1 also increased compared to the control group and the rate of IgG2a was higher compared to IgG1. Chitosan containing HPERC vaccine could induce a high level of specific cytokines in mice. The group of mice which first received BCG and then HPERC as booster vaccine could produce significant amounts of IFN-γ, IL-17, and IgG2a.

Peptide-Based Vaccines for Tuberculosis

Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis. As a result of the coronavirus disease 2019 (COVID-19) pandemic, the global TB mortality rate in 2020 is rising, making TB prevention and control more challenging. Vaccination has been considered the best approach to reduce the TB burden. Unfortunately, BCG, the only TB vaccine currently approved for use, offers some protection against childhood TB but is less effective in adults. Therefore, it is urgent to develop new TB vaccines that are more effective than BCG. Accumulating data indicated that peptides or epitopes play essential roles in bridging innate and adaptive immunity and triggering adaptive immunity. Furthermore, innovations in bioinformatics, immunoinformatics, synthetic technologies, new materials, and transgenic animal models have put wings on the research of peptide-based vaccines for TB. Hence, this review seeks to give an overview of current tools that can be used to design a peptide-based vaccine, the research status of peptide-based vaccines for TB, protein-based bacterial vaccine delivery systems, and animal models for the peptide-based vaccines. These explorations will provide approaches and strategies for developing safer and more effective peptide-based vaccines and contribute to achieving the WHO’s End TB Strategy.

A review of the BCG vaccine and other approaches toward tuberculosis eradication

Despite aggressive eradication efforts, Tuberculosis (TB) remains a global health burden, one that disproportionally affects poorer, less developed nations. The only vaccine approved for TB, the Bacillus of Calmette and Guérin (BCG) vaccine remains controversial because it's stated efficacy has been cited as anywhere from 0 to 80%. Nevertheless, there have been exciting discoveries about the mechanism of action of the BCG vaccine that suggests it has a role in immunization schedules today. We review recent data suggesting the vaccine imparts protection against both tuberculosis and non-tuberculosis pathogens via a newly discovered immune system called trained immunity. BCG's efficacy also appears to be tied to its affect on granulocytes at the epigenetic and hematopoietic stem cell levels, which we discuss in this article at length. We also write about how the different strains of the BCG vaccine elicit different immune responses, suggesting that certain BCG strains are more immunogenic than others. Finally, our review delves into how the current vaccine is being reformulated to be more efficacious, and track the development of the next generation vaccines against TB.

Novel personalized cancer vaccine platform based on Bacillus Calmette-Guèrin

Background

Intratumoral BCG therapy, one of the earliest immunotherapies, can lead to infiltration of immune cells into a treated tumor. However, an increase in the number of BCG-induced tumor-specific T cells in the tumor microenvironment could lead to enhanced therapeutic effects.

Methods

Here, we have developed a novel cancer vaccine platform based on BCG that can broaden BCG-induced immune responses to include tumor antigens. By physically attaching tumor-specific peptides onto the mycobacterial outer membrane, we were able to induce strong systemic and intratumoral T cell-specific immune responses toward the attached tumor antigens. These therapeutic peptides can be efficiently attached to the mycobacterial outer membrane using a poly-lysine sequence N-terminally fused to the tumor-specific peptides.

Results

Using two mouse models of melanoma and a mouse model of colorectal cancer, we observed that the antitumor immune responses of BCG could be improved by coating the BCG with tumor-specific peptides. In addition, by combining this novel cancer vaccine platform with anti-programmed death 1 (anti-PD-1) immune checkpoint inhibitor (ICI) therapy, the number of responders to anti-PD-1 immunotherapy was markedly increased.

Conclusions

This study shows that intratumoral BCG immunotherapy can be improved by coating the bacteria with modified tumor-specific peptides. In addition, this improved BCG immunotherapy can be combined with ICI therapy to obtain enhanced tumor growth control. These results warrant clinical testing of this novel cancer vaccine platform.

The immunological impact of adenovirus early genes on vaccine-induced responses in mice and nonhuman primates

Adenovirus (Ad) is being explored for use in the prevention and treatment of a variety of infectious diseases and cancers. Ad with a deletion in early region 3 (ΔE3) provokes a stronger immune response than Ad with deletions in early regions 1 and E3 (ΔE1/ΔE3). The ΔE1/ΔE3 Ads are more popular because they can carry a larger transgene and because of the deleted E1 (E1A and E1B), are perceived safer for clinical use. Ad with a deletion in E1B55K (ΔE1B55K) has been in phase III clinical trials for use in cancer therapy in the US and has been approved for use in head and neck tumor therapy in China, demonstrating that Ad containing E1A are safe for clinical use. We have shown previously that ΔE1B55K Ad, even while promoting lower levels of an inserted transgene, promoted similar levels of transgene-specific immune responses as a ΔE3 Ad. Products of the Ad early region 4 (E4) limit the ability of cells to mount an innate immune response. Using this knowledge, we deleted the Ad E4 open reading frames 1-4 (E4orf1-4) from the ΔE1B55K Ad. Here, we show that innate cytokine network genes are elevated in the ΔE4 Ad-infected cells beyond that of ΔE3 Ad-infected cells. Further, in immunized mice the IgG2a subclass was favored as was the IgG1 subclass in immunized nonhuman primates. Thus, Ad E4 impacts immune responses in cells, in immunized mice, and immunized nonhuman primates. These Ad may offer advantages that are beneficial for clinical use.Importance: Adenovirus (Ad) is being explored for use in the prevention and treatment of a variety of infectious diseases and cancers. Here we provide evidence in cells, mice, and nonhuman primates supporting the notion that Ad early gene-products limit specific immune responses. Ad constructed with deletions in early genes and expressing HIV envelope protein was shown to induce greater HIV-specific cellular immune responses and higher titer antibodies compared to the parental Ad with the early genes. In addition to eliciting enhanced immunity, the deleted Ad possesses more space for insertion of additional or larger transgenes needed for targeting other infectious agents or cancers.

A novel formulation of Mtb72F DNA vaccine for immunization against tuberculosis

Objective(s):

Mycobacterium tuberculosis (M. tuberculosis), an intracellular pathogen, causes 1.5 million deaths globally. Bacilli Calmette-Guérin (BCG) is commonly administered to protect people against M. tuberculosis infection; however, there are some obstacles with this first-generation vaccine. DNA vaccines, the third generation vaccines, can induce cellular immune responses for tuberculosis (TB) protection. In this study, optimized DNA vaccine (pcDNA3.1-Mtb72F) entrapped in poly (lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) was used to achieve higher immunogenicity.

Materials and Methods:

Plasmid Mtb72F was formulated in PLGA NPs using double emulsion method in the presence of TB10.4 and/or CpG as an adjuvant. Female BALB/c mice were immunized either with NP-encapsulated Mtb72F or naked Mtb72F with or without each adjuvant, using the BCG-prime DNA boost regimen.

Results:

These NPs were approximately 250 nm in diameter and the nucleic acid and protein encapsulation efficiency were 80% and 25%, respectively. The NPs smaller than 200 nm are able to promote cellular rather than humoral responses. The immunization with the formulation consisting of Mtb72F DNA vaccine and TB10.4 entrapped in PLGA NPs showed significant immunogenicity and induced predominantly interferon-ɣ (IFN-ɣ) production and higher INF-ɣ/interleukin-4 (IL-4) ratio in the cultured spleen cells supernatant.

Conclusion:

PLGA NPs loaded with Mtb72F DNA-based vaccine with TB10.4 could be considered as a promising candidate for vaccination against TB. These results represent an excellent initial step toward development of novel vaccine for TB protection.

EXPRESSION OF IMMUNOGLOBULIN, GRANZYME-B AND PERFORIN AGAINST Ag85A AND Ag85B PROTEINS OF MYCOBACTERIUM TUBERCULOSIS IN BALB/C MICE

Background:

Ag85 is a protein that may maintain survival of M. tuberculosis in intracellular parts of host cells and is considered as a virulence factor. The expression of Ag85 protein can stimulate proliferation and differentiation of B- cells and T-cells in patients with tuberculosis. This research aimed to determine the ability of Ag85A and Ag85B proteins in activating the response of antibodies, granzyme-B and perforin in Balb/c mice.

Materials and Methods:

Twenty-five male Balb/c mice were assigned into five groups. Group I was treated with adjuvant, group II with Bacillus Calmette-Guerin (BCG) vaccine, group III with a combination of BCG and Ag85A, group IV with a combination of BCG and Ag85B and group V with a combination of BCG, Ag85A and Ag85B. Concentrations of immunoglobulin G, granzyme-B and perforin were examined using ELISA and the number of CD8+ T-cells and NK T-cells were checked by flow cytometry.

Results:

The highest concentration of immunoglobulin G was found in group V with 62.49±5.4327 ng/ml. The highest mean number of CD8+ T-cells, NK T-cells, granzyme-B and perforin was found in group IV with 4.32%, 1.03%, 35.11±1.7789 pg/ml and 6.19±0.2235 pg/ml, respectively. The results of One-Way ANOVA test showed that there were significant differences in immunoglobulin responses, with p<0.05. The expressions of granzyme-B and perforin were higher in mice treated with combination of BCG and recombinant proteins.

Conclusions:

Ag85 protein can be combined with the BCG vaccine to improve protection against M. tuberculosis infection.

Boosting BCG with proteins or rAd5 does not enhance protection against tuberculosis in rhesus macaques

Tuberculosis (TB) is the leading cause of death from infection worldwide. The only approved vaccine, BCG, has variable protective efficacy against pulmonary TB, the transmissible form of the disease. Therefore, improving this efficacy is an urgent priority. This study assessed whether heterologous prime-boost vaccine regimens in which BCG priming is boosted with either (i) protein and adjuvant (M72 plus AS01_E or H56 plus CAF01) delivered intramuscularly (IM), or (ii) replication-defective recombinant adenovirus serotype 5 (Ad5) expressing various Mycobacterium tuberculosis (Mtb) antigens (Ad5(TB): M72, ESAT-6/Ag85b, or ESAT-6/Rv1733/Rv2626/RpfD) administered simultaneously by IM and aerosol (AE) routes, could enhance blood- and lung-localized T-cell immunity and improve protection in a nonhuman primate (NHP) model of TB infection. Ad5(TB) vaccines administered by AE/IM routes following BCG priming elicited ~10-30% antigen-specific CD4 and CD8 T-cell multifunctional cytokine responses in bronchoalveolar lavage (BAL) but did not provide additional protection compared to BCG alone. Moreover, AE administration of an Ad5(empty) control vector after BCG priming appeared to diminish protection induced by BCG. Boosting BCG by IM immunization of M72/AS01_E or H56:CAF01 elicited ~0.1-0.3% antigen-specific CD4 cytokine responses in blood with only a transient increase of ~0.5-1% in BAL; these vaccine regimens also failed to enhance BCG-induced protection. Taken together, this study shows that boosting BCG with protein/adjuvant or Ad-based vaccines using these antigens, by IM or IM/AE routes, respectively, do not enhance protection against primary infection compared with BCG alone, in the highly susceptible rhesus macaque model of tuberculosis.

Multi-subunit BCG booster vaccine GamTBvac: Assessment of immunogenicity and protective efficacy in murine and guinea pig TB models

New innovative vaccines are highly needed to combat the global threat posed by tuberculosis. Efficient components-antigens and adjuvants-are crucial for development of modern recombinant TB vaccines. This study describes a new vaccine (GamTBvac) consisting of two mycobacterial antigen fusions (Ag85A and ESAT6-CFP10)-with dextran-binding domain immobilized on dextran and mixed with an adjuvant consisting of DEAE-dextran core, and with CpG oligodeoxynucleotides (TLR9 agonists). GamTBvac and its components were assessed for immunogenicity and protective efficacy in GamTBvac-prime/boost and BCG-prime/ GamTBvac-boost in murine and guinea pig TB models. Results show that in both infectious models, GamTBvac has a strong immunogenicity and significant protective effect against Mycobacterium tuberculosis strain H37Rv under aerosol and intravenous challenges. GamTBvac showed a particularly strong protective effect as a BCG booster vaccine.

Immunogenicity and protective efficacy of recombinant Bacille Calmette-Guerin strains expressing mycobacterium antigens Ag85A, CFP10, ESAT-6, GM-CSF and IL-12p70

OBJECTIVE

This study aimed to evaluate the immunogenicity and protective efficacy of recombinant bacille calmette-guerin (rBCG) strains expressing Ag85A (A), CFP10 (C), ESAT6 (E), IL-12p70 (I), and fusion protein GM-CSF (G).

METHOD

rBCGs were established by integrating of A, C, E, I, G, AE, CE, IE, GC, GE and GCE into Mycobacterium bovis BCG-1173 and BCG-SH. The macro-effects of rBCGs on mice were evaluated by phenotype and weight. The immunogenicity of rBCGs was analyzed by lgG, lgG1 and lgG2a antibody titers, and IFN-γ and IL-4 contents through Enzyme-linked immunosorbent assay (ELISA). Meanwhile, the proportions of CD4⁺ and CD8⁺ T splenic lymphocytes were determined using flow cytometry. The protective efficacy of rBCGs was evaluated by bacterial load in spleen and lung tissues from immunized mice.

RESULTS

rBCGs exhibited no obvious side effects on mice. The antibody titers of lgG, lgG1 and lgG2a, proportion of CD4⁺ and CD8⁺ T cells, and concentrations of IFN-γ were found to be significantly higher in multiple-gene rBCGs than that in single-gene rBCGs (P < 0.05). Bacterial load in both spleen and lung tissues from mice infected with M. tuberculosis H37Rv were significantly reduced by rBCGs. A significantly lower bacterial load was revealed in rBCG-1173:A compared with multiple-gene rBCGs (P < 0.05).

CONCLUSION

Immunogenicity was better on multiple-gene rBCGs than on single-gene rBCGs, while excellent protective efficacy was exhibited on rBCG-1173:A and BCG-1173.

Adenoviral vector-based strategies against infectious disease and cancer

Adenoviral vectors are widely employed against infectious diseases or cancers, as they can elicit specific antibody responses and T cell responses when they are armed with foreign genes as vaccine carriers, and induce apoptosis of the cancer cells when they are genetically modified for cancer therapy. In this review, we summarize the biological characteristics of adenovirus (Ad) and the latest development of Ad vector-based strategies for the prevention and control of emerging infectious diseases or cancers. Strategies to circumvent the pre-existing neutralizing antibodies which dampen the immunogenicity of Ad-based vaccines are also discussed.