Potential of recombinant Mycobacterium paragordonae expressing HIV-1 Gag as a prime vaccine for HIV-1 infection

Protection against tuberculosis achieved by dissolving microneedle patches loaded with live Mycobacterium paragordonae in a BCG prime-boost strategy

Introduction

Skin vaccination using dissolving microneedle patch (MNP) technology for transdermal delivery is a promising vaccine delivery strategy to overcome the limitations of the existing vaccine administration strategies using syringes. To improve the traditional microneedle mold fabrication technique, we introduced droplet extension (DEN) to reduce drug loss. Tuberculosis remains a major public health problem worldwide, and BCG revaccination had failed to increase the protective efficacy against tuberculosis. We developed an MNP with live Mycobacterium paragordonae (Mpg) (Mpg-MNP) as a candidate of tuberculosis booster vaccine in a heterologous prime-boost strategy to increase the BCG vaccine efficacy.

Materials and methods

The MNPs were fabricated by the DEN method on a polyvinyl alcohol mask film and hydrocolloid-adhesive sheet with microneedles composed of a mixture of mycobacteria and hyaluronic acid. We assessed the transdermal delivery efficiency by comparing the activation of the dermal immune system with that of subcutaneous injection. A BCG prime Mpg-MNP boost regimen was administered to a mouse model to evaluate the protective efficacy against M. tuberculosis.

Results

We demonstrated the successful transdermal delivery achieved by Mpg-MNP compared with that observed with BCG-MNP or subcutaneous vaccination via an increased abundance of MHCII-expressing Langerin+ cells within the dermis that could migrate into draining lymph nodes to induce T-cell activation. In a BCG prime-boost regimen, Mpg-MNP was more protective than BCG-only immunization or BCG-MNP boost, resulting in a lower bacterial burden in the lungs of mice infected with virulent M. tuberculosis. Mpg-MNP-boosted mice showed higher serum levels of IgG than BCG-MNP-boosted mice. Furthermore, Ag85B-specific T-cells were activated after BCG priming and Mpg-MNP boost, indicating increased production of Th1-related cytokines in response to M. tuberculosis challenge, which is correlated with enhanced protective efficacy.

Discussion

The MNP fabricated by the DEN method maintained the viability of Mpg and achieved effective release in the dermis. Our data demonstrate a potential application of Mpg-MNP as a booster vaccine to enhance the efficacy of BCG vaccination against M. tuberculosis. This study produced the first MNP loaded with nontuberculous mycobacteria (NTM) to be used as a heterologous booster vaccine with verified protective efficacy against M. tuberculosis.

An Automated Strategy to Handle Antigenic Variability in Immunisation Protocols, Part II: In Vitro Transcribed mRNA Vector Design for Inoculation Against Infectious Agent Variants

A fully automated strategy to handle antigenic variability in immunisation protocols is here presented. The method comprises of (1) nanopore sequencing of infectious agent variants, with focus on the SARS-CoV-2 and its variants, followed by (2) in-vitro transcribed mRNA vector design for immunotherapy. This chapter introduces the mRNA vector design protocol and Chapter 16 presents the nano-pore sequencing step.

Mycobacterium paragordonae is an emerging pathogen in human pulmonary disease: clinical features, antimicrobial susceptibility testing and outcomes

Objectives: Mycobacterium paragordonae (MPG) is an emerging and less common type of Non-tuberculous mycobacteria (NTM) and we know little about its characteristics and prognosis, hence we constructed this retrospective cohort study. Methods: MPG was identified using MALD-TOF MS, multi-target combined gene sequencing and WGS. Clinical information was collected, antimicrobial susceptibility testing was measured using the SLOMYCO panel, and optimal growth temperature testing was measured using Lowenstein-Jensen medium. Results: Eight MPGs were isolated from 1730 NTMs (0.46%); the mean age of MPG pulmonary disease (MPG-PD) patients was 42.38 ± 9.92 years, 37.5% were male, and the average BMI was 18.4 ± 0.51 kg/m². All patients had the symptoms of cough and sputum and CT images mainly presented in patchy or streaky shadows, MPG grew at 25°C, 30°C and 37°C, and the optimal growth temperature is 37°C. MPGs were sensitive to clarithromycin, rifabutin, amikacin, linezolid, moxifloxacin, cotrimoxazole and ciprofloxacin, two isolates were resistant to rifampicin. Two patients had follow up information, their imaging remained stable during the follow-up. Conclusions: MPG-PD is a rare NTM disease and is more likely to develop in middle-aged, female, and low BMI patients. The patients present with no specific features within the symptoms as well as the CT imaging. The optimal growth temperature of MPG is at 37°C, MPG-PD has excellent sensitivity to drugs recommended by CLSI and presents with a stable disease.

COVID-19 vaccine development based on recombinant viral and bacterial vector systems: combinatorial effect of adaptive and trained immunity

Severe acute respiratory syndrome coronavirus 2 virus (SARS-CoV-2) infection, which causes coronavirus disease 2019 (COVID-19), has led to many cases and deaths worldwide. Therefore, a number of vaccine candidates have been developed to control the COVID-19 pandemic. Of these, to date, 21 vaccines have received emergency approval for human use in at least one country. However, the recent global emergence of SARS-CoV-2 variants has compromised the efficacy of the currently available vaccines. To protect against these variants, the use of vaccines that modulate T cell-mediated immune responses or innate immune cell memory function, termed trained immunity, is needed. The major advantage of a vaccine that uses bacteria or viral systems for the delivery of COVID-19 antigens is the ability to induce both T cell-mediated and humoral immune responses. In addition, such vaccine systems can also exert off-target effects via the vector itself, mediated partly through trained immunity; compared to other vaccine platforms, suggesting that this approach can provide better protection against even vaccine escape variants. This review presents the current status of the development of COVID-19 vaccines based on recombinant viral and bacterial delivery systems. We also discuss the current status of the use of licensed live vaccines for other infections, including BCG, oral polio and MMR vaccines, to prevent COVID-19 infections.

Recombinant Mycobacterium paragordonae Expressing SARS-CoV-2 Receptor-Binding Domain as a Vaccine Candidate Against SARS-CoV-2 Infections

At present, concerns that the recent global emergence of SARS-CoV-2 variants could compromise the current vaccines have been raised, highlighting the urgent demand for new vaccines capable of eliciting T cell-mediated immune responses, as well as B cell-mediated neutralizing antibody production. In this study, we developed a novel recombinant Mycobacterium paragordonae expressing the SARS-CoV-2 receptor-binding domain (RBD) (rMpg-RBD-7) that is capable of eliciting RBD-specific immune responses in vaccinated mice. The potential use of rMpg-RBD-7 as a vaccine for SARS-CoV-2 infections was evaluated in in vivo using mouse models of two different modules, one for single-dose vaccination and the other for two-dose vaccination. In a single-dose vaccination model, we found that rMpg-RBD-7 versus a heat-killed strain could exert an enhanced cell-mediated immune (CMI) response, as well as a humoral immune response capable of neutralizing the RBD and ACE2 interaction. In a two-dose vaccination model, rMpg-RBD-7 in a two-dose vaccination could also exert a stronger CMI and humoral immune response to neutralize SARS-CoV-2 infections in pseudoviral or live virus infection systems, compared to single dose vaccinations of rMpg-RBD or two-dose RBD protein immunization. In conclusion, our data showed that rMpg-RBD-7 can lead to an enhanced CMI response and humoral immune responses in mice vaccinated with both single- or two-dose vaccination, highlighting its feasibility as a novel vaccine candidate for SARS-CoV-2. To the best of our knowledge, this study is the first in which mycobacteria is used as a delivery system for a SARS-CoV-2 vaccine.

Vaccine strategies for the Mtb/HIV copandemic

One-third of world’s population is predicted to be infected with tuberculosis (TB). The resurgence of this deadly disease has been inflamed by comorbidity with human immunodeficiency virus (HIV). The risk of TB in people living with HIV (PLWH) is 15–22 times higher than people without HIV. Development of a single vaccine to combat both diseases is an ardent but tenable ambition. Studies have focused on the induction of specific humoral and cellular immune responses against HIV-1 following recombinant BCG (rBCG) expressing HIV-1 antigens. Recent advances in the TB vaccines led to the development of promising candidates such as MTBVAC, the BCG revaccination approach, H4:IC31, H56:IC31, M72/AS01 and more recently, intravenous (IV) BCG. Modification of these vaccine candidates against TB/HIV coinfection could reveal key correlates of protection in a representative animal model. This review discusses the (i) potential TB vaccine candidates that can be exploited for use as a dual vaccine against TB/HIV copandemic (ii) progress made in the realm of TB/HIV dual vaccine candidates in small animal model, NHP model, and human clinical trials (iii) the failures and promising targets for a successful vaccine strategy while delineating the correlates of vaccine-induced protection.

I-152, a supplier of N-acetyl-cysteine and cysteamine, inhibits immunoglobulin secretion and plasma cell maturation in LP-BM5 murine leukemia retrovirus-infected mice by affecting the unfolded protein response

Excessive production of immunoglobulins (Ig) causes endoplasmic reticulum (ER) stress and triggers the unfolded protein response (UPR). Hypergammaglobulinemia and lymphadenopathy are hallmarks of murine AIDS that develops in mice infected with the LP-BM5 murine leukemia retrovirus complex. In these mice, Th2 polarization and aberrant humoral response have been previously correlated to altered intracellular redox homeostasis. Our goal was to understand the role of the cell's redox state in Ig secretion and plasma cell (PC) maturation. To this aim, LP-BM5-infected mice were treated with I-152, an N-acetyl-cysteine and cysteamine supplier. Intraperitoneal I-152 administration (30 μmol/mouse three times a week for 9 weeks) decreased plasma IgG and increased IgG/Syndecan 1 ratio in the lymph nodes where IgG were in part accumulated within the ER. PC containing cytoplasmic inclusions filled with IgG were present in all animals, with fewer mature PC in those treated with I-152. Infection induced up-regulation of signaling molecules involved in the UPR, i.e. CHAC1, BiP, sXBP-1 and PDI, that were generally unaffected by I-152 treatment except for PDI and sXBP-1, which have a key role in protein folding and PC maturation, respectively. Our data suggest that one of the mechanisms through which I-152 can limit hypergammaglobulinemia in LP-BM5-infected mice is by influencing IgG folding/assembly as well as secretion and affecting PC maturation.

Heat-killed Mycobacterium paragordonae therapy exerts an anti-cancer immune response via enhanced immune cell mediated oncolytic activity in xenograft mice model

A therapeutic strategy capable of skewing toward a Th1-type immune response is crucial for cancer treatment. Recently, we reported Mycobacterium paragordonae (Mpg) as a potential live vaccine for mycobacterium infections. In this study, we explored the immunotherapeutic potential of heat-killed Mpg (HK-Mpg) in a mouse tumor xenograft model and elucidated its underlying antitumor mechanisms. MC38 cells derived from murine colon adenocarcinoma were implanted by subcutaneously injecting mice. The anticancer effects of HK-Mpg therapy were compared with HK-M. bovis BCG, an effective adjuvant for cancer immunotherapy. HK-Mpg treatment enhanced tumor reduction and mouse survival. Furthermore, HK-Mpg treatment synergistically enhanced the anticancer therapeutic effect of cisplatin. In addition, HK-Mpg enhanced inflammatory cytokine production and recruitment of immune cell into tumor-infiltrating sites and splenocytes in vaccinated mice. Our mechanistic study demonstrates that HK-Mpg therapy elicits a strong antitumor immune response in mice, mainly through natural killer cell-mediated oncolytic activity via the activation of dendritic cells (DCs) and by enhancing inflammatory cytokines production such as IL-12 from DC. Hence, HK-Mpg can be a potential immunotherapy adjuvant, enhancing the effect of cancer chemotherapy.