Dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN) is a cellular receptor for delta inulin adjuvant.

Delta inulin, or Advax, is a polysaccharide vaccine adjuvant that significantly enhances vaccine-mediated immune responses against multiple pathogens and was recently licensed for use in the coronavirus disease 2019 (COVID-19) vaccine SpikoGen. Although Advax has proven effective as an immune adjuvant, its specific binding targets have not been characterized. In this report, we identify a cellular receptor for Advax recognition. In vitro uptake of Advax particles by macrophage cell lines was substantially greater than that of latex beads of comparable size, suggesting an active uptake mechanism by phagocytic cells. Using a lectin array, Advax particles were recognized by lectins specific for various carbohydrate structures including mannosyl, N-acetylgalactosamine and galactose moieties. Expression in nonphagocytic cells of dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN), a C-type lectin receptor, resulted in enhanced uptake of fluorescent Advax particles compared with mock-transfected cells. Advax uptake was reduced with the addition of ethylenediaminetetraacetic acid and mannan to cells, which are known inhibitors of DC-SIGN function. Finally, a specific blockade of DC-SIGN using a neutralizing antibody abrogated Advax uptake in DC-SIGN-expressing cells. Together, these results identify DC-SIGN as a putative receptor for Advax. Given the known immunomodulatory role of DC-SIGN, the findings described here have implications for the use of Advax adjuvants in humans and inform future mechanistic studies.

Zebrafish tsc1 and cxcl12a increase susceptibility to mycobacterial infection.

Regulation of host miRNA expression is a contested node that controls the host immune response to mycobacterial infection. The host must counter subversive efforts of pathogenic mycobacteria to launch a protective immune response. Here, we examine the role of miR-126 in the zebrafish-Mycobacterium marinum infection model and identify a protective role for infection-induced miR-126 through multiple effector pathways. We identified a putative link between miR-126 and the tsc1a and cxcl12a/ccl2/ccr2 signalling axes resulting in the suppression of non-tnfa expressing macrophage accumulation at early M. marinum granulomas. Mechanistically, we found a detrimental effect of tsc1a expression that renders zebrafish embryos susceptible to higher bacterial burden and increased cell death via mTOR inhibition. We found that macrophage recruitment driven by the cxcl12a/ccl2/ccr2 signalling axis was at the expense of the recruitment of classically activated tnfa-expressing macrophages and increased cell death around granulomas. Together, our results delineate putative pathways by which infection-induced miR-126 may shape an effective immune response to M. marinum infection in zebrafish embryos.

Lung IL-17A-Producing CD4+ T Cells Correlate with Protection after Intrapulmonary Vaccination with Differentially Adjuvanted Tuberculosis Vaccines.

Tuberculosis (TB), caused by Mycobacterium tuberculosis, results in approximately 1.6 million deaths annually. BCG is the only TB vaccine currently in use and offers only variable protection; however, the development of more effective vaccines is hindered by a lack of defined correlates of protection (CoP) against M. tuberculosis. Pulmonary vaccine delivery is a promising strategy since it may promote lung-resident immune memory that can respond rapidly to respiratory infection. In this study, CysVac2, a subunit protein previously shown to be protective against M. tuberculosis in mouse models, was combined with either Advax® adjuvant or a mixture of alum plus MPLA and administered intratracheally into mice. Peripheral immune responses were tracked longitudinally, and lung-local immune responses were measured after challenge. Both readouts were then correlated with protection after M. tuberculosis infection. Although considered essential for the control of mycobacteria, induction of IFN-γ-expressing CD4+ T cells in the blood or lungs did not correlate with protection. Instead, CD4+ T cells in the lungs expressing IL-17A correlated with reduced bacterial burden. This study identified pulmonary IL-17A-expressing CD4+ T cells as a CoP against M. tuberculosis and suggests that mucosal immune profiles should be explored for novel CoP.

CXCR3 Provides a Competitive Advantage for Retention of Mycobacterium tuberculosis-Specific Tissue-Resident Memory T Cells Following a Mucosal Tuberculosis Vaccine.

Mycobacterium tuberculosis is a major human pathogen, and new vaccines are needed to prevent transmission. Mucosal vaccination may confer protection against M. tuberculosis by stimulating tissue-resident memory (TRM) CD4+ T cells in the lungs. The chemokine receptor CXCR3 promotes lung recruitment of T cells, but its role in TRM development is unknown. This study demonstrates the recombinant influenza A virus vaccine PR8.p25, expressing the immunodominant M. tuberculosis T cell epitope p25, induces CXCR3 expression on p25-specific CD4+ T cells in the lungs so that the majority of vaccine-induced CD4+ TRM expresses CXCR3 at 6 weeks. However, CXCR3-/- mice developed equivalent antigen-specific CD4+ T cell responses to wild-type (WT) mice following PR8.p25, and surprisingly retained more p25-specific CD4+ TRM in the lungs than WT mice at 6 weeks. The adoptive transfer of CXCR3-/- and WT P25 T cells into WT mice revealed that the initial recruitment of vaccine-induced CD4+ T cells into the lungs was independent of CXCR3, but by 6 weeks, CXCR3-deficient P25 T cells, and especially CXCR3-/- TRM, were significantly reduced compared to CXCR3-sufficient P25 T cells. Therefore, although CXCR3 was not essential for CD4+ TRM recruitment or retention, it provided a competitive advantage for the induction of M. tuberculosis-specific CD4+ TRM in the lungs following pulmonary immunization.

Patient and Clinician Perceptions of the Pulse Oximeter in a Remote Monitoring Setting for COVID-19: Qualitative Study.

BACKGROUND: As a response to the COVID-19 pandemic, the Sydney Local Health District in New South Wales, Australia, launched the rpavirtual program, the first full-scale virtual hospital in Australia, to remotely monitor and follow up stable patients with COVID-19. As part of the intervention, a pulse oximeter wearable device was delivered to patients to monitor their oxygen saturation levels, a critical indicator of COVID-19 patient deterioration. Understanding users' perceptions toward the device is fundamental to assessing its usability and acceptability and contributing to the effectiveness of the intervention, but no research to date has explored the user experience of the pulse oximeter for remote monitoring in this setting. OBJECTIVE: This study aimed to explore the use, performance, and acceptability of the pulse oximeter by clinicians and patients in rpavirtual during COVID-19. METHODS: Semistructured interviews and usability testing were conducted. Stable adult patients with COVID-19 (aged ≥18 years) who used the pulse oximeter and were monitored by rpavirtual, and rpavirtual clinicians monitoring these patients were interviewed. Clinicians could be nurses, doctors, or staff who were part of the team that assisted patients with the use of the pulse oximeter. Usability testing was conducted with patients who had the pulse oximeter when they were contacted. Interviews were coded using the Theoretical Framework of Acceptability. Usability testing was conducted using a think-aloud protocol. Data were collected until saturation was reached. RESULTS: Twenty-one patients (average age 51, SD 13 years) and 15 clinicians (average age 41, SD 11 years) completed the interview. Eight patients (average age 51, SD 13 years) completed the usability testing. All participants liked the device and thought it was easy to use. They also had a good understanding of how to use the device and the device's purpose. Patients' age and device use-related characteristics (eg, the warmth of hands and hand steadiness) were identified by users as factors negatively impacting the accurate use of the pulse oximeter. CONCLUSIONS: Patients and clinicians had very positive perceptions of the pulse oximeter for COVID-19 remote monitoring, indicating high acceptability and usability of the device. However, factors that may impact the accuracy of the device should be considered when delivering interventions using the pulse oximeter for remote monitoring. Targeted instructions about the use of the device may be necessary for specific populations (eg, older people and patients unfamiliar with technology). Further research should focus on the integration of the pulse oximeter data into electronic medical records for real-time and secure patient monitoring.

A unique cytotoxic CD4+ T cell-signature defines critical COVID-19.

Objectives: SARS-CoV-2 infection causes a spectrum of clinical disease presentation, ranging from asymptomatic to fatal. While neutralising antibody (NAb) responses correlate with protection against symptomatic and severe infection, the contribution of the T-cell response to disease resolution or progression is still unclear. As newly emerging variants of concern have the capacity to partially escape NAb responses, defining the contribution of individual T-cell subsets to disease outcome is imperative to inform the development of next-generation COVID-19 vaccines. Methods: Immunophenotyping of T-cell responses in unvaccinated individuals was performed, representing the full spectrum of COVID-19 clinical presentation. Computational and manual analyses were used to identify T-cell populations associated with distinct disease states. Results: Critical SARS-CoV-2 infection was characterised by an increase in activated and cytotoxic CD4+ lymphocytes (CTL). These CD4+ CTLs were largely absent in asymptomatic to severe disease states. In contrast, non-critical COVID-19 was associated with high frequencies of naïve T cells and lack of activation marker expression. Conclusion: Highly activated and cytotoxic CD4+ T-cell responses may contribute to cell-mediated host tissue damage and progression of COVID-19. Induction of these potentially detrimental T-cell responses should be considered when developing and implementing effective COVID-19 control strategies.

L-selectin-dependent and -independent homing of naïve lymphocytes through the lung draining lymph node support T cell response to pulmonary Mycobacterium tuberculosis infection.

Recruiting large numbers of naïve lymphocytes to lymph nodes is critical for mounting an effective adaptive immune response. While most naïve lymphocytes utilize homing molecule L-selectin to enter lymph nodes, some circulating cells can traffic to the lung-draining mediastinal lymph node (mLN) through lymphatics via the intermediate organ, lung. However, whether this alternative trafficking mechanism operates in infection and contributes to T cell priming are unknown. We report that in pulmonary Mycobacterium tuberculosis-infected mice, homing of circulating lymphocytes to the mLN is significantly less efficient than to non-draining lymph node. CD62L blockade only partially reduced the homing of naïve T lymphocytes, consistent with L-selectin-independent routing of naïve lymphocytes to the site. We further demonstrated that lymphatic vessels in infected mLN expanded significantly and inhibiting lymphangiogenesis with a vascular endothelial growth factor receptor 3 kinase inhibitor reduced the recruitment of intravenously injected naïve lymphocytes to the mLN. Finally, mycobacterium-specific T cells entering via the L-selectin-independent route were readily activated in the mLN. Our study suggests that both L-selectin-dependent and -independent pathways contribute to naïve lymphocyte entry into mLN during M. tuberculosis infection and the latter pathway may represent an important mechanism for orchestrating host defence in the lungs.

Effectiveness of population-wide screening and mass drug administration for leprosy control in Kiribati: the COMBINE protocol.

INTRODUCTION: Progress towards leprosy elimination is threatened by increasing incidence in 'hot-spot' areas where more effective control strategies are urgently required. In these areas, active case finding and leprosy prevention limited to known contacts is insufficient for control. Population-wide active case-finding together with universal prevention through mass drug administration (MDA) has been shown to be effective in 'hot-spot' areas, but is logistically challenging and expensive. Combining leprosy screening and MDA with other population-wide screening activities such as for tuberculosis may increase programme efficiency. There has been limited evaluation of the feasibility and effectiveness of combined screening and MDA interventions. The COMBINE study aims to bridge this knowledge gap. METHODS AND ANALYSIS: This implementation study will assess the feasibility and effectiveness of active leprosy case-finding and treatment, combined with MDA using either single-dose rifampicin or rifamycin-containing tuberculosis preventive or curative treatment, for reducing leprosy incidence in Kiribati. The leprosy programme will run over 2022-2025 in concert with population-wide tuberculosis screening-and-treatment in South Tarawa. The primary research question is to what extent the intervention reduces the annual leprosy new case detection rate (NCDR) in adults and children compared with routine screening and postexposure prophylaxis (PEP) among close contacts (baseline leprosy control activities). Comparisons will be made with (1) the preintervention NCDR separably among adults and children in South Tarawa (before-after study) and (2) the corresponding NCDRs in the rest of the country. Additionally, the postintervention prevalence of leprosy obtained from a survey of a 'hot-spot' sub-population will be compared with prevalence documented during the intervention. The intervention will be implemented in collaboration with the Kiribati National Leprosy Programme. ETHICS AND DISSEMINATION: Approval has been obtained from the Kiribati Ministry of Health and Medical Services (MHMS), the University of Otago (H22/111) and the University of Sydney (2021/127) Human Research Ethics Committees. Findings will be shared with the MHMS, local communities and internationally through publication.

Emergence and antibody evasion of BQ, BA.2.75 and SARS-CoV-2 recombinant sub-lineages in the face of maturing antibody breadth at the population level.

BACKGROUND: The Omicron era of the COVID-19 pandemic commenced at the beginning of 2022 and whilst it started with primarily BA.1, it was latter dominated by BA.2 and the related sub-lineage BA.5. Following resolution of the global BA.5 wave, a diverse grouping of Omicron sub-lineages emerged derived from BA.2, BA.5 and recombinants thereof. Whilst emerging from distinct lineages, all shared similar changes in the Spike glycoprotein affording them an outgrowth advantage through evasion of neutralising antibodies. METHODS: Over the course of 2022, we monitored the potency and breadth of antibody neutralization responses to many emerging variants in the Australian community at three levels: (i) we tracked over 420,000 U.S. plasma donors over time through various vaccine booster roll outs and Omicron waves using sequentially collected IgG pools; (ii) we mapped the antibody response in individuals using blood from stringently curated vaccine and convalescent cohorts. (iii) finally we determine the in vitro efficacy of clinically approved therapies Evusheld and Sotrovimab. FINDINGS: In pooled IgG samples, we observed the maturation of neutralization breadth to Omicron variants over time through continuing vaccine and infection waves. Importantly, in many cases, we observed increased antibody breadth to variants that were yet to be in circulation. Determination of viral neutralization at the cohort level supported equivalent coverage across prior and emerging variants with isolates BQ.1.1, XBB.1, BR.2.1 and XBF the most evasive. Further, these emerging variants were resistant to Evusheld, whilst increasing neutralization resistance to Sotrovimab was restricted to BQ.1.1 and XBF. We conclude at this current point in time that dominant variants can evade antibodies at levels equivalent to their most evasive lineage counterparts but sustain an entry phenotype that continues to promote an additional outgrowth advantage. In Australia, BR.2.1 and XBF share this phenotype and, in contrast to global variants, are uniquely dominant in this region in the later months of 2022. INTERPRETATION: Whilst the appearance of a diverse range of omicron lineages has led to primary or partial resistance to clinically approved monoclonal antibodies, the maturation of the antibody response across both cohorts and a large donor pools importantly observes increasing breadth in the antibody neutralisation responses over time with a trajectory that covers both current and known emerging variants. FUNDING: This work was primarily supported by Australian Medical Foundation research grants MRF2005760 (SGT, GM & WDR), Medical Research Future Fund Antiviral Development Call grant (WDR), the New South Wales Health COVID-19 Research Grants Round 2 (SGT & FB) and the NSW Vaccine Infection and Immunology Collaborative (VIIM) (ALC). Variant modeling was supported by funding from SciLifeLab's Pandemic Laboratory Preparedness program to B.M. (VC-2022-0028) and by the European Union's Horizon 2020 research and innovation programme under grant agreement no. 101003653 (CoroNAb) to B.M.

Development of a novel angiotensin converting enzyme 2 stimulator with broad implications in SARS-CoV2 and type 1 diabetes.

Angiotensin-converting enzyme 2 (ACE2) is protective in cardiovascular disease, lung injury and diabetes yet paradoxically underlies our susceptibility to SARs-CoV2 infection and the fatal heart and lung disease it can induce. Furthermore, diabetic patients have chronic, systemic inflammation and altered ACE2 expression resulting in increased risk of severe COVID-19 and the associated mortality. A drug that could increase ACE2 activity and inhibit cellular uptake of severe acute respiratory syndrome coronavirus 2 (SARs-CoV2), thus decrease infection, would be of high relevance to cardiovascular disease, diabetes and SARs-CoV2 infection. While the need for such a drug lead was highlighted over a decade ago receiving over 600 citations,1 to date, no such drugs are available.2 Here, we report the development of a novel ACE2 stimulator, designated '2A'(international PCT filed), which is a 10 amino acid peptide derived from a snake venom, and demonstrate its in vitro and in vivo efficacy against SARs-CoV2 infection and associated lung inflammation. Peptide 2A also provides remarkable protection against glycaemic dysregulation, weight loss and disease severity in a mouse model of type 1 diabetes. No untoward effects of 2A were observed in these pre-clinical models suggesting its strong clinical translation potential.

Spatial mapping reveals granuloma diversity and histopathological superstructure in human tuberculosis.

The hallmark of tuberculosis (TB) is the formation of immune cell-enriched aggregates called granulomas. While granulomas are pathologically diverse, their tissue-wide heterogeneity has not been spatially resolved at the single-cell level in human tissues. By spatially mapping individual immune cells in every lesion across entire tissue sections, we report that in addition to necrotizing granulomas, the human TB lung contains abundant non-necrotizing leukocyte aggregates surrounding areas of necrotizing tissue. These cellular lesions were more diverse in composition than necrotizing lesions and could be stratified into four general classes based on cellular composition and spatial distribution of B cells and macrophages. The cellular composition of non-necrotizing structures also correlates with their proximity to necrotizing lesions, indicating these are foci of distinct immune reactions adjacent to necrotizing granulomas. Together, we show that during TB, diseased lung tissue develops a histopathological superstructure comprising at least four different types of non-necrotizing cellular aggregates organized as satellites of necrotizing granulomas.

Bacteriophage endolysin powders for inhaled delivery against pulmonary infections.

Endolysins are bacteriophage-encoded enzymatic proteins that have great potential to treat multidrug-resistant bacterial infections. Bacteriophage endolysins Cpl-1 and ClyJ-3 have shown promising antimicrobial activity against Streptococcus pneumoniae, which causes pneumonia in humans. This is the first study to investigate the feasibility of spray-dried endolysins Cpl-1 and ClyJ-3 with excipients to produce inhalable powders. The two endolysins were individually tested with leucine and sugar (lactose or trehalose) for spray drying method followed by characterization of biological and physico-chemical properties. A complete loss of ClyJ-3 bioactivity was observed after atomization of the liquid feed solution（before the drying process）, while Cpl-1 maintained its bioactivity in the spray-dried powders. Cpl-1 formulations containing leucine with lactose or trehalose showed promising physico-chemical properties (particle size, crystallinity, hygroscopicity, etc.) and aerosol performances (fine particle fraction values above 65%). The results indicated that endolysin Cpl-1 can be formulated as spray dried powders suitable for inhaled delivery to the lungs for the potential treatment of pulmonary infections.

Assembly of Immunogenic Protein Particles toward Advanced Synthetic Vaccines.

Immunogenic carrier proteins such as the non-toxic diphtheria toxin variant, cross-reacting material 197 (CRM197), are widely used in subunit vaccine formulations to boost immunogenicity of chemically conjugated antigens. Conjugate vaccines are inherently expensive due to laborious manufacturing steps. Here, this work develops a particulate vaccine platform based on using engineered Escherichia coli to assemble CRM197-antigen fusion proteins into discrete submicron-sized particles. This approach enables precise loading of diverse antigens and epitopes enhancing their immunogenicity. A cost-effective, high-yield, and scalable biomanufacturing process is developed. Purified particulate CRM197-antigen vaccines are ambient-temperature stable. CRM197 particles incorporating pathogen-specific antigens or epitopes from SARS-CoV-2, Streptococcus pyogenes (group A), and Mycobacterium tuberculosis induced cell-mediated and humoral immune responses mediating protective immunity in respective animal models of infection. The CRM197 particle vaccine platform is versatile, enabling co-delivery of selected antigens/epitopes together with immunogenic CRM197 as discrete stable particles avoiding laborious manufacture of soluble CRM197 and antigen followed by chemical conjugation.

Mucosal TLR2-activating protein-based vaccination induces potent pulmonary immunity and protection against SARS-CoV-2 in mice.

Current vaccines against SARS-CoV-2 substantially reduce mortality, but protection against infection is less effective. Enhancing immunity in the respiratory tract, via mucosal vaccination, may provide protection against infection and minimise viral spread. Here, we report testing of a subunit vaccine in mice, consisting of SARS-CoV-2 Spike protein with a TLR2-stimulating adjuvant (Pam2Cys), delivered to mice parenterally or mucosally. Both routes of vaccination induce substantial neutralising antibody (nAb) titres, however, mucosal vaccination uniquely generates anti-Spike IgA, increases nAb in the serum and airways, and increases lung CD4+ T-cell responses. TLR2 is expressed by respiratory epithelia and immune cells. Using TLR2 deficient chimeric mice, we determine that TLR2 expression in either compartment facilitates early innate responses to mucosal vaccination. By contrast, TLR2 on hematopoietic cells is essential for optimal lung-localised, antigen-specific responses. In K18-hACE2 mice, vaccination provides complete protection against disease and sterilising lung immunity against SARS-CoV-2, with a short-term non-specific protective effect from mucosal Pam2Cys alone. These data support mucosal vaccination as a strategy to improve protection in the respiratory tract against SARS-CoV-2 and other respiratory viruses.

Stromal structure remodeling by B lymphocytes limits T cell activation in lymph nodes of Mycobacterium tuberculosis-infected mice.

An effective adaptive immune response depends on the organized architecture of secondary lymphoid organs, including the lymph nodes (LNs). While the cellular composition and microanatomy of LNs under steady state are well defined, the impact of chronic tissue inflammation on the structure and function of draining LNs is incompletely understood. Here we showed that Mycobacterium tuberculosis infection remodeled LN architecture by increasing the number and paracortical translocation of B cells. The formation of paracortical B lymphocyte and CD35+ follicular dendritic cell clusters dispersed CCL21-producing fibroblastic reticular cells and segregated pathogen-containing myeloid cells from antigen-specific CD4+ T cells. Depletion of B cells restored the chemokine and lymphoid structure and reduced bacterial burdens in LNs of the chronically infected mice. Importantly, this remodeling process impaired activation of naive CD4+ T cells in response to mycobacterial and unrelated antigens during chronic tuberculosis infection. Our studies reveal a mechanism in the regulation of LN microanatomy during inflammation and identify B cells as a critical element limiting the T cell response to persistent intracellular infection in LNs.

Mucosal immunization with a delta-inulin adjuvanted recombinant spike vaccine elicits lung-resident immune memory and protects mice against SARS-CoV-2.

Multiple SARS-CoV-2 vaccine candidates have been approved for use and have had a major impact on the COVID-19 pandemic. There remains, however, a significant need for vaccines that are safe, easily transportable and protective against infection, as well as disease. Mucosal vaccination is favored for its ability to induce immune memory at the site of infection, making it appealing for SARS-CoV-2 vaccine strategies. In this study we performed in-depth analysis of the immune responses in mice to a subunit recombinant spike protein vaccine formulated with the delta-inulin adjuvant Advax when administered intratracheally (IT), versus intramuscular delivery (IM). Both routes produced robust neutralizing antibody titers (NAb) and generated sterilizing immunity against SARS-CoV-2. IT delivery, however, produced significantly higher systemic and lung-local NAb that resisted waning up to six months post vaccination, and only IT delivery generated inducible bronchus-associated lymphoid tissue (iBALT), a site of lymphocyte antigen presentation and proliferation. This was coupled with robust and long-lasting lung tissue-resident memory CD4+ and CD8+ T cells that were not observed in IM-vaccinated mice. This study provides a detailed view of the lung-resident cellular response to IT vaccination against SARS-CoV-2 and demonstrates the importance of delivery site selection in the development of vaccine candidates.

Prevalence and genetic basis of first-line drug resistance of Mycobacterium tuberculosis in Ca Mau, Vietnam.

Background and objective: Data on the prevalence of anti-tuberculous drug resistance and its association with genetic mutations in Mycobacterium tuberculosis are limited. Our study explores the genomics of tuberculosis in Ca Mau, Vietnam. Methods: Patients ≥15 years in Ca Mau Province, Vietnam, were screened annually for tuberculosis between 2014 and 2017. Isolates underwent drug susceptibility testing (DST) using the breakpoint method. DNA was extracted and whole genome sequencing (WGS) was performed. Results: We identified 365 positive sputum cultures for M. tuberculosis and processed 237 for DST and 265 for WGS. Resistance to isoniazid was present in 19.8% (95% CI 14.7 to 24.9%), rifampicin in 3.5% (1.1 to 5.7%) and ethambutol in 2.5% (0.9 to 5.4%) of isolates. Relevant mutations in rpoB gene were detected in 3.8% (1.8 to 6.8%). katG, inhA or fabG1 mutations were found in 19.6% (15.0 to 24.9%) with KatG being most common at 12.8% (9.1-17.5%). We found 38.4% of isolates were of Beijing lineage, 49.4% East-African-Indian lineage and 8.4% European-American lineage. There were no associations between resistance profiles and clinical features. Conclusion: The high burden of isoniazid resistance and the katG mutation highlights the challenges facing Vietnam in its efforts to achieve its EndTB goals.

Understanding the pathogenesis of occupational coal and silica dust-associated lung disease.

Workers in the mining and construction industries are at increased risk of respiratory and other diseases as a result of being exposed to harmful levels of airborne particulate matter (PM) for extended periods of time. While clear links have been established between PM exposure and the development of occupational lung disease, the mechanisms are still poorly understood. A greater understanding of how exposures to different levels and types of PM encountered in mining and construction workplaces affect pathophysiological processes in the airways and lungs and result in different forms of occupational lung disease is urgently required. Such information is needed to inform safe exposure limits and monitoring guidelines for different types of PM and development of biomarkers for earlier disease diagnosis. Suspended particles with a 50% cut-off aerodynamic diameter of 10 µm and 2.5 µm are considered biologically active owing to their ability to bypass the upper respiratory tract's defences and penetrate deep into the lung parenchyma, where they induce potentially irreversible damage, impair lung function and reduce the quality of life. Here we review the current understanding of occupational respiratory diseases, including coal worker pneumoconiosis and silicosis, and how PM exposure may affect pathophysiological responses in the airways and lungs. We also highlight the use of experimental models for better understanding these mechanisms of pathogenesis. We outline the urgency for revised dust control strategies, and the need for evidence-based identification of safe level exposures using clinical and experimental studies to better protect workers' health.

Characterization of the Protective Immune Responses Conferred by Recombinant BCG Overexpressing Components of Mycobacterium tuberculosis Sec Protein Export System.

Mycobacterium bovis Bacillus Calmette-Guérin (BCG) is the only approved vaccine against tuberculosis (TB). However, its efficacy in preventing pulmonary TB in adults is limited. Despite its variable efficacy, BCG offers a number of unique and beneficial characteristics, which make it suitable as a vaccine vehicle to express recombinant molecules. In Mycobacterium tuberculosis, the general Sec pathway is an essential cellular process, and it is responsible for exporting the majority of proteins across the cytoplasmic membrane, including potent immune-protective antigens, such as members of the antigen 85 (Ag85) complex. We engineered BCG to overexpress the M. tuberculosis SecDFG proteins in order to improve the efficiency of the Sec-dependent export system and, thus, enhance the secretion of immunogenic proteins. BCGSecDFG displayed increased intracellular survival within macrophages in vitro and greater persistence in the lymphoid organs of vaccinated mice than parental BCG. In addition, vaccination with BCGSecDFG generated higher numbers of IFN-γ-secreting T cells in response to secreted mycobacterial antigens compared to BCG, particularly members of the Ag85 complex. Furthermore, vaccination with BCGSecDFG significantly reduced the bacterial load in the lungs and spleens of M. tuberculosis-infected mice, which was comparable to the protection afforded by parental BCG. Therefore, the modification of protein secretion in BCG can improve antigen-specific immunogenicity.

Harnessing new mHealth technologies to Strengthen the Management of Multidrug-Resistant Tuberculosis in Vietnam (V-SMART trial): a protocol for a randomised controlled trial.

INTRODUCTION: Multidrug-resistant tuberculosis (MDR-TB) remains a major public health problem globally. Long, complex treatment regimens coupled with frequent adverse events have resulted in poor treatment adherence and patient outcomes. Smartphone-based mobile health (mHealth) technologies offer national TB programmes an appealing platform to improve patient care and management; however, clinical trial evidence to support their use is lacking. This trial will test the hypothesis that an mHealth intervention can improve treatment success among patients with MDR-TB and is cost-effective compared with standard practice. METHODS AND ANALYSIS: A community-based, open-label, parallel-group randomised controlled trial will be conducted among patients treated for MDR-TB in seven provinces of Vietnam. Patients commencing therapy for microbiologically confirmed rifampicin-resistant or multidrug-resistant tuberculosis within the past 30 days will be recruited to the study. Participants will be individually randomised to an intervention arm, comprising use of an mHealth application for treatment support, or a 'standard care' arm. In both arms, patients will be managed by the national TB programme according to current national treatment guidelines. The primary outcome measure of effectiveness will be the proportion of patients with treatment success (defined as treatment completion and/or bacteriological cure) after 24 months. A marginal Poisson regression model estimated via a generalised estimating equation will be used to test the effect of the intervention on treatment success. A prospective microcosting of the intervention and within-trial cost-effectiveness analysis will also be undertaken from a societal perspective. Cost-effectiveness will be presented as an incremental cost per patient successfully treated and an incremental cost per quality-adjusted life-year gained. ETHICS: Ethical approval for the study was granted by The University of Sydney Human Research Ethics Committee (2019/676). DISSEMINATION: Study findings will be disseminated to participants and published in peer-reviewed journals and conference proceedings. TRIAL REGISTRATION NUMBER: ACTRN12620000681954.