Advancing research through collaboration is at the heart of the JHU TRAC mission. Research is organized around scientific programs and working groups that represent a cross-section of member strengths and disciplines. Learn more about key dates and information for past awards. 2023 award opportunities will be posted early fall.
Development of a novel diagnostic assay for pediatric tuberculosis
Tuberculosis (TB) is a significant problem in both adults and children. Diagnosis of pediatric TB is challenging. Children fail to produce quality sputum, and therefore sensitivity and specificity of the current sputum-based assays are low. Since children swallow sputum, a stool specimen is a potential alternative for bacteriological confirmation of pulmonary TB. Previous studies with stool using Xpert had limitations, including low analytical and diagnostic sensitivity and a lack of a standard stool processing method. Previously, we innovated a low-resource-settings-adapted simple and sensitive stool processing method coupled with isothermal amplification assay named “RLDT” to detect enteric pathogens (JHTV C16784). We evaluated this assay in several endemic countries, and has attracted multiple grants, including NIH R21 and R01. We propose to develop RLDT platform-based “TB-RIF-RLDT,” a simple, rapid, and sensitive assay to detect TB and resistance to rifampin (RIF) from stool in children with the following specific aims: a) Develop TB-RIF-RLDT using spiked stool samples with M. tuberculosis bacteria. b) Determine performance specifications of TB-RIF-RLDT. c) Evaluate TB-RIF-RLDT at JHU with stool samples from TB-positive and negative children. With the preliminary data from this feasibility pilot study, we will apply for NIH grants to evaluate the TB-RIF RLDT in endemic countries.
A therapeutic mRNA vaccine targeting Mycobacterium tuberculosis persisters
The key stringent response enzyme RelMtb is essential for prolonged Mycobacterium tuberculosis (Mtb) survival and antibiotic tolerance in vivo. We have demonstrated that DNA vaccination targeting RelMtb enhanced the activity of isoniazid in a murine tuberculosis (TB) model. After we fused relMtb to the gene encoding Macrophage Inflammatory Protein-3 alpha (MIP-3α), targeting the antigen to immature dendritic cells, we showed substantially enhanced adjunctive therapeutic efficacy of that vaccine resulting in robust Th1 pathway response. The recently demonstrated safety and efficacy of mRNA vaccines in the current pandemic raise the potential of using that vaccine platform, which is closer to the clinical application than are current DNA vaccine candidates due to the historical difficulties with their effective delivery into human cells. This proposal explores whether a similar mRNA vaccine delivered with biodegradable nanoparticles would show equivalent immunogenicity and therapeutic efficacy in TB preclinical models. This study will help the PI obtain preliminary data to submit an R21 proposal focusing on understanding the immune mechanisms of the MIP-3α/relMtb mRNA vaccine and whether it shortens the curative TB treatment in preclinical models. This project is in collaboration with Markham Lab (Bloomberg School of Public Health) and Green Lab (Biomedical Engineering, Johns Hopkins University).
Exploring Host Determinants of Mycobacterium tuberculosis Control
Mtb infection is associated with a range of clinical outcomes, from latent infection with few clinical indicators through severe, progressive infection. While there are several conditions associated with a heightened risk of transition between latent and active infection, there are fewer known mechanisms for why immune control is lost. Understanding the precise immunologic features associated with development of progressive infection will better inform host-directed therapeutics for TB disease. Two features of increased risk are HIV infection and pregnancy. This proposal will explore these two distinct, but often overlapping, risk conditions. In the first aim, studies will build on preliminary work that has already defined transcriptional and epigenetic shifts in the monocyte compartment within individuals with HIV infection before and after HIV viral suppression. We will use these same samples to define the capacity of these monocytes to control Mtb infection with a goal of linking the changes observed after HIV viral suppression to pathways of immune control. In the second aim, we will explore the impact of pregnancy on the development and differentiation of monocyte derived macrophages. These studies will model the first and third trimester of pregnancy with in vitro conditions and test the impact on Mtb control. For both HIV infection and pregnancy, the drivers of increased risk of progressive disease are unknown, and there is a clear need for optimization of treatment. The work from this proposal will be used to expand on previous, HIV-focused studies to support a new application for funding on the impact of HIV on TB innate immune control, and as data to support an R01 on the immunologic determinants of pregnancy related risk of active TB in women with and without HIV coinfection.
Assessing the role of preventive therapy in advancing goals of TB Free Nepal
A national prevalence survey completed in 2019 estimated that the prevalence of tuberculosis (TB) in Nepal was 416 per 100,000. This was 1.8 times larger than previously estimated by the World Health Organization (WHO); and it revealed that the majority of incident cases (54%) are not notified. As in many high-burden countries, reducing the burden of TB has been a major challenge in Nepal, despite advances in TB diagnosis and treatment, and more intensive active case finding efforts. This prompted the Ministry of Health to announce a bold vision entitled “TB Free Nepal” in 2020, with a goal of reducing TB incidence by 25% in the next five years, and ultimately eliminating TB by 2050. Scaling up TB preventive therapy (TPT) is a major component of this vision. However, it is unclear (i) how impactful TPT will be in a high-transmission setting (where individuals may have high risk of re-exposure on one hand, whereas only treating diagnosed TB cases may be too little too late); (ii) whether prioritizing scale up of preventive therapy is cost-effective (given challenges associated with testing for latent TB, TPT uptake, and completion of TPT); and (iii) what implementation strategies for TPT scale up should be prioritized to make progress toward the vision of TB Free Nepal.
This pilot study, will augment an ongoing study (2021-2023; IMPACT 2 TB; PI: Dr. Maxine Caws; funded by Nick Simons Foundation) that assesses the feasibility of implementing 3HP (3 months of weekly isoniazid and rifapentine) in two districts in Nepal: a predominantly rural western district, Pyuthan, and densely populated district with large urban center, Chitwan. We propose to conduct two primary research activities: 1. Collection of site-specific data on implemention of preventive therapy from Pyuthan and Chitwan including (a) yield (numbers of people diagnosed with TB and LTBI, using TST); (b) prevalence of LTBI among household contacts (c) uptake of TPT; (d) TPT completion; and (e) costs of WHO screening algorithm. Additionally, we will recruit local study staff to collate programmatic data that are already collected as a part of the ongoing study and to collect additional data on household contacts. 2. Development of transmission models, calibrated to rural and urban settings, to project the epidemiological impact, and cost-effectiveness of TPT. Dr. Shrestha will train a junior researcher currently based at Birat Nepal Medical Trust (BNMT), Mr. Rajan Paudel, to develop these models under his supervision with input from the PI of ongoing IMPACT 2 TB study, Dr Maxine Caws, and mentor Dr David Dowdy.
Determination of the mid-treatment molecular clock for multidrug resistant tuberculosis
MDR-TB represents 3% of new and 18% of repeat TB infections, with 70% representing primary infection with resistant Mtb. Several molecular epidemiology programs use a well-established Mtb “molecular clock” to rule-out transmission between infected people by comparing acquisition of single nucleotide polymorphisms–SNPs–over time. Unfortunately, the Mtb molecular clock was originally defined among laboratory isolates or people with drug-susceptible TB without selective pressure from treatment. Recently, large mutation rate differences have been found by Mtb clade, undermining the generalizability of established thresholds. Similarly, selection pressure of multidrug MDR-TB treatment likely increases the rate of genetic polymorphisms identified before culture conversion, with direct implications for contact tracing and transmission inferences. To determine the molecular clock of MDR-TB during effective MDR-TB treatment, we will leverage a biorepository of well-characterized isolates collected through a completed longitudinal cohort study in which participants with MDR-TB completed baseline susceptibility testing, individualized treatment, and monthly sputum collection until symptom resolution. Of 204 study participants with baseline WGS results, 58 additional culture-positive mid-treatment samples are available from 41 participants. We will complete WGS from longitudinal samples to identify the time-normalized average pairwise SNP distances between paired MDR-TB isolates, with secondary stratification by phenotypic resistance and treatment regimen.