Memory CD8⁺ T cells exhibit tissue imprinting and non-stable exposure-dependent reactivation characteristics following blood-stage Plasmodium berghei ANKA infections

Experimental cerebral malaria (ECM) is a severe complication of Plasmodium berghei ANKA (PbA) infection in mice, characterized by CD8(+) T‐cell accumulation within the brain. Whilst the dynamics of CD8(+) T‐cell activation and migration during extant primary PbA infection have been extensively researched, the fate of the parasite‐specific CD8(+) T cells upon resolution of ECM is not understood. In this study, we show that memory OT‐I cells persist systemically within the spleen, lung and brain following recovery from ECM after primary PbA‐OVA infection. Whereas memory OT‐I cells within the spleen and lung exhibited canonical central memory (Tcm) and effector memory (Tem) phenotypes, respectively, memory OT‐I cells within the brain post‐PbA‐OVA infection displayed an enriched CD69(+)CD103(−) profile and expressed low levels of T‐bet. OT‐I cells within the brain were excluded from short‐term intravascular antibody labelling but were targeted effectively by longer‐term systemically administered antibodies. Thus, the memory OT‐I cells were extravascular within the brain post‐ECM but were potentially not resident memory cells. Importantly, whilst memory OT‐I cells exhibited strong reactivation during secondary PbA‐OVA infection, preventing activation of new primary effector T cells, they had dampened reactivation during a fourth PbA‐OVA infection. Overall, our results demonstrate that memory CD8(+) T cells are systemically distributed but exhibit a unique phenotype within the brain post‐ECM, and that their reactivation characteristics are shaped by infection history. Our results raise important questions regarding the role of distinct memory CD8(+) T‐cell populations within the brain and other tissues during repeat Plasmodium infections

Exhausted CD4+ T Cells during Malaria Exhibit Reduced mTORc1 Activity Correlated with Loss of T-bet Expression

CD4<sup>+</sup> T cell functional inhibition (exhaustion) is a hallmark of malaria and correlates with impaired parasite control and infection chronicity. However, the mechanisms of CD4<sup>+</sup> T cell exhaustion are still poorly understood. In this study, we show that Ag-experienced (<i>Ag-exp</i>) CD4<sup>+</sup> T cell exhaustion during <i>Plasmodium yoelii</i> nonlethal infection occurs alongside the reduction in mammalian target of rapamycin (mTOR) activity and restriction in CD4<sup>+</sup> T cell glycolytic capacity. We demonstrate that the loss of glycolytic metabolism and mTOR activity within the exhausted <i>Ag-exp</i>CD4<sup>+</sup> T cell population during infection coincides with reduction in T-bet expression. T-bet was found to directly bind to and control the transcription of various mTOR and metabolism-related genes within effector CD4<sup>+</sup> T cells. Consistent with this, <i>Ag-exp</i>Th1 cells exhibited significantly higher and sustained mTOR activity than effector T-bet- (non-Th1) <i>Ag-exp</i>T cells throughout the course of malaria. We identified mTOR to be redundant for sustaining T-bet expression in activated Th1 cells, whereas mTOR was necessary but not sufficient for maintaining IFN-γ production by Th1 cells. Immunotherapy targeting PD-1, CTLA-4, and IL-27 blocked CD4<sup>+</sup> T cell exhaustion during malaria infection and was associated with elevated T-bet expression and a concomitant increased CD4<sup>+</sup> T cell glycolytic metabolism. Collectively, our data suggest that mTOR activity is linked to T-bet in <i>Ag-exp</i>CD4<sup>+</sup> T cells but that reduction in mTOR activity may not directly underpin <i>Ag-exp</i>Th1 cell loss and exhaustion during malaria infection. These data have implications for therapeutic reactivation of exhausted CD4<sup>+</sup> T cells during malaria infection and other chronic conditions

Memory CD8 + T cells exhibit tissue imprinting and non‐stable exposure‐dependent reactivation characteristics following blood‐stage Plasmodium berghei ANKA infections

From Wiley via Jisc Publications RouterHistory: received 2020-11-02, rev-recd 2021-08-09, accepted 2021-08-13, pub-electronic 2021-08-27Article version: VoRPublication status: PublishedFunder: Medical Research Council; Id: http://dx.doi.org/10.13039/501100000265; Grant(s): G0900487, MR/R010099/1Abstract: Experimental cerebral malaria (ECM) is a severe complication of Plasmodium berghei ANKA (PbA) infection in mice, characterized by CD8+ T‐cell accumulation within the brain. Whilst the dynamics of CD8+ T‐cell activation and migration during extant primary PbA infection have been extensively researched, the fate of the parasite‐specific CD8+ T cells upon resolution of ECM is not understood. In this study, we show that memory OT‐I cells persist systemically within the spleen, lung and brain following recovery from ECM after primary PbA‐OVA infection. Whereas memory OT‐I cells within the spleen and lung exhibited canonical central memory (Tcm) and effector memory (Tem) phenotypes, respectively, memory OT‐I cells within the brain post‐PbA‐OVA infection displayed an enriched CD69+CD103− profile and expressed low levels of T‐bet. OT‐I cells within the brain were excluded from short‐term intravascular antibody labelling but were targeted effectively by longer‐term systemically administered antibodies. Thus, the memory OT‐I cells were extravascular within the brain post‐ECM but were potentially not resident memory cells. Importantly, whilst memory OT‐I cells exhibited strong reactivation during secondary PbA‐OVA infection, preventing activation of new primary effector T cells, they had dampened reactivation during a fourth PbA‐OVA infection. Overall, our results demonstrate that memory CD8+ T cells are systemically distributed but exhibit a unique phenotype within the brain post‐ECM, and that their reactivation characteristics are shaped by infection history. Our results raise important questions regarding the role of distinct memory CD8+ T‐cell populations within the brain and other tissues during repeat Plasmodium infections

Moxifloxacin resistance in the F15/LAM4/KZN extensively drug-resistant strain of Mycobacterium tuberculosis

Navisha Dookie, A Willem Sturm, Prashini Moodley Department of Infection Prevention and Control, Nelson R Mandela School of Medicine, School of Laboratory Medicine and Medical Science, College of Health Science, University of KwaZulu-Natal, Durban, South Africa Objectives: Moxifloxacin (MXF) has been advocated for the treatment of extensively drug-resistant (XDR) tuberculosis despite resistance to older-generation fluoroquinolones. We investigated the relationship between the minimum inhibitory concentration (MIC) of MXF and mutations in the gyrA and gyrB genes in Mycobacterium tuberculosis (MTB) isolates from KwaZulu-Natal (KZN) Province of South Africa. Materials and methods: MICs of 56 MTB isolates were compared to the mutations in the quinolone resistance-determining region known to confer fluoroquinolone resistance. Isolates were genotyped by IS6110 restriction fragment length polymorphism analysis. Results: The circulating F15/LAM4/KZN XDR strain circulating in KZN Province harbored the A90V mutation and displayed high-level resistance with MICs of 8 mg/L for ciprofloxacin and ofloxacin and ≥1 mg/L for MXF. Conclusion: The inclusion of MXF in XDR-TB treatment regimens requires careful consideration in our setting, where clinical outcome data in MXF-containing regimens are unavailable. Keywords: fluoroquinolones, susceptibility testing, strain typing, drug-resistanc

Atypical presentation of critical left main disease in an HIV-infected patient

Rajeev Seecheran,1 Valmiki Seecheran,2 Sangeeta Persad,2 Taarik Dookie,3 Naveen Anand Seecheran1 1Department of Clinical Medical Sciences, University of the West Indies, St. Augustine, Trinidad and Tobago; 2Cardiovascular Services Division, North West Regional Health Authority, Mt. Hope, Trinidad and Tobago; 3Cardiology Unit, Advanced Cardiovascular Institute, Port of Spain, Trinidad and Tobago Abstract: Coronary artery disease is currently one of the leading causes of mortality in patients with HIV. Severe left main disease (LMD) occurs in ~6% of the HIV-infected patients. We describe a case report of an atypical presentation of silent critical LMD in an HIV-infected patient who underwent a low-risk exercise stress test. The cardiovascular disease team should be vigilant for this latent phenomenon, specifically within this subpopulation despite the high Duke treadmill score. Keywords: left main disease, left main lesion, left main stenosis, human immunodeficiency virus, HI

Lateral displacement of liquefaction induced ground using least square support vector machine

The determination of lateral displacement of liquefaction induced ground during an earthquake is an imperative task in disaster mitigation. This study investigates the possibility of using least square support vector machine (LSSVM) for the prediction of lateral displacement of liquefaction induced ground during an earthquake. The results have been compared with those obtained using artificial neural network (ANN) models and observed that LSSVM outperformed the ANN models. Model equation has been presented based on the model parameters, which can be used by the professionals. Sensitivity analysis has also been performed to determine the importance of each of the input parameters

Mycobacterium tuberculosis Intra-Host Evolution Among Drug-Resistant Tuberculosis Patients Failing Treatment

Rubeshan Perumal,1,2 Azraa Khan,1 Kogieleum Naidoo,1,2 Senamile L Ngema,1 Louansha Nandlal,1,2 Nesri Padayatchi,1,2 Navisha Dookie1,2 1Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu-Natal, Durban, KwaZulu Natal, South Africa; 2South African Medical Research Council (SAMRC) – CAPRISA HIV-TB Pathogenesis and Treatment Research Unit, Durban, KwaZulu Natal, South AfricaCorrespondence: Rubeshan Perumal, Doris Duke Medical Research Institute (2nd Floor), Nelson R. Mandela School of Medicine, University of KwaZulu-Natal, Private Bag X7, Congella, Durban, 4013, South Africa, Tel +27 31 260 4555, Fax +27 31 260 4566, Email [email protected]: Understanding Mycobacterium tuberculosis (Mtb) intra-host evolution of drug resistance is important for successful drug-resistant tuberculosis (DR-TB) treatment and control strategies. This study aimed to characterise the acquisition of genetic mutations and low-frequency variants associated with treatment-emergent Mtb drug resistance in longitudinally profiled clinical isolates from patients who experienced DR-TB treatment failure.Patients and Methods: We performed deep Whole Genome Sequencing on 23 clinical isolates obtained longitudinally across nine timepoints from five patients who experienced DR-TB treatment failure enrolled in the CAPRISA 020 InDEX study. The minimum inhibitory concentrations (MICs) were established on the BACTEC™ MGIT 960™ instrument on 15/23 longitudinal clinical isolates for eight anti-TB drugs (rifampicin, isoniazid, ethambutol, levofloxacin, moxifloxacin, linezolid, clofazimine, bedaquiline).Results: In total, 22 resistance associated mutations/variants were detected. We observed four treatment-emergent mutations in two out of the five patients. Emerging resistance to the fluoroquinolones was associated with 16- and 64-fold elevated levofloxacin (2– 8 mg/L) and moxifloxacin (1– 2 mg/L) MICs, respectively, resulting from the D94G/N and A90V variants in the gyrA gene. We identified two novel mutations associated with elevated bedaquiline MICs (> 66-fold): an emerging frameshift variant (D165) on the Rv0678 gene and R409Q variant on the Rv1979c gene present from baseline.Conclusion: Genotypic and phenotypic resistance to the fluoroquinolones and bedaquiline was acquired in two out of five patients who experienced DR-TB treatment failure. Deep sequencing of multiple longitudinal clinical isolates for resistance-associated mutations coupled with phenotypic MIC testing confirmed intra-host Mtb evolution.Keywords: tuberculosis, phenotypic resistance, drug resistance acquisition, whole genome sequencing, emerging mutations, bedaquilin

Recurrent tuberculosis among HIV-coinfected patients: a case series from KwaZulu-Natal

Kogieleum Naidoo,1,2 Navisha Dookie,1,3 Kasavan Naidoo,2 Nonhlanhla Yende-Zuma,1 Benjamin Chimukangara,1,3,4 Ambika Bhushan,1 Dhineshree Govender,1 Santhanalakshmi Gengiah,1 Nesri Padayatchi1,2 1Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu-Natal, Durban, South Africa; 2South African Medical Research Council (SAMRC) - CAPRISA HIV-TB Pathogenesis and Treatment Research Unit, Durban, South Africa; 3KwaZulu Natal Research Innovation and Sequencing Platform (KRISP), University of KwaZulu-Natal, Durban, South Africa; 4Department of Virology, National Health Laboratory Service, University of KwaZulu-Natal, Durban, South Africa Background: Recurrent tuberculosis (TB) following TB treatment completion in HIV-infected individuals remains a major public health burden. We assessed the role of various risk factors in mediating the development of recurrent TB and subsequent resistance to antiretroviral therapy and anti-TB drugs. Patients and methods: We analyzed secondary demographic, clinical, and laboratory data from medical records of five HIV-infected TB patients enrolled between 2009 and 2014 in a prospective observational study investigating TB recurrence. Paired clinical isolates of Mycobacterium tuberculosis were typed by IS6110 restriction fragment length polymorphism analysis to determine the mechanism of TB recurrence. Plasma samples were genotyped to determine acquisition of HIV drug resistance mutations on antiretroviral treatment (ART). Results: All five patients were HIV-coinfected, with a previous history of TB infection and prior exposure to anti-TB treatment, and residual lung damage, and demonstrated poor treatment adherence – significant risk factors linked to the development of recurrent TB disease. Furthermore, three of the five patients had multiple episodes of drug-susceptible TB infection with subsequent drug-resistant TB infection. Genotyping of the initial and recurrent M. tuberculosis isolates demonstrated three cases of recurrent TB because of relapse and two because of reinfection. All five patients had no mutations at ART initiation; however, by the end of the study follow-up, all patients developed dual class resistance. Conclusion: This series demonstrates the complexity of recurrent TB in HIV coinfection. We highlight the challenges of managing coinfected patients and the increased propensity for the development of drug resistance. We report on the role of various risk factors mediating the development of resistance and subsequent clinical impact. This report underscores the need for structural clinical and adherence interventions for the management of complex treatment and dosing. Keywords: adherence, TB–HIV coinfection, social risk factors, IS6110 RFLP, drug resistanc