Insights from the complete genome sequence of Mycobacterium marinum on the evolution of Mycobacterium tuberculosis

Mycobacterium marinum, a ubiquitous pathogen of fish and amphibia, is a near relative of Mycobacterium tuberculosis, the etiologic agent of tuberculosis in humans. The genome of the M strain of M. marinum comprises a 6,636,827-bp circular chromosome with 5424 CDS, 10 prophages, and a 23-kb mercury-resistance plasmid. Prominent features are the very large number of genes (57) encoding polyketide synthases (PKSs) and nonribosomal peptide synthases (NRPSs) and the most extensive repertoire yet reported of the mycobacteria-restricted PE and PPE proteins, and related-ESX secretion systems. Some of the NRPS genes comprise a novel family and seem to have been acquired horizontally. M. marinum is used widely as a model organism to study M. tuberculosis pathogenesis, and genome comparisons confirmed the close genetic relationship between these two species, as they share 3000 orthologs with an average amino acid identity of 85%. Comparisons with the more distantly related Mycobacterium avium subspecies paratuberculosis and Mycobacterium smegmatis reveal how an ancestral generalist mycobacterium evolved into M. tuberculosis and M. marinum. M. tuberculosis has undergone genome downsizing and extensive lateral gene transfer to become a specialized pathogen of humans and other primates without retaining an environmental niche. M. marinum has maintained a large genome so as to retain the capacity for environmental survival while becoming a broad host range pathogen that produces disease strikingly similar to M. tuberculosis. The work described herein provides a foundation for using M. marinum to better understand the determinants of pathogenesis of tuberculosis.     

Event free survival at 24 months is a strong surrogate prognostic endpoint of peripheral T cell lymphoma

Event free survival at 24 months (EFS24) has been described as a powerful predictor for outcome in several subtypes of B cell lymphoma. However, it was limitedly described in T cell lymphoma. We explored the implication of EFS24 as a predictor marker for peripheral T cell lymphoma (PTCL). We reviewed 293 systemic PTCL patients at 13 nationwide major university hospitals in Thailand from 2007 to 2014. The median event free survival (EFS) and overall survival (OS) of PTCL patients in our cohort was 16.3 and 27.7 months with corresponding 2‐year EFS and 2‐year OS of 45.8% and 51.9%, respectively. A total of 118 patients achieved EFS24 (no events during the first 24 mo). Patients who achieved EFS24 had better OS than patients who did not (2‐y OS 92% vs 18.8%; HR, 0.1; P < .001). The standardized mortality ratio of patients achieving EFS24 was 18.7 (95% CI, 14.6‐22.8). Multivariable analysis demonstrated performance status, histologic subtype, remission status, and EFS24 achievement as independent predictors for OS. Our study affirmed the value of EFS24 as a powerful prognostic factor for PTCL. Further validation in prospective study setting is warranted.     

Reproducibility of minimum rim width and retinal nerve fibre layer thickness using the Anatomic Positioning System in glaucoma patients

ObjectiveTo determine the test?retest repeatability of minimum rim width and retinal nerve fibre layer thickness measurements obtained by spectral-domain optical coherence tomography using the Anatomic Positioning System protocol in glaucoma patients and controls. Also, to assess the ability of the minimum rim width and retinal nerve fibre layer thickness to diagnose glaucoma in 2 circular peripapillary locations.MethodsSpectral domain optical coherence tomography scans of the optic nerve head were obtained twice during the same visit using the Anatomic Positioning System eye-tracking protocol. The minimum rim width and retinal nerve fibre layer thickness were measured at 3 circular diameters (3.5 mm, 4.1 mm, and 4.7 mm). Intraclass correlation coefficients and area under the receiver operating characteristic were calculated for these parameters.ResultsA total of 36 glaucomatous eyes and 59 control eyes were included in the analysis. The intraclass correlation coefficients of minimum rim width and retinal nerve fibre layer thickness global measurement for 3.5 mm and 4.1 mm circles ranged between 0.98 and 1.00 and for 4.7 mm circle was between 0.76 and 1.00. The minimum rim width had an area under the receiver operating characteristic of 0.97, while the retinal nerve fibre layer thickness measurements had an area under the receiver operating characteristic of 0.95, 0.95, and 0.96 for the 3.5 mm, 4.1 mm, and 4.7 mm circles, respectively.ConclusionsThe minimum rim width and retinal nerve fibre layer thickness measurements using the Anatomic Positioning System protocol had overall excellent reproducibility and diagnostic performance. Using this protocol and the novel minimum rim width parameter may be useful in more accurate diagnosis and follow-up of patients with glaucoma.     

Therapeutic potential of probiotics – Lactobacillus plantarum UBLP40 and Bacillus clausii UBBC07 on thioacetamide-induced acute hepatic encephalopathy in rats

Metabolic Brain Disease - Hepatic encephalopathy (HE) or hepatic coma is a demanding, not utterly understood complication of acute and chronic liver dysfunction and portosystemic shunting. In HE,...     

Magneto-Rheological Fluid Assisted Abrasive Nanofinishing of β-Phase Ti-Nb-Ta-Zr Alloy: Parametric Appraisal and Corrosion Analysis

The present work explores the potential of magneto-rheological fluid assisted abrasive finishing (MRF-AF) for obtaining precise surface topography of an in-house developed β-phase Ti-Nb-Ta-Zr (TNTZ) alloy for orthopedic applications. Investigations have been made to study the influence of the concentration of carbonyl iron particles (CIP), rotational speed (Nt), and working gap (Gp) in response to material removal (MR) and surface roughness (Ra) of the finished sample using a design of experimental technique. Further, the corrosion performance of the finished samples has also been analyzed through simulated body fluid (SBF) testing. It has been found that the selected input process parameters significantly influenced the observed MR and Ra values at 95% confidence level. Apart from this, it has been found that Gp and Nt exhibited the maximum contribution in the optimized values of the MR and Ra, respectively. Further, the corrosion analysis of the finished samples specified that the resistance against corrosion is a direct function of the surface finish. The morphological analysis of the corroded morphologies indicated that the rough sites of the implant surface have provided the nuclei for corrosion mechanics that ultimately resulted in the shredding of the appetite layer. Overall results highlighted that the MRF-AF is a potential technique for obtaining nano-scale finishing of the high-strength β-phase Ti-Nb-Ta-Zr alloy.     

Human antibody responses after dengue virus infection are highly cross-reactive to Zika virus

Zika virus (ZIKV) is an emerging mosquito-borne flavivirus of significant public health concern. ZIKV shares a high degree of sequence and structural homology compared with other flaviviruses, including dengue virus (DENV), resulting in immunological cross-reactivity. Improving our current understanding of the extent and characteristics of this immunological cross-reactivity is important, as ZIKV is presently circulating in areas that are highly endemic for dengue. To assess the magnitude and functional quality of cross-reactive immune responses between these closely related viruses, we tested acute and convalescent sera from nine Thai patients with PCR-confirmed DENV infection against ZIKV. All of the sera tested were cross-reactive with ZIKV, both in binding and in neutralization. To deconstruct the observed serum cross-reactivity in depth, we also characterized a panel of DENV-specific plasmablast-derived monoclonal antibodies (mAbs) for activity against ZIKV. Nearly half of the 47 DENV-reactive mAbs studied bound to both whole ZIKV virion and ZIKV lysate, of which a subset also neutralized ZIKV. In addition, both sera and mAbs from the dengue-infected patients enhanced ZIKV infection of Fc gamma receptor (FcγR)-bearing cells in vitro. Taken together, these findings suggest that preexisting immunity to DENV may impact protective immune responses against ZIKV. In addition, the extensive cross-reactivity may have implications for ZIKV virulence and disease severity in DENV-experienced populations.Zika virus (ZIKV) is a mosquito-borne virus belonging to the Flaviviridae family of single-stranded positive-sense RNA viruses. First isolated in Uganda in 1947 (1), this virus remained largely dormant for the next six decades until it reemerged as the cause of an epidemic on Yap Islands, Micronesia in 2007 (2). ZIKV has since then been linked with several outbreaks in the Pacific and Americas, along with sporadic human cases in Africa and Asia (3, 4). Until its appearance in French Polynesia in 2013 and more recently in Brazil in 2015, ZIKV infection was primarily associated with mild self-limiting illness, with symptoms similar to and often milder than dengue virus (DENV) or Chikungunya virus (CHIKV) infections (2–4). However, the more recent outbreaks have caused severe neurological complications including Guillain–Barré Syndrome in adults and an increase in congenital microcephaly and other adverse birth outcomes in Brazil (5–7). The Pan American Health Organization has reported that as of May 2016, local transmission of ZIKV had spread to over 38 countries or territories in the Americas. In addition, a recent WHO report states that 44 new countries are experiencing their first ZIKV outbreak since 2015. Despite the improving surveillance of the virus, accurate diagnosis has been challenging given the similarities in the clinical presentation of ZIKV to other arboviral infections endemic in these regions, among other factors.During the viremic period, ZIKV can be found in patient blood, saliva, urine, and other bodily fluids early after symptom onset (8–10). During the Yap Islands epidemic in 2007, anti-ZIKV IgM ELISAs and ZIKV plaque reduction neutralization titer (PRNT) assays were performed to confirm infection in RT-PCR negative cases (2, 8). However, as these studies showed, the cross-reactivity between ZIKV and other flaviviruses makes confirmation of infection difficult, especially when patients may have had flavivirus exposures before their suspected ZIKV infection (2, 8). Given the overlapping presence of DENV and other flaviviruses in a majority of ZIKV epidemic regions (11), there are great challenges in serology-based testing of flavivirus-immune patients (12).The DENV envelope (E) protein, considered a major imunodominant target for antibody responses in dengue patients (13–15), bears greater than 50% homology to ZIKV E protein (16). In addition to complicating the serology-based diagnosis of ZIKV infection, this raises an interesting question about the biological implications of the cross-reactivity on protection, virulence, and immunopathology of ZIKV infections. At present, the effect of preexisting immunity to DENV or other flaviviruses on immune responses induced by ZIKV infection is unknown. To this end, we were interested in determining the degree to which dengue-induced antibodies cross-react with ZIKV in terms of binding, virus neutralization, and antibody-dependent enhancement (ADE) of ZIKV infection, both at the serum and single-cell level.In this study, we provide an analysis of the cross-reactivity of acute and convalescent dengue-immune sera against ZIKV. The sera were collected from nine patients admitted to Siriraj Hospital in Bangkok, Thailand with confirmed DENV infection. Both acute and convalescent sera showed high binding titers to ZIKV lysate and could also neutralize ZIKV in vitro. To understand the origin and characteristics of these cross-reactive serum responses, we also analyzed a panel of plasmablast-derived DENV-reactive monoclonal antibodies (mAbs). Of the 47 mAbs tested, nearly half (22/47) bound to ZIKV lysate and an additional four to the whole virus. Seven of these mAbs also neutralized ZIKV in vitro. Five sera and a subset of the mAbs were also tested for ADE activity using the FcγR-bearing monocytic U937 cell line. All sera and ZIKV-reactive mAbs tested enhanced infection in vitro, whereas two DENV-specific but ZIKV-nonreactive mAbs did not. The data presented here have important implications for clinical diagnosis given that the current ZIKV outbreak in the Americas and the Caribbean is largely ongoing in dengue-endemic areas. Equally important, these findings set the stage for more in-depth studies that explore how preexisting flavivirus immunity may shape immune responses to ZIKV infection.     

Effect of mosquito midgut trypsin activity on dengue-2 virus infection and dissemination in Aedes aegypti

The effect of mosquito midgut trypsins in dengue serotype 2 flavivirus (DENV-2) infectivity to Aedes aegypti was studied. Addition of soybean trypsin inhibitor (STI) in a DENV-2 infectious blood meal resulted in a 91-97% decrease in midgut DENV-2 RNA copies (qRT-PCR analysis). STI treatment also resulted in slower DENV-2 replication in the midgut, less DENV-2 E protein expression, and decreased dissemination to the thorax and the head. A second uninfected blood meal, 7 days after the STI-treated infectious meal, significantly increased DENV-2 replication in the midgut and recovered oogenesis, suggesting that the lower viral infection caused by STI was in part due to a nutritional effect. Mosquitoes fed DENV-2 digested in vitro with bovine trypsin (before STI addition) exhibited a transient increase in midgut DENV-2 4 days postinfection. Blood digestion and possibly DENV-2 proteolytic processing, mediated by midgut trypsins, influence the rate of DENV-2 infection, replication, and dissemination in Ae. aegypti.