Exploring Onchocerca volvulus Cysteine Protease Inhibitor for Multi-epitope Subunit Vaccine Against Onchocerciasis: An Immunoinformatics Approach

Onchocerciasis, caused by Onchocerca volvulus, affects more than 37 million people worldwide. Despite the progress achieved with mass drug distribution, suitable vaccines against onchocerciasis are needed to effectively eliminate the infection. The O. volvulus cysteine protease inhibitor (onchocystatin) is an immuno-dominant antigen detected in O. volvulus infections, capable of inducing protective immunity. Here, we explore the onchocystatin for a multi-epitope subunit vaccine candidate targeted against onchocerciasis. A multi-epitope vaccine candidate composed of RS-09 as adjuvant, a CD8⁺ T cell peptide, a CD4⁺ T cell peptide and a B cell peptide concatenated with suitable linkers was computationally constructed. Immune simulation of the vaccine response predicted several aspects of antibody-dependent and cellular-mediated immunity with accompanied B cell and helper T cell immune memory development. The levels of lFN-γ and IL-2 were also predicted to be elevated. Collectively, our results suggest that the multi-epitope vaccine construct has the potential to mimic the natural immunity targeted against onchocerciasis and other related filarial infections, and should be considered for further experimental validations.

     

Targeted therapy for gastric cancer: Molecular pathways and ongoing investigations

Gastric cancer is currently the second leading cause of worldwide cancer mortality. Ongoing collaborative sequencing efforts have highlighted recurrent somatic genomic aberrations in gastric cancer, however, despite advances in characterizing the genomic landscape, there have been few advances in patient outcomes. Prognosis remains poor with a median overall survival of 12 months for advanced disease. The improved survival with trastuzumab, and more recently ramucirumab, underscore the promise of targeted and biologic therapies and the importance of molecular tumor characterization in gastric cancer. Here we review the most frequent actionable alterations in gastric cancer and highlight ongoing clinical investigations attempting to translate biologic understanding into improved clinical outcomes.     

Protein synthesis at synapse versus cell body: Enhanced but transient expression of long‐term facilitation at isolated synapses

Protein synthesis at synaptic terminals contributes to LTP in hippocampus and to the formation of new synaptic connections by sensory neurons (SNs) of Aplysia. Here we report that after removal of the SN cell body, isolated SN synapses of Aplysia in culture express protein‐synthesis dependent long‐term facilitation (LTF) produced by 5‐HT that decays rapidly. Changes in expression of a SN‐specific neuropeptide sensorin in isolated SN varicosities parallel the changes in synaptic efficacy. At 24 h after 5‐HT the magnitude of LTF produced at isolated SN synapses was significantly greater than that produced when SN cell bodies were present. LTF was maintained at 48 h at connections with SN cell bodies, but not at isolated SN synapses. The increase in synaptic efficacy at isolated SN synapses at 24 h was blocked by the protein synthesis inhibitor anisomycin. LTF was accompanied by changes in expression of sensorin. The increase in sensorin level at isolated SN varicosities with 5‐HT was blocked by anisomycin or was reversed 48 h after 5‐HT treatment alone. The results suggest that, as is the case for initial synapse formation between SNs and L7, changes in protein synthesis at synaptic terminals may contribute directly to LTF of stable synapses. Changes in expression within the cell body provide additional contributions for long‐term maintenance of the new level of synaptic efficacy that was initiated directly by local changes in protein synthesis at or near synaptic terminals. © 2003 Wiley Periodicals, Inc. J Neurobiol 56: 275–286, 2003     

Structure activity relationship studies on rhodanines and derived enethiol inhibitors of metallo-β-lactamases

Metallo-β-lactamases (MBLs) enable bacterial resistance to almost all classes of β-lactam antibiotics. We report studies on enethiol containing MBL inhibitors, which were prepared by rhodanine hydrolysis. The enethiols inhibit MBLs from different subclasses. Crystallographic analyses reveal that the enethiol sulphur displaces the di-Zn(II) ion bridging ‘hydrolytic’ water. In some, but not all, cases biophysical analyses provide evidence that rhodanine/enethiol inhibition involves formation of a ternary MBL enethiol rhodanine complex. The results demonstrate how low molecular weight active site Zn(II) chelating compounds can inhibit a range of clinically relevant MBLs and provide additional evidence for the potential of rhodanines to be hydrolysed to potent inhibitors of MBL protein fold and, maybe, other metallo-enzymes, perhaps contributing to the complex biological effects of rhodanines. The results imply that any medicinal chemistry studies employing rhodanines (and related scaffolds) as inhibitors should as a matter of course include testing of their hydrolysis products.     

The impact of endogenous content,replicates and pooling on genome capture from faecal samples

Target‐capture approach has improved over the past years, proving to be very efficient tool for selectively sequencing genetic regions of interest. These methods have also allowed the use of noninvasive samples such as faeces (characterized by their low quantity and quality of endogenous DNA) to be used in conservation genomic, evolution and population genetic studies. Here we aim to test different protocols and strategies for exome capture using the Roche SeqCap EZ Developer kit (57.5 Mb). First, we captured a complex pool of DNA libraries. Second, we assessed the influence of using more than one faecal sample, extract and/or library from the same individual, to evaluate its effect on the molecular complexity of the experiment. We validated our experiments with 18 chimpanzee faecal samples collected from two field sites as a part of the Pan African Programme: The Cultured Chimpanzee. Those two field sites are in Kibale National Park, Uganda (N = 9) and Loango National Park, Gabon (N = 9). We demonstrate that at least 16 libraries can be pooled, target enriched through hybridization, and sequenced allowing for the genotyping of 951,949 exome markers for population genetic analyses. Further, we observe that molecule richness, and thus, data acquisition, increase when using multiple libraries from the same extract or multiple extracts from the same sample. Finally, repeated captures significantly decrease the proportion of off‐target reads from 34.15% after one capture round to 7.83% after two capture rounds, supporting our conclusion that two rounds of target enrichment are advisable when using complex faecal samples.     

Long-Term Persistence of Yersinia pseudotuberculosis in Entomopathogenic Nematodes

Entomopathogenic nematodes (EPNs) are small worms whose ecological behaviour consists to invade, kill insects and feed on their cadavers thanks to a species-specific symbiotic bacterium belonging to any of the genera Xenorhabdus or Photorhabdus hosted in the gastro-intestinal tract of EPNs. The symbiont provides a number of biological functions that are essential for its EPN host including the production of entomotoxins, of enzymes able to degrade the insect constitutive macromolecules and of antimicrobial compounds able to prevent the growth of competitors in the insect cadaver. The question addressed in this study was to investigate whether a mammalian pathogen taxonomically related to Xenorhabdus was able to substitute for or “hijack” the symbiotic relationship associating Xenorhabdus and Steinernema EPNs. To deal with this question, a laboratory experimental model was developed consisting in Galleria mellonella insect larvae, Steinernema EPNs with or without their natural Xenorhabdus symbiont and Yersinia pseudotuberculosis brought artificially either in the gut of EPNs or in the haemocoel of the insect larva prior to infection. The developed model demonstrated the capacity of EPNs to act as an efficient reservoir ensuring exponential multiplication, maintenance and dissemination of Y. pseudotuberculosis.     

Preparing for the Rollout of Pre-Exposure Prophylaxis (PrEP): A Vignette Survey to Identify Intended Sexual Behaviors among Women in Kenya and South Africa if Using PrEP

Introduction

Several clinical trials have demonstrated the efficacy of pre-exposure prophylaxis (PrEP) in reducing HIV risk. One concern with introducing PrEP is whether users will engage in riskier sexual behaviors.

Methods

We assessed the effect that PrEP may have on sexual risk behaviors by administering a survey to 799 women in Bondo, Kenya, and Pretoria, South Africa. Participants were asked about their sexual behavior intentions twice — once as if they were taking PrEP and once as if they were not taking PrEP — within four risk situations (vignettes). They responded using a 5-point ordinal scale. We used a series of linear mixed effects models with an unstructured residual covariance matrix to estimate the between- and within-subject differences in the mean likelihood of engaging in risky sexual behavior across the PrEP and non-PrEP contexts. We also calculated the total percentage of participants who reported a greater likelihood of engaging in risky sexual behavior if taking PrEP than if not taking PrEP, by vignette.

Results

We found statistically significant differences in the mean likelihood of engaging in risky sexual behavior with the between-subject comparison (-0.17, p < 0.01) and with the within-subject comparison (-0.31, p < 0.001). Depending on the vignette, 27% to 40% of participants reported a greater likelihood of engaging in risky sexual behavior if taking PrEP than if not taking PrEP.

Conclusions

Our findings indicate that modest increases in risky sexual behavior could occur with PrEP. Although responses from the majority of participants suggest they would not be more likely to engage in risky sexual behavior if they took PrEP, a substantial proportion might. Programs rolling out PrEP should be prepared to assist similar women in making informed choices about reducing their risk of HIV and about their sexual health beyond HIV prevention.     

T-Helper1/T-Helper2 Cytokine Imbalance in the Iris of Patients with Glaucoma

The mechanistic study of glaucoma pathogenesis has shifted to seeking to understand the effects of immune responses on retinal ganglion cell damage and protection. Cytokines mediate the biological effects of the immune system, and our previous study revealed an imbalance of T-helper (Th) 1-derived and Th2-derived cytokines in the serum of patients with glaucoma. In this study, we collected irises from normal individuals and patients with primary open-angle closure (POAG) or chronic angle-closure glaucoma (CACG). We used real-time polymerase chain reaction (PCR) to measure the expression of Th1 (interleukin (IL)-2, interferon-gamma (IFN-γ)), Th2 (IL-4, IL-6, IL-10), and Th3 (transforming growth factor-beta (TGF-β)) cytokines. We then performed immunohistochemical staining to characterize the localization of the upregulated cytokines in iris cryosections. We observed an upward trend in the expression of IL-2 and IFN-γ and a downward trend in IL-6 expression in the iris of POAG and CACG patients. Expression of TGF-β also increased. Immunohistochemistry revealed that IL-2 expression in POAG and CACG patients was localized in the anterior surface of the blood vessel wall in the stroma of the iris, in the cytoplasm of some cells, in the anterior epithelium, and in the posterior pigment epithelium. These findings indicate that immune status differed between the iris tissues of POAG and CACG patients and those of normal individuals. A T-helper cytokine imbalance may modulate the immune microenvironment in glaucomatous eyes and thus influence optic neuropathy.     

Detecting Nasal Vowels in Speech Interfaces Based on Surface Electromyography

Nasality is a very important characteristic of several languages, European Portuguese being one of them. This paper addresses the challenge of nasality detection in surface electromyography (EMG) based speech interfaces. We explore the existence of useful information about the velum movement and also assess if muscles deeper down in the face and neck region can be measured using surface electrodes, and the best electrode location to do so. The procedure we adopted uses Real-Time Magnetic Resonance Imaging (RT-MRI), collected from a set of speakers, providing a method to interpret EMG data. By ensuring compatible data recording conditions, and proper time alignment between the EMG and the RT-MRI data, we are able to accurately estimate the time when the velum moves and the type of movement when a nasal vowel occurs. The combination of these two sources revealed interesting and distinct characteristics in the EMG signal when a nasal vowel is uttered, which motivated a classification experiment. Overall results of this experiment provide evidence that it is possible to detect velum movement using sensors positioned below the ear, between mastoid process and the mandible, in the upper neck region. In a frame-based classification scenario, error rates as low as 32.5% for all speakers and 23.4% for the best speaker have been achieved, for nasal vowel detection. This outcome stands as an encouraging result, fostering the grounds for deeper exploration of the proposed approach as a promising route to the development of an EMG-based speech interface for languages with strong nasal characteristics.