Validation of a chloroquine-induced cell death mechanism for clinical use against malaria

An alternative antimalarial pathway of an ‘outdated’ drug, chloroquine (CQ), may facilitate its return to the shrinking list of effective antimalarials. Conventionally, CQ is believed to interfere with hemozoin formation at nanomolar concentrations, but resistant parasites are able to efflux this drug from the digestive vacuole (DV). However, we show that the DV membrane of both resistant and sensitive laboratory and field parasites is compromised after exposure to micromolar concentrations of CQ, leading to an extrusion of DV proteases. Furthermore, only a short period of exposure is required to compromise the viability of late-stage parasites. To study the feasibility of this strategy, mice malaria models were used to demonstrate that high doses of CQ also triggered DV permeabilization in vivo and reduced reinvasion efficiency. We suggest that a time-release oral formulation of CQ may sustain elevated blood CQ levels sufficiently to clear even CQ-resistant parasites

A whole cell pathway screen reveals seven novel chemosensitizers to combat chloroquine resistant malaria

Due to the widespread prevalence of resistant parasites, chloroquine (CQ) was removed from front-line antimalarial chemotherapy in the 1990s despite its initial promise of disease eradication. Since then, resistance-conferring mutations have been identified in transporters such as the PfCRT, that allow for the efflux of CQ from its primary site of action, the parasite digestive vacuole. Chemosensitizing/ chemoreversing compounds interfere with the function of these transporters thereby sensitizing parasites to CQ once again. However, compounds identified thus far have disappointing in vivo efficacy and screening for alternative candidates is required to revive this strategy. In this study, we propose a simple and direct means to rapidly screen for such compounds using a fluorescent-tagged CQ molecule. When this screen was applied to a small library, seven novel chemosensitizers (octoclothepin, methiothepin, metergoline, loperamide, chlorprothixene, L-703,606 and mibefradil) were quickly elucidated, including two which showed greater potency than the classical chemosensitizers verapamil and desipramine

Strategic treatment optimization for HCV (STOPHCV1): a randomised controlled trial of ultrashort duration therapy for chronic hepatitis C [version 1; peer review: awaiting peer review]

Background: The world health organization (WHO) has identified the need for a better understanding of which patients with hepatitis C virus (HCV) can be cured with ultrashort course HCV therapy. Methods: A total of 202 individuals with chronic HCV were randomised to fixed-duration shortened therapy (8 weeks) vs variable duration ultrashort strategies (VUS1/2). Participants not cured following first-line treatment were retreated with 12 weeks’ sofosbuvir/ledipasvir/ribavirin. The primary outcome was sustained virological response 12 weeks (SVR12) after first-line treatment and retreatment. Participants were factorially randomised to receive ribavirin with first-line treatment. Results: All evaluable participants achieved SVR12 overall (197/197, 100% [95% CI 98-100]) demonstrating non-inferiority between fixedduration and variable-duration strategies (difference 0% [95% CI - 3.8%, +3.7%], 4% pre-specified non-inferiority margin). First-line SVR12 was 91% [86%-97%] (92/101) for fixed-duration vs 48% [39%-57%] (47/98) for variable-duration, but was significantly higher for VUS2 (72% [56%-87%] (23/32)) than VUS1 (36% [25%-48%] (24/66)). Overall, first-line SVR12 was 72% [65%-78%] (70/101) without ribavirin and 68% [61%-76%] (69/98) with ribavirin (p=0.48). At treatment failure, the emergence of viral resistance was lower with ribavirin (12% [2%-30%] (3/26)) than without (38% [21%-58%] (11/29), p=0.01). Conclusions: Unsuccessful first-line short-course therapy did not compromise retreatment with sofosbuvir/ledipasvir/ribavirin (100% SVR12). SVR12 rates were significantly increased when ultrashort treatment varied between 4-7 weeks rather than 4-6 weeks. Ribavirin significantly reduced resistance emergence in those failing first-line therapy. ISRCTN Registration: 37915093 (11/04/2016)

Five Questions about Viral Trafficking in Neurons

One of the most exciting areas in biology is the nervous system and how it works. Viral infections of the nervous system have provided exceptional insight at many levels, from pathogenesis to basic biology. The nervous system has evolved rather complicated barriers that facilitate access to nutrients and contact with the outside world, but block entry of pathogens and toxins [1]. However, when these barriers are reduced for any number of reasons, nervous system infections are possible. When they occur, they can be devastating and, even with good antiviral drugs, difficult to manage. Viral infections can enter the brain via the blood (e.g., HIV, various encephalitis viruses) or by spread inside neurons from the body surface (e.g., rabies and alpha herpes viruses) [2,3]. In vertebrates, the nervous system comprises a peripheral collection of neurons (the peripheral nervous system, PNS) and a central set found in the brain and spinal cord (the central nervous system, CNS). While neurons are central players in neurobiology, it is important to realize that the majority of cells that comprise the nervous system are highly specialized, nonneuronal cells (e.g., different types of glial cells) [4]. Cells of the immune system also engage with and signal to the PNS to affect changes in the CNS [5]. We will focus on neurons, despite the other cellular complexity, because neurons provide direct avenues for viral infection. Recognition that viral infection follows nerve pathways enabled the development of viruses for neuronal circuit tracing [6–8]

Targeting of Pseudorabies Virus Structural Proteins to Axons Requires Association of the Viral Us9 Protein with Lipid Rafts

The pseudorabies virus (PRV) Us9 protein plays a central role in targeting viral capsids and glycoproteins to axons of dissociated sympathetic neurons. As a result, Us9 null mutants are defective in anterograde transmission of infection in vivo. However, it is unclear how Us9 promotes axonal sorting of so many viral proteins. It is known that the glycoproteins gB, gC, gD and gE are associated with lipid raft microdomains on the surface of infected swine kidney cells and monocytes, and are directed into the axon in a Us9-dependent manner. In this report, we determined that Us9 is associated with lipid rafts, and that this association is critical to Us9-mediated sorting of viral structural proteins. We used infected non-polarized and polarized PC12 cells, a rat pheochromocytoma cell line that acquires many of the characteristics of sympathetic neurons in the presence of nerve growth factor (NGF). In these cells, Us9 is highly enriched in detergent-resistant membranes (DRMs). Moreover, reducing the affinity of Us9 for lipid rafts inhibited anterograde transmission of infection from sympathetic neurons to epithelial cells in vitro. We conclude that association of Us9 with lipid rafts is key for efficient targeting of structural proteins to axons and, as a consequence, for directional spread of PRV from pre-synaptic to post-synaptic neurons and cells of the mammalian nervous system

Differential Spatial Expression and Subcellular Localization of CtBP Family Members in Rodent Brain

C-terminal binding proteins (CtBPs) are well-characterized nuclear transcriptional co-regulators. In addition, cytoplasmic functions were discovered for these ubiquitously expressed proteins. These include the involvement of the isoform CtBP1-S/BARS50 in cellular membrane-trafficking processes and a role of the isoform RIBEYE as molecular scaffolds in ribbons, the presynaptic specializations of sensory synapses. CtBPs were suggested to regulate neuronal differentiation and they were implied in the control of gene expression during epileptogenesis. However, the expression patterns of CtBP family members in specific brain areas and their subcellular localizations in neurons in situ are largely unknown. Here, we performed comprehensive assessment of the expression of CtBP1 and CtBP2 in mouse brain at the microscopic and the ultra-structural levels using specific antibodies. We quantified and compared expression levels of both CtBPs in biochemically isolated brain fractions containing cellular nuclei or synaptic compartment. Our study demonstrates differential regional and subcellular expression patterns for the two CtBP family members in brain and reveals a previously unknown synaptic localization for CtBP2 in particular brain regions. Finally, we propose a mechanism of differential synapto-nuclear targeting of its splice variants CtBP2-S and CtBP2-L in neurons