J o u r n a l P r e -p r o o f Highlights  The article provides a summary on cellular receptors involved in virus immunity.  It presents an overview of the current understanding of inflammasomes complex activation, comparing its different types with special focus on NLRP3.  The article summarizes key findings on viroporins, a novel class of viral proteins and their role in the virus life cycle and host cell interactions.  The article sheds the light on the correlation between viroporins and inflammasomes activation and their possible contribution to aggravated inflammatory cytokines production.  The article proposes targeting inflammasomes in combination with viroporin inhibitors in virus-induced disease as an emerging attractive therapeutic option. Abstract Viroporins are virus encoded proteins that alter membrane permeability and can trigger subsequent cellular signals. Oligomerization of viroporin subunits results in formation of a hydrophilic pore which facilitates ion transport across host cell membranes. These viral channel proteins may be involved in different stages of the virus infection cycle. J o u r n a l P r e -p r o o f List of abbreviationsAIM Absent in melanoma ASC Apoptosis-associated speck-like protein containing a carboxy-terminal CARD ATP Adenosine triphosphate BMDC Bone marrow derived dendritic cells BMM Bone marrow derived macrophages CARD Caspase activation and recruitment domain CD Cluster of differentiation CoV Coronavirus CSFV Classical swine fever virus DAMPs Danger associated molecular patterns DC Dendritic cells EMCV Encephalomyocarditis virus HCV Hepatitis C virus HIV Human immune deficiency virus LPS Lipopolysaccharide LRR Leucine rich repeats MAL MyD88-adaptor-like MAM Mitochondrial-associated membrane MAVS Mitochondrial antiviral signaling protein MDA5 Melanoma differentiation-associated protein 5 MERS Middle East respiratory syndrome-related coronavirus MHC Major histocompatibility complex J o u r n a l P r e -p r o o f MSU Monosodium urate MyD88 Myeloid differentiation primary response 88 NADPH Nicotinamide adenine dinucleotide phosphate NALP NACHT, LRR and PYD domains-containing protein NFκB Nuclear factor kappa b NLR Nucleotide-binding domain, leucine-rich repeat NLRP3 NLR family, pyrin domain containing 3 Nod Nucleotide oligomerization domain PAMP Pathogen associated molecular patterns PRR Pattern recognition receptors PYD Pyrin domain RIG-1 Retinoic acid-inducible gene I RLR RIG-1 like receptor ROS Reactive Oxygen species RSV Respiratory syncytial virus

Hepatitis C is a major worldwide disease and health hazard, affecting ∼3% of the world population. The p7 protein of hepatitis C virus (HCV) is an intracellular ion channel and pH regulator that is involved in the viral replication cycle. It is targeted by various classical ion channel blockers. Here, we generated p7 constructs corresponding to HCV genotypes 1a, 2a, 3a, and 4a for recombinant expression in HEK293 cells, and studied p7 channels using patch-clamp recording techniques. The pH50 values for recombinant p7 channels were between 6.0 and 6.5, as expected for proton-activated channels, and current-voltage dependence did not show any differences between genotypes. Inhibition of p7-mediated currents by amantadine, however, exhibited significant, genotype-specific variation. The IC50 values of p7-1a and p7-4a were 0.7 ± 0.1 nM and 3.2 ± 1.2 nM, whereas p7-2a and p7-3a had 50- to 1000-fold lower sensitivity, with IC50 values of 2402 ± 334 nM and 344 ± 64 nM, respectively. The IC50 values for rimantadine were low across all genotypes, ranging from 0.7 ± 0.1 nM, 1.6 ± 0.6 nM, and 3.0 ± 0.8 nM for p7-1a, p7-3a, and p7-4a, respectively, to 24 ± 4 nM for p7-2a. Results from patch-clamp recordings agreed well with cellular assays of p7 activity, namely, measurements of intracellular pH and hemadsorption assays, which confirmed the much reduced amantadine sensitivity of genotypes 2a and 3a. Thus, our results establish patch-clamp studies of recombinant viroporins as a valid analytical tool that can provide quantitative information about viroporin channel properties, complementing established techniques.

Hepatitis C is one of the most widespread infectious diseases worldwide and hepatitis C virus (HCV)-induced chronic inflammation is highly associated with progredient liver damage. It was shown that HCV infection increases levels of pro-inflammatory cytokines via activation of NOD-like receptor (NLRP3) inflammasomes, yet the underlying mechanism is still under question. We propose modulation of intracellular pH by p7, a 63 residue ion channel produced by the hepatitis C virus as a possible pathomechanism for hepatitis C-associated inflammation. Recombinant constructs corresponding to HCV genotypes 1-4 were expressed in HEK 293 and RAW 264.7 cells and changes of intracellular pH were monitored using pH-sensitive fluorescent probes as well as production of inflammatory cytokines. Presence of p7 induced general loss of vesicular acidity as well as producing a significant increase in the levels of interleukin-1β (IL-1β). Effects showed a genotype-dependent pattern of IL-1β production, in agreement with the pH-response profile of p7 channels corresponding to hepatitis C genotypes. Lowering the pH of the extracellular medium increased activity of p7 channels as well as production of IL-1β for genotypes 1, 3, and 4, but less for genotype 2. Our data are in agreement with the hypothesis that p7 activity can trigger intracellular signaling cascades that are involved in HCV-associated cytopathy.

No abstract

BackgroundCandida albicans is a common cause of a variety of superficial and invasive disseminated infections the majority of which are associated with biofilm growth on implanted devices. The aim of the study is to evaluate the activity of amphotericin B and voriconazole against the biofilm and the biofilm-dispersed cells of Candida albicans using a newly developed in vitro pharmacokinetic model which simulates the clinical situation when the antifungal agents are administered intermittently.MethodsRPMI medium containing 1–5 X 106 CFU/ml of C. albicans was continuously delivered to the device at 30 ml/h for 2 hours. The planktonic cells were removed and biofilms on the catheter were kept under continuous flow of RPMI medium at 10 ml/h. Five doses of amphotericin B or voriconazole were delivered to 2, 5 and 10 day-old biofilms at initial concentrations (2 and 3 μg/ml respectively) that were exponentially diluted. Dispersed cells in effluents from the device were counted and the adherent cells on the catheter were evaluated after 48 h of the last dose.ResultsThe minimum inhibitory concentration of voriconazole and amphotericin B against the tested isolate was 0.0325 and 0.25 μg/ml respectively. Amphotericin B significantly reduced the dispersion of C. albicans cells from the biofilm. The log10 reduction in the dispersed cells was 2.54-3.54, 2.30-3.55, and 1.94-2.50 following addition of 5 doses of amphotericin B to 2-, 5- and 10-day old biofilms respectively. The number of the viable cells within the biofilm was reduced by 18 (±7.63), 5 and 4% following addition of the 5 doses of amphotericin B to the biofilms respectively. Voriconazole showed no significant effect on the viability of C. albicans within the biofilm.ConclusionBoth antifungal agents failed to eradicate C. albicans biofilm or stop cell dispersion from them and the resistance progressed with maturation of the biofilm. These findings go along with the need for removal of devices in spite of antifungal therapy in patients with device-related infection. This is the first study which investigates the effects of antifungal agents on the biofilm and biofilm-dispersion of C. albicans in an in vitro pharmacokinetic biofilm model.