Three-Dimensional Reconstruction of the Hepatitis C Virus Envelope Glycoprotein E1E2 Heterodimer by Electron Microscopic Analysis.

Despite the development of highly effective hepatitis C virus (HCV) treatments, an effective prophylactic vaccine is still lacking. HCV infection is mediated by its envelope glycoproteins, E1 and E2, during the entry process, with E2 binding to cell receptors and E1 mediating endosomal fusion. The structure of E1E2 has only been partially resolved by X-ray crystallography of the core domain of E2 protein (E2c) and its complex with various neutralizing antibodies. Structural understanding of the E1E2 heterodimer in its native form can advance the design of candidates for HCV vaccine development. Here, we analyze the structure of the recombinant HCV E1E2 heterodimer with the aid of well-defined monoclonal anti-E1 and E2 antibodies, as well as a small-molecule chlorcyclizine-diazirine-biotin that can target and cross-link the putative E1 fusion domain. Three-dimensional (3D) models were generated after extensive 2D classification analysis with negative-stain single-particle data sets. We modeled the available crystal structures of the E2c and Fabs into 3D volumes of E1E2-Fab complexes based on the shape and dimension of the domain density. The E1E2 heterodimer exists in monomeric form and consists of a main globular body, presumably depicting the E1 and E2 stem/transmembrane domain, and a protruding structure representing the E2c region, based on anti-E2 Fab binding. At low resolution, a model generated from negative-stain analysis revealed the unique binding and orientation of individual or double Fabs onto the E1 and E2 components of the complex. Cryo-electron microscopy (cryo-EM) of the double Fab complexes resulted in a refined structural model of the E1E2 heterodimer, presented here. IMPORTANCE Recombinant HCV E1E2 heterodimer is being developed as a vaccine candidate. Using electron microscopy, we demonstrated unique features of E1E2 in complex with various neutralizing antibodies and small molecule inhibitors that are important to understanding its antigenicity and induction of immune response.

Challenge Inoculum for Hepatitis C Virus Controlled Human Infection Model.

For any controlled human infection model (CHIM), a safe, standardized, and biologically relevant challenge inoculum is necessary. For hepatitis C virus (HCV) CHIM, we propose that human-derived high-titer inocula of several viral genotypes with extensive virologic, serologic, and molecular characterizations should be the most appropriate approach. These inocula should first be tested in human volunteers in a step-wise manner to ensure safety, reproducibility, and curability prior to using them for testing the efficacy of candidate vaccines.

Utilization of a Glucometer Test Strip and Enzymatic Reactions to Quantify Anti-SARS-CoV-2 Spike RBD IgG Antibody and SARS-CoV-2 Virus in Saliva and Serum.

A sensor capable of quantifying both anti-SARS-CoV-2 spike receptor-binding domain (RBD) antibody levels and the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus in saliva and serum was developed. This was accomplished by exploiting the enzymatic reaction of maltose and orthophosphate (PO43-) in the presence of maltose phosphorylase to generate an equivalent amount of glucose that was detected using a commercial glucometer test strip and a potentiostat. Important for this approach is the ability to generate PO43- in an amount that is directly related to the concentration of the analytes. RBD-modified magnetic microparticles were used to capture anti-SARS-CoV-2 spike RBD antibodies, while particles modified with anti-SARS-CoV-2 nucleocapsid antibodies were used to capture SARS-CoV-2 nucleocapsid protein from inactivated virus samples. A magnet was used to isolate and purify the magnetic microparticles (with analyte attached), and alkaline phosphatase-conjugated secondary antibodies were bound to the analytes attached to the respective magnetic microparticles. Finally, through enzymatic reactions, specific amounts of PO43- (and subsequently glucose) were generated in proportion to the analyte concentration, which was then quantified using a commercial glucometer test strip. Utilizing glucose test strips makes the sensor relatively inexpensive, with a cost per test of ∼US $7 and ∼US $12 for quantifying anti-SARS-CoV-2 spike RBD antibody and SARS-CoV-2, respectively. Our sensor exhibited a limit of detection of 0.42 ng/mL for anti-SARS-CoV-2 spike RBD antibody, which is sensitive enough to quantify typical concentrations of antibodies in COVID-19-infected or vaccinated individuals (>1 µg/mL). The limit of detection for the SARS-CoV-2 virus is 300 pfu/mL (5.4 × 106 RNA copies/mL), which exceeds the performance recommended by the WHO (500 pfu/mL). In addition, the sensor exhibited good selectivity when challenged with competing analytes and could be used to quantify analytes in saliva and serum matrices with an accuracy of >94% compared to RT-qPCR.

Randomized trial of three airway management techniques for restricted access in a simulated pediatric scenario.

PURPOSE: Emergency pediatric airway management during restricted access to the head is challenging and may relate to an entrapped motor vehicle trauma. Video laryngoscopy and supraglottic airways have separately been described to facilitate face-to-face airway management. We hypothesized that video laryngoscopy might be superior to direct laryngoscopy or supraglottic device use to establish ventilation during face-to-face airway management, studied in a simulated pediatric entrapped motor vehicle scenario. METHODS: Ethics approval was obtained from local REB. 45 experienced airway practitioners managed the airway of a pediatric manikin representing a 6 year old (SimJunior). With a cervical collar applied and in the sitting position, the manikin's head was only accessible from the left anterolateral side. Following a standardized demonstration, airway management using a Macintosh #2 blade (DL), a Storz C-MAC® D-Blade (VL) and a #2.5 LMA Supreme™ (SGD) was performed once each in a random order. Outcomes included success rate, time to ventilation (TTV), percentage of glottic opening (POGO) for DL and VL and ease of use on a 10-point Likert scale (VAS). Data was analyzed using analysis of variance for TTV and VAS and t-test for POGO. Statistical significance was deemed at P < 0.05. Data are presented as median and interquartile range. RESULTS: Success rate was 95% for both DL and SGD and 93% for VL. TTV was significantly less with SGD compared to DL and VL. TTV was 31 s (28, 35) for DL, 46 s (31, 62) for VL and 20 s (17, 24) for SGD. POGO was significantly improved with VL (100%) compared to DL (80%). Participants rated SGD significantly easier to use than VL, but not easier than DL. DISCUSSION: All three techniques have high success rates. Time to establish ventilation with the SGD was significantly faster compared to DL and VL and participants rated SGD easiest to use. The utility of VL was limited due to significantly longer time to ventilation, despite significantly improved view compared to DL, similar to adult studies. Since time and success are clinically important, this study suggests that supraglottic devices should be considered for primary emergency pediatric airway management in situations with restricted access to the head.

A Recombinant Hepatitis C Virus Genotype 1a E1/E2 Envelope Glycoprotein Vaccine Elicits Antibodies That Differentially Neutralize Closely Related 2a Strains through Interactions of the N-Terminal Hypervariable Region 1 of E2 with Scavenger Receptor B1.

The global health burden for hepatitis C virus (HCV) remains high, despite available effective treatments. To eliminate HCV, a prophylactic vaccine is needed. One major challenge in the development of a vaccine is the genetic diversity of the virus, with 7 major genotypes and many subtypes. A global vaccine must be effective against all HCV genotypes. Our previous data showed that the 1a E1/E2 glycoprotein vaccine component elicits broad cross-neutralizing antibodies in humans and animals. However, some variation is seen in the effectiveness of these antibodies to neutralize different HCV genotypes and isolates. Of interest was the differences in neutralizing activity against two closely related isolates of HCV genotype 2a, the J6 and JFH-1 strains. Using site-directed mutagenesis to generate chimeric viruses between the J6 and JFH-1 strains, we found that variant amino acids within the core E2 glycoprotein domain of these two HCV genotype 2a viruses do not influence isolate-specific neutralization. Further analysis revealed that the N-terminal hypervariable region 1 (HVR1) of the E2 protein determines the sensitivity of isolate-specific neutralization, and the HVR1 of the resistant J6 strain binds scavenger receptor class-B type-1 (SR-B1), while the sensitive JFH-1 strain does not. Our data provide new information on mechanisms of isolate-specific neutralization to facilitate the optimization of a much-needed HCV vaccine.IMPORTANCE A vaccine is still urgently needed to overcome the hepatitis C virus (HCV) epidemic. It is estimated that 1.75 million new HCV infections occur each year, many of which will go undiagnosed and untreated. Untreated HCV can lead to continued spread of the disease, progressive liver fibrosis, cirrhosis, and eventually, end-stage liver disease and/or hepatocellular carcinoma (HCC). Previously, our 1a E1/E2 glycoprotein vaccine was shown to elicit broadly cross-neutralizing antibodies; however, there remains variation in the effectiveness of these antibodies against different HCV genotypes. In this study, we investigated determinants of differential neutralization sensitivity between two highly related genotype 2a isolates, J6 and JFH-1. Our data indicate that the HVR1 region determines neutralization sensitivity to vaccine antisera through modulation of sensitivity to antibodies and interactions with SR-B1. Our results provide additional insight into optimizing a broadly neutralizing HCV vaccine.

Application of Molecular Dynamics Simulations to the Design of Nucleotide Inhibitors Binding to Norovirus Polymerase.

The RNA-dependent RNA polymerase (RdRp) of norovirus is an attractive target of antiviral agents aimed at providing protection against norovirus-associated gastroenteritis. Here, we perform molecular dynamics simulations of the crystal structure of norovirus RdRp in complex with several known binders, as well as free-energy simulations by free-energy perturbation (FEP) to determine binding free energies of these molecules relative to the natural nucleotide substrates. We determine experimental EC50 values and nucleotide incorporation efficiencies for several of these compounds. Moreover, we investigate the mechanism of inhibition of some of these ligands. Using FEP, we screened a virtual nucleotide library with 121 elements for binding to the polymerase and successfully identified two novel chain terminators.

Functional and immunogenic characterization of diverse HCV glycoprotein E2 variants.

BACKGROUND & AIMS: Induction of cross-reactive antibodies targeting conserved epitopes of the envelope proteins E1E2 is a key requirement for an hepatitis C virus vaccine. Conserved epitopes like the viral CD81-binding site are targeted by rare broadly neutralizing antibodies. However, these viral segments are occluded by variable regions and glycans. We aimed to identify antigens exposing conserved epitopes and to characterize their immunogenicity. METHODS: We created hepatitis C virus variants with mutated glycosylation sites and/or hypervariable region 1 (HVR1). Exposure of the CD81 binding site and conserved epitopes was quantified by soluble CD81 and antibody interaction and neutralization assays. E2 or E1-E2 heterodimers with mutations causing epitope exposure were used to immunize mice. Vaccine-induced antibodies were examined and compared with patient-derived antibodies. RESULTS: Mutant viruses bound soluble CD81 and antibodies targeting the CD81 binding site with enhanced efficacy. Mice immunized with E2 or E1E2 heterodimers incorporating these modifications mounted strong, cross-binding, and non-interfering antibodies. E2-induced antibodies neutralized the autologous virus but they were not cross-neutralizing. CONCLUSIONS: Viruses lacking the HVR1 and selected glycosylation sites expose the CD81 binding site and cross-neutralization antibody epitopes. Recombinant E2 proteins carrying these modifications induce strong cross-binding but not cross-neutralizing antibodies. LAY SUMMARY: Conserved viral epitopes can be made considerably more accessible for binding of potently neutralizing antibodies by deletion of hypervariable region 1 and selected glycosylation sites. Recombinant E2 proteins carrying these mutations are unable to elicit cross-neutralizing antibodies suggesting that exposure of conserved epitopes is not sufficient to focus antibody responses on production of cross-neutralizing antibodies.

Role of the E2 Hypervariable Region (HVR1) in the Immunogenicity of a Recombinant Hepatitis C Virus Vaccine.

Current evidence supports a protective role for virus-neutralizing antibodies in immunity against hepatitis C virus (HCV) infection. Many cross-neutralizing monoclonal antibodies have been identified. These antibodies have been shown to provide protection or to clear infection in animal models. Previous clinical trials have shown that a gpE1/gpE2 vaccine can induce antibodies that neutralize the in vitro infectivity of all the major cell culture-derived HCV (HCVcc) genotypes around the world. However, cross-neutralization appeared to favor certain genotypes, with significant but lower neutralization against others. HCV may employ epitope masking to avoid antibody-mediated neutralization. Hypervariable region 1 (HVR1) at the amino terminus of glycoprotein E2 has been shown to restrict access to many neutralizing antibodies. Consistent with this, other groups have reported that recombinant viruses lacking HVR1 are hypersensitive to neutralization. It has been proposed that gpE1/gpE2 lacking this domain could be a better vaccine antigen to induce broadly neutralizing antibodies. In this study, we examined the immunogenicity of recombinant gpE1/gpE2 lacking HVR1 (ΔHVR1). Our results indicate that wild-type (WT) and ΔHVR1 gpE1/gpE2 antigens induced antibodies targeting many well-characterized cross-genotype-neutralizing epitopes. However, while the WT gpE1/gpE2 vaccine can induce cross-genotype protection against various genotypes of HCVcc and/or HCV-pseudotyped virus (HCVpp), antisera from ΔHVR1 gpE1/gpE2-immunized animals exhibited either reduced homologous neutralization activity compared to that of the WT or heterologous neutralization activity similar to that of the WT. These data suggest that ΔHVR1 gpE1/gpE2 is not a superior vaccine antigen. Based on previously reported chimpanzee protection data using WT gpE1/gpE2 and our current findings, we are preparing a combination vaccine including wild-type recombinant gpE1/gpE2 for clinical testing in the future.IMPORTANCE An HCV vaccine is an unmet medical need. Current evidence suggests that neutralizing antibodies play an important role in virus clearance, along with cellular immune responses. Previous clinical data showed that gpE1/gpE2 can effectively induce cross-neutralizing antibodies, although they favor certain genotypes. HCV employs HVR1 within gpE2 to evade host immune control. It has been hypothesized that the removal of this domain would improve the production of cross-neutralizing antibodies. In this study, we compared the immunogenicities of WT and ΔHVR1 gpE1/gpE2 antigens as vaccine candidates. Our results indicate that the ΔHVR1 gpE1/gpE2 antigen confers no advantages in the neutralization of HCV compared with the WT antigen. Previously, we showed that this WT antigen remains the only vaccine candidate to protect chimpanzees from chronic infection, contains multiple cross-neutralizing epitopes, and is well tolerated and immunogenic in humans. The current data support the further clinical development of this vaccine antigen component.

Computational Prediction of the Heterodimeric and Higher-Order Structure of gpE1/gpE2 Envelope Glycoproteins Encoded by Hepatitis C Virus.

Despite the recent success of newly developed direct-acting antivirals against hepatitis C, the disease continues to be a global health threat due to the lack of diagnosis of most carriers and the high cost of treatment. The heterodimer formed by glycoproteins E1 and E2 within the hepatitis C virus (HCV) lipid envelope is a potential vaccine candidate and antiviral target. While the structure of E1/E2 has not yet been resolved, partial crystal structures of the E1 and E2 ectodomains have been determined. The unresolved parts of the structure are within the realm of what can be modeled with current computational modeling tools. Furthermore, a variety of additional experimental data is available to support computational predictions of E1/E2 structure, such as data from antibody binding studies, cryo-electron microscopy (cryo-EM), mutational analyses, peptide binding analysis, linker-scanning mutagenesis, and nuclear magnetic resonance (NMR) studies. In accordance with these rich experimental data, we have built an in silico model of the full-length E1/E2 heterodimer. Our model supports that E1/E2 assembles into a trimer, which was previously suggested from a study by Falson and coworkers (P. Falson, B. Bartosch, K. Alsaleh, B. A. Tews, A. Loquet, Y. Ciczora, L. Riva, C. Montigny, C. Montpellier, G. Duverlie, E. I. Pecheur, M. le Maire, F. L. Cosset, J. Dubuisson, and F. Penin, J. Virol. 89:10333-10346, 2015, https://doi.org/10.1128/JVI.00991-15). Size exclusion chromatography and Western blotting data obtained by using purified recombinant E1/E2 support our hypothesis. Our model suggests that during virus assembly, the trimer of E1/E2 may be further assembled into a pentamer, with 12 pentamers comprising a single HCV virion. We anticipate that this new model will provide a useful framework for HCV envelope structure and the development of antiviral strategies.IMPORTANCE One hundred fifty million people have been estimated to be infected with hepatitis C virus, and many more are at risk for infection. A better understanding of the structure of the HCV envelope, which is responsible for attachment and fusion, could aid in the development of a vaccine and/or new treatments for this disease. We draw upon computational techniques to predict a full-length model of the E1/E2 heterodimer based on the partial crystal structures of the envelope glycoproteins E1 and E2. E1/E2 has been widely studied experimentally, and this provides valuable data, which has assisted us in our modeling. Our proposed structure is used to suggest the organization of the HCV envelope. We also present new experimental data from size exclusion chromatography that support our computational prediction of a trimeric oligomeric state of E1/E2.

Native Folding of a Recombinant gpE1/gpE2 Heterodimer Vaccine Antigen from a Precursor Protein Fused with Fc IgG.

A recombinant strain HCV1 (hepatitis C virus [HCV] genotype 1a) gpE1/gpE2 (E1E2) vaccine candidate was previously shown by our group to protect chimpanzees and generate broad cross-neutralizing antibodies in animals and humans. In addition, recent independent studies have highlighted the importance of conserved neutralizing epitopes in HCV vaccine development that map to antigenic clusters in E2 or the E1E2 heterodimer. E1E2 can be purified using Galanthis nivalis lectin agarose (GNA), but this technique is suboptimal for global production. Our goal was to investigate a high-affinity and scalable method for isolating E1E2. We generated an Fc tag-derived (Fc-d) E1E2 that was selectively captured by protein G Sepharose, with the tag being removed subsequently using PreScission protease. Surprisingly, despite the presence of the large Fc tag, Fc-d E1E2 formed heterodimers similar to those formed by GNA-purified wild-type (WT) E1E2 and exhibited nearly identical binding profiles to HCV monoclonal antibodies that target conserved neutralizing epitopes in E2 (HC33.4, HC84.26, and AR3B) and the E1E2 heterodimer (AR4A and AR5A). Antisera from immunized mice showed that Fc-d E1E2 elicited anti-E2 antibody titers and neutralization of HCV pseudotype viruses similar to those with WT E1E2. Competition enzyme-linked immunosorbent assays (ELISAs) showed that antisera from immunized mice inhibited monoclonal antibody binding to neutralizing epitopes. Antisera from Fc-d E1E2-immunized mice exhibited stronger competition for AR3B and AR5A than the WT, whereas the levels of competition for HC84.26 and AR4A were similar. We anticipate that Fc-d E1E2 will provide a scalable purification and manufacturing process using protein A/G-based chromatography. IMPORTANCE: A prophylactic HCV vaccine is still needed to control this global disease despite the availability of direct-acting antivirals. Previously, we demonstrated that a recombinant envelope glycoprotein (E1E2) vaccine (genotype 1a) elicited cross-neutralizing antibodies from human volunteers. A challenge for isolating the E1E2 antigen is the reliance on GNA, which is unsuitable for large scale-up and global vaccine delivery. We have generated a novel Fc domain-tagged E1E2 antigen that forms functional heterodimers similar to those with native E1E2. Affinity purification and removal of the Fc tag from E1E2 resulted in an antigen with a nearly identical profile of cross-neutralizing epitopes. This antigen elicited anti-HCV antibodies that targeted conserved neutralizing epitopes of E1E2. Owing to the high selectivity and cost-effective binding capacity of affinity resins for capture of the Fc-tagged rE1E2, we anticipate that our method will provide a means for large-scale production of this HCV vaccine candidate.

Prevention of hepatitis C virus infection using a broad cross-neutralizing monoclonal antibody (AR4A) and epigallocatechin gallate.

The anti-hepatitis C virus (HCV) activity of a novel monoclonal antibody (mAb; AR4A) and epigallocatechin gallate (EGCG) were studied in vitro using a HCV cell culture system and in vivo using a humanized liver mouse model capable of supporting HCV replication. Alone, both exhibit reliable cross-genotype HCV inhibition in vitro, and combination therapy completely prevented HCV infection. In vitro AR4A mAb (alone and combined with EGCG) robustly protects against the establishment of HCV genotype 1a infection. EGCG alone fails to reliably protect against an HCV challenge. In conclusion, AR4A mAb represents a safe and efficacious broadly neutralizing antibody against HCV applicable to strategies to safely prevent HCV reinfection following liver transplantation, and it lends further support to the concept of HCV vaccine development. The poor bioavailability of EGCG limits HCV antiviral activity in vitro.

Breaking good: a chemist wanders into entomology.

In this highly personal account of my career in science, I try to show how many others influenced its course. I was able to abandon work in pure chemistry and microbiology and to take up research in entomology only with the help of others. My faith in the value of collaborative, interdisciplinary work has been the key to success. Our focus on proteins of insect hemolymph has provided valuable insights into insect biochemistry and physiology.

Recombinant hepatitis C virus envelope glycoprotein vaccine elicits antibodies targeting multiple epitopes on the envelope glycoproteins associated with broad cross-neutralization.

UNLABELLED: Although effective hepatitis C virus (HCV) antivirals are on the horizon, a global prophylactic vaccine for HCV remains elusive. The diversity of the virus is a major concern for vaccine development; there are 7 major genotypes of HCV found globally. Therefore, a successful vaccine will need to protect against HCV infection by all genotypes. Despite the diversity, many monoclonal antibodies (MAbs) with broadly cross-neutralizing activity have been described, suggesting the presence of conserved epitopes that can be targeted to prevent infection. Similarly, a vaccine comprising recombinant envelope glycoproteins (rE1E2) derived from the genotype 1a HCV-1 strain has been shown to be capable of eliciting cross-neutralizing antibodies in guinea pigs, chimpanzees, and healthy human volunteers. In order to investigate the basis for this cross-neutralization, epitope mapping of anti-E1E2 antibodies present within antisera from goats and humans immunized with HCV-1 rE1E2 was conducted through peptide mapping and competition studies with a panel of cross-neutralizing MAbs targeting various epitopes within E1E2. The immunized-goat antiserum was shown to compete with the binding of all MAbs tested (AP33, HC33.4, HC84.26, 1:7, AR3B, AR4A, AR5A, IGH526, and A4). Antisera showed the best competition against HC84.26 and AR3B and the weakest competition against AR4A. Furthermore, antisera from five immunized human vaccinees were shown to compete with five preselected MAbs (AP33, AR3B, AR4A, AR5A, and IGH526). These data show that immunization with HCV-1 rE1E2 elicits antibodies targeting multiple cross-neutralizing epitopes. Our results further support the use of such a vaccine antigen to induce cross-genotype neutralization. IMPORTANCE: An effective prophylactic vaccine for HCV is needed for optimal control of the disease burden. The high diversity of HCV has posed a challenge for developing vaccines that elicit neutralizing antibodies for protection against infection. Despite this, we have previously shown that a vaccine comprising recombinant envelope glycoproteins derived from a single genotype 1a strain was capable of eliciting a cross-neutralizing antibody response in human volunteers. Here, we have used competition binding assays and peptide binding assays to show that antibodies present in the antisera from vaccinated goats and humans bind epitopes overlapping with those of a variety of well-characterized cross-neutralizing monoclonal antibodies. This provides a mechanism for the cross-neutralizing human antisera: antibodies present in the antisera bind to conserved regions associated with cross-neutralization. Importantly, this work provides further support for a vaccine comprising recombinant envelope glycoproteins, perhaps in a formulation with a vaccine component eliciting strong anti-HCV CD4(+) and CD8(+) T cell responses.

Human serum leads to differentiation of human hepatoma cells, restoration of very-low-density lipoprotein secretion, and a 1000-fold increase in HCV Japanese fulminant hepatitis type 1 titers.

UNLABELLED: In this study, we differentiated the human hepatoma cell line Huh7.5 by supplementing tissue culture media with human serum (HS) and examined the production of hepatitis C virus (HCV) by these cells. We compared the standard tissue culture protocol, using media supplemented with 10% fetal bovine serum (FBS), to media supplemented with 2% HS. Cells cultured in HS undergo rapid growth arrest, have a hepatocyte-like morphology, and increase the expression of hepatocyte differentiation markers. In addition, expression of cell adhesion proteins claudin-1, occludin, and e-cadherin are also increased. The lipid droplet content of these cells is highly increased, as are key lipid metabolism regulators liver X receptor alpha, peroxisome proliferator-activated receptor (PPAR)-α, and PPAR-γ. Very-low-density lipoprotein secretion, which is absent in FBS-grown cells, is restored in Huh7.5 cells that are cultured in HS. All these factors have been implicated in the life cycle of HCV. We show that viral production of Japanese fulminant hepatitis type 1 increases 1,000-fold when cells are grown in HS, compared to standard FBS culture conditions. The virus produced under these conditions is associated with apolipoprotein B, has a lower density, higher specific infectivity, and has a longer half-life than virus produced in media supplemented with FBS. CONCLUSION: We describe a convenient, cost-effective method to produce hepatocyte-like cells, which produce large amounts of virus that more closely resemble HCV present in serum of infected patients.

Comparison of the king vision video laryngoscope with the macintosh laryngoscope.

BACKGROUND: Endotracheal intubation is a common procedure in the emergency department, and new devices may improve intubation time, success, or view. OBJECTIVE: We compared the King Vision video laryngoscope (KVVL; King Systems, Noblesville, IN) to the Macintosh direct laryngoscope (DL) in simulated normal and difficult airways. METHODS: Using manikins and clinical-grade cadavers, difficult airway scenarios were simulated using head movement restriction or a cervical spine collar. Four scenarios were studied using the KVVL and DL: normal manikin airway, difficult manikin airway, normal cadaver airway, and difficult cadaver airway. Primary outcomes were time to intubation and rate of successful intubation. Secondary outcomes were the percent of glottic opening and Cormack-Lehane grade visualized. RESULTS: Thirty-two paramedics participated in the study. In the normal manikin airway scenario, time to intubation was 3.4 s (99% confidence interval [CI] 0.1-6.6) faster with the KVVL compared with DL. Time to intubation was 11.3 s (99% CI 2.4-20.2) faster with the KVVL in the difficult cadaver airway scenario. There was no difference in time to intubation in the other 2 scenarios. In the difficult cadaver airway, 10 of 32 participants failed to successfully intubate the trachea using DL, whereas all KVVL intubations were successful. All scenarios found a lower Cormack-Lehane grade and higher percentage of glottic opening with the KVVL compared to DL. CONCLUSION: The KVVL was slightly faster than Macintosh DL in two of four studied airway scenarios, and had a higher success rate in the difficult cadaver airway scenario. Further study is required in the clinical setting.

A correlative STS: lessons from a Chinese medical practice.

How might Science and Technology Studies learn more from the intersection between 'Western' and 'other' forms of knowledge? In this article, we use Eduardo Viveiros de Castro's writing on equivocal translation to explore a moment of encounter in a Chinese Medical consultation in Taiwan in which a practitioner hybridizes Chinese Medicine and biomedicine. Our description is symmetrical, but creates a descriptive equivocation in which 'Western' analytical terms are used to describe a 'Chinese' medical reality. Drawing on the history of Chinese Medicine, we argue that the latter is not analytical, but 'correlative' in a specifically 'Chinese' manner that explores patternings, flows, and propensities in local collections of things and symptoms. In particular, it both handles difference without seeking to unearth stable causal mechanisms and absorbs new elements including relevant features of biomedicine. We conclude by briefly considering the scope of a possible post-colonial and 'correlative' STS and show that a 'correlative' description of the same Chinese Medical consultation would differ markedly from one making use of 'Western' analytical assumptions.

Detailed computational study of the active site of the hepatitis C viral RNA polymerase to aid novel drug design.

The hepatitis C virus (HCV) RNA polymerase, NS5B, is a leading target for novel and selective HCV drug design. The enzyme has been the subject of intensive drug discovery aimed at developing direct acting antiviral (DAA) agents that inhibit its activity and hence prevent the virus from replicating its genome. In this study, we focus on one class of NS5B inhibitors, namely nucleos(t)ide mimetics. Forty-one distinct nucleotide structures have been modeled within the active site of NS5B for the six major HCV genotypes. Our comprehensive modeling protocol employed 287 different molecular dynamics simulations combined with the molecular mechanics/Poisson-Boltzmann surface area (MM-PBSA) methodology to rank and analyze these structures for all genotypes. The binding interactions of the individual compounds have been investigated and reduced to the atomic level. The present study significantly refines our understanding of the mode of action of NS5B-nucleotide-inhibitors, identifies the key structural elements necessary for their activity, and implements the tools for ranking the potential of additional much needed novel inhibitors of NS5B.

Bovine Serum Albumin-Protected Gold Nanoclusters for Sensing of SARS-CoV-2 Antibodies and Virus.

An approach to assess severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (and past infection) was developed. For virus detection, the SARS-CoV-2 virus nucleocapsid protein (NP) was targeted. To detect the NP, antibodies were immobilized on magnetic beads to capture the NPs, which were subsequently detected using rabbit anti-SARS-CoV-2 nucleocapsid antibodies and alkaline phosphatase (AP)-conjugated anti-rabbit antibodies. A similar approach was used to assess SARS-CoV-2-neutralizing antibody levels by capturing spike receptor-binding domain (RBD)-specific antibodies utilizing RBD protein-modified magnetic beads and detecting them using AP-conjugated anti-human IgG antibodies. The sensing mechanism for both assays is based on cysteamine etching-induced fluorescence quenching of bovine serum albumin-protected gold nanoclusters where cysteamine is generated in proportion to the amount of either SARS-CoV-2 virus or anti-SARS-CoV-2 receptor-binding domain-specific immunoglobulin antibodies (anti-RBD IgG antibodies). High sensitivity can be achieved in 5 h 15 min for the anti-RBD IgG antibody detection and 6 h 15 min for virus detection, although the assay can be run in "rapid" mode, which takes 1 h 45 min for the anti-RBD IgG antibody detection and 3 h 15 min for the virus. By spiking the anti-RBD IgG antibodies and virus in serum and saliva, we demonstrate that the assay can detect the anti-RBD IgG antibodies with a limit of detection (LOD) of 4.0 and 2.0 ng/mL in serum and saliva, respectively. For the virus, we can achieve an LOD of 8.5 × 105 RNA copies/mL and 8.8 × 105 RNA copies/mL in serum and saliva, respectively. Interestingly, this assay can be easily modified to detect myriad analytes of interest.