Low-density hepatitis C virus infectious particles are protected from oxidation by secreted cellular proteins

IMPORTANCE

Assessments of viral stability on surfaces or in body fluids under different environmental conditions and/or temperatures are often performed, as they are key to understanding the routes and parameters of viral transmission and to providing clues on the epidemiology of infections. However, for most viruses, the mechanisms of inactivation vs stability of viral particles remain poorly defined. Although they are structurally diverse, with different compositions, sizes, and shapes, enveloped viruses are generally less stable than non-enveloped viruses, pointing out the role of envelopes themselves in virus lability. In this report, we investigated the properties of hepatitis C virus (HCV) particles with regards to their stability. We found that, compared to alternative enveloped viruses such as Dengue virus (DENV), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), hepatitis delta virus (HDV), and Crimean-Congo hemorrhagic fever virus (CCHFV) that infect the liver, HCV particles are intrinsically labile. We determined the mechanisms that drastically alter their specific infectivity through oxidation of their lipids, and we highlighted that they are protected from lipid oxidation by secreted cellular proteins, which can protect their membrane fusion capacity and overall infectivity.

Preexisting autoantibodies as predictor of immune related adverse events (irAEs) for advanced solid tumors treated with immune checkpoint inhibitors (ICIs)

INTRODUCTION

Immune checkpoint inhibitors (ICIs) are now standard of care in many cancers. They can generate immune-related adverse events (irAEs), but no biomarkers are available to identify patients who are more likely to develop irAEs. We assess the association between pre-existing autoantibodies and occurrence of irAEs.

PATIENTS AND METHODS

We prospectively collected data from consecutive patients receiving ICIs for advanced cancers, in a single center between May 2015 and July 2021. Autoantibodies testing was performed before ICIs initiation including AntiNeutrophil Cytoplasmic Antibodies, Antinuclear Antibodies, Rheumatoid Factor anti-Thyroid Peroxidase and anti-Thyroglobulin. We analyzed the associations of pre-existing autoantibodies with onset, severity, time to irAEs and with survival outcomes.

RESULTS

Of the 221 patients included, most had renal cell carcinoma (n = 99; 45%) or lung carcinoma (n = 90; 41%). Grade ≥2 irAEs were more frequent among patients with pre-existing autoantibodies: 64 (50%) vs. 20 (22%) patients (Odds-Ratio= 3.5 [95% CI=1.8-6.8]; p < 0.001) in the positive vs negative group, respectively. irAEs occurred earlier in the positive group with a median time interval between ICI initiation and irAE of 13 weeks (IQR = 8.8-21.6) vs. 28.5 weeks (IQR=10.6-55.1) in the negative group (p = 0.01). Twelve patients (9.4%) experienced multiple (≥2) irAEs in the positive group vs. 2 (2%) in the negative group (OR = 4.5 [95% CI: 0.98-36], p = 0.04). After a median follow-up of 25 months, median PFS and OS were significantly longer among patients experiencing irAE (p = 0.00034 and p = 0.016, respectively).

CONCLUSION

The presence of pre-existing autoantibodies is significantly associated with the occurrence of grade ≥2 irAEs, with earlier and multiple irAEs in patients treated with ICIs.

Introduction to the AQ-WATCH Project and the AQ-WATCH Toolkit to fight air pollution

Background

WHO states that 9 out of 10 persons in the world do not breath clean air and 8 million people die prematurely from air pollution each year. The problem is well understood, but actions to mitigate it are lacking. The purpose of the EU-funded AQ-WATCH Project is precisely to develop effective tools based on the most advanced science technologies to help decision-makers in government and the private sector to address air pollution issues in regions of the world where they operate.

Objectives

AQ-WATCH aims to develops a supply chain to generate innovative downstream products for improving air quality forecasts and attribution based on existing space/in-situ observations to improve public health and to optimize renewable energy in regions of the world. The project consortium includes research and business-oriented partners, who brings together the required expertise to define the optimal functionalities of these products to bring them to the market.

Results

The AQ-WATCH products are organized into 5 modules: (1) Air quality atlas, (2) Air quality attribution & mitigation, (3) Dust and fire forecast, (4) Fracking analysis, and (5) Air quality forecast. They are developed for 3 target regions (Beijing, Colorado and Santiago de Chile) and are integrated into a unified user-interface, the AQ-WATCH Toolkit. Product developers and prime users in the target regions are constantly interacting, and the user feedback is collected, analyzed and included during the product development.

Conclusions

Collaborative work done in AQ-WATCH shows strategic interaction between our research and business-oriented partners. Contributions from local parties are proven to be valuable for regional adaption of the products. A throughout dissemination including regional workshops is essential to ensure proper knowledge uptake by the target audience. Constant exchange with the private sector is required for a smooth transfer from scientific results to commercialized marketable products.

Key messages

• The AQ-WATCH Project follows EU’s initiative to utilize its space observations with added values to develop easily-accessible tools to fight air pollution applicable to regions of the world.

• The AQ-WATCH Toolkit is developed with iterative feedback exchanges between product developers and local users to address air pollution issues, and will be eventually exploited to the market.

Marginally stable current sheets in collisionless magnetic reconnection

Noncollisional current sheets that form during the nonlinear development of spontaneous magnetic reconnection are characterized by a small thickness, of the order of the electron skin depth. They can become unstable to the formation of plasmoids, which allows the magnetic reconnection process to reach high reconnection rates. In this work, we investigate the marginal stability conditions for the development of plasmoids when the forming current sheet is purely collisionless and in the presence of a strong guide field. We analyze the geometry that characterizes the reconnecting current sheet, and what promotes its elongation. Once the reconnecting current sheet is formed, we identify the regimes for which it is plasmoid unstable. Our study shows that plasmoids can be obtained, in this context, from current sheets with an aspect ratio much smaller than in the collisional regime, and that the plasma flow channel of the marginally stable current layers maintains an inverse aspect ratio of 0.1.

Immunotherapy in older patients with cancer

Ageing implicates a remodeling of our immune system, which is a consequence of the physiological senescence of our cells and tissues coupled with environmental factors and chronic antigen exposure. An immune system that senesces includes more differentiated cells with accumulation of highly differentiated CD4 and CD8 T cells. The pool of naive T cells decreases with the exponential thymic involution induced by age. Differentiated T cells have similar, if not higher, functional capacities but scarce studies are looking at the impact of senescence among specific T cells. After a stimulation, other immune cells (monocytes, dendritic cells and NK) are functionally altered during ageing. It is as if the immune system was more efficient at the basal level, but less efficient after a stimulation in the old compared to young people, likely due to less reserve. Concerning the clinical impact, older people are more prone to certain pathogens and their clinical manifestations differ from the younger people. Severe flu and VZV reactivation are more frequent with an altered cellular response to vaccination. Vaccination failure can have detrimental consequences in people presenting frailty criteria. Old people frailty is majored by their comorbidities and diseases like cancer. Thus, chemotherapies are employed with circumspection in older patients. The use of anti-PD-1/PD-L1 immunotherapies is therefore attractive, because of less side effects with a better response compared to chemotherapy. Old persons inclusion is lacking in current studies and clinical trials. Some subgroups or pooled analyses confirm the gain in response without increased toxicities in older patients but their inclusion criteria differ from the real-life practice. Specific studies focusing on this population are needed because of the increasing cancer incidence with age and the overall ageing of the population.

HCV Interplay with Lipoproteins: Inside or Outside the Cells?

Hepatitis C virus (HCV) infection is a major public health issue leading to chronic liver diseases. HCV particles are unique owing to their particular lipid composition, namely the incorporation of neutral lipids and apolipoproteins. The mechanism of association between HCV virion components and these lipoproteins factors remains poorly understood as well as its impact in subsequent steps of the viral life cycle, such as entry into cells. It was proposed that the lipoprotein biogenesis pathway is involved in HCV morphogenesis; yet, recent evidence indicated that HCV particles can mature and evolve biochemically in the extracellular medium after egress. In addition, several viral, cellular and blood components have been shown to influence and regulate this specific association. Finally, this specific structure and composition of HCV particles was found to influence entry into cells as well as their stability and sensitivity to neutralizing antibodies. Due to its specific particle composition, studying the association of HCV particles with lipoproteins remains an important goal towards the rational design of a protective vaccine.

Therapeutic cancer vaccine: building the future from lessons of the past

Anti-cancer vaccines have raised many hopes from the start of immunotherapy but have not yet been clinically successful. The few positive results of anti-cancer vaccines have been observed in clinical situations of low tumor burden or preneoplastic lesions. Several new concepts and new results reposition this therapeutic approach in the field of immunotherapy. Indeed, cancers that respond to anti-PD-1/PD-L1 (20-30%) are those that are infiltrated by anti-tumor T cells with an inflammatory infiltrate. However, 70% of cancers do not appear to have an anti-tumor immune reaction in the tumor microenvironment. To induce this anti-tumor immunity, therapeutic combinations between vaccines and anti-PD-1/PD-L1 are being evaluated. In addition, the identification of neoepitopes against which the immune system is less tolerated is giving rise to a new enthusiasm by the first clinical results of the vaccine including these neoepitopes in humans. The ability of anti-cancer vaccines to induce a population of anti-tumor T cells called memory resident T cells that play an important role in immunosurveillance is also a new criterion to consider in the design of therapeutic vaccines.

Novel insights on new particle formation derived from a pan-european observing system

The formation of new atmospheric particles involves an initial step forming stable clusters less than a nanometre in size (<~1 nm), followed by growth into quasi-stable aerosol particles a few nanometres (~1–10 nm) and larger (>~10 nm). Although at times, the same species can be responsible for both processes, it is thought that more generally each step comprises differing chemical contributors. Here, we present a novel analysis of measurements from a unique multi-station ground-based observing system which reveals new insights into continental-scale patterns associated with new particle formation. Statistical cluster analysis of this unique 2-year multi-station dataset comprising size distribution and chemical composition reveals that across Europe, there are different major seasonal trends depending on geographical location, concomitant with diversity in nucleating species while it seems that the growth phase is dominated by organic aerosol formation. The diversity and seasonality of these events requires an advanced observing system to elucidate the key processes and species driving particle formation, along with detecting continental scale changes in aerosol formation into the future.

A retrospective study of ketamine administration and the development of acute or post-traumatic stress disorder in 274 war-wounded soldiers

The objective of this study was to explore whether ketamine prevents or exacerbates acute or post-traumatic stress disorders in military trauma patients. We conducted a retrospective study of a database from the French Military Health Service, including all soldiers surviving a war injury in Afghanistan (2010-2012). The diagnosis of post-traumatic stress disorder was made by a psychiatrist and patients were analysed according to the presence or absence of this condition. Analysis included the following covariables: age; sex; acute stress disorder; blast injury; associated fatality; brain injury; traumatic amputation; Glasgow coma scale; injury severity score; administered drugs; number of surgical procedures; physical, neurosensory or aesthetic sequelae; and the development chronic pain. Covariables related to post-traumatic and acute stress disorders with a p ≤ 0.10 were included in a multivariable logistic regression model. The data from 450 soldiers were identified; 399 survived, of which 274 were analysed. Among these, 98 (36%) suffered from post-traumatic stress disorder and 89 (32%) had received ketamine. Fifty-four patients (55%) in the post-traumatic stress disorder group received ketamine vs. 35 (20%) in the no PTSD group (p < 0.001). The 89 injured soldiers who received ketamine had a median (IQR [range]) injury severity score of 5 (3-13 [1-26]) vs. 3 (2-4 [1-6] in the 185 patients who did not (p < 0.001). At multivariable analysis, only acute stress disorder and total number of surgical procedures were independently associated with the development of post-traumatic stress disorder. In this retrospective study, ketamine administration was not a risk factor for the development of post-traumatic stress disorder in the military trauma setting.

Tissue-resident memory T cells play a key role in the efficacy of cancer vaccines

Resident memory CD8⁺T cells (T_RM) usually defined by the CD103 marker represent a new subset of long-lived memory T cells that remain in the tissues. We directly demonstrate their specific role in cancer vaccine-induced tumor regression. In human, they also seem to play a major role in tumor immunosurveillance.

Identification of protective B-cell epitopes of Atroxlysin-I: A metalloproteinase from Bothrops atrox snake venom

Atroxlysin-I (Atr-I) is a hemorrhagic snake venom metalloproteinase (SVMP) from Bothrops atrox venom, the snake responsible for the majority of bites in the north region of South America. SVMPs like Atr-I produce toxic effects in victims including hemorrhage, inflammation, necrosis and blood coagulation deficiency. Mapping of B-cell epitopes in SVMPs might result in the identification of non-toxic molecules capable of inducing neutralizing antibodies and improving the anti-venom therapy. Here, using the SPOT-synthesis technique we identified two epitopes located in the N-ter region of Atr-I (AtrEp1-(22)YNGNSDKIRRRIHQM(36); and AtrEp2-(55)GVEIWSNKDLINVQ(68)). Based on the sequence of AtrEp1 and AtrEp2 a third peptide named Atr-I biepitope (AtrBiEp) was designed and synthesized ((23)NGNSDKIRRRIH(34)GG(55)GVEIWSNKDLINVQ(68)). AtrBiEp was used to immunize BALB/c mice. Anti-AtrBiEp serum cross-reacted against Atr-I in western blot and was able to fully neutralize the hemorrhagic activity of Atr-I. Our results provide a rational basis for the identification of neutralizing epitopes on Atr-I snake venom toxin and show that the use of synthetic peptides could improve the generation of immuno-therapeutics.

Functional and Biochemical Characterization of Hepatitis C Virus (HCV) Particles Produced in a Humanized Liver Mouse Model

Lipoprotein components are crucial factors for hepatitis C virus (HCV) assembly and entry. As hepatoma cells producing cell culture-derived HCV (HCVcc) particles are impaired in some aspects of lipoprotein metabolism, it is of upmost interest to biochemically and functionally characterize the in vivo produced viral particles, particularly regarding how lipoprotein components modulate HCV entry by lipid transfer receptors such as scavenger receptor BI (SR-BI). Sera from HCVcc-infected liver humanized FRG mice were separated by density gradients. Viral subpopulations, termed HCVfrg particles, were characterized for their physical properties, apolipoprotein association, and infectivity. We demonstrate that, in contrast to the widely spread distribution of apolipoproteins across the different HCVcc subpopulations, the most infectious HCVfrg particles are highly enriched in apoE, suggesting that such apolipoprotein enrichment plays a role for entry of in vivo derived infectious particles likely via usage of apolipoprotein receptors. Consistent with this salient feature, we further reveal previously undefined functionalities of SR-BI in promoting entry of in vivo produced HCV. First, unlike HCVcc, SR-BI is a particularly limiting factor for entry of HCVfrg subpopulations of very low density. Second, HCVfrg entry involves SR-BI lipid transfer activity but not its capacity to bind to the viral glycoprotein E2. In conclusion, we demonstrate that composition and biophysical properties of the different subpopulations of in vivo produced HCVfrg particles modulate their levels of infectivity and receptor usage, hereby featuring divergences with in vitro produced HCVcc particles and highlighting the powerfulness of this in vivo model for the functional study of the interplay between HCV and liver components.

Infection of Human Liver Myofibroblasts by Hepatitis C Virus: A Direct Mechanism of Liver Fibrosis in Hepatitis C

Background

Chronic hepatitis C is a major cause of liver fibrosis and cirrhosis. It is generally accepted that inflammation that occurs in response to hepatocyte infection by the hepatitis C virus (HCV) is the main mechanism that triggers myofibroblast differentiation and stimulation in chronic hepatitis C. The aim of this study was to determine if HCV might infect human liver myofibroblasts (HLMF) and directly stimulate their fibrogenic activities.

Methods

We evaluated the expression of the viral entry receptors, levels of HCV-RNA and HCV-protein and the expression of fibrosis markers in HLMF by using quantitative PCR, western blot and immunofluorescence analyses. Pseudoparticles (HCVpp) and cell culture–derived HCV (HCVcc) were used to study the ability of HLMF to support viral entry, replication and fibrosis induction.

Results

We showed that HLMF expressed all known molecules of the HCV receptor complex, i.e. CD81, LDL-R, scavenger receptor-BI, claudin-1 and occludin. These cells were also permissive to HCVpp entry. Inoculation with HCVcc caused short-term infection of these cells, as shown by their content in positive- and negative-strand HCV RNA, in core and NS3 viral proteins, and by their release of core protein levels in the culture supernatants. HCV infection stimulated myofibroblastic differentiation, proliferation and collagen production in these cells. In addition, evidence of in vivo infection was provided by the detection of positive- and negative-strand HCV RNA in preparations of HLMF obtained from HCV-infected patients.

Conclusion

These findings indicate that HCV infection of HLMF can occur and trigger extracellular matrix overproduction, thereby contributing to the development of HCV-related liver fibrosis.

Anti-A2 and anti-A1 domain antibodies are potential predictors of immune tolerance induction outcome in children with hemophilia A

BACKGROUND

Hemophilia A (HA) is a congenital bleeding disorder resulting from factor VIII deficiency. The most serious complication of HA management is the appearance of inhibitory antibodies (Abs) against injected FVIII concentrates. To eradicate inhibitors, immune tolerance induction (ITI) is usually attempted, but it fails in up to 30% of cases. Currently, no undisputed predictive marker of ITI outcome is available to facilitate the clinical decision.

OBJECTIVES

To identify predictive markers of ITI efficacy.

METHODS

The isotypic and epitopic repertoires of inhibitory Abs were analyzed in plasma samples collected before ITI initiation from 15 children with severe HA and high-titer inhibitors, and their levels were compared in the two outcome groups (ITI success [n = 7] and ITI failure [n = 8]). The predictive value of these candidate biomarkers and of the currently used indicators (inhibitor titer and age at ITI initiation, highest inhibitor titer before ITI, and interval between inhibitor diagnosis and ITI initiation) was then compared by statistical analysis (Wilcoxon test and receiver receiver operating characteristic [ROC] curve analysis).

RESULTS

Whereas current indicators seemed to fail in discriminating patients in the two outcome groups (ITI success or failure), anti-A1 and anti-A2 Ab levels before ITI initiation appeared to be good potential predictive markers of ITI outcome (P < 0.018). ROC analysis showed that anti-A1 and anti-A2 Abs were the best at discriminating between outcome groups (area under the ROC curve of > 0.875).

CONCLUSION

Anti-A1 and anti-A2 Abs could represent new promising tools for the development of ITI outcome prediction tests for children with severe HA.

Computer-predicted peptides that mimic discontinuous epitopes on the A2 domain of factor VIII

Development of antibodies (Abs) against factor VIII (FVIII) is a severe complication of haemophilia A treatment. Recent publications suggest that domain specificity of anti-FVIII antibodies, particularly during immune tolerance induction (ITI), might be related to the outcome of the treatment. Obtaining suitable tools for a fine mapping of discontinuous epitopes could thus be helpful. The aim of this study was to map discontinuous epitopes on FVIII A2 domain using a new epitope prediction functionality of the PEPOP bioinformatics tool and a peptide inhibition assay based on the Luminex technology. We predicted, selected and synthesized 40 peptides mimicking discontinuous epitopes on the A2 domain of FVIII. A new inhibition assays using Luminex technology was performed to identify peptides able to inhibit the binding of anti-A2 Abs to A2 domain. We identified two peptides (IFKKLYHVWTKEVG and LYSRRLPKGVKHFD) able to block the binding of anti-A2 allo-antibodies to this domain. The three-dimensional representation of these two peptides on the A2 domain revealed that they are localized on a limited region of A2. We also confirmed that residues 484-508 of the A2 domain define an antigenic site. We suggest that dissection of the antibody response during ITI using synthetic peptide epitopes could provide important information for the management of patients with inhibitors.

Virus-like particle vaccine induces cross-protection against human metapneumovirus infections in mice

Human metapneumovirus (HMPV) is a paramyxovirus that causes acute respiratory-tract infections in children and adults worldwide. A safe and effective vaccine could decrease the burden of disease associated with this novel pathogen. We engineered HMPV viral-like particles (HMPV-VLPs) derived from retroviral core particles that mimic the properties of the viral surface of two HMPV viruses of either lineage A or B. These VLPs functionally display F and G HMPV surface glycoproteins. When injected in mice, HMPV-VLPs induce strong humoral immune response against both homologous and heterologous strains. Moreover, the induced neutralizing antibodies prevented mortality upon subsequent infection of the lungs with both homologous and heterologous viruses. Upon challenge, viral titers in the lungs of immunized animals were significantly reduced as compared to those of control animals. In conclusion, a HMPV-VLP vaccine that induces cross-protective immunity in mice is a promising approach to prevent HMPV infections.

Characterization of hepatitis C virus particle subpopulations reveals multiple usage of the scavenger receptor BI for entry steps

Hepatitis C virus (HCV) particles assemble along the very low density lipoprotein pathway and are released from hepatocytes as entities varying in their degree of lipid and apolipoprotein (apo) association as well as buoyant densities. Little is known about the cell entry pathway of these different HCV particle subpopulations, which likely occurs by regulated spatiotemporal processes involving several cell surface molecules. One of these molecules is the scavenger receptor BI (SR-BI), a receptor for high density lipoprotein that can bind to the HCV glycoprotein E2. By studying the entry properties of infectious virus subpopulations differing in their buoyant densities, we show that these HCV particles utilize SR-BI in a manifold manner. First, SR-BI mediates primary attachment of HCV particles of intermediate density to cells. These initial interactions involve apolipoproteins, such as apolipoprotein E, present on the surface of HCV particles, but not the E2 glycoprotein, suggesting that lipoprotein components in the virion act as host-derived ligands for important entry factors such as SR-BI. Second, we found that in contrast to this initial attachment, SR-BI mediates entry of HCV particles independent of their buoyant density. This function of SR-BI does not depend on E2/SR-BI interaction but relies on the lipid transfer activity of SR-BI, probably by facilitating entry steps along with other HCV entry co-factors. Finally, our results underscore a third function of SR-BI governed by specific residues in hypervariable region 1 of E2 leading to enhanced cell entry and depending on SR-BI ability to bind to E2.

The IgG autoimmune response in postpartum acquired hemophilia A targets mainly the A1a1 domain of FVIII

BACKGROUND

Acquired hemophilia A (AHA) is a severe life-threatening autoimmune disease due to the development of autoantibodies that neutralize the procoagulant activity of factor VIII (FVIII). In rare cases, AHA occurs in the postpartum period as a serious complication of an otherwise normal pregnancy and delivery. Due to its rarity, little is known about the features of the antibody response to FVIII in AHA.

OBJECTIVES

Our study wanted to (i) determine the epitope specificity and the immunoglobulin (Ig) subclasses of anti-FVIII autoantibodies in plasma samples from a large cohort of AHA patients, and (ii) compare the epitope specificity of anti-FVIII autoantibodies in plasma samples from postpartum AHA and other AHA patients.

PATIENTS/METHODS

Seventy-three plasma samples from patients with postpartum AHA (n = 10) or associated with malignancies (n = 16) or autoimmune diseases (n = 11) or without underlying disease (n = 36) were analyzed with three multiplexed assays.

RESULTS AND CONCLUSIONS

Our results showed a stronger response against the A1a1-A2a2-B fragments of FVIII and more specifically against the A1a1 domain in patients with postpartum AHA than in the other AHA groups (P < 0.01). Moreover, although IgG4 was the predominant IgG subclass in all groups, anti-A1a1-A2a2-B and anti-A1a1 domain autoantibodies of the IgG(1) and IgG3 subclasses were more frequently detected in postpartum AHA than in the other AHA groups. These findings support the involvement of the Th1-driven response in the generation of autoantibodies in women with postpartum AHA compared with the other groups of AHA patients in whom production of Th2-driven IgG4 was predominant.

Clearance of genotype 1b hepatitis C virus in chimpanzees in the presence of vaccine-induced E1-neutralizing antibodies

Accumulating evidence indicates that neutralizing antibodies play an important role in protection from chronic hepatitis C virus (HCV) infection. Efforts to elicit such responses by immunization with intact heterodimeric E1E2 envelope proteins have met with limited success. To determine whether antigenic sites, which are not exposed by the combined E1E2 heterodimer structure, are capable of eliciting neutralizing antibody responses, we expressed and purified each as separate recombinant proteins E1 and E2, from which the immunodominant hypervariable region (HVR-1) was deleted. Immunization of chimpanzees with either E1 or E2 alone induced antigen-specific T-helper cytokines of similar magnitude. Unexpectedly, the capacity to neutralize HCV was observed in E1 but not in animals immunized with E2 devoid of HVR-1. Furthermore, in vivo only E1-vaccinated animals exposed to the heterologous HCV-1b inoculum cleared HCV infection.

Mimotopes of mutalysin-II from Lachesis muta snake venom induce hemorrhage inhibitory antibodies upon vaccination of rabbits

Mutalysin-II (mut-II) from Lachesis muta snake venom is an endopeptidase with hemorrhagic activity. A mAb against mutalysin-II that neutralized the hemorrhagic effect was produced previously. To identify the mAb epitopes, sets of 15-mer overlapping peptides covering the mut-II amino acid sequence were synthesized using the SPOT method and tested but failed to react with the mAb. Using a phage-display approach seventeen clones reactive with mAb were identified. Additional immunoassays with the peptides and mAb identified the QCTMDQGRLRCR, TCATDQGRLRCT, HCFHDQGRVRCA, HCTMDQGRLRCR and SCMLDQGRSRCR sequences as possible epitopes. Immunization of rabbits with these peptides induced antibodies that recognize mut-II and protected against the hemorrhagic effects of Lachesis venom.

Immunodiagnosis of human neurocysticercosis using a synthetic peptide selected by phage-display

The usefulness of a synthetic peptide in the serodiagnosis of Taenia solium human neurocysticercosis (NC) has been evaluated. Phage-displayed peptides were screened with human antibodies to scolex protein antigen from cysticercus cellulosae (SPACc). One clone was found to interact specifically with anti-SPACc IgGs. The corresponding synthetic peptide was found to be recognized in ELISA by NC patient's sera. The study was carried out with sera from 28 confirmed NC patients, 13 control sera and 73 sera from patients suffering from other infectious diseases. A 93% sensibility and a 94.3% specificity was achieved. Figures of 89% and 31.4% of sensibility and specificity were obtained in a SPACc-based ELISA. Immunoblotting of SPACc with anti-peptide antibodies revealed a single band of approximately 45 kDa in 1D and four 45 kDa isoforms in 2D-gel electrophoresis. A strong and specific immunostaining in the fibers beneath the suckers, at the base of the rostellum, and in the tissue surrounding the scolex of cysticerci was observed by immunomicroscopy. Our results show that a peptide-based immunodiagnostic of neurocisticercosis can be envisioned.

Risk genotypes and haplotypes of the GLUT1 gene for type 2 diabetic nephropathy in the Tunisian population

OBJECTIVE

Diabetic nephropathy (DN) is a long-term complication of both type 1 and type 2 diabetes. Genetic studies on DN have been of little help so far, since several genetic association studies have shown conflicting results. Here we report the findings of a case-control study on five SNPs in the glucose transporter 1 (GLUT1) gene. The study investigated the association of five GLUT1 genotypes and haplotypes with DN.

RESEARCH DESIGN AND METHODS

All subjects, 126 DN (cases) and 273 type 2 diabetes (controls), were genotyped using the polymerase chain reaction restriction fragment length polymorphism.

RESULTS

The TT and the AA genotypes of the Haell and Enh2 SNP1, increased the risk of DN. The study also identified CGT as the highest risk haplotype (4.4-fold) followed by CAT with an increased risk of DN of 2.6-fold.

CONCLUSIONS

The GLUT1 gene confers susceptibility to DN in type 2 diabetes patients in the Tunisian population.

Association of glucose transporter 1 polymorphisms with type 2 diabetes in the Tunisian population

BACKGROUND

T2DM is a complex metabolic disease. Genetic studies on T2DM have been of little help so far because several genetic association studies have shown conflicting results. In this study, we report the findings of a case-control study on three SNPs in the GLUT1 gene. For this, we investigated the association of GLUT1 genotypes and haplotypes with T2DM.

RESEARCH DESIGN AND METHODS

All 273 T2DM subjects (cases) and 343 healthy subjects (controls) were genotyped using the polymerase chain reaction restriction fragment length polymorphism.

RESULTS

Results showed that the GT genotype of XbaI SNP could increase the risk of susceptibility to T2DM to 2.4 and that TAT is a 'risk haplotype' conferring a risk of 3.4 to T2DM.

CONCLUSION

The TAT haplotype of the GLUT1 gene confers susceptibility to T2DM in the Tunisian population.

Reactivity profile of anti-factor VIII antibodies with designed synthetic peptides mimicking epitopes of the C2 and a1 domains

Antibodies (Abs) that block factor VIII (FVIII) activity occur in hemophilia A patients treated with FVIII replacement therapy and severely impair treatment. In this work, we designed and synthesized ten peptides whose sequences are found in putative epitopes at the surface of a1 and C2 domains of the FVIII molecule. These peptides were screened for their ability to inhibit the binding of anti-FVIII Abs from plasmas of hemophilia A patients to FVIII. All peptides were efficient in inhibiting anti-FVIII Abs in plasma from patients with inhibitors, with however different efficiencies. It was found that each tested patient's plasma had a different profile of reactivity with peptides, consistent with an individual anti-FVIII Ab specificity. The profile of recognized peptides was also changing during the treatment of the patients. Three peptides were used in an affinity chromatography assay to attempt to remove anti-FVIII Abs from patients' plasma. Anti-FVIII IgGs were significantly captured by the peptide-Sepharose affinity matrixes as assessed by enzyme-linked immunosorbent assay. However, due to the low level of Abs in the plasma samples, other methods (Chromogenic and Bethesda assays) were not sensitive enough to properly detect the reduction of inhibitors.

The Loxtox protein family in Loxosceles intermedia (Mello-Leitão) venom

We isolated cDNA sequences coding for dermonecrotic/sphingomyelinases factor proteins from the brown spider Loxosceles intermedia, here named Loxtox proteins. The amino acid sequences based on cloned cDNA of several Loxtox proteins revealed at least six distinct groups of proteins expressed in the venom gland. The level of similarity among the toxins varied from 99% to 55%. The finding of several isoforms of Loxtox in the venom of this spider may reflect an evolutionary adaptation for different prey types and reinforces the idea of an efficient mutational mechanism in the venom gland of spiders.

Vascular emergencies in liver trauma

The use of CT in the diagnosis and management of liver trauma is responsible for the shift from routine surgical versus non-surgical treatment in the management of traumatic liver injuries, even when they are of high grade. The main cause of complication and of death in liver trauma is related to vascular injury. The goal of this review focussed on the vascular complications of liver trauma is to describe the elementary lesions shown by CT in liver trauma including laceration, parenchymal hematoma and contusions, partial devascularisation, subcapsular hematomas, hemoperitoneum, active bleeding, pseudoaneurysm of the hepatic artery, bile leak, and periportal oedema, to illustrate the possible pitfalls in CT diagnosis of liver trauma and to underline the key-points which may absolutely be present in a CT report of liver trauma. Then we will remind the grading system based on the CT features and we will analyze the interest and limitations of such grading systems. Last we will discuss the diagnostic strategy at the early phase in patients with suspected liver trauma according to their clinical conditions and underline the conditions of arterial embolization, and then we will discuss the diagnosis strategy at the delayed phase according to the suspected complications.

An acidic cluster of the cytoplasmic tail of the RD114 virus glycoprotein controls assembly of retroviral envelopes

Retroviral core proteins, Gag and envelope (Env) glycoproteins are expressed from distinct cellular areas and therefore need to encounter to assemble infectious particles. The intrinsic cell localisation properties of either viral component or their capacity to mutually interact determines the assembly of infectious particles. Here, we address how Env determinants and cellular sorting proteins allow the Env derived from gamma retroviruses, murine leukemia virus (MLV) and RD114, to travel to or from late endosomes (LE), which may represent the Env assembly site of retroviruses in some cells. The individual expression of MLV Env resulted in its accumulation in LE in contrast to RD114 Env that required the presence of gamma retroviral Gag proteins. To discriminate between intrinsic intracellular Env localisation and gamma retroviral Gag/Env interactions in influencing Env viral incorporation, we studied Env assembly on heterologous lentiviral particles on which they are passively recruited. We found that an acidic cluster present at the C-terminus of the RD114 Env cytoplasmic tail determines its sub-cellular localisation and retrograde transport. Mutation of this motif induced late endosomal concentration of the RD114 Env, correlating with increased viral incorporation and infectivity. Reciprocally, the reinforcement of a poorly functional acidic motif in the MLV Env resulted in a marked decrease of its late endosomal localisation, leading to weakly infectious lentiviral particles with low Env densities. Finally, through upregulation versus downregulation of its cellular expression, we show that phosphofurin acidic-cluster-sorting protein 1 (PACS-1) controls the function of the RD114 Env acidic cluster, assigning to this cellular effector a crucial role in modulation of Env assembly of some retroviruses.

Functional characterization and epitope analysis of a recombinant dermonecrotic protein from Loxosceles intermedia spider

In the present study the recombinant form (recLiD1) of a dermonecrotic protein present in the Brazilian brown spider Loxosceles intermedia venom was expressed in Escherichia coli cells and purified by reversed-phase HPLC using a C8 Vydac column. About 25.8mg of purified recLiD1 was produced from a litre of bacterial culture. SDS/PAGE and immunoblot analysis of the recombinant protein revealed an apparent molecular weight of 32-35kDa. The later result was confirmed by mass spectrometry (32,758Da). recLiD1 displayed dermonecrotic and platelet aggregation activities which were qualitatively similar to that displayed by the crude L. intermedia venom. However, very low sphingomyelinase D enzymatic activity and complement-dependent haemolytic activities were observed. recLiD1 immunized BALB/c mice developed an antibody response. Anti-recLiD1 antibodies recognized L. intermedia venom in an indirect enzyme-linked immunosorbent assay (ELISA) and cross-reacted with crude venoms from L. intermedia, L. gaucho and L. laeta. An in vivo protection assay carried out 5 weeks after the end of the immunization protocol showed that 75% of the vaccinated mice could resist the challenge by 2.5LD(50) of L. intermedia venom. To characterize epitopes associated with protective antibodies, we prepare sets of immobilized synthetic 15 mer overlapping peptides covering the complete amino acid sequences of the recLiD1. Antibodies revealed one antigenic region in the N-terminal part of the toxin. The amino acid sequence of this epitope was found in several dermonecrotic proteins and some of its residues have been implicated with the active site of the toxin.

Antibodies against synthetic epitopes inhibit the enzymatic activity of mutalysin II, a metalloproteinase from bushmaster snake venom

Mutalysin II (mut-II), a 22.5kDa zinc endopeptidase isolated from bushmaster (Lachesis muta muta) snake venom, is a direct acting fibrin(ogen)olytic proteinase. It induces monoclonal and polyclonal antibodies which efficiently neutralize the hemorrhagic effect of L. muta and several Bothrops whole venoms. To characterize epitopes of protective antibodies we have used the Spot method of multiple peptide synthesis to prepare 64 overlapping dodecapeptides frameshifted by three residues, covering the complete amino acid sequence of mut-II. The rabbit anti-mut-II antibodies binding pattern to peptides revealed several continuous antigenic regions: one in the N-terminal part, two in the central region and the other in the C-terminal of mut-II. By using homology modelling, a three-dimensional model of mut-II was built which showed that epitopes are surface exposed. Anti-peptide antibodies were raised against three peptides (one representative of each epitope region) covalently coupled as a mixture to keyhole limpet hemocyanin. Purified IgG from the resulting anti- peptide antibodies cross-reacted with mut-II and induced a dose-dependent inhibition of the mut-II catalyzed proteolysis of fibrinogen.

High Density Lipoprotein Inhibits Hepatitis C Virus-neutralizing Antibodies by Stimulating Cell Entry via Activation of the Scavenger Receptor BI

Hepatitis C virus (HCV) exploits serum-dependent mechanisms that inhibit neutralizing antibodies. Here we demonstrate that high density lipoprotein (HDL) is a key serum factor that attenuates neutralization by monoclonal and HCV patient-derived polyclonal antibodies of infectious pseudo-particles (HCVpp) harboring authentic E1E2 glycoproteins and cell culture-grown genuine HCV (HCVcc). Over 10-fold higher antibody concentrations are required to neutralize either HCV-enveloped particles in the presence of HDL or human serum, and less than 3-5-fold reduction of infectious titers are obtained at saturating antibody concentrations, in contrast to complete inhibition in serum-free conditions. We show that HDL interaction with the scavenger receptor BI (SR-BI), a proposed cell entry co-factor of HCV and a receptor mediating lipid transfer with HDL, strongly reduces neutralization of HCVpp and HCVcc. We found that HDL activation of target cells strongly stimulates cell entry of viral particles by accelerating their endocytosis, thereby suppressing a 1-h time lag during which cell-bound virions are not internalized and can be targeted by antibodies. Compounds that inhibit lipid transfer functions of SR-BI fully restore neutralization by antibodies in human serum. We demonstrate that this functional HDL/SR-BI interaction only interferes with antibodies blocking HCV-E2 binding to CD81, a major HCV receptor, reflecting its prominent role during the cell entry process. Moreover, we identify monoclonal antibodies targeted to epitopes in the E1E2 complex that are not inhibited by HDL. Consistently, we show that antibodies targeted to HCV-E1 efficiently neutralize HCVpp and HCVcc in the presence of human serum.

Assembly of functional hepatitis C virus glycoproteins on infectious pseudoparticles occurs intracellularly and requires concomitant incorporation of E1 and E2 glycoproteins

Hepatitis C virus (HCV) E1 and E2 envelope glycoproteins (GPs) displayed on retroviral cores (HCVpp) are a powerful and highly versatile model system to investigate wild-type HCV entry. To further characterize this model system, the cellular site of HCVpp assembly and the respective roles of the HCV GPs in this process were investigated. By using a combination of biochemical methods with confocal and electron microscopic techniques, it was shown that, in cells producing HCVpp, both E1 and E2 colocalized with retroviral core proteins intracellularly, presumably in multivesicular bodies, but not at the cell surface. When E1 and E2 were expressed individually with retroviral core proteins, only E2 colocalized with and was incorporated on retroviral cores. Conversely, the colocalization of E1 with retroviral core proteins and its efficient incorporation occurred only upon co-expression of E2. Moreover, HCVpp infectivity correlated strictly with the presence of both E1 and E2 on retroviral cores. Altogether, these results confirm that the E1E2 heterodimer constitutes the prebudding form of functional HCV GPs and, more specifically, show that dimerization with E2 is a prerequisite for efficient E1 incorporation onto particles.