Analysis of HIV-1 fusion peptide inhibition by synthetic peptides from E1 protein of GB virus C

Liposomes as selenium nanocarriers for foliar application to wheat plants: A biofortification strategy

In the present work, liposomes have been used as nanocarriers in the biofortification of wheat plants with selenium (Se) through foliar application. Liposomal formulations were prepared using 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and Phospholipon®90H (P90H) (average size <100 nm), loaded with different concentrations of inorganic Se (selenite and selenate) and applied twice to the plants in the stage of vegetative growth. Liposomes enhanced Se uptake by wheat plants compared to direct application. The highest Se enrichment was achieved using the phospholipid DPPC and a concentration of 1000 μmol·L-1 of Se without affecting the biomass, chlorophylls, carotenoids, and the concentration of mineral nutrients of the plants. The chemical speciation of Se in the plants was further investigated by X-ray absorption spectroscopy (XAS). The results from XAS spectra revealed that most of the inorganic Se was transformed to organic Se and that the use of liposomes influenced the proportion of C-Se-C over C-Se-Se-C species.

Human Pegivirus Type 1: A Common Human Virus That Is Beneficial in Immune-Mediated Disease?

Two groups identified a novel human flavivirus in the mid-1990s. One group named the virus hepatitis G virus (HGV) and the other named it GB Virus type C (GBV-C). Sequence analyses found these two isolates to be the same virus, and subsequent studies found that the virus does not cause hepatitis despite sharing genome organization with hepatitis C virus. Although HGV/GBV-C infection is common and may cause persistent infection in humans, the virus does not appear to directly cause any other known disease state. Thus, the virus was renamed “human pegivirus 1” (HPgV-1) for “persistent G” virus. HPgV-1 is found primarily in lymphocytes and not hepatocytes, and several studies found HPgV-1 infection associated with prolonged survival in people living with HIV. Co-infection of human lymphocytes with HPgV-1 and HIV inhibits HIV replication. Although three viral proteins directly inhibit HIV replication in vitro, the major effects of HPgV-1 leading to reduced HIV-related mortality appear to result from a global reduction in immune activation. HPgV-1 specifically interferes with T cell receptor signaling (TCR) by reducing proximal activation of the lymphocyte specific Src kinase LCK. Although TCR signaling is reduced, T cell activation is not abolished and with sufficient stimulus, T cell functions are enabled. Consequently, HPgV-1 is not associated with immune suppression. The HPgV-1 immunomodulatory effects are associated with beneficial outcomes in other diseases including Ebola virus infection and possibly graft-versus-host-disease following stem cell transplantation. Better understanding of HPgV-1 immune escape and mechanisms of inflammation may identify novel therapies for immune-based diseases.

Development of Protein- and Peptide-Based HIV Entry Inhibitors Targeting gp120 or gp41

Application of highly active antiretroviral drugs (ARDs) effectively reduces morbidity and mortality in HIV-infected individuals. However, the emergence of multiple drug-resistant strains has led to the increased failure of ARDs, thus calling for the development of anti-HIV drugs with targets or mechanisms of action different from those of the current ARDs. The first peptide-based HIV entry inhibitor, enfuvirtide, was approved by the U.S. FDA in 2003 for treatment of HIV/AIDS patients who have failed to respond to the current ARDs, which has stimulated the development of several series of protein- and peptide-based HIV entry inhibitors in preclinical and clinical studies. In this review, we highlighted the properties and mechanisms of action for those promising protein- and peptide-based HIV entry inhibitors targeting the HIV-1 gp120 or gp41 and discussed their advantages and disadvantages, compared with the current ARDs.

Design, Characterization, and Biopharmaceutical Behavior of Nanoparticles Loaded with an HIV-1 Fusion Inhibitor Peptide

New therapeutic alternatives to fight against the spread of HIV-1 are based on peptides designed to inhibit the early steps of HIV-1 fusion in target cells. However, drawbacks, such as bioavailability, short half-life, rapid clearance, and poor ability to cross the physiological barriers, make such peptides unattractive for the pharmaceutical industry. Here we developed, optimized, and characterized polymeric nanoparticles (NPs) coated with glycol chitosan to incorporate and release an HIV-1 fusion inhibitor peptide (E1) inside the vaginal mucosa. The NPs were prepared by a modified double emulsion method, and optimization was carried out by a factorial design. In vitro, ex vivo, and in vivo studies were carried out to evaluate the optimized formulation. The results indicate that the physicochemical features of these NPs enable them to incorporate and release HIV fusion inhibitor peptides to the vaginal mucosa before the fusion step takes place.

Prevalence of human pegivirus (HPgV) infection in patients carrying HIV-1C or non-C in southern Brazil

Previous studies have demonstrated that coinfection with HPgV is a protective factor for human immunodeficiency virus (HIV)-infected patients, leading to slower disease progression, and longer survival after established disease. The present study sought to estimate the prevalence of HPgV infection and associated risk factors in patients harboring C or non-C HIV-1 subtypes followed-up at HU-FURG, southern Brazil. Samples from 347 HIV-1-infected subjects were subjected to plasma RNA extraction, cDNA synthesis, HPgV RNA detection, and HIV-1 genotyping. The overall prevalence of HPgV RNA was 34%. Individuals aged 18-30 years had higher chances of infection compared with those 50 years or older (95%CI 1.18-52.36, P = 0.03). The number of sexual partner between one and three was a risk factor for HPgV infection (95%CI 1.54-10.23; P < 0.01), as well as the time since diagnosis of HIV-1 ≥ 11 years (95%CI 1.01-2.89; P = 0.04). Patients infected with HIV non-C subtypes had six times more chance of being HPgV-infected when compared to subtype C-infected subjects (95%CI 2.28-14.78; P < 0.01). This was the first study conducted in southern Brazil to find the circulation of HPgV. HIV/HPgV coinfection was associated with a longer survival among HIV⁺ patients. Of novelty, individuals infected by HIV non-C subtypes were more susceptible to HPgV infection. However, additional studies are needed to correlate the HIV-1 subtypes with HPgV infection and to clarify cellular and molecular pathways through which such associations are ruled. J. Med. Virol 88:2106-2114, 2016. © 2016 Wiley Periodicals, Inc.

Definition of an 18-mer Synthetic Peptide Derived from the GB virus C E1 Protein as a New HIV-1 Entry Inhibitor

BACKGROUND

A slower progression of AIDS and increased survival in GBV-C positive individuals, compared with GBV-C negative individuals has been demonstrated; while the loss of GBV-C viremia was closely associated with a rise in mortality and increased progression of AIDS. Following on from the previous reported studies that support the thesis that GBV-C E2 interferes with HIV-1 entry, in this work we try to determine the role of the GBV-C E1 protein in HIV-1 inhibition.

METHODS

The present work involves the construction of several overlapping peptide libraries scanning the GBV-C E1 protein and the evaluation of their anti-HIV activity.

RESULTS

Specifically, an 18-mer synthetic peptide from the GBV-C E1 protein, E1(139-156), showed similar antiviral activity against HIVs from viruses from clades A, B, C, D and AE. Competitive ELISA using specific gp41-targeting mAbs, fluorescence resonance energy transfer as well as haemolysis assays demonstrated that this E1 peptide sequence interacts with the highly conserved N-terminal region of the HIV-1 gp41 (the fusion peptide) which is essential for viral entry.

CONCLUSIONS

We have defined a novel peptide lead compound and described the inhibitory role of a highly conserved fragment of the E1 protein.

GENERAL SIGNIFICANCE

The results together allow us to consider the non-pathogenic E1 GBV-C protein as an attractive source of peptides for the development of novel anti-HIV therapies.

Surface behavior of peptides from E1 GBV-C protein: Interaction with anionic model membranes and importance in HIV-1 FP inhibition

The interaction between a peptide sequence from GB virus C E1 protein (E1P8) and its structural analogs (E1P8-12), (E1P8-13), and (E1P8-21) with anionic lipid membranes (POPG vesicles and POPG, DPPG or DPPC/DPPG (2:1) monolayers) and their association with HIV-1 fusion peptide (HIV-1 FP) inhibition at the membrane level were studied using biophysical methods. All peptides showed surface activity but leakage experiments in vesicles as well as insertion kinetics in monolayers and lipid/peptide miscibility indicated a low level of interaction: neither E1P8 nor its analogs induced the release of vesicular content and the exclusion pressure values (πe) were clearly lower than the biological membrane pressure (24-30 mN m(-1)) and the HIV-1 FP (35 mN m(-1)). Miscibility was elucidated in terms of the additivity rule and excess free energy of mixing (GE). E1P8, E1P8-12 and E1P8-21 (but not E1P8-13) induced expansion of the POPG monolayer. The mixing process is not thermodynamically favored as the positive GE values indicate. To determine how E1 peptides interfere in the action of HIV-1 FP at the membrane level, mixed monolayers of HIV-1 FP/E1 peptides (2:1) and POPG were obtained. E1P8 and its derivative E1P8-21 showed the greatest HIV-1 FP inhibition. The LC-LE phase lipid behavior was morphologically examined via fluorescence microscopy (FM) and atomic force microscopy (AFM). Images revealed that the E1 peptides modify HIV-1 FP-lipid interaction. This fact may be attributed to a peptide/peptide interaction as indicated by AFM results. Finally, hemolysis assay demonstrated that E1 peptides inhibit HIV-1 FP activity.

Interaction of two overlapped synthetic peptides from GB virus C with charged mono and bilayers

The physical chemistry properties and interactions of E2 (125-139) and E2 (120-139) peptide sequences from GB virus C with model cell membranes were investigated by means of several biophysical techniques in order to gain better understanding of the effect of peptide length and lipid charge on membrane binding. The peptides, having one net negative charge at the pH of the assays, interacted with monolayers of all the phospholipids regardless of the charge but with more extent with the cationic DPTAP thus indicating that the interaction had both a hydrophobic and an electrostatic component as has been observed for other peptides of the same family. The peptides were able to leakage contents of liposomes and showed fluorescence energy transfer in vesicles depending on the vesicles lipid composition. On another hand, circular dichroism has shown that the peptides exist mainly as a mixture of disordered structure and β-type conformations in aqueous solution but diminished its unstructured content, folding preferentially into α-helical conformation upon interaction with hydrophobic solvents or positively charged lipid surfaces. Altogether, results of this work indicate that the peptides interact at a surface level, penetrate into bilayers composed of fluid lipids and that conformational changes could be responsible for this effect.

GB virus C: the good boy virus?

GB virus C (GBV-C) is a lymphotropic human virus discovered in 1995 that is related to hepatitis C virus (HCV). GBV-C infection has not been convincingly associated with any disease; however, several studies found an association between persistent GBV-C infection and improved survival in HIV-positive individuals. GBV-C infection modestly alters T cell homeostasis in vivo through various mechanisms, including modulation of chemokine and cytokine release and receptor expression, and by diminution of T cell activation, proliferation and apoptosis, all of which may contribute to improved HIV clinical outcomes. In vitro studies confirm these clinical observations and demonstrate an anti-HIV replication effect of GBV-C. This review summarizes existing data on potential mechanisms by which GBV-C interferes with HIV, and the research needed to capitalize on this epidemiological observation.