Homologous Peptides Research Articles

Homologous Peptide Foldamer Promotes FUS Aggregation and Triggers Cancer Cell Death.

Fused in sarcoma (FUS), a multifunctional deoxyribonucleic acid (DNA)/ribonucleic acid (RNA)-binding protein, has been implicated in various cancer types, including sarcoma and leukemia. Despite its association with these diseases, there has been limited exploration of FUS as a cancer therapy target, primarily because its dynamic nature makes it difficult to target specifically. In this study, we explored a kind of β-sheet peptide foldamer, named β4-TAT, to influence FUS aggregation by targeting its RNA recognition motifs (RRM). This approach leverages the noncovalent interaction characteristics of peptide self-assembly processes. The β4 sequence, derived from the FUS RRM β-sheet, in combination with TAT, a peptide known for its nuclear targeting capability, enables β4-TAT to bind specifically to the analogous β4 sequence within FUS. Notably, β4-TAT effectively induces FUS aggregation within cells, leading to the death of cancer cells. Our work developed a novel peptide foldamer-based strategy for inducing protein aggregation, paving the way for innovative therapeutic approaches in targeting FUS-associated cancers.

Identification of antibody targets associated with lower HIV viral load and viremic control.

High HIV viral loads (VL) are associated with increased morbidity, mortality, and on-going transmission. HIV controllers maintain low VLs in the absence of antiretroviral therapy (ART). We previously used a massively multiplexed antibody profiling assay (VirScan) to compare antibody profiles in HIV controllers and persons living with HIV (PWH) who were virally suppressed on ART. In this report, we used VirScan to evaluate whether antibody reactivity to specific HIV targets and broad reactivity across the HIV genome was associated with VL and controller status 1-2 years after infection. Samples were obtained from participants who acquired HIV infection in a community-randomized trial in Africa that evaluated an integrated strategy for HIV prevention (HPTN 071 PopART). Controller status was determined using VL and antiretroviral (ARV) drug data obtained at the seroconversion visit and 1 year later. Viremic controllers had VLs <2,000 copies/mL at both visits; non-controllers had VLs >2,000 copies/mL at both visits. Both groups had no ARV drugs detected at either visit. VirScan testing was performed at the second HIV-positive visit (1-2 years after HIV infection). The study cohort included 13 viremic controllers and 64 non-controllers. We identified ten clusters of homologous peptides that had high levels of antibody reactivity (three in gag, three in env, two in integrase, one in protease, and one in vpu). Reactivity to 43 peptides (eight unique epitopes) in six of these clusters was associated with lower VL; reactivity to six of the eight epitopes was associated with HIV controller status. Higher aggregate antibody reactivity across the eight epitopes (more epitopes targeted, higher mean reactivity across all epitopes) and across the HIV genome was also associated with lower VL and controller status. We identified HIV antibody targets associated with lower VL and HIV controller status 1-2 years after infection. Robust aggregate responses to these targets and broad antibody reactivity across the HIV genome were also associated with lower VL and controller status. These findings provide novel insights into the relationship between humoral immunity and viral containment that could help inform the design of antibody-based approaches for reducing HIV VL.

T-Cell Receptors Cross-Reactive to Coronaviral Epitopes Homologous to the SPR Peptide.

The COVID-19 pandemic caused by the rapid spread of the novel coronavirus SARS-CoV-2, has promoted an interest in studying the T-cell immune response. It was found that the polyclonal and cross-reactive T-cell response against seasonal coronaviruses and other SARS-CoV-2 strains reduced disease severity. We investigated the immunodominant T-cell epitope SPRWYFYYYL from the nucleocapsid protein of SARS-CoV-2. The immune response to this epitope is characterized by the formation of highly homologous (convergent) receptors that have been found in the T-cell receptor (TCR) repertoires of different individuals. This epitope belongs to a group of highly conserved peptides that are rarely mutated in novel SARS-CoV-2 strains and are homologous to the epitopes of seasonal coronaviruses. It has been suggested that the cross-reactive response to homologous peptides contributes to the reduction of COVID-19 severity. However, some investigators have questioned this hypothesis, suggesting that the low affinity of the cross-reactive receptors reduces the strength of the immune response. The aim of this study was to evaluate the effect of amino acid substitutions in the SPR epitope on its binding affinity to specific TCRs. For this, we performed antigen-dependent cellular expansions were performed using samples from four COVID-19-transfected donors and sequenced their TCR repertoires. The resulting SPR-specific repertoire of β-chains in TCRs had a greater sequence diversity than the repertoire of α-chains. However, the TCR repertoires of all four donors contained public receptors, three of which were cloned and used to generate the Jurkat E6-1 TPR cell line. Only one of these receptors was activated by the SPR peptide and recognized with the same affinity by its mutant homologue LPRWYFYYY from seasonal coronaviruses. This indicates that the presence of the mutation did not affect the strength of the immune response, which may explain why the cross-reactive response to the SPR epitope is so frequent and contributes positively to COVID-19 infection.

Universal peptide-based potential vaccine design against canine distemper virus (CDV) using a vaccinomic approach

Canine distemper virus (CDV) affects many domestic and wild animals. Variations among CDV genome linages could lead to vaccination failure. To date, there are several vaccine alternatives, such as a modified live virus and a recombinant vaccine; however, most of these alternatives are based on the ancestral strain Onderstepoort, which has not been circulating for years. Vaccine failures and the need to update vaccines have been widely discussed, and the development of new vaccine candidates is necessary to reduce circulation and mortality. Current vaccination alternatives cannot be used in wildlife animals due to the lack of safety data for most of the species, in addition to the insufficient immune response against circulating strains worldwide in domestic species. Computational tools, including peptide-based therapies, have become essential for developing new-generation vaccines for diverse models. In this work, a peptide-based vaccine candidate with a peptide library derived from CDV H and F protein consensus sequences was constructed employing computational tools. The molecular docking and dynamics of the selected peptides with canine MHC-I and MHC-II and with TLR-2 and TLR-4 were evaluated. In silico safety was assayed through determination of antigenicity, allergenicity, toxicity potential, and homologous canine peptides. Additionally, in vitro safety was also evaluated through cytotoxicity in cell lines and canine peripheral blood mononuclear cells (cPBMCs) and through a hemolysis potential assay using canine red blood cells. A multiepitope CDV polypeptide was constructed, synthetized, and evaluated in silico and in vitro by employing the most promising peptides for comparison with single CDV immunogenic peptides. Our findings suggest that predicting immunogenic CDV peptides derived from most antigenic CDV proteins could aid in the development of new vaccine candidates, such as multiple single CDV peptides and multiepitope CDV polypeptides, that are safe in vitro and optimized in silico. In vivo studies are being conducted to validate potential vaccines that may be effective in preventing CDV infection in domestic and wild animals.

Commensal HPVs Have Evolved to Be More Immunogenic Compared with High-Risk α-HPVs.

Commensal human papillomaviruses (HPVs) are responsible for persistent asymptomatic infection in the human population by maintaining low levels of the episomal genome in the stratified epithelia. Herein, we examined the immunogenicity of cutaneotropic HPVs that are commonly found in the skin. Using an in silico platform to determine human leukocyte antigen (HLA)-peptide complex binding affinity, we observed that early genes of cutaneotropic HPV types within the same species can generate multiple conserved, homologous peptides that bind with high affinity to HLA class I alleles. Interestingly, we discovered that commensal β, γ, μ, and ν HPVs contain significantly more immunogenic peptides compared with α-HPVs, which include high-risk, oncogenic HPV types. Our findings indicate that commensal HPV proteins have evolved to generate peptides that better complement their host's HLA repertoire. Promoting higher control by host T cell immunity in this way could be a mechanism by which HPVs achieve widespread asymptomatic colonization in humans. This work supports the role of commensal HPVs as immunogenic targets within epithelial cells, which may contribute to the immune regulation of the skin and mucosa.

An Intestinal Microbiome Intervention Affects Biochemical Disease Activity in Patients with Antiphospholipid Syndrome.

Background The origin of autoantibodies in patients with antiphospholipid syndrome (APS) is unknown. The gut microbiome contributes to autoimmunity and contains peptide homologues to the main APS autoantigen, which affect disease activity in animal models. Alteration of the gut microbiota with vancomycin diminishes disease activity in mice but no data on the effect of gut microbiota alteration in APS patients are available to date. Objective To evaluate whether the gut microbiome affects disease activity in human APS. Methods This was a pre-post design intervention study in APS patients with stable disease and no gastrointestinal comorbidity. Subjects received oral vancomycin, 500 mg four times daily for 7 days, previously shown to alter gut microbiota composition without systemic effects. Disease activity was assessed at four time points by measuring a panel of clinical phenotype-related biomarkers: antiphospholipid antibodies (APLAs), complement and inflammation markers, and hemostatic parameters. The primary outcome was the composite of the biomarker panel determined by multilevel principal component analysis. Results A total of 15 subjects completed the study. The primary outcome, the first principal component of the biomarker panel data, was significantly different after 7 days of vancomycin treatment ( p = 0.03), but not at day 42. APLA titers were unaffected. Unexpectedly, 4 out of 15 patients were negative for APLAs at baseline. In a post-hoc analysis, there was a prolonged effect for subjects with positive antibodies at baseline ( p = 0.03). In subjects with negative APLAs at baseline, the intervention showed no effect. Conclusion The intestinal microbiome affects the biochemical disease activity in APS patients. The mechanism is yet unknown but appears to be APS-specific.

A High-Homology Region Provides the Possibility of Detecting β-Barrel Pore-Forming Toxins from Various Bacterial Species.

The pathogenicity of many bacteria, including Bacillus cereus and Staphylococcus aureus, depends on pore-forming toxins (PFTs), which cause the lysis of host cells by forming pores in the membranes of eukaryotic cells. Bioinformatic analysis revealed a region homologous to the Lys171-Gly250 sequence in hemolysin II (HlyII) from B. cereus in over 600 PFTs, which we designated as a "homologous peptide". Three β-barrel PFTs were used for a detailed comparative analysis. Two of them-HlyII and cytotoxin K2 (CytK2)-are synthesized in Bacillus cereus sensu lato; the third, S. aureus α-toxin (Hla), is the most investigated representative of the family. Protein modeling showed certain amino acids of the homologous peptide to be located on the surface of the monomeric forms of these β-barrel PFTs. We obtained monoclonal antibodies against both a cloned homologous peptide and a 14-membered synthetic peptide, DSFNTFYGNQLFMK, as part of the homologous peptide. The HlyII, CytK2, and Hla regions recognized by the obtained antibodies, as well as an antibody capable of suppressing the hemolytic activity of CytK2, were identified in the course of this work. Antibodies capable of recognizing PFTs of various origins can be useful tools for both identification and suppression of the cytolytic activity of PFTs.

The funnel-web spider venom derived single knot peptide Hc3a modulates acid-sensing ion channel 1a desensitisation

Acid-sensing ion channel 1a (ASIC1a) is a proton-gated channel involved in synaptic transmission, pain signalling, and several ischemia-associated pathological conditions. The spider venom-derived peptides PcTx1 and Hi1a are two of the most potent ASIC1a inhibitors known and have been instrumental in furthering our understanding of the structure, function, and biological roles of ASICs. To date, homologous spider peptides with different pharmacological profiles at ASIC1a have yet to be discovered. Here we report the characterisation of Hc3a, a single inhibitor cystine knot peptide from the Australian funnel-web spider Hadronyche cerberea with sequence similarity to PcTx1. We show that Hc3a has complex pharmacology and binds different ASIC1a conformational states (closed, open, and desensitised) with different affinities, with the most prominent effect on desensitisation. Hc3a slows the desensitisation kinetics of proton-activated ASIC1a currents across multiple application pHs, and when bound directly to ASIC1a in the desensitised conformation promotes current inhibition. The solution structure of Hc3a was solved, and the peptide-channel interaction examined via mutagenesis studies to highlight how small differences in sequence between Hc3a and PcTx1 can lead to peptides with distinct pharmacology. The discovery of Hc3a expands the pharmacological diversity of spider venom peptides targeting ASIC1a and adds to the toolbox of compounds to study the intricacies of ASIC1 gating.

Cross-reactive CD8+ T cell responses to tumor-associated antigens (TAAs) and homologous microbiota-derived antigens (MoAs)

BackgroundWe have recently shown extensive sequence and conformational homology between tumor-associated antigens (TAAs) and antigens derived from microorganisms (MoAs). The present study aimed to assess the breadth of T-cell recognition specific to MoAs and the corresponding TAAs in healthy subjects (HS) and patients with cancer (CP).MethodA library of > 100 peptide-MHC (pMHC) combinations was used to generate DNA-barcode labelled multimers. Homologous peptides were selected from the Cancer Antigenic Peptide Database, as well as Bacteroidetes/Firmicutes-derived peptides. They were incubated with CD8 + T cells from the peripheral blood of HLA-A*02:01 healthy individuals (n = 10) and cancer patients (n = 16). T cell recognition was identified using tetramer-staining analysis. Cytotoxicity assay was performed using as target cells TAP-deficient T2 cells loaded with MoA or the paired TuA.ResultsA total of 66 unique pMHC recognized by CD8+ T cells across all groups were identified. Of these, 21 epitopes from microbiota were identified as novel immunological targets. Reactivity against selected TAAs was observed for both HS and CP. pMHC tetramer staining confirmed CD8+ T cell populations cross-reacting with CTA SSX2 and paired microbiota epitopes. Moreover, PBMCs activated with the MoA where shown to release IFNγ as well as to exert cytotoxic activity against cells presenting the paired TuA.ConclusionsSeveral predicted microbiota-derived MoAs are recognized by T cells in HS and CP. Reactivity against TAAs was observed also in HS, primed by the homologous bacterial antigens. CD8+ T cells cross-reacting with MAGE-A1 and paired microbiota epitopes were identified in three subjects. Therefore, the microbiota can elicit an extensive repertoire of natural memory T cells to TAAs, possibly able to control tumor growth (“natural anti-cancer vaccination”). In addition, non-self MoAs can be included in preventive/therapeutic off-the-shelf cancer vaccines with more potent anti-tumor efficacy than those based on TAAs.

The Role of Gut Microbiota in Neuromyelitis Optica Spectrum Disorder.

Neuromyelitis optica spectrum disorder (NMOSD) is a rare, disabling inflammatory disease of the central nervous system (CNS). Aquaporin-4 (AQP4)-specific T cells play a key role in the pathogenesis of NMOSD. In addition to immune factors, T cells recognizing the AQP4 epitope showed cross-reactivity with homologous peptide sequences in C. perfringens proteins, suggesting that the gut microbiota plays an integral role in the pathogenicity of NMOSD. In this review, we summarize research on the involvement of the gut microbiota in the pathophysiology of NMOSD and its possible pathogenic mechanisms. Among them, Clostridium perfringens and Streptococcus have been confirmed to play a role by multiple studies. Based on this evidence, metabolites produced by gut microbes, such as short-chain fatty acids (SCFAs), tryptophan (Trp), and bile acid (BA) metabolites, have also been found to affect immune cell metabolism. Therefore, the role of the gut microbiota in the pathophysiology of NMOSD is very important. Alterations in the composition of the gut microbiota can lead to pathological changes and alter the formation of microbiota-derived components and metabolites. It can serve as a biomarker for disease onset and progression and as a potential disease-modifying therapy.

Illuminating the neuropeptide Y4 receptor and its ligand pancreatic polypeptide from a structural, functional, and therapeutic perspective

The neuropeptide Y4 receptor (Y4R), a rhodopsin-like G protein-coupled receptor (GPCR) and the hormone pancreatic polypeptide (PP) are members of the neuropeptide Y family consisting of four receptors (Y1R, Y2R, Y4R, Y5R) and three highly homologous peptide ligands (neuropeptide Y, peptide YY, PP). In this family, the Y4R is of particular interest as it is the only subtype with high affinity to PP over NPY. The Y4R, as a mediator of PP signaling, has a pivotal role in appetite regulation and energy homeostasis, offering potential avenues for the treatment of metabolic disorders such as obesity. PP as anorexigenic peptide is released postprandial from the pancreas in response to food intake, induces satiety signals and contributes to hamper excessive food intake. Moreover, this system was also described to be associated with different types of cancer: overexpression of Y4R have been found in human adenocarcinoma cells, while elevated levels of PP are related to the development of pancreatic endocrine tumors. The pharmacological relevance of the Y4R advanced the search for potent and selective ligands for this receptor subtype, which will be significantly progressed through the elucidation of the active state PP-Y4R cryo-EM structure. This review summarizes the development of novel PP-derived ligands, like Obinepitide as dual Y2R/Y4R agonist in clinical trials or UR-AK86c as small hexapeptide agonist with picomolar affinity, as well as the first allosteric modulators that selectively target the Y4R, e.g. VU0506013 as potent Y4R positive allosteric modulator or (S)-VU0637120 as allosteric antagonist. Here, we provide valuable insights into the complex physiological functions of the Y4R and PP and the pharmacological relevance of the system in appetite regulation to open up new avenues for the development of tool compounds for targeted therapies with potential applications in metabolic disorders.

The small protein MntS evolved from a signal peptide and acquired a novel function regulating manganese homeostasis in Escherichia coli.

Small proteins (<50 amino acids) are emerging as ubiquitous and important regulators in organisms ranging from bacteria to humans, where they commonly bind to and regulate larger proteins during stress responses. However, fundamental aspects of small proteins, such as their molecular mechanism of action, downregulation after they are no longer needed, and their evolutionary provenance, are poorly understood. Here, we show that the MntS small protein involved in manganese (Mn) homeostasis binds and inhibits the MntP Mn transporter. Mn is crucial for bacterial survival in stressful environments but is toxic in excess. Thus, Mn transport is tightly controlled at multiple levels to maintain optimal Mn levels. The small protein MntS adds a new level of regulation for Mn transporters, beyond the known transcriptional and post-transcriptional control. We also found that MntS binds to itself in the presence of Mn, providing a possible mechanism of downregulating MntS activity to terminate its inhibition of MntP Mn export. MntS is homologous to the signal peptide of SitA, the periplasmic metal-binding subunit of a Mn importer. Remarkably, the homologous signal peptide regions can substitute for MntS, demonstrating a functional relationship between MntS and these signal peptides. Conserved gene neighborhoods support that MntS evolved from the signal peptide of an ancestral SitA protein, acquiring a life of its own with a distinct function in Mn homeostasis.

Biological Diversity of Genes Encoding Wheat Defensin Homologues

Antimicrobial peptides (AMPs) are major components of innate immunity in plants and animals. AMP genes have significant intra- and interspecific polymorphism, the role of which is poorly understood. Previously, by high throughput transcriptome sequencing of wheat plants, we identified defensin genes up-regulated upon infection with the pathogenic fungus Fusarium oxysporum and/or treatment with resistance inducers. In the present work, a bioinformatic search in NCBI databases for peptide homologues of these defensins was carried out using the sequences of their γ-cores, the sites of the molecules responsible for antimicrobial activity. DEFL1-16 homologues were identified in 95 species of angiosperms belonging to 48 families and 30 orders of monocotyledonous and dicotyledonous plants. The ubiquitous distribution of this defensin in angiosperms suggests its involvement not only in defense, but also in other processes in flowering plants. Homologues of other defensins induced by infection were found only in plants of the Poaceae family, which suggests the existence of a Poaceae-specific defense mechanism associated with the expression of these defensins. Among the γ-core variants of wild plant defensins identified in the study, the peptides with better antimicrobial activity compared to wheat, might be present, which are of considerable interest for the development of new antibiotics for medicine and agriculture.

T cells specific to multiple Bet v 1 peptides are highly cross-reactive toward the corresponding peptides from the homologous group of tree pollens.

Allergens from Fagales trees frequently cause spring allergy in Europe, North America, and some parts of Asia. The definition of the birch homologous group, which includes birch (Bet v), oak (Que a), alder (Aln g), hazel (Cor a), hornbeam (Car b), beech (Fag s), and chestnut (Cas s), is based on high allergen sequence identity and extensive IgE cross-reactivity. Clinical effect was seen during the alder/hazel, birch, and oak pollen seasons after treatment with tree SLIT-tablets containing only birch allergen extract. Here, we characterize T-cell reactivity with respect to epitope specificities and cross-reactivity toward various Bet v 1 family members, (PR-10/group 1 major allergens). This cross-reactivity may be part of the immunological basis of clinical effect or cross-protection when exposed to birch homologous tree species. T-cell lines were generated from 29 birch-allergic individuals through stimulation of peripheral blood mononuclear cells (PBMCs) with birch/Bet v or oak/Que a allergen extracts. T-cell responses to allergen extracts, purified group 1 allergens, and overlapping 20-mer peptides (Bet v 1, Aln g 1, Cor a 1, and Que a 1) were investigated by T-cell proliferation and cytokine production. Cross-reactivity was evaluated based on Pearson's correlations of response strength and further investigated by flow cytometry using tetramer staining for homologous peptide pairs. T-cell reactivity toward extracts and group 1 allergens from across the birch homologous group was observed for birch/Bet v as well as oak/Que a T-cell lines. T-cell lines responded to multiple Bet v 1 homologous peptides from Aln g 1 and Cor a 1 and a subset of Que a 1 peptides. Significant Pearson's correlations between frequently recognized peptides derived from Bet v 1 and the corresponding peptides derived from alder, hazel, and oak strongly supported the T-cell cross-reactivity toward these allergens. Cross-reactivity between birch and birch homologous peptides was confirmed by pMHCII tetramer staining. T cells from birch tree pollen allergic individuals respond to multiple trees within the birch homologous group in accordance with the level of sequence homology between Bet v 1 family members, (PR-10 allergens) from these allergen sources, confirming the basis for clinical cross-protection.

Gene deletion of the PACAP/VIP receptor, VPAC2R, alters glycemic responses during metabolic and psychogenic stress in adult female mice.

Pituitary adenylate cyclase-activating polypeptide (PACAP) and the homologous peptide, vasoactive intestinal peptide (VIP), participate in glucose homeostasis using insulinotropic and counterregulatory processes. The role of VIP receptor 2 (VPAC2R) in these opposing actions needs further characterization. In this study, we examined the participation of VPAC2R on basal glycemia, fasted levels of glucoregulatory hormones and on glycemia responses during metabolic and psychogenic stress using gene-deleted (Vipr2-/- ) female mice. The mean basal glycemia was significantly greater in Vipr2-/- in the fed state and after an 8-h overnight fast as compared to wild-type (WT) mice. Insulin tolerance testing following a 5-h fast (morning fast, 0.38 U/kg insulin) indicated no effect of genotype. However, during a more intense metabolic challenge (8 h, ON fast, 0.25 U/kg insulin), Vipr2-/- females displayed significantly impaired insulin hypoglycemia. During immobilization stress, the hyperglycemic response and plasma epinephrine levels were significantly elevated above basal in Vipr2-/- , but not WT mice, in spite of similar stress levels of plasma corticosterone. Together, these results implicate participation of VPAC2R in upregulated counterregulatory processes influenced by enhanced sympathoexcitation. Moreover, the suppression of plasma GLP-1 levels in Vipr2-/- mice may have removed the inhibition on hepatic glucose production and the promotion of glucose disposal by GLP-1. qPCR analysis indicated deregulation of central gene markers of PACAP/VIP signaling in Vipr2-/- , upregulated medulla tyrosine hydroxylase (Th) and downregulated hypothalamic Vip transcripts. These results demonstrate a physiological role for VPAC2R in glucose metabolism, especially during insulin challenge and psychogenic stress, likely involving the participation of sympathoadrenal activity and/or metabolic hormones.

Cross-reactivity between Mycobacterium avium subspecies paratuberculosis 4027 peptide and Human IRF5 may contribute to Multiple Sclerosis in Iranian patients

BackgroundThe etiology of Multiple sclerosis (MS) is complicated and can be affected by several environmental factors, such as Mycobacterium avium subspecies paratuberculosis (MAP) infection in genetically predisposed individuals. The link between MAP and MS depends on host genetic and epigenetic aspects and population-based features that require further investigation. We aimed to study the possible role of MAP in triggering MS using molecular and serological methods. Materials and methodsThis case-control study examined 200 blood samples (100 MS patients and 100 HCs) to search for the MAP-specific IS900 gene. In addition, ELISA was conducted to determine the humoral response against MAP_402718-32 and its human IRF5424–434 peptide homolog. ResultsThe frequency of MAP detection based on the molecular method in MS patients and HCs was 48 % and 13 %, respectively (p < 0.0001). The presence of antibodies against MAP_402718-32 and IRF5424–434 was 55 % and 65 % in MS patients versus 9 % and 7 % in HCs, respectively (p < 0.0001). A good correlation was observed between MAP_4027 and IRF5 antibodies (r = 0.5782, p < 0.0001), indicating that the same antibodies recognized common peptide epitopes. ConclusionOur research revealed a significant association between MAP and MS, highlighting the possible role of MAP as an important infection trigger factor of MS. It is hypothesized that cross-reactivity between MAP4027 and IRF5 may dysregulate immune homeostasis.

SLAM (CD150) receptor homologous peptides block the peste des petits ruminants virus entry into B95a cells.

The fusion of haemagglutinin-neuraminidase (HN) protein of peste des petits ruminant (PPR) virus with signaling lymphocyte activation molecules (SLAM) host cell receptor consequences the virus entry and multiplication inside the host cell. The use of synthetic SLAM homologous peptides (i.e., molecular decoy for HN protein of PPR virus) may check PPR infection at the preliminary stage. Hence, the predicted SLAM homologous peptides using bioinformatics tools were synthesized by solid phase chemistry with standard Merrifield's 9-fluorenylmethoxycarbonyl (Fmoc) chemistry and were purified by reverse phase high performance liquid chromatography. The secondary structures of synthesized peptides were elucidated by circular dichroism spectroscopy. The in vitro interactions of these peptides were studied through indirect Enzyme Linked Immuno Sorbent Assay (ELISA) and visual surface plasmon UV-visible spectroscopy. The SLAM homologous peptides were able to interact with the peste des petits ruminant virus (PPRV) with varying binding efficiency. The interaction of SLAM homologous peptide with the PPR virus was ascertained by the change in the plasmon color from red wine to purple during visual detection and also by bathochromic shift in absorbance spectra under UV-visible spectrophotometry. The cytotoxic and anti-PPRV effect of these peptides were also evaluated in B95a cell line using PPR virus (Sungri/96). The cytotoxic concentration 50 (CC50 ) value of each peptide was greater than 1000 μg mL-1 . The anti-PPRV efficiency of SLAM-22 was relatively high among SLAM homologous peptides, SLAM-22 at 25 μg mL-1 concentration showed a reduction of more than log10 3 virus titer by priming of B95a cell line while the use of SLAM-15 and Muco-17 at the same concentration dropped virus titer from log10 4.8 to log10 2.5 and log10 3.1 respectively. The concentration of SLAM homologous peptide (25 μg mL-1 ) to exert its anti-PPRV effect was much less than its CC50 level (>1000 μg mL-1 ). Therefore, the synthetic SLAM homologous peptides may prove to be better agents to target PPRV.

Development of Hemagglutinin-Neuraminidase Homologous Peptides as Novel Promising Therapeutic Agents Against Peste des Petits Ruminants Virus.

The lack of specific antiviral therapy and complications associated with the existing peste des petits ruminants (PPR) vaccines accentuates the search of novel antiviral blocking agents in order to curtail the PPR infection at initial level. The synthetic hemagglutinin-neuraminidase (HN) homologous peptides may compete with the natural HN protein of PPR virus for binding to signaling lymphocytic activation molecule (SLAM) receptor, consequently, may disrupt peste des petits ruminants virus (PPRV) at entry level. Therefore, insilico analysis, synthesis, purification and subsequent characterization of HN homologous peptides were conducted in this study. The HN homologous peptides were synthesized by means of solid phase chemistry and were purified by reversed-phase-high performance liquid chromatography. The mass as well as sequence of HN homologous peptides were assessed by mass spectroscopy while its secondary structure was elucidated by circular dichroism spectroscopy. The binding (interaction) efficacy of HN homologous peptides with PPRV antibodies was assessed via indirect enzyme linked immunosorbent assay, visual detection test (red wine to purple), bathochromic shift under UV-Vis spectrophotometry and lateral flow immunochromatographic strip test. The antiviral properties and cytotoxicity of these peptides were also assessed in B95a cell line with changes in cytopathic effect and titer of PPRV (Sungri/96). The presence of green fluorescein isothiocyanate over the B95a cell surface pointed towards the binding of HN homologous peptides with surface SLAM receptor. Moreover, the intact beta sheet configuration in water and lower cytotoxicity [cytotoxic concentration 50 (CC50) > 1000µg/ml] of these peptides signifies its in vivo use. Among HN homologous peptides, the binding efficacy and antiviral properties of pep A was relatively high in comparison to pep B and Pep ppr peptides. The prerequisite concentration of HN homologous peptides (pep A = 12.5µg/ml; pep B = 25µg/ml; pep ppr = 25µg/ml) to exemplify its antiviral effect was much lower than its CC50 level. Hence, this study signifies the therapeutic potential of synthetic HN homologous peptides.

Varicella-zoster virus proteome-wide T-cell screening demonstrates low prevalence of virus-specific CD8 T-cells in latently infected human trigeminal ganglia

BackgroundTrigeminal ganglia (TG) neurons are an important site of lifelong latent varicella-zoster virus (VZV) infection. Although VZV-specific T-cells are considered pivotal to control virus reactivation, their protective role at the site of latency remains uncharacterized.MethodsPaired blood and TG specimens were obtained from ten latent VZV-infected adults, of which nine were co-infected with herpes simplex virus type 1 (HSV-1). Short-term TG-derived T-cell lines (TG-TCL), generated by mitogenic stimulation of TG-derived T-cells, were probed for HSV-1- and VZV-specific T-cells using flow cytometry. We also performed VZV proteome-wide screening of TG-TCL to determine the fine antigenic specificity of VZV reactive T-cells. Finally, the relationship between T-cells and latent HSV-1 and VZV infections in TG was analyzed by reverse transcription quantitative PCR (RT-qPCR) and in situ analysis for T-cell proteins and latent viral transcripts.ResultsVZV proteome-wide analysis of ten TG-TCL identified two VZV antigens recognized by CD8 T-cells in two separate subjects. The first was an HSV-1/VZV cross-reactive CD8 T-cell epitope, whereas the second TG harbored CD8 T-cells reactive with VZV specifically and not the homologous peptide in HSV-1. In silico analysis showed that HSV-1/VZV cross reactivity of TG-derived CD8 T-cells reactive with ten previously identified HSV-1 epitopes was unlikely, suggesting that HSV-1/VZV cross-reactive T-cells are not a common feature in dually infected TG. Finally, no association was detected between T-cell infiltration and VZV latency transcript abundance in TG by RT-qPCR or in situ analyses.ConclusionsThe low presence of VZV- compared to HSV-1-specific CD8 T-cells in human TG suggests that VZV reactive CD8 T-cells play a limited role in maintaining VZV latency.

Comparative Study of Molecular Mechanics Force Fields for β-Peptidic Foldamers: Folding and Self-Association.

Computer-assisted study and design of non-natural peptidomimetics is increasingly important in the development of novel constructs with widespread applicability. Among these methods, molecular dynamics can accurately describe monomeric as well as oligomeric states of these compounds. We studied seven different sequences composed of cyclic and acyclic β-amino acids, the closest homologues of natural peptides, and compared the performance on them of three force field families in which specific modifications were made to improve reproduction of β-peptide structures. Altogether 17 systems were simulated, each for 500 ns, testing multiple starting conformations and in three cases also oligomer formation and stability from eight β-peptide monomers. The results indicated that our recently developed CHARMM force field extension, based on torsional energy path matching of the β-peptide backbone against quantum-chemical calculations, performs best overall, reproducing the experimental structures accurately in all monomeric simulations and correctly describing all the oligomeric examples. The Amber and GROMOS force fields could only treat some of the seven peptides (four in each case) without further parametrization. Amber was able to reproduce the experimental secondary structure of those β-peptides which contained cyclic β-amino acids, while the GROMOS force field had the lowest performance in this sense. From the latter two, Amber was able to hold together already formed associates in the prepared state but was not able to yield spontaneous oligomer formation in the simulations.