Mature Particles Research Articles

Complex transcriptional regulations of a hyperparasitic quadripartite system in giant viruses infecting protists

Hyperparasitism is a common pattern in nature that is not limited to cellular organisms. Giant viruses infecting protists can be hyperparasitized by smaller ones named virophages. In addition, both may carry episomal DNA molecules known as transpovirons in their particles. They all share transcriptional regulatory elements that dictate the expression of their genes within viral factories built by giant viruses in the host cytoplasm. This suggests the existence of interactions between their respective transcriptional networks. Here we investigated Acanthamoeba castellanii cells infected by a giant virus (megavirus chilensis), and coinfected with a virophage (zamilon vitis) and/or a transpoviron (megavirus vitis transpoviron). Infectious cycles were monitored through time-course RNA sequencing to decipher the transcriptional program of each partner and its impact on the gene expression of the others. We found highly diverse transcriptional responses. While the giant virus drastically reshaped the host cell transcriptome, the transpoviron had no effect on the gene expression of any of the players. In contrast, the virophage strongly modified the giant virus gene expression, albeit transiently, without altering the protein composition of mature viral particles. The virophage also induced the overexpression of transpoviron genes, likely through the indirect upregulation of giant virus-encoded transcription factors. Together, these analyses document the intricated transcriptionally regulated networks taking place in the infected cell.

Systematic analysis of traditional Chinese medicine prescriptions provides new insights into drug combination therapy for pox

Ethnopharmacological relevanceThe decline in cross-protection provided by the smallpox vaccine increases the risk of infection from other poxviruses. While drug combinations are a promising management, they remain underdeveloped for poxviruses. Prior to the development of the smallpox vaccine, China had long relied on herbal medicine to combat pox and accumulated a wealth of knowledge regarding different herb combinations and symptoms related to pox. The information was documented in the form of prescriptions. Aim of the studyThe extensive data of prescriptions offer the potential for uncovering commonalities underlying these prescriptions, thereby providing valuable insights into the development of drug combinations against pox. Materials and methodsThe 2344 prescriptions were collected from the LTM-TCM database and 12 traditional Chinese medicine books. Firstly, the relative frequency of citation was utilized to identify the most used herbs among these prescriptions. TCMSP and LTM-TCM databases were employed to gather information about active compounds and their targets. GeneCards and DisGeNET databases were utilized to determine the associated targets for smallpox, cowpox, chickenpox, and mpox. Subsequently, network pharmacology analysis was conducted to investigate potential pathway information related to the most used herbs. A comparison of active compounds from these herbs resulted in the identification of 29 high-frequency compounds. The functions of these compounds were elucidated through gene overlap analysis, docking, and literature review. Finally, we summarized pox-related symptoms and used fidelity levels to distinguish specific herbs for corresponding symptoms. ResultsBased on 2344 traditional pox-related prescriptions, we identified 19 most used herbs and 64 associated bio-functional modules for poxvirus treatment, with the most significant one being immunoregulation primarily involving CD4+ regulation. We also identified 29 leads that possess anti-inflammatory, antimicrobial, and antiviral properties. These herbs and leads hold the potential for pox treatment. Additionally, docking analysis suggested that these leads could inhibit poxvirus DNA synthesis, RNA capping machinery processes, and mature poxvirus particle formation, as well as immunosuppressors. The clinical features of mpox in 2022 were found to align well with our description of symptoms related to the pox. ConclusionThrough the analysis of 2344 prescriptions for pox treatment, we obtained a comprehensive library of the most used herbs and high-frequency compounds, along with their potential functional spectrum. These libraries served as raw resources for drug combination development, while the identified symptom patterns and specific herbs greatly enhanced our insight into diverse treatments for pox patients.

Subnanometer structure of medusavirus capsid during maturation using cryo-electron microscopy.

Medusavirus is a giant virus classified into an independent family of Mamonoviridae. Amoebae infected with medusavirus release immature particles in addition to virions. These particles were suggested to exhibit the maturation process of this virus, but the structure of these capsids during maturation remains unknown. Here, we apply a block-based reconstruction method in cryo-electron microscopy (cryo-EM) single particle analysis to these viral capsids, extending the resolution to 7-10 Å. The maps reveal a novel network composed of minor capsid proteins (mCPs) supporting major capsid proteins (MCPs). A predicted molecular model of the MCP fitted into the cryo-EM maps clarified the boundaries between the MCP and the underlining mCPs, as well as between the MCP and the outer spikes, and identified molecular interactions between the MCP and these components. Several structural changes of the mCPs under the fivefold vertices of the immature particles were observed, depending on the presence or absence of the underlying internal membrane. In addition, the lower part of the penton proteins on the fivefold vertices was also missing in mature virions. These dynamic conformational changes of mCPs indicate an important function in the maturation process of medusavirus.IMPORTANCEThe structural changes of giant virus capsids during maturation have not thus far been well clarified. Medusavirus is a unique giant virus in which infected amoebae release immature particles in addition to mature virus particles. In this study, we used cryo-electron microscopy to investigate immature and mature medusavirus particles and elucidate the structural changes of the viral capsid during the maturation process. In DNA-empty particles, the conformation of the minor capsid proteins changed dynamically depending on the presence or absence of the underlying internal membranes. In DNA-full particles, the lower part of the penton proteins was lost. This is the first report of structural changes of the viral capsid during the maturation process of giant viruses.

Functions of the UL51 protein during the herpesvirus life cycle.

The herpesvirus UL51 protein is a multifunctional tegument protein involved in the regulation of multiple aspects of the viral life cycle. This article reviews the biological characteristics of the UL51 protein and its functions in herpesviruses, including participating in the maintenance of the viral assembly complex (cVAC) during viral assembly, affecting the production of mature viral particles and promoting primary and secondary envelopment, as well as its positive impact on viral cell-to-cell spread (CCS) through interactions with multiple viral proteins and its key role in the proliferation and pathogenicity of the virus in the later stage of infection. This paper discusses how the UL51 protein participates in the life cycle of herpesviruses and provides new ideas for further research on UL51 protein function.

Membrane curvature sensing and symmetry breaking of the M2 proton channel from Influenza A.

The M2 proton channel aids in the exit of mature influenza viral particles from the host plasma membrane through its ability to stabilize regions of high negative Gaussian curvature (NGC) that occur at the neck of budding virions. The channels are homo-tetramers that contain a cytoplasm-facing amphipathic helix (AH) that is necessary and sufficient for NGC generation; however, constructs containing the transmembrane spanning helix, which facilitates tetramerization, exhibit enhanced curvature generation. Here, we used all-atom molecular dynamics (MD) simulations to explore the conformational dynamics of M2 channels in lipid bilayers revealing that the AH is dynamic, quickly breaking the fourfold symmetry observed in most structures. Next, we carried out MD simulations with the protein restrained in four- and twofold symmetric conformations to determine the impact on the membrane shape. While each pattern was distinct, all configurations induced pronounced curvature in the outer leaflet, while conversely, the inner leaflets showed minimal curvature and significant lipid tilt around the AHs. The MD-generated profiles at the protein-membrane interface were then extracted and used as boundary conditions in a continuum elastic membrane model to calculate the membrane-bending energy of each conformation embedded in different membrane surfaces characteristic of a budding virus. The calculations show that all three M2 conformations are stabilized in inward-budding, concave spherical caps and destabilized in outward-budding, convex spherical caps, the latter reminiscent of a budding virus. One of the C2-broken symmetry conformations is stabilized by 4 kT in NGC surfaces with the minimum energy conformation occurring at a curvature corresponding to 33 nm radii. In total, our work provides atomistic insight into the curvature sensing capabilities of M2 channels and how enrichment in the nascent viral particle depends on protein shape and membrane geometry.

Evidence of oxygenated species in laser-irradiated carbon particles

Combustion-generated carbon nanoparticles exhibit a variety of optical and physicochemical properties. Therefore, when applying laser diagnostic tools for monitoring purpose, it is important to consider the different response of the particles with varying properties as well as the impact of laser irradiation on these properties. In this work, we analyze the possible modification of particle optical and physicochemical properties by coupling extinction measurements with FT-IR and Raman spectroscopy. The aim is to retrieve optical, chemical, and structural properties of the particles under analysis. To our knowledge, the approach proposed in this work has not yet been performed on irradiated particles. Particles are sampled from a premixed flame at two heights above the burner, representing two different aging stages. While extinction measurements are carried out in-flow, FT-IR and Raman spectroscopy are performed on particles collected for ex-situ analysis. Moreover, the analysis is conducted on both pristine and irradiated nanoparticles with one and ten laser shots. While nascent particles do not exhibit relevant modification under laser irradiation, heating mature particles with one or more laser pulses of relatively high energy density is observed to significantly affect absorption properties, particle structures and specific surface functionalities. The presence of oxygenated species in mature particles and in particular the structures spectroscopically correlated with graphene oxide indicates that specific chemical reaction pathways can occur under laser irradiation, likely promoted in the ambient condition under analysis.

Enterovirus-A71 exploits RAB11 to recruit chaperones for virus morphogenesis

BackgroundEnterovirus 71 (EV-A71) causes Hand, Foot and Mouth Disease (HFMD) in children and has been associated with neurological complications. The molecular mechanisms involved in EV-A71 pathogenesis have remained elusive.MethodsA siRNA screen in EV-A71 infected-motor neurons was performed targeting 112 genes involved in intracellular membrane trafficking, followed by validation of the top four hits using deconvoluted siRNA. Downstream approaches including viral entry by-pass, intracellular viral genome quantification by qPCR, Western blot analyses, and Luciferase reporter assays allowed determine the stage of the infection cycle the top candidate, RAB11A was involved in. Proximity ligation assay, co-immunoprecipitation and multiplex confocal imaging were employed to study interactions between viral components and RAB11A. Dominant negative and constitutively active RAB11A constructs were used to determine the importance of the protein’s GTPase activity during EV-A71 infection. Mass spectrometry and protein interaction analyses were employed for the identification of RAB11A’s host interacting partners during infection.ResultsSmall GTPase RAB11A was identified as a novel pro-viral host factor during EV-A71 infection. RAB11A and RAB11B isoforms were interchangeably exploited by strains from major EV-A71 genogroups and by Coxsackievirus A16, another major causative agent of HFMD. We showed that RAB11A was not involved in viral entry, IRES-mediated protein translation, viral genome replication, and virus exit. RAB11A co-localized with replication organelles where it interacted with structural and non-structural viral components. Over-expression of dominant negative (S25N; GDP-bound) and constitutively active (Q70L; GTP-bound) RAB11A mutants had no effect on EV-A71 infection outcome, ruling out RAB11A’s involvement in intracellular trafficking of viral or host components. Instead, decreased ratio of intracellular mature viral particles to viral RNA copies and increased VP0:VP2 ratio in siRAB11-treated cells supported a role in provirion maturation hallmarked by VP0 cleavage into VP2 and VP4. Finally, chaperones, not trafficking and transporter proteins, were found to be RAB11A’s top interacting partners during EV-A71 infection. Among which, CCT8 subunit from the chaperone complex TRiC/CCT was further validated and shown to interact with viral structural proteins specifically, representing yet another novel pro-viral host factor during EV-A71 infection.ConclusionsThis study describes a novel, unconventional role for RAB11A during viral infection where it participates in the complex process of virus morphogenesis by recruiting essential chaperone proteins.

Advances in the immunoescape mechanisms exploited by alphaherpesviruses.

Alphaherpesviruses, categorized as viruses with linear DNA composed of two complementary strands, can potentially to induce diseases in both humans and animals as pathogens. Mature viral particles comprise of a core, capsid, tegument, and envelope. While herpesvirus infection can elicit robust immune and inflammatory reactions in the host, its persistence stems from its prolonged interaction with the host, fostering a diverse array of immunoescape mechanisms. In recent years, significant advancements have been achieved in comprehending the immunoescape tactics employed by alphaherpesviruses, including pseudorabies virus (PRV), herpes simplex virus (HSV), varicella-zoster virus (VZV), feline herpesvirus (FeHV), equine herpesvirus (EHV), and caprine herpesvirus type I (CpHV-1). Researchers have unveiled the intricate adaptive mechanisms existing between viruses and their natural hosts. This review endeavors to illuminate the research advancements concerning the immunoescape mechanisms of alphaherpesviruses by delineating the pertinent proteins and genes involved in virus immunity. It aims to furnish valuable insights for further research on related mechanisms and vaccine development, ultimately contributing to virus control and containment efforts.

Novel Anti-Enterovirus A71 Compounds Discovered by Repositioning Antivirals from the Open-Source MMV Pandemic Response Box.

The open-source drug library, namely, MMV Pandemic Response Box, contains 153 antiviral agents, a chemically and pharmacologically diverse mixture of early-stage, emerging anti-infective scaffolds, and mature compounds currently undergoing clinical development. Hence, the Pandemic Response Box might contain compounds that bind and interfere with target molecules or cellular pathways that are conserved or shared among the closely related viruses with enterovirus A71 (EV-A71). This study aimed to screen antiviral agents included in the Pandemic Response Box for repurposing to anti-EV-A71 activity and investigate the inhibitory effects of the compounds on viral replication. The compounds' cytotoxicity and ability to rescue infected cells were determined by % cell survival using an SRB assay. The hit compounds were verified for anti-EV-A71 activity by virus reduction assays for viral RNA copy numbers, viral protein synthesis, and mature particle production using qRT-PCR, Western blot analysis, and CCID50 assay, respectively. It was found that some of the hit compounds could reduce EV-A71 genome replication and protein synthesis. D-D7 (2-pyridone-containing human rhinovirus 3C protease inhibitor) exhibited the highest anti-EV-A71 activity. Even though D-D7 has been originally indicated as a polyprotein processing inhibitor of human rhinovirus 3C protease, it could be repurposed as an anti-EV-A71 agent.

Mutagenesis and functional analysis of the varicella-zoster virus portal protein.

Herpesviruses replicate by cleaving concatemeric dsDNA into single genomic units that are packaged through an oligomeric portal present in preformed procapsids. In contrast to what is known about phage portal proteins, details concerning herpesvirus portal structure and function are not as well understood. A panel of 65 Varicella-Zoster virus (VZV) recombinant portal proteins with five amino acid in-frame insertions were generated by random transposon mutagenesis of the VZV portal gene, ORF54. Subsequently, 65 VZVLUC recombinant viruses (TNs) were generated via recombineering. Insertions were mapped to predicted portal domains (clip, wing, stem, wall, crown, and β-hairpin tunnel-loop) and recombinant viruses were characterized for plaque morphology, replication kinetics, pORF54 expression, and classified based on replication in non-complementing (ARPE19) or complementing (ARPE54C50) cell lines. The N- and C-termini were tolerant to insertion mutagenesis, as were certain clip sub-domains. The majority of mutants mapping to the wing, wall, β-hairpin tunnel loop, and stem domains were lethal. Elimination of the predicted ORF54 start codon revealed that the first 40 amino acids of the N-terminus were not required for viral replication. Stop codon insertions in the C-terminus showed that the last 100 amino acids were not required for viral replication. Lastly, a putative protease cleavage site was identified in the C-terminus of pORF54. Cleavage was likely orchestrated by a viral protease; however, processing was not required for DNA encapsidation and viral replication. The panel of recombinants should prove valuable in future studies to dissect mammalian portal structure and function.IMPORTANCEThough nucleoside analogs and a live-attenuated vaccine are currently available to treat some human herpesvirus family members, alternate methods of combating herpesvirus infection could include blocking viral replication at the DNA encapsidation stage. The approval of Letermovir provided proof of concept regarding the use of encapsidation inhibitors to treat herpesvirus infections in the clinic. We propose that small-molecule compounds could be employed to interrupt portal oligomerization, assembly into the capsid vertex, or affect portal function/dynamics. Targeting portal at any of these steps would result in disruption of viral DNA packaging and a decrease or absence of mature infectious herpesvirus particles. The oligomeric portals of herpesviruses are structurally conserved, and therefore, it may be possible to find a single compound capable of targeting portals from one or more of the herpesvirus subfamilies. Drug candidates from such a series would be effective against viruses resistant to the currently available antivirals.

Nsp1 facilitates SARS-CoV-2 replication through calcineurin-NFAT signaling.

Cyclosporine A (CsA), commonly used to inhibit immune responses, is also known to have anti-SARS-CoV-2 activity, but its mode of action remains elusive. Here, we provide a model to explain how CsA antagonizes SARS-CoV-2 through three critical proteins: DDX5, NFAT1, and Nsp1. DDX5 is a cellular facilitator of SARS-CoV-2 replication, and NFAT1 controls the production of DDX5. Nsp1 is a viral protein absent from the mature viral particle and capable of activating the function of NFAT1 and DDX5. CsA and similar agents suppress Nsp1, NFAT1, and DDX5 to exert their anti-SARS-CoV-2 activity either alone or in combination with Paxlovid.

An easy but quantitative assessment of soot production rate and its dependence on temperature and pressure

The challenge of soot emission persists in combustion research due to the complexities of tracking the crucial stages of growth from fuel to soot nuclei and ultimately mature particles. Studying soot formation in flames often requires a sophisticated approach, involving detailed measurements of gaseous soot precursors and soot particles using multiple complementary diagnostics. On the other end of the spectrum of studies are simpler methods that capture the sooting tendency using a single index, akin to the cetane number in compression ignition engines and the octane number in spark ignition engines. This article seeks a middle ground, aiming to quantify the soot production rate while maintaining the simplicity of single-index characterizations. The approach involves establishing counterflow diffusion flames, measuring soot volume fraction through pyrometry, and accurately computing velocity and temperature profiles using a commercial code. These data allow for the quantification of the production rate from the soot governing equation. The methodology is applied to counterflow ethylene diffusion flames to examine the temperature dependence of the soot production rate across peak temperatures varying by several hundred degrees and pressures in the 1–32 atm range. The soot production rate per unit flame area falls within the range of 10−7–10−3 g/(cm2s) range and, when normalized with respect to the carbon flux, it ranges between 10−6 and nearly 10−2. On a logarithmic scale, it linearly correlates with the peak temperature at a fixed pressure. Although this study deals only with flames of ethylene, the approach can be generalized to any fuel. The resulting database should be valuable not only for industry practitioners but also to the scientific community for the global validation of detailed soot models.

Efficient delivery of the immunodominant genes of African swine fever virus by adeno-associated virus serotype 2.

Adeno-associated virus serotype 2 (AAV2) represents a promising basis for developing a virus-vector vaccine against African swine fever (ASF). This study aimed to create genetic constructs based on AAV2 to deliver the immunodominant genes of ASF virus (ASFV) and to evaluate their functionality in vitro. The efficiency and specificity of transgene expression, as well as their non-toxicity in cells of target animals, were evaluated. Bioinformatics analysis methods were used to identify the immunodominant genes of ASFV. The target genes B646L, E183L, CP204L, and CP530R were identified and subsequently cloned into the pAAV-MCS vector. Assembly of recombinant AAV2 (rAAV2) was performed by cotransfection of AAV293 cells with the following plasmids: pAAV-MCS with the gene of interest, envelope, and packaging. Quantitative polymerase chain reaction was used to determine the AAV2 titer. The functionality of the constructs was evaluated in HEK293 and SPEV cells by determining the presence of mature proteins in the cell lysate and the expression levels of messenger RNA. The specificity of the target proteins in cell lysates was confirmed by Western blotting. The proposed AAV2 assembly protocol makes it possible to achieve a concentration of mature viral particles of at least 280 billion/mL of virus-containing material. The rAAV2 could effectively transduce host SPEV cells. The expression of both cistrons was detectable during the transduction of cells; therefore, the combined expression of immunogens in the cells of target animals should be possible using this method. This study demonstrated the potential of using genetic constructs based on AAV2 for the delivery of ASFV genes in vitro.

Isolation and molecular characterization of the Salmonella Typhimurium orphan phage Arash

The current threat of multidrug resistant strains necessitates development of alternatives to antibiotics such as bacteriophages. This study describes the isolation and characterization of a novel Salmonella Typhimurium phage ‘Arash’ from hospital wastewater in Leuven, Belgium. Arash has a myovirus morphology with a 95 nm capsid and a 140 nm tail. The host range of Arash is restricted to its isolation host. Approximately 86% of the phage particles are adsorbed to a host cell within 10 min. Arash has latent period of 65 min and burst size of 425 PFU/cell. Arash has a dsDNA genome of 180,819 bp with GC content of 53.02% with no similarities to any characterized phages, suggesting Arash as a novel species in the novel ‘Arashvirus’ genus. Arash carries no apparent lysogeny-, antibiotic resistance- nor virulence-related genes. Proteome analysis revealed 116 proteins as part of the mature phage particles of which 27 could be assigned a function. Therefore, the present findings shed light on the morphological, microbiological and genomic characteristics of Arash and suggest its potential application as therapeutic and/or biocontrol agent.

Correlation between IL-35 and viral load in patients with liver hepatitis type B in Baghdad

Hepatitis, including autoimmune hepatitis, alcoholic hepatitis, drug-induced hepatitis, bacterial hepatitis, viral hepatitis, and others, was a typical occurrence in clinical work. Hepatitis B virus (HBV) and hepatitis C virus (HCV), both non-cytopathic viruses, were shown to be frequent in liver damage. It has been observed that IL-35 is linked to a reduction in inflammation and can limit T-cell proliferation and the activity of its effector cells. The hepatitis B virus is a virus that causes liver disease. Serum IL-35 was shown to be higher in chronic hepatitis B virus patients. At the same time, research has discovered that Tregs and other cell types (such as activated myeloid, endothelial cells, and regulatory B cells) can secrete IL-35. The quantity of specific viral DNA or RNA in a blood sample is known as viral load count, and it is one of the potential biomarkers of hepatitis. A high viral load suggests that the immune system has failed to combat viruses. Real-time quantification of hepatitis B (HBV) DNA viral load is possible. Hepatic chronic, cirrhosis, and undetected patients are measured using polymerase chain reaction (PCR) and non-invasive methods. In the ordinary course of HBV infection, HBV DNA is the only thing that survives. HBV DNA levels represent viral levels and derive from mature infectious particles. Reproducibility. Various hospital-based and community-based case-control and cohort studies have repeatedly demonstrated substantial correlations between blood HBV DNA levels and the risk of liver cirrhosis and HCC. Chronic hepatitis B has a variable course in disease activity with a risk of clinical complications like liver cirrhosis and hepatocellular carcinoma. As clinical symptoms present in a late stage of the disease, identifying risk factors is important for early detection and, therefore, improving prognosis. Recently, two REVEAL-HBV studies from Iraq have shown a positive correlation between viral load at any point in time and the development of cirrhosis and hepatocellular carcinoma. Keywords: Hepatitis B virus HBV, Interleukin-35 IL-35, polymerase chain reaction PCR.

Laser irradiation of differently aged carbon nanoparticles: effect on optical properties

The effect of laser irradiation on carbon nanoparticles of different maturity sampled from a premixed flame is investigated. To this purpose, extinction and laser-induced incandescence measurements are carried out on pristine and pre-irradiated nanoparticles. From extinction measurements, a spectral trend of the absorption coefficient of the particles is retrieved. Moreover, two-color laser-induced incandescence versus fluence is used to investigate the behavior of signal and temperature fluence curves in the different conditions under analysis. By coupling these results, interesting outcomes are obtained depending on the nature (nascent vs mature) of the particles. For nascent particles, a significant shift of the fluence curves is observed for the pre-irradiated particles, suggesting an increase in the absorption efficiency. However, no changes in the spectral trend of the absorption coefficient are observed from extinction measurements. On the contrary, for mature particles the absorption properties are strongly affected by irradiation resulting in an increase in the absorption efficiency in the spectral region below 600 nm. Moreover, a decrease of the temperature at the plateau regime for pre-irradiated mature particles towards the temperature value reached by nascent particles is observed. Two processes, namely fragmentation and sublimation followed by nucleation of new particles are suggested to occur under laser irradiation, especially for mature carbon nanoparticles.

Novel mutations in UL24 and gH rescue efficient infection of an HSV vector retargeted to TrkA

Transductional targeting of herpes simplex virus (HSV)-based gene therapy vectors offers the potential for improved tissue-specific delivery and can be achieved by modification of the viral entry machinery to incorporate ligands that bind the desired cell surface proteins. The interaction of nerve growth factor (NGF) with tropomyosin receptor kinase A (TrkA) is essential for survival of sensory neurons during development and is involved in chronic pain signaling. We targeted HSV infection to TrkA-bearing cells by replacing the signal peptide and HVEM binding domain of glycoprotein D (gD) with pre-pro-NGF. This TrkA-targeted virus (KNGF) infected cells via both nectin-1 and TrkA. However, infection through TrkA was inefficient, prompting a genetic search for KNGF mutants showing enhanced infection following repeat passage on TrkA-expressing cells. These studies revealed unique point mutations in envelope glycoprotein gH and in UL24, a factor absent from mature particles. Together these mutations rescued efficient infection of TrkA-expressing cells, including neurons, and facilitated the production of a completely retargeted KNGF derivative. These studies provide insight into HSV vector improvements that will allow production of replication-defective TrkA-targeted HSV for delivery to the peripheral nervous system and may be applied to other retargeted vector studies in the central nervous system.

Influence of the diagenetic oxidation and allochthonous organic matter input on geochemical and petrological results – Insights from the Upper/Middle Triassic strata, Polish Basin

Set of 24 Lower Keuperian (Upper Ladinian) and Grabfeld Formation (Lower Carnian) grey/black claystones core samples from the central part of the Polish Basin was examined by geochemical (Rock-Eval and Gas Chromatography-Mass Spectrometry) and petrological analyses. The Rock-Eval and petrological analyses revealed that the analysed organic matter is mostly mature/overmature (1.0–2.5%Ro). A combination of biomarker maturity indicators and petrological analyses suggest that autochthonous organic matter did not reach 0.9%Ro, and the higher mature organic matter particles have an allochthonous origin. Most samples contain significant input of allochthonous organic matter, which influenced the results of some geochemical indicators describing the origin of organic matter and palaeoenvironmental conditions.Investigated strata contain mostly mixed planktonic-bacterial and terrigenous organic matter. A higher contribution of terrigenous organic matter was observed within the Grabfeld Fm., where geochemical traces of fluvial-deltaic palaeoenvironment was recorded. Deposition of both strata occurred mostly under anoxic bottom waters in brackish or normal-saline marine conditions. However, an elevated salinity level was observed within Grabfeld Fm. sample from Byczyna 1 borehole.All samples contain phenylnaphthalenes (PhN), phenylphenanthrenes (PhP), and aromatic ketones, widely used as diagenetic oxidation indicators. The juxtaposition of two ratios based on phenanthrene (P), methylphenanthrenes (MP), and PhP was proposed to define the degree of organic matter diagenetic oxidation. Combined results of ƩMP/(ƩMP + ƩPhP) and P/(P + ƩPhP) revealed that Grabfeld Fm. contains more oxidised organic matter than Lower Keuperian strata. Moreover, the distribution of the PhN isomers – 1-PhN and 2-PhN – is controlled mainly by maturity level only in the least oxidised samples, where P/(P + ƩPhP) values range from 0.8 to 1.0. In other samples, the PhN distribution is controlled by the diagenetic oxidation degree. For this reason, the distribution of 1-PhN versus 2-PhN should not be used as a maturity indicator within more oxidised samples.

Peptidyl-prolyl cis/trans isomerase Pin1 interacts with hepatitis B virus core particle, but not with HBc protein, to promote HBV replication.

Here, we demonstrate that the peptidyl-prolyl cis/trans isomerase Pin1 interacts noncovalently with the hepatitis B virus (HBV) core particle through phosphorylated serine/threonine-proline (pS/TP) motifs in the carboxyl-terminal domain (CTD) but not with particle-defective, dimer-positive mutants of HBc. This suggests that neither dimers nor monomers of HBc are Pin1-binding partners. The 162TP, 164SP, and 172SP motifs within the HBc CTD are important for the Pin1/core particle interaction. Although Pin1 dissociated from core particle upon heat treatment, it was detected as an opened-up core particle, demonstrating that Pin1 binds both to the outside and the inside of the core particle. Although the amino-terminal domain S/TP motifs of HBc are not involved in the interaction, 49SP contributes to core particle stability, and 128TP might be involved in core particle assembly, as shown by the decreased core particle level of S49A mutant through repeated freeze and thaw and low-level assembly of the T128A mutant, respectively. Overexpression of Pin1 increased core particle stability through their interactions, HBV DNA synthesis, and virion secretion without concomitant increases in HBV RNA levels, indicating that Pin1 may be involved in core particle assembly and maturation, thereby promoting the later stages of the HBV life cycle. By contrast, parvulin inhibitors and PIN1 knockdown reduced HBV replication. Since more Pin1 proteins bound to immature core particles than to mature core particles, the interaction appears to depend on the stage of virus replication. Taken together, the data suggest that physical association between Pin1 and phosphorylated core particles may induce structural alterations through isomerization by Pin1, induce dephosphorylation by unidentified host phosphatases, and promote completion of virus life cycle.

Spectral investigation of soot absorption properties during laser-induced incandescence measurements

The effect of rapid laser irradiation on the optical properties of mature soot particles is investigated by performing wavelength-resolved extinction measurements in the visible spectral region. In particular, the spectral behavior of the absorption properties is explored during laser irradiation, at the peak of the incandescence signal (prompt LII) and few nanoseconds after the peak, and finally when particles have reached an equilibrium condition with the surrounding gas. A significant variation of the absorption coefficient of the laser-irradiated soot particles compared to that of the pristine ones is observed already at the LII peak. Such variation keeps evolving with time until it reaches a final permanent value. Results are presented in relation to the laser fluence used for irradiation and discussed with the aim of stressing the need of knowing the entity of the modification of soot absorption properties during laser irradiation for a correct interpretation of LII data.