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Journal of Virology Jun 2024The picornavirus genome encodes a large, single polyprotein that is processed by viral proteases to form an active replication complex. The replication complex is formed...
UNLABELLED
The picornavirus genome encodes a large, single polyprotein that is processed by viral proteases to form an active replication complex. The replication complex is formed with the viral genome, host proteins, and viral proteins that are produced/translated directly from each of the viral genomes (viral proteins provided in ). Efficient complementation of replication complex formation by viral proteins provided in , thus exogenous or ectopically expressed viral proteins, remains to be demonstrated. Here, we report an efficient complementation system for the replication of defective poliovirus (PV) mutants by a viral polyprotein precursor in HEK293 cells. Viral 3AB in the polyprotein, but not 2BC, was processed exclusively in . Replication of a defective PV replicon mutant, with a disrupted cleavage site for viral 3C protease between 3C and 3D (3C/D[A/G] mutant) could be rescued by a viral polyprotein provided in . Only a defect of 3D activity of the replicon could be rescued in ; inactivating mutations in 2C, 3B, and 3C of the replicon completely abrogated the -rescued replication. An intact N-terminus of the 3C domain of the 3CD provided in was essential for the -active function. By using this complementation system, a high-titer defective PV pseudovirus (PV) (>10 infectious units per mL) could be produced with the defective mutants, whose replication was completely dependent on complementation. This work reveals potential roles of exogenous viral proteins in PV replication and offers insights into protein/protein interaction during picornavirus infection.
IMPORTANCE
Viral polyprotein processing is an elaborately controlled step by viral proteases encoded in the polyprotein; fully processed proteins and processing intermediates need to be correctly produced for replication, which can be detrimentally affected even by a small modification of the polyprotein. Purified/isolated viral proteins can retain their enzymatic activities required for viral replication, such as protease, helicase, polymerase, etc. However, when these proteins of picornavirus are exogenously provided (provided in ) to the viral replication complex with a defective viral genome, replication is generally not rescued/complemented, suggesting the importance of viral proteins endogenously provided (provided in ) to the replication complex. In this study, I discovered that only the viral polymerase activity of poliovirus (PV) (the typical member of picornavirus family) could be efficiently rescued by exogenously expressed viral proteins. The current study reveals potential roles for exogenous viral proteins in viral replication and offers insights into interactions during picornavirus infection.
PubMed: 38837378
DOI: 10.1128/jvi.00523-24 -
Long-term trial of protection provided by adenovirus-vectored vaccine expressing the PPRV H protein.NPJ Vaccines Jun 2024A recombinant, replication-defective, adenovirus-vectored vaccine expressing the H surface glycoprotein of peste des petits ruminants virus (PPRV) has previously been...
A recombinant, replication-defective, adenovirus-vectored vaccine expressing the H surface glycoprotein of peste des petits ruminants virus (PPRV) has previously been shown to protect goats from challenge with wild-type PPRV at up to 4 months post vaccination. Here, we present the results of a longer-term trial of the protection provided by such a vaccine, challenging animals at 6, 9, 12 and 15 months post vaccination. Vaccinated animals developed high levels of anti-PPRV H protein antibodies, which were virus-neutralising, and the level of these antibodies was maintained for the duration of the trial. The vaccinated animals were largely protected against overt clinical disease from the challenge virus. Although viral genome was intermittently detected in blood samples, nasal and/or ocular swabs of vaccinated goats post challenge, viral RNA levels were significantly lower compared to unvaccinated control animals and vaccinated goats did not appear to excrete live virus. This protection, like the antibody response, was maintained at the same level for at least 15 months after vaccination. In addition, we showed that animals that have been vaccinated with the adenovirus-based vaccine can be revaccinated with the same vaccine after 12 months and showed an increased anti-PPRV antibody response after this boost vaccination. Such vaccines, which provide a DIVA capability, would therefore be suitable for use when the current live attenuated PPRV vaccines are withdrawn at the end of the ongoing global PPR eradication campaign.
PubMed: 38830899
DOI: 10.1038/s41541-024-00892-2 -
Research Square May 2024SARS-CoV-2 uses the double-membrane vesicles as replication organelles. However, how virion assembly occurs has not been fully understood. Here we identified a...
SARS-CoV-2 uses the double-membrane vesicles as replication organelles. However, how virion assembly occurs has not been fully understood. Here we identified a SARS-CoV-2-driven membrane structure named the 3a dense body (3DB). 3DBs have unusual electron-dense and dynamic inner structures, and their formation is driven by the accessory protein ORF3a via hijacking a specific subset of the -Golgi network (TGN) and early endosomal membranes. 3DB formation is conserved in related bat and pangolin coronaviruses yet lost during the evolution to SARS-CoV. 3DBs recruit the viral structural proteins spike (S) and membrane (M) and undergo dynamic fusion/fission to facilitate efficient virion assembly. A recombinant SARS-CoV-2 virus with an ORF3a mutant specifically defective in 3DB formation showed dramatically reduced infectivity for both extracellular and cell-associated virions. Our study uncovers the crucial role of 3DB in optimal SARS-CoV-2 infectivity and highlights its potential as a target for COVID-19 prophylactics and therapeutics.
PubMed: 38798602
DOI: 10.21203/rs.3.rs-4292014/v1 -
Viruses May 2024People with HIV exhibit persistent inflammation that correlates with HIV-associated comorbidities including accelerated aging, increased risk of cardiovascular disease,... (Review)
Review
People with HIV exhibit persistent inflammation that correlates with HIV-associated comorbidities including accelerated aging, increased risk of cardiovascular disease, and neuroinflammation. Mechanisms that perpetuate chronic inflammation in people with HIV undergoing antiretroviral treatments are poorly understood. One hypothesis is that the persistent low-level expression of HIV proviruses, including RNAs generated from defective proviral genomes, drives the immune dysfunction that is responsible for chronic HIV pathogenesis. We explore factors during HIV infection that contribute to the generation of a pool of defective proviruses as well as how HIV-1 mRNA and proteins alter immune function in people living with HIV.
Topics: Humans; HIV Infections; Inflammation; HIV-1; Transcription, Genetic; Proviruses; Protein Biosynthesis; RNA, Viral
PubMed: 38793632
DOI: 10.3390/v16050751 -
Viruses May 2024The pathogenesis of viral infection is attributed to two folds: intrinsic cell death pathway activation due to the viral cytopathic effect, and immune-mediated extrinsic... (Review)
Review
The pathogenesis of viral infection is attributed to two folds: intrinsic cell death pathway activation due to the viral cytopathic effect, and immune-mediated extrinsic cellular injuries. The immune system, encompassing both innate and adaptive immunity, therefore acts as a double-edged sword in viral infection. Insufficient potency permits pathogens to establish lifelong persistent infection and its consequences, while excessive activation leads to organ damage beyond its mission to control viral pathogens. The innate immune response serves as the front line of defense against viral infection, which is triggered through the recognition of viral products, referred to as pathogen-associated molecular patterns (PAMPs), by host cell pattern recognition receptors (PRRs). The PRRs-PAMPs interaction results in the induction of interferon-stimulated genes (ISGs) in infected cells, as well as the secretion of interferons (IFNs), to establish a tissue-wide antiviral state in an autocrine and paracrine manner. Cumulative evidence suggests significant variability in the expression patterns of PRRs, the induction potency of ISGs and IFNs, and the IFN response across different cell types and species. Hence, in our understanding of viral hepatitis pathogenesis, insights gained through hepatoma cell lines or murine-based experimental systems are uncertain in precisely recapitulating the innate antiviral response of genuine human hepatocytes. Accordingly, this review article aims to extract and summarize evidence made possible with bona fide human hepatocytes-based study tools, along with their clinical relevance and implications, as well as to identify the remaining gaps in knowledge for future investigations.
Topics: Humans; Hepatitis D; Hepatitis Delta Virus; Hepatocytes; Host-Pathogen Interactions; Immunity, Innate; Interferons; Pathogen-Associated Molecular Pattern Molecules; Receptors, Pattern Recognition
PubMed: 38793622
DOI: 10.3390/v16050740 -
Viruses Apr 2024Chronic Hepatitis B and D Virus (HBV and HDV) co-infection is responsible for the most severe form of viral Hepatitis, the Hepatitis Delta. Despite an efficient vaccine... (Review)
Review
Chronic Hepatitis B and D Virus (HBV and HDV) co-infection is responsible for the most severe form of viral Hepatitis, the Hepatitis Delta. Despite an efficient vaccine against HBV, the HBV/HDV infection remains a global health burden. Notably, no efficient curative treatment exists against any of these viruses. While physiologically distinct, HBV and HDV life cycles are closely linked. HDV is a deficient virus that relies on HBV to fulfil is viral cycle. As a result, the cellular response to HDV also influences HBV replication. In vitro studying of HBV and HDV infection and co-infection rely on various cell culture models that differ greatly in terms of biological relevance and amenability to classical virology experiments. Here, we review the various cell culture models available to scientists to decipher HBV and HDV virology and host-pathogen interactions. We discuss their relevance and how they may help address the remaining questions, with one objective in mind: the development of new therapeutic approaches allowing viral clearance in patients.
Topics: Humans; Hepatitis Delta Virus; Hepatitis B virus; Hepatitis D; Virus Replication; Animals; Host-Pathogen Interactions; Coinfection; Cell Culture Techniques; Hepatitis B
PubMed: 38793598
DOI: 10.3390/v16050716 -
Molecular Therapy : the Journal of the... May 2024Sepsis-associated encephalopathy (SAE) is a frequent complication of severe systemic infection resulting in delirium, premature death, and long-term cognitive...
Sepsis-associated encephalopathy (SAE) is a frequent complication of severe systemic infection resulting in delirium, premature death, and long-term cognitive impairment. We closely mimicked SAE in a murine peritoneal contamination and infection (PCI) model. We found long-lasting synaptic pathology in the hippocampus including defective long-term synaptic plasticity, reduction of mature neuronal dendritic spines, and severely affected excitatory neurotransmission. Genes related to synaptic signaling, including the gene for activity-regulated cytoskeleton-associated protein (Arc/Arg3.1) and members of the transcription-regulatory EGR gene family, were downregulated. At the protein level, ARC expression and mitogen-activated protein kinase signaling in the brain were affected. For targeted rescue we used adeno-associated virus-mediated overexpression of ARC in the hippocampus in vivo. This recovered defective synaptic plasticity and improved memory dysfunction. Using the enriched environment paradigm as a non-invasive rescue intervention, we found improvement of defective long-term potentiation, memory, and anxiety. The beneficial effects of an enriched environment were accompanied by an increase in brain-derived neurotrophic factor (BDNF) and ARC expression in the hippocampus, suggesting that activation of the BDNF-TrkB pathway leads to restoration of the PCI-induced reduction of ARC. Collectively, our findings identify synaptic pathomechanisms underlying SAE and provide a conceptual approach to target SAE-induced synaptic dysfunction with potential therapeutic applications to patients with SAE.
PubMed: 38788710
DOI: 10.1016/j.ymthe.2024.05.001 -
Journal of Virology Jun 2024Obesity is well established as a risk factor for many noncommunicable diseases; however, its consequences for infectious disease are poorly understood. Here, we...
Obesity is well established as a risk factor for many noncommunicable diseases; however, its consequences for infectious disease are poorly understood. Here, we investigated the impact of host obesity on influenza A virus (IAV) genetic variation using a diet-induced obesity ferret model and the A/Hong Kong/1073/1999 (H9N2) strain. Using a co-caging study design, we investigated the maintenance, generation, and transmission of intrahost IAV genetic variation by sequencing viral genomic RNA obtained from nasal wash samples over multiple days of infection. We found evidence for an enhanced role of positive selection acting on mutations in obese hosts that led to nonsynonymous changes that rose to high frequency. In addition, we identified numerous cases of mutations throughout the genome that were specific to obese hosts and that were preserved during transmission between hosts. Despite detection of obese-specific variants, the overall viral genetic diversity did not differ significantly between obese and lean hosts. This is likely due to the high supply rate of variation and common evolutionary adaptations to the ferret host regardless of obesity status, which we show are mediated by variation in the hemagglutinin and polymerase genes (PB2 and PB1). We also identified defective viral genomes (DVGs) that were found uniquely in either obese or lean hosts, but the overall DVG diversity and dynamics did not differ between the two groups. Our study suggests that obesity may result in a unique selective environment impacting intrahost IAV evolution, highlighting the need for additional genetic and functional studies to confirm these effects.IMPORTANCEObesity is a chronic health condition characterized by excess adiposity leading to a systemic increase in inflammation and dysregulation of metabolic hormones and immune cell populations. Influenza A virus (IAV) is a highly infectious pathogen responsible for seasonal and pandemic influenza. Host risk factors, including compromised immunity and pre-existing health conditions, can contribute to increased infection susceptibility and disease severity. During viral replication in a host, the negative-sense single-stranded RNA genome of IAV accumulates genetic diversity that may have important consequences for viral evolution and transmission. Our study provides the first insight into the consequences of host obesity on viral genetic diversity and adaptation, suggesting that host factors associated with obesity alter the selective environment experienced by a viral population, thereby impacting the spectrum of genetic variation.
Topics: Animals; Obesity; Influenza A virus; Genetic Variation; Orthomyxoviridae Infections; Ferrets; Genome, Viral; Mutation; RNA, Viral; Disease Models, Animal
PubMed: 38785423
DOI: 10.1128/jvi.01778-23 -
Frontiers in Molecular Neuroscience 2024Chronic pain is common and inadequately treated, making the development of safe and effective analgesics a high priority. Our previous data indicate that carbonic...
Chronic pain is common and inadequately treated, making the development of safe and effective analgesics a high priority. Our previous data indicate that carbonic anhydrase-8 (CA8) expression in dorsal root ganglia (DRG) mediates analgesia via inhibition of neuronal ER inositol trisphosphate receptor-1 (ITPR1) via subsequent decrease in ER calcium release and reduction of cytoplasmic free calcium, essential to the regulation of neuronal excitability. This study tested the hypothesis that novel JDNI8 replication-defective herpes simplex-1 viral vectors (rdHSV) carrying a CA8 transgene (vHCA8) reduce primary afferent neuronal excitability. Whole-cell current clamp recordings in small DRG neurons showed that vHCA8 transduction caused prolongation of their afterhyperpolarization (AHP), an essential regulator of neuronal excitability. This AHP prolongation was completely reversed by the specific Kv7 channel inhibitor XE-991. Voltage clamp recordings indicate an effect via Kv7 channels in vHCA8-infected small DRG neurons. These data demonstrate for the first time that vHCA8 produces Kv7 channel activation, which decreases neuronal excitability in nociceptors. This suppression of excitability may translate as non-opioid dependent behavioral- or clinical analgesia, if proven behaviorally and clinically.
PubMed: 38783904
DOI: 10.3389/fnmol.2024.1398839 -
Nature Communications May 2024Human immunodeficiency virus type-1 (HIV-1) is responsible for significant mortality and morbidity worldwide. Despite complete control of viral replication with...
Human immunodeficiency virus type-1 (HIV-1) is responsible for significant mortality and morbidity worldwide. Despite complete control of viral replication with antiretrovirals, cells with integrated HIV-1 provirus can produce viral transcripts. In a cross-sectional study of 84 HIV+ individuals of whom 43 were followed longitudinally, we found that HIV-1 RNAs are present in extracellular vesicles (EVs) derived from cerebrospinal fluid and serum of all individuals. We used seven digital droplet polymerase chain reaction assays to evaluate the transcriptional status of the latent reservoir. EV-associated viral RNA was more abundant in the CSF and correlated with neurocognitive dysfunction in both, the cross-sectional and longitudinal studies. Sequencing studies suggested compartmentalization of defective viral transcripts in the serum and CSF. These findings suggest previous studies have underestimated the viral burden and there is a significant relationship between latent viral transcription and CNS complications of long-term disease despite the adequate use of antiretrovirals.
Topics: Humans; Extracellular Vesicles; HIV-1; RNA, Viral; Male; Cross-Sectional Studies; HIV Infections; Female; Adult; Middle Aged; Longitudinal Studies; Viral Load; Virus Latency; Neurocognitive Disorders
PubMed: 38782925
DOI: 10.1038/s41467-024-48644-z