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Keywords = reactivation of viral reservoirs

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10 pages, 1491 KiB  
Article
Development of a Point-of-Care Immunochromatographic Lateral Flow Strip Assay for the Detection of Nipah and Hendra Viruses
by Jianjun Jia, Wenjun Zhu, Guodong Liu, Sandra Diederich, Bradley Pickering, Logan Banadyga and Ming Yang
Viruses 2025, 17(7), 1021; https://doi.org/10.3390/v17071021 - 21 Jul 2025
Viewed by 401
Abstract
Nipah virus (NiV) and Hendra virus (HeV), which both belong to the genus henipavirus, are zoonotic pathogens that cause severe systemic, neurological, and/or respiratory disease in humans and a variety of mammals. Therefore, monitoring viral prevalence in natural reservoirs and rapidly diagnosing cases [...] Read more.
Nipah virus (NiV) and Hendra virus (HeV), which both belong to the genus henipavirus, are zoonotic pathogens that cause severe systemic, neurological, and/or respiratory disease in humans and a variety of mammals. Therefore, monitoring viral prevalence in natural reservoirs and rapidly diagnosing cases of henipavirus infection are critical to limiting the spread of these viruses. Current laboratory methods for detecting NiV and HeV include virus isolation, reverse transcription quantitative real-time PCR (RT-qPCR), and antigen detection via an enzyme-linked immunosorbent assay (ELISA), all of which require highly trained personnel and specialized equipment. Here, we describe the development of a point-of-care customized immunochromatographic lateral flow (ILF) assay that uses recombinant human ephrin B2 as a capture ligand on the test line and a NiV-specific monoclonal antibody (mAb) on the conjugate pad to detect NiV and HeV. The ILF assay detects NiV and HeV with a diagnostic specificity of 94.4% and has no cross-reactivity with other viruses. This rapid test may be suitable for field testing and in countries with limited laboratory resources. Full article
(This article belongs to the Section General Virology)
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25 pages, 2198 KiB  
Review
Oxidative Stress in HIV-Associated Neurodegeneration: Mechanisms of Pathogenesis and Therapeutic Targets
by Sophia Gagliardi, Tristan Hotchkin, Grace Hillmer, Maeve Engelbride, Alexander Diggs, Hasset Tibebe, Coco Izumi, Cailyn Sullivan, Cecelia Cropp, Olive Lantz, Dacia Marquez, Jason Chang, Jiro Ezaki, Alexander George Zestos, Anthony L. Riley and Taisuke Izumi
Int. J. Mol. Sci. 2025, 26(14), 6724; https://doi.org/10.3390/ijms26146724 - 13 Jul 2025
Viewed by 1698
Abstract
Treatment for HIV infection has become more manageable due to advances in combination antiretroviral therapy (cART). However, HIV still significantly affects the central nervous system (CNS) in infected individuals, even with effective plasma viral suppression, due to persistent viral reservoirs and chronic neuroinflammation. [...] Read more.
Treatment for HIV infection has become more manageable due to advances in combination antiretroviral therapy (cART). However, HIV still significantly affects the central nervous system (CNS) in infected individuals, even with effective plasma viral suppression, due to persistent viral reservoirs and chronic neuroinflammation. This ongoing inflammation contributes to the development of HIV-associated neurocognitive disorders (HANDs), including dementia and Alzheimer’s disease-like pathology. These complications are particularly prevalent among the aging population with HIV. This review aims to provide a comprehensive overview of HAND, with a focus on the contribution of oxidative stress induced by HIV-mediated reactive oxygen species (ROS) production through viral proteins such as gp120, Tat, Nef, Vpr, and reverse transcriptase. In addition, we discuss current and emerging therapeutic interventions targeting HAND, including antioxidant strategies and poly (ADP-ribose) polymerase (PARP) inhibitors. These are potential adjunctive approaches to mitigate neuroinflammation and oxidative damage in the CNS. Full article
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20 pages, 941 KiB  
Review
HIV-1 Tat: Molecular Switch in Viral Persistence and Emerging Technologies for Functional Cure
by Kaixin Yu, Hanxin Liu and Ting Pan
Int. J. Mol. Sci. 2025, 26(13), 6311; https://doi.org/10.3390/ijms26136311 - 30 Jun 2025
Viewed by 727
Abstract
HIV-1 Tat acts as a central molecular switch governing the transition between viral latency and active replication, making it a pivotal target for HIV-1 functional cure strategies. By binding to the viral long terminal repeat (LTR) and hijacking host transcriptional machinery, Tat dynamically [...] Read more.
HIV-1 Tat acts as a central molecular switch governing the transition between viral latency and active replication, making it a pivotal target for HIV-1 functional cure strategies. By binding to the viral long terminal repeat (LTR) and hijacking host transcriptional machinery, Tat dynamically regulates RNA polymerase II processivity to alter viral transcription states. Recent studies reveal its context-dependent variability: while Tat recruits chromatin modifiers and scaffolds non-coding RNAs to stabilize epigenetic silencing in latently infected cells, it also triggers rapid transcriptional amplification upon cellular activation. This review systematically analyzes the bistable regulatory mechanism of Tat and investigates advanced technologies for reprogramming this switch to eliminateviral reservoirs and achieve functional cures. Conventional approaches targeting Tat are limited by compensatory viral evolution and poor bioavailability. Next-generation interventions will employ precision-engineered tools, such as AI-optimized small molecules blocking Tat-P-TEFb interfaces and CRISPR-dCas9/Tat chimeric systems, for locus-specific LTR silencing or reactivation (“block and lock” or “shock and kill”). Advanced delivery platforms, including brain-penetrant lipid nanoparticles (LNPs), enable the targeted delivery of Tat-editing mRNA or base editors to microglial reservoirs. Single-cell multiomics elucidates Tat-mediated clonal heterogeneity, identifying “switchable” subpopulations for timed interventions. By integrating systems-level Tat interactomics, epigenetic engineering, and spatiotemporally controlled delivery, this review proposes a roadmap to disrupt HIV-1 persistence by hijacking the Tat switch, ultimately bridging mechanistic insights to clinical applications. Full article
(This article belongs to the Section Molecular Microbiology)
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23 pages, 3242 KiB  
Hypothesis
Vaxtherapy, a Multiphase Therapeutic Protocol Approach for Longvax, the COVID-19 Vaccine-Induced Disease: Spike Persistence as the Core Culprit and Its Downstream Effects
by Jose Crespo-Barrios
Diseases 2025, 13(7), 204; https://doi.org/10.3390/diseases13070204 - 30 Jun 2025
Viewed by 2082
Abstract
Background/Objectives: Chronic illness after COVID-19 vaccination (longvax) lacks a therapeutic protocol anchored in pathophysiology. Persistent vaccine derived spike protein appears to trigger microvascular fibrin amyloid microclots, immune dysfunction, pathogen reactivation and multisystem injury. This article proposes an integrative approach, Vaxtherapy, to tackle these [...] Read more.
Background/Objectives: Chronic illness after COVID-19 vaccination (longvax) lacks a therapeutic protocol anchored in pathophysiology. Persistent vaccine derived spike protein appears to trigger microvascular fibrin amyloid microclots, immune dysfunction, pathogen reactivation and multisystem injury. This article proposes an integrative approach, Vaxtherapy, to tackle these mechanisms. Methods: A narrative synthesis of peer reviewed literature from 2021 to 2025 on spike related injury and vaccine adverse events was conducted, supplemented by clinical case series and mechanistic observations from long COVID. The findings were arranged into a four stage therapeutic sequence ordered by pathophysiological precedence. Results: Stage one aims to reopen hypoperfused tissue through oral fibrinolytics that degrade fibrin amyloid resistant microclots; stage two intends to neutralise circulating or tissue bound spike via a receptor binding domain monoclonal antibody cocktail; stage three seeks to eliminate reactivated viral or microbial reservoirs with targeted antivirals or antimicrobials once perfusion is improved; and stage four aspires to support tissue repair with mitochondrial supplements and, when indicated, cell based therapies. Omitting or reordering stages may reduce efficacy or foster resistance. Conclusions: This hypothesis driven framework outlines a biologically plausible roadmap for longvax research. By matching interventions to specific mechanisms (fibrinolysis, spike neutralisation, pathogen clearance and regeneration), it aims to guide controlled trials and compassionate pilot programs directed at durable recovery rather than chronic symptom management. Full article
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60 pages, 6483 KiB  
Review
The Challenge of Lyssavirus Infections in Domestic and Other Animals: A Mix of Virological Confusion, Consternation, Chagrin, and Curiosity
by Charles E. Rupprecht, Aniruddha V. Belsare, Florence Cliquet, Philip P. Mshelbwala, Janine F. R. Seetahal and Vaughn V. Wicker
Pathogens 2025, 14(6), 586; https://doi.org/10.3390/pathogens14060586 - 13 Jun 2025
Viewed by 2390
Abstract
Lyssaviruses are RNA viruses in the Family Rhabdoviridae, Genus Lyssavirus. They represent the causative agents of acute, progressive encephalitis, known historically as rabies. Regardless of specific etiology, their collective viral morphology, biochemistry, pathobiology, associated clinical signs, diagnosis, epizootiology, and management are essentially [...] Read more.
Lyssaviruses are RNA viruses in the Family Rhabdoviridae, Genus Lyssavirus. They represent the causative agents of acute, progressive encephalitis, known historically as rabies. Regardless of specific etiology, their collective viral morphology, biochemistry, pathobiology, associated clinical signs, diagnosis, epizootiology, and management are essentially the same. Despite centuries of clinical recognition, these quintessential neurotropic agents remain significant pathogens today, with substantive consequences to agriculture, public health, and conservation biology. Notably, the singular morbidity caused by lyssaviruses is incurable and constitutes the highest case fatality of any viral disease. All warm-blooded vertebrates are believed to be susceptible. The dog is the only domestic animal that serves as a reservoir, vector, and victim. In contrast, felids are effective vectors, but not reservoirs. All other rabid domestic species, such as livestock, constitute spillover infections, as a bellwether to local lyssavirus activity. Frequently, professional confusion abounds among the veterinary community, because although the viral species Lyssavirus rabies is inarguably the best-known representative in the Genus, at least 20 other recognized or putative members of this monophyletic group are known. Frequently, this is simply overlooked. Moreover, often the ‘taxonomic etiology’ (i.e., ‘Lyssavirus x’) is mistakenly referenced in a biopolitcal context, instead of the obvious clinical illness (i.e., ‘rabies’). Global consternation persists, if localities believe they are ‘disease-free’, when documented lyssaviruses circulate or laboratory-based surveillance is inadequate to support such claims. Understandably, professional chagrin develops when individuals mistake the epidemiological terminology of control, prevention, elimination, etc. Management is not simple, given that the only licensed veterinary and human vaccines are against rabies virus, sensu lato. There are no adequate antiviral drugs for any lyssaviruses or cross-reactive biologics developed against more distantly related viral members. While representative taxa among the mammalian Orders Chiroptera, Carnivora, and Primates exemplify the major global reservoirs, which mammalian species are responsible for the perpetuation of other lyssaviruses remains a seemingly academic curiosity. This zoonosis is neglected. Clearly, with such underlying characteristics as a fundamental ‘disease of nature’, rabies, unlike smallpox and rinderpest, is not a candidate for eradication. With the worldwide zeal to drive human fatalities from canine rabies viruses to zero by the rapidly approaching year 2030, enhanced surveillance and greater introspection of the poorly appreciated burden posed by rabies virus and diverse other lyssaviruses may manifest as an epidemiological luxury to the overall global program of the future. Full article
(This article belongs to the Special Issue Current Challenges in Veterinary Virology)
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16 pages, 1307 KiB  
Article
Synergistic Activity of Second Mitochondrial-Derived Activator of Caspases Mimetic with Toll-like Receptor 8 Agonist Reverses HIV-1-Latency and Enhances Antiviral Immunity
by Killian E. Vlaming, Jade Jansen, Godelieve J. de Bree, Neeltje A. Kootstra and Teunis B. H. Geijtenbeek
Int. J. Mol. Sci. 2025, 26(6), 2575; https://doi.org/10.3390/ijms26062575 - 13 Mar 2025
Cited by 1 | Viewed by 733
Abstract
HIV-1 infection is successfully treated by antiretroviral therapy; however, it is not curative as HIV-1 remains present in the viral reservoir. A strategy to eliminate the viral reservoir relies on the reactivation of the latent provirus to subsequently trigger immune-mediated clearance. Here, we [...] Read more.
HIV-1 infection is successfully treated by antiretroviral therapy; however, it is not curative as HIV-1 remains present in the viral reservoir. A strategy to eliminate the viral reservoir relies on the reactivation of the latent provirus to subsequently trigger immune-mediated clearance. Here, we investigated whether the activation of Toll-like receptor 8 (TLR8) or RIG-I-like receptor (RLR) together with the latency reversal agent (LRA) second mitochondrial-derived activator of caspases mimetics (SMACm) leads to HIV-1 reservoir reduction and antiviral immune activation. The TLR8 and RLR agonist elicited a robust pro-inflammatory cytokine response in PBMCs from both PWH and uninfected people. Notably, co-stimulation with SMACm specifically enhanced TLR8 induced pro-inflammatory cytokine as well as CD8 T cell responses. Ex vivo treatment of PBMCs from PWH with SMACm significantly decreased the size of the inducible HIV-1 reservoir, whereas targeting TLR8 or RLR reduced the HIV-1 reservoir in 50% of PWH ex vivo. Although co-stimulation with TLR8/RLR agonists further reduced the HIV-1 reservoir in 25% of PWH ex vivo, effectively inducing antiviral immunity may help eliminate reactivated HIV-1 cells in vivo. Our findings strongly suggest that LRAs can be used in combination with agonists for pattern recognition receptors to reactivate HIV-1 and induce antiviral immunity. Full article
(This article belongs to the Special Issue Viral Infections and Host Immune Responses)
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21 pages, 702 KiB  
Review
Latency Reversing Agents and the Road to an HIV Cure
by Louis Tioka, Rafael Ceña Diez, Anders Sönnerborg and Maarten A. A. van de Klundert
Pathogens 2025, 14(3), 232; https://doi.org/10.3390/pathogens14030232 - 27 Feb 2025
Viewed by 3340
Abstract
HIV-1 infection cannot be cured due to the presence of HIV-1 latently infected cells. These cells do not produce the virus, but they can resume virus production at any time in the absence of antiretroviral therapy. Therefore, people living with HIV (PLWH) need [...] Read more.
HIV-1 infection cannot be cured due to the presence of HIV-1 latently infected cells. These cells do not produce the virus, but they can resume virus production at any time in the absence of antiretroviral therapy. Therefore, people living with HIV (PLWH) need to take lifelong therapy. Strategies have been coined to eradicate the viral reservoir by reactivating HIV-1 latently infected cells and subsequently killing them. Various latency reversing agents (LRAs) that can reactivate HIV-1 in vitro and ex vivo have been identified. The most potent LRAs also strongly activate T cells and therefore cannot be applied in vivo. Many LRAs that reactivate HIV in the absence of general T cell activation have been identified and have been tested in clinical trials. Although some LRAs could reduce the reservoir size in clinical trials, so far, they have failed to eradicate the reservoir. More recently, immune modulators have been applied in PLWH, and the first results seem to indicate that these may reduce the reservoir and possibly improve immunological control after therapy interruption. Potentially, combinations of LRAs and immune modulators could reduce the reservoir size, and in the future, immunological control may enable PLWH to live without developing HIV-related disease in the absence of therapy. Full article
(This article belongs to the Section Viral Pathogens)
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19 pages, 2874 KiB  
Article
Youth Who Control HIV on Antiretroviral Therapy Display Unique Plasma Biomarkers and Cellular Transcriptome Profiles Including DNA Repair and RNA Processing
by Samiksha A. Borkar, Li Yin, Guglielmo M. Venturi, Jerry Shen, Kai-Fen Chang, Bernard M. Fischer, Upasana Nepal, Isaac D. Raplee, John W. Sleasman and Maureen M. Goodenow
Cells 2025, 14(4), 285; https://doi.org/10.3390/cells14040285 - 15 Feb 2025
Cited by 1 | Viewed by 942
Abstract
Combination antiretroviral therapy (ART) suppresses detectible HIV-1 replication, but latent reservoirs and persistent immune activation contribute to residual viral-associated morbidities and potential viral reactivation. youth with HIV (YWH) virally suppressed on ART early in infection before CD4 T cell decline with fewer comorbidities [...] Read more.
Combination antiretroviral therapy (ART) suppresses detectible HIV-1 replication, but latent reservoirs and persistent immune activation contribute to residual viral-associated morbidities and potential viral reactivation. youth with HIV (YWH) virally suppressed on ART early in infection before CD4 T cell decline with fewer comorbidities compared to adults represent a critical population for identifying markers associated with viral control and predictors of viral breakthrough. This study employed a multi-omics approach to evaluate plasma biomarkers and cellular gene expression profiles in 52 participants, including 27 YWH on ART for 144 weeks and 25 youth with no infection (NI) (ages 18–24). Among the 27 YWH, 19 were virally suppressed (VS; <50 RNA copies/mL), while eight were non-suppressed (VNS; >50 RNA copies/mL). VS YWH displayed unique bioprofiles distinct from either VNS or NI. Early viral suppression mitigates inflammatory pathways and normalizes key biomarkers associated with HIV-related comorbidities. Genes upregulated in pathways linked to cellular homeostasis such as DNA repair, RNA processing, and transcription regulation may diminish viral breakthrough and maintain sustained HIV control on ART. Candidate markers and putative molecular mechanisms were identified, offering potential therapeutic targets to limit viral persistence, enhance HIV treatment strategies, and pave the way for improved clinical outcomes. Full article
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14 pages, 2356 KiB  
Review
HBV cccDNA: The Molecular Reservoir of Hepatitis B Persistence and Challenges to Achieve Viral Eradication
by André Boonstra and Gulce Sari
Biomolecules 2025, 15(1), 62; https://doi.org/10.3390/biom15010062 - 4 Jan 2025
Cited by 2 | Viewed by 4234
Abstract
Hepatitis B virus (HBV) is a major global health issue, with an estimated 254 million people living with chronic HBV infection worldwide as of 2022. Chronic HBV infection is the leading cause of cirrhosis and liver cancer. Current treatment with nucleos(t)ide analogs is [...] Read more.
Hepatitis B virus (HBV) is a major global health issue, with an estimated 254 million people living with chronic HBV infection worldwide as of 2022. Chronic HBV infection is the leading cause of cirrhosis and liver cancer. Current treatment with nucleos(t)ide analogs is effective in the suppression of viral activity but generally requires lifelong treatment. They fail to eradicate the HBV viral reservoir, called covalently closed circular DNA (cccDNA), which replicates in the nucleus of liver cells. The cccDNA serves as the sole template for viral replication, as it generates the pregenomic RNA (pgRNA) necessary for producing new viral genomes. This stable form of viral DNA can reactivate the virus when treatment is stopped. HBV cccDNA is therefore one of the main challenges in curing chronic HBV infections. By targeting steps such as cccDNA formation, capsid assembly, or particle secretion, researchers continue to seek ways to interfere with HBV replication and to reduce its persistence, ultimately to eradicate HBV as a global health problem. This review provides an overview of what is currently known about cccDNA formation and biogenesis and the ongoing efforts to target and eradicate it to cure chronic HBV infections. Full article
(This article belongs to the Special Issue Molecular Mechanisms Underlying Liver Diseases)
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23 pages, 1732 KiB  
Review
The Proviral Reservoirs of Human Immunodeficiency Virus (HIV) Infection
by Andrey I. Murzin, Kirill A. Elfimov and Natalia M. Gashnikova
Pathogens 2025, 14(1), 15; https://doi.org/10.3390/pathogens14010015 - 30 Dec 2024
Viewed by 2128
Abstract
Human Immunodeficiency Virus (HIV) proviral reservoirs are cells that harbor integrated HIV proviral DNA within their nuclear genomes. These cells form a heterogeneous group, represented by peripheral blood mononuclear cells (PBMCs), tissue-resident lymphoid and monocytic cells, and glial cells of the central nervous [...] Read more.
Human Immunodeficiency Virus (HIV) proviral reservoirs are cells that harbor integrated HIV proviral DNA within their nuclear genomes. These cells form a heterogeneous group, represented by peripheral blood mononuclear cells (PBMCs), tissue-resident lymphoid and monocytic cells, and glial cells of the central nervous system. The importance of studying the properties of proviral reservoirs is connected with the inaccessibility of integrated HIV proviral DNA for modern anti-retroviral therapies (ARTs) that block virus reproduction. If treatment is not effective enough or is interrupted, the proviral reservoir can reactivate. Early initiation of ART improves the prognosis of the course of HIV infection, which is explained by the reduction in the proviral reservoir pool observed in the early stages of the disease. Different HIV subtypes present differences in the number of latent reservoirs, as determined by structural and functional differences. Unique signatures of patients with HIV, such as elite controllers, have control over viral replication and can be said to have achieved a functional cure for HIV infection. Uncovering the causes of this phenomenon will bring humanity closer to curing HIV infection, potential approaches to which include stem cell transplantation, clustered regularly interspaced short palindromic repeats (CRISPR)/cas9, “Shock and kill”, “Block and lock”, and the application of broad-spectrum neutralizing antibodies (bNAbs). Full article
(This article belongs to the Special Issue Retroviruses: Molecular Biology, Immunology and Pathogenesis)
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20 pages, 14462 KiB  
Article
Peripheral B Lymphocyte Serves as a Reservoir for the Persistently Covert Infection of Mandarin Fish Siniperca chuatsi Ranavirus
by Wenfeng Zhang, Hui Gong, Qianqian Sun, Yuting Fu, Xiaosi Wu, Hengwei Deng, Shaoping Weng, Jianguo He and Chuanfu Dong
Viruses 2024, 16(12), 1895; https://doi.org/10.3390/v16121895 - 9 Dec 2024
Cited by 2 | Viewed by 1275
Abstract
Mandarin fish ranavirus (MRV) is a distinctive member among the genus Ranavirus of the family Iridoviridae. The persistently covert infection of MRV was previously observed in a natural outbreak of MRV, but the underlying mechanism remains unclear. Here, we show that mandarin [...] Read more.
Mandarin fish ranavirus (MRV) is a distinctive member among the genus Ranavirus of the family Iridoviridae. The persistently covert infection of MRV was previously observed in a natural outbreak of MRV, but the underlying mechanism remains unclear. Here, we show that mandarin fish peripheral B lymphocytes are implemented as viral reservoirs to maintain the persistent infection. When mandarin fish were infected with a sublethal dosage of MRV under a nonpermissive temperature (19 °C) and a permissive temperature (26 °C), all of the fish in the 19 °C group survived and entered the persistent phase of infection, characterized by a very low viral load in white blood cells, whereas some of the fish died of MRV infection in the 26 °C group, and the survival fish then initiated a persistent infection status. Raising the temperature, vaccination and dexamethasone treatment can reactivate the quiescent MRV to replicate and result in partial mortality. The viral reservoir investigation showed that IgM+-labeled B lymphocytes, but not CD3Δ+-labeled T lymphocytes and MRC-1+-labeled macrophages, are target cells for the persistent infection of MRV. Moreover, the reactivation of the quiescent MRV was confirmed through a non-TLR5 signal pathway manner. Collectively, we demonstrate the presence of the B cell-dependent persistent infection of ranavirus, and provide a new clue for better understanding the complex infection mechanism of vertebrate iridovirus. Full article
(This article belongs to the Section Animal Viruses)
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13 pages, 3030 KiB  
Article
Gastrointestinal Shedding of Rubulaviruses from Egyptian Rousette Bats: Temporal Dynamics and Spillover Implications
by Tauya S. Muvengi, Marinda Mortlock, Morgan P. Kain and Wanda Markotter
Microorganisms 2024, 12(12), 2505; https://doi.org/10.3390/microorganisms12122505 - 4 Dec 2024
Viewed by 1147
Abstract
Bats are recognized as reservoirs for diverse paramyxoviruses, some of which are closely related to known human pathogens or directly implicated in zoonotic transmission. The emergence of the zoonotic Sosuga virus (SOSV) from Egyptian rousette bats (ERBs), which caused an acute febrile illness [...] Read more.
Bats are recognized as reservoirs for diverse paramyxoviruses, some of which are closely related to known human pathogens or directly implicated in zoonotic transmission. The emergence of the zoonotic Sosuga virus (SOSV) from Egyptian rousette bats (ERBs), which caused an acute febrile illness in a reported human case in Africa, has increased the focus on the zoonotic potential of the Rubulavirinae subfamily. Previous studies identified human parainfluenza virus 2 (HPIV2)- and mumps (MuV)-related viruses in ERBs from South Africa, with HPIV2-related viruses restricted to gastrointestinal samples, an underexplored target for rubulavirus biosurveillance, suggesting that sample-type bias may have led to their oversight. To address this, we performed a longitudinal analysis of population-level fecal samples from an ERB maternity roost for rubulavirus RNA, employing a broadly reactive hemi-nested RT-PCR assay targeting the polymerase gene. We detected HPIV2- and MuV-related viruses in addition to numerous pararubulaviruses, highlighting significant viral diversity. Temporal analysis of three major clades revealed peaks in rubulavirus shedding that correlated with seasonal environmental changes and host reproductive cycles, although shedding patterns varied between clades. These findings identify specific periods of increased risk for the spillover of bat-associated rubulaviruses to humans, providing critical information for developing targeted mitigation strategies to minimize zoonotic transmission risk within the local community. Full article
(This article belongs to the Section Virology)
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21 pages, 3291 KiB  
Article
NSC95397 Is a Novel HIV-1 Latency-Reversing Agent
by Randilea Nichols Doyle, Vivian Yang, Yetunde I. Kayode, Robert Damoiseaux, Harry E. Taylor and Oliver I. Fregoso
Viruses 2024, 16(11), 1783; https://doi.org/10.3390/v16111783 - 16 Nov 2024
Viewed by 1745
Abstract
The latent viral reservoir represents one of the major barriers to curing HIV-1. Focus on the “kick and kill” (also called “shock and kill”) approach, in which virus expression is reactivated, and then cells producing virus are selectively depleted, has led to the [...] Read more.
The latent viral reservoir represents one of the major barriers to curing HIV-1. Focus on the “kick and kill” (also called “shock and kill”) approach, in which virus expression is reactivated, and then cells producing virus are selectively depleted, has led to the discovery of many latency-reversing agents (LRAs) that have furthered our understanding of the mechanisms driving HIV-1 latency and latency reversal. Thus far, individual compounds have yet to be robust enough to work as a therapy, highlighting the importance of identifying new compounds that target novel pathways and synergize with known LRAs. In this study, we identified a promising LRA, NSC95397, from a screen of ~4250 compounds. We validated that NSC95397 reactivates latent viral transcription and protein expression from cells with unique integration events and across different latency models. Co-treating cells with NSC95397 and known LRAs demonstrated that NSC95397 synergizes with different drugs under both standard normoxic and physiological hypoxic conditions. NSC95397 does not globally increase open chromatin, and bulk RNA sequencing revealed that NSC95397 does not greatly increase cellular transcription. Instead, NSC95397 downregulates pathways key to metabolism, cell growth, and DNA repair—highlighting the potential of these pathways in regulating HIV-1 latency. Overall, we identified NSC95397 as a novel LRA that does not largely alter global transcription, shows potential for synergy with known LRAs, and may act through novel pathways not previously recognized for their ability to modulate HIV-1 latency. Full article
(This article belongs to the Special Issue Unraveling the Pathogenesis of Persistent Virus Infection)
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10 pages, 1651 KiB  
Article
Virus-Specific Nanobody-Chimeras Degrade the Human Cytomegalovirus US28 Protein in CD34+ Cells
by Emma Poole, Janika Schmitt, Stephen C. Graham, Bernard T. Kelly and John Sinclair
Pathogens 2024, 13(10), 821; https://doi.org/10.3390/pathogens13100821 - 24 Sep 2024
Cited by 1 | Viewed by 1679
Abstract
After primary infection, human cytomegalovirus (HCMV) establishes lifelong persistence, underpinned by latent carriage of the virus with spontaneous reactivation events. In the immune-competent, primary infection or reactivation from latency rarely causes disease. However, HCMV can cause significant disease in immune-compromised individuals such as [...] Read more.
After primary infection, human cytomegalovirus (HCMV) establishes lifelong persistence, underpinned by latent carriage of the virus with spontaneous reactivation events. In the immune-competent, primary infection or reactivation from latency rarely causes disease. However, HCMV can cause significant disease in immune-compromised individuals such as immune-suppressed transplant patients. Latency, where the viral genome is carried in the absence of the production of infectious virions, can be established in undifferentiated cells of the myeloid lineage. A number of stimuli can cause virus reactivation from latency to occur, beginning with the induction of viral immediate-early (IE) lytic gene expression. The suppression of viral IE gene expression to establish and maintain latent infection is known to result from a balance of viral and cellular factors. One key viral factor involved in this is the G protein-coupled receptor US28. Recently, we have shown that US28 is targeted for degradation by a modified nanobody (PCTD-Vun100bv) based on the novel PACTAC (PCSK9-antibody clearance-targeting chimeras) approach for targeted protein degradation. Furthermore, we have shown that this PCTD-Vun100bv-induced degradation of US28 results in IE gene expression in experimentally latently infected CD14+ monocytes. However, HCMV also establishes latency in CD34+ bone marrow cells, the progenitors of CD14+ cells. Here, we show that PCTD-Vun100bv also causes US28 degradation in these CD34+ primary cells, again resulting in the induction of viral IE gene expression. Additionally, we show that PCTD-Vun100bv can target US28 in naturally latently infected CD14+ monocytes from an HCMV-seropositive donor, allowing these latently infected cells to be killed by HCMV-specific cytotoxic T cells from that same donor. These observations support the view that targeting US28 for degradation during natural latency could be a tractable ‘shock-and-kill’ strategy to target the latent HCMV reservoir in myeloid cells. Full article
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16 pages, 2172 KiB  
Article
Adeno-Associated Virus (AAV)-Delivered Exosomal TAT and BiTE Molecule CD4-αCD3 Facilitate the Elimination of CD4 T Cells Harboring Latent HIV-1
by Xiaoli Tang, Huafei Lu, Patrick M. Tarwater, David L. Silverberg, Christoph Schorl and Bharat Ramratnam
Microorganisms 2024, 12(8), 1707; https://doi.org/10.3390/microorganisms12081707 - 18 Aug 2024
Cited by 2 | Viewed by 2951
Abstract
Combinatorial antiretroviral therapy (cART) has transformed HIV infection from a death sentence to a controllable chronic disease, but cannot eliminate the virus. Latent HIV-1 reservoirs are the major obstacles to cure HIV-1 infection. Previously, we engineered exosomal Tat (Exo-Tat) to reactivate latent HIV-1 [...] Read more.
Combinatorial antiretroviral therapy (cART) has transformed HIV infection from a death sentence to a controllable chronic disease, but cannot eliminate the virus. Latent HIV-1 reservoirs are the major obstacles to cure HIV-1 infection. Previously, we engineered exosomal Tat (Exo-Tat) to reactivate latent HIV-1 from the reservoir of resting CD4+ T cells. Here, we present an HIV-1 eradication platform, which uses our previously described Exo-Tat to activate latent virus from resting CD4+ T cells guided by the specific binding domain of CD4 in interleukin 16 (IL16), attached to the N-terminus of exosome surface protein lysosome-associated membrane protein 2 variant B (Lamp2B). Cells with HIV-1 surface protein gp120 expressed on the cell membranes are then targeted for immune cytolysis by a BiTE molecule CD4-αCD3, which colocalizes the gp120 surface protein of HIV-1 and the CD3 of cytotoxic T lymphocytes. Using primary blood cells obtained from antiretroviral treated individuals, we find that this combined approach led to a significant reduction in replication-competent HIV-1 in infected CD4+ T cells in a clonal in vitro cell system. Furthermore, adeno-associated virus serotype DJ (AAV-DJ) was used to deliver Exo-Tat, IL16lamp2b and CD4-αCD3 genes by constructing them in one AAV-DJ vector (the plasmid was named pEliminator). The coculture of T cells from HIV-1 patients with Huh-7 cells infected with AAV-Eliminator viruses led to the clearance of HIV-1 reservoir cells in the in vitro experiment, which could have implications for reducing the viral reservoir in vivo, indicating that Eliminator AAV viruses have the potential to be developed into therapeutic biologics to cure HIV-1 infection. Full article
(This article belongs to the Special Issue Viral Diseases: Current Research and Future Directions)
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