Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “viral pathogenesis”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2001

Bunyamwera bunyavirus nonstructural protein NSs is a nonessential gene product that contributes to viral pathogenesis.

Bunyamwera virus (family Bunyaviridae, genus Bunyavirus) contains a tripartite negative-sense RNA genome. The smallest RNA segment, S, encodes the nucleocapsid protein N and a nonstructural protein, NSs, in overlapping reading frames. We have generated a mutant virus lacking NSs, called BUNdelNSs, by reverse genetics. Compared with the wild-type (wt) virus, BUNdelNSs exhibited a smaller plaque size and generated titers of virus approximately 1 log lower. In mammalian cells, the mutant expressed greatly increased levels of N protein; significantly, the marked inhibition of host cell protein synthesis shown by wt virus was considerably impaired by BUNdelNSs. When inoculated by the intracerebral route BUNdelNSs killed BALB/c mice with a slower time course than wt and exhibited a reduced cell-to-cell spread, and titers of virus in the brain were lower. In addition, the abrogation of NSs expression changed Bunyamwera virus from a noninducer to an inducer of an interferon-beta promoter. These results suggest that, although not essential for growth in tissue culture or in mice, the bunyavirus NSs protein has several functions in the virus life cycle and contributes to viral pathogenesis.

Aedes↗
PubMed2026

Rab9 depletion enhances human adenovirus type 26 transduction efficiency through increased internalization and reduced late endosomal/lysosomal retention.

Understanding intracellular trafficking is central to decoding viral pathogenesis and engineering optimized viral vectors. How a virus or vector is routed through the endocytic pathway directly dictates its genome release, immune sensing, and overall transduction efficiency. Human adenovirus type 26 (HAdV-D26) presents a promising platform for vector design due to its low preexisting immunity, potent immune stimulation, scalable production, and versatile genetic engineering capacity. Although increasingly significant, the fundamental mechanisms governing HAdV-D26 intracellular trafficking are still not fully understood. Our study demonstrates that compared to well-described human adenovirus type 5 (HAdV-C5), HAdV-D26 undergoes prolonged intracellular trafficking, transiently localizing to early endosomes before residing in late endosomes/lysosomes for up to four hours post-infection. Inhibition of lysosomal acidification modestly enhances HAdV-D26 transduction efficiency, whereas blocking transport from early to late endosomes/lysosomes does not. Strikingly, Rab9 knockdown reduces HAdV-D26 late endosomal/lysosomal localization while increasing both virus internalization and genome delivery to the host cell nucleus. These findings indicate that late endosomal sorting pathways actively influence HAdV-D26 infection outcomes. By identifying a previously unappreciated role for Rab9 in adenovirus transduction, our results provide new mechanistic insight into HAdV-D26 intracellular trafficking, highlight serotype-specific differences in adenovirus entry pathways, and identify endosomal trafficking steps that may be targeted to improve adenoviral vector performance.

Humans↗
PubMed2026

Application of emerging technologies in the antiviral field.

Viral diseases pose a serious threat to global public health, agriculture, and biosecurity. Conventional antiviral strategies are often limited by an incomplete understanding of disease mechanisms, poor targeting precision, and slow response times. Emerging technologies are now reshaping the landscape of antiviral research. This review examines the roles of four key frontiers, including organoid models, gene editing, AI-driven molecular design, and synthetic biology. Organoids provide physiologically relevant platforms that model virus-host interactions and disease progression. Viral infections remain a major challenge to human and animal health, agriculture, and biosecurity. Progress in antiviral research is constrained by the complexity of viral pathogenesis, the diversity and rapid evolution of viruses, and the limited translational relevance of some traditional model systems. Recent advances in organoid technology, gene editing, artificial intelligence, and synthetic biology are expanding the toolkit available for antiviral research and development. In this review, we discuss how these four technological frontiers contribute to disease modeling, target discovery, molecular design, and translational innovation. Organoids, in particular, provide physiologically relevant systems for investigating viral infection, tissue tropism, host responses, and pathogenesis. Gene editing tools, such as CRISPR, enable precise manipulation of host and viral genomes, facilitating the development of resistant organisms and next-generation vaccine platforms. AI technologies, including AlphaFold for structure prediction and platforms for de novo protein design, address long-standing bottlenecks in structural biology and offer powerful means to engineer antiviral proteins, antibodies, and vaccine antigens. Synthetic biology, guided by the Design-Build-Test-Learn cycle, integrates computational design, genetic assembly, and functional validation into a cohesive pipeline. Together, these technologies form a synergistic workflow that spans disease modeling, target discovery, molecular design, construction, testing, and iterative optimization. This integrated approach is shifting antiviral development from traditional empirical methods toward more precise, intelligent strategies. The review also highlights ongoing challenges in integration and scalability, stressing that high-quality biological datasets and stronger interdisciplinary collaboration are essential for realizing translational potential. By presenting a cohesive view of these converging methodologies, this review offers a framework to guide the intelligent evolution of antiviral strategies in both human and animal health.

Antiviral↗
PubMed2026

Structural biology of the dengue virus NS2B-NS3 protease as a target for antiviral drug development.

Dengue is the most common global problem in recent times, particularly in tropical and subtropical areas, yet antivirals for therapy or prophylaxis are lacking. Millions of people are affected by this dengue virus, but no proper medication is available yet to cure this disease. One polyprotein that is encoded by the DENV genome is converted into structural and non-structural proteins that are necessary for viral pathogenesis and replication. Among these, the non-structural protein complex NS2B-NS3 is essential for viral polyprotein processing, replication, and host innate immune response control. It acts as a trypsin-like serine protease. The NS2B/NS3 protease is a key enzyme involved in viral replication and serves as a major target for drug development against the dengue virus. The NS3 protease has a conserved catalytic triad (His-Asp-Ser), whereas NS2B serves as an essential cofactor that stabilizes the active conformation of the enzyme and aids in substrate recognition. By disrupting interferon signalling pathways, the NS2B-NS3 protease not only aids in viral replication but also makes immune evasion easier. The compound that inhibits the action of this enzyme could be pioneering in the antiviral drug discovery process. This article provides a comprehensive overview of the detailed structural information of the viral protease (NS2B/NS3) enzyme with the mechanistic role of this enzyme, and highlights various inhibitors related to the NS2B/NS3 protease. A more thorough comprehension of this protease could facilitate the logical development of potent antiviral medications to prevent dengue infection.

Dengue↗
PubMed2026

Influence of Major Histocompatibility Complex (MHC) Diversity on Immune Modulation, Pathogenesis, and Control of Lumpy Skin Disease Virus.

INTRODUCTION: Lumpy Skin Disease Virus (LSDV), a member of the genus Capripoxvirus within the family Poxviridae, is an economically important transboundary viral pathogen affecting cattle and water buffalo. The disease causes severe production losses through decreased milk yield, infertility, hide damage, reduced growth performance, and occasional mortality. The rapid geographic spread of LSDV, together with its vectorborne transmission and emerging recombinant strains, has intensified the need for improved understanding of viral pathogenesis, host immune responses, and effective prevention strategies. In particular, the role of the bovine Major Histocompatibility Complex (BoLA/MHC) in regulating antiviral immunity, disease susceptibility, and vaccine responsiveness has gained increasing scientific attention. METHODS: This review summarises the published literature related to the epidemiology, transmission, structure, pathogenesis, diagnosis, prevention, and control of LSDV, with special emphasis on the immunological and molecular role of bovine MHC molecules. Relevant studies concerning BoLA-mediated antigen presentation, immunoinformaticsbased epitope prediction, vaccine development, antiviral drug repurposing, molecular docking, genomic surveillance, and diagnostic approaches, including PCR- and ELISAbased assays, were critically evaluated. Recent advances in computational biology, molecular virology, and host-pathogen interaction studies were also reviewed. RESULTS: The reviewed studies demonstrate that Lumpy Skin Disease Virus (LSDV) possesses a complex double-stranded DNA genome enabling immune modulation and efficient transmission through arthropod vectors such as mosquitoes, ticks, and biting flies. Disease progression involves systemic viral replication, vascular injury, dermal necrosis, and inflammatory skin lesions. Real-time PCR remains the most sensitive diagnostic method for early detection, while ELISA supports surveillance. Evidence highlights the central role of bovine Major Histocompatibility Complex (BoLA) molecules in antigen presentation and T-cell activation. Computational studies identified promising BoLA-binding epitopes and repurposed antiviral candidates, including ivermectin, theaflavin, canagliflozin, and tepotinib, for future therapeutic development. DISCUSSION: Current evidence indicates that effective LSDV control requires integration of molecular diagnostics, vector management, vaccination, and host immunogenetics. BoLAguided immunoinformatics provides promising opportunities for developing multi-epitope vaccines, although experimental validation remains essential. Similarly, repurposed antiviral candidates require comprehensive in vivo and pharmacological evaluation before clinical application. Future research should focus on elucidating viral immune-evasion mechanisms, validating predicted epitopes, and translating computational findings into practical vaccines and therapeutics for sustainable disease control. CONCLUSION: Lumpy Skin Disease continues to pose a major threat to global cattle health and livestock economies. Advances in molecular diagnostics, genomic surveillance, antiviral drug discovery, and BoLA-guided vaccine design provide promising opportunities for improved disease control. Understanding the interaction between LSDV and the bovine MHC system is essential for developing next-generation vaccines, immunotherapeutics, and precision disease-management strategies. Future research should prioritise experimental validation of predicted epitopes, large-scale vaccine trials, and mechanistic studies on host-virus immune interactions to establish effective and sustainable global control programs for LSDV.

BoLA↗
PubMed2026

AP2: an indispensable host factor in virus infection.

Adaptor protein complex 2 (AP2), a central regulator of clathrin-mediated endocytosis and intracellular cargo trafficking, is hijacked by numerous viruses to complete their infectious cycles. This review systematically synthesizes the multifaceted roles of AP2 across the entire viral life cycle, from entry and replication to assembly and release, as well as in immune evasion. By delineating how diverse viruses exploit this key host machinery, we further consolidate the rationale and current progress in developing broad-spectrum antiviral strategies that target AP2 and its regulatory pathways. This work aims to provide a unified perspective on AP2 as a critical host-pathogen interface, offering new insights into viral pathogenesis and antiviral drug discovery.

Humans↗
PubMed2025

Global siRNA screen identifies human host factors critical for SARS-CoV-2 replication and late stages of infection.

Defining the subset of cellular factors governing SARS-CoV-2 replication can provide critical insights into viral pathogenesis and identify targets for host-directed antiviral therapies. While a number of genetic screens have previously reported SARS-CoV-2 host dependency factors, most of these approaches relied on utilizing pooled genome-scale CRISPR libraries, which are biased toward the discovery of host proteins impacting early stages of viral replication. To identify host factors involved throughout the SARS-CoV-2 infectious cycle, we conducted an arrayed genome-scale siRNA screen. Resulting data were integrated with published functional screens and proteomics data to reveal (i) common pathways that were identified in all OMICs datasets-including regulation of Wnt signaling and gap junctions, (ii) pathways uniquely identified in this screen-including NADH oxidation, or (iii) pathways supported by this screen and proteomics data but not published functional screens-including arachionate production and MAPK signaling. The identified proviral host factors were mapped into the SARS-CoV-2 infectious cycle, including 32 proteins that were determined to impact viral replication and 27 impacting late stages of infection, respectively. Additionally, a subset of proteins was tested across other coronaviruses revealing a subset of proviral factors that were conserved across pandemic SARS-CoV-2, epidemic SARS-CoV-1 and MERS-CoV, and the seasonal coronavirus OC43-CoV. Further studies illuminated a role for the heparan sulfate proteoglycan perlecan in SARS-CoV-2 viral entry and found that inhibition of the non-canonical NF-kB pathway through targeting of BIRC2 restricts SARS-CoV-2 replication both in vitro and in vivo. These studies provide critical insight into the landscape of virus-host interactions driving SARS-CoV-2 replication as well as valuable targets for host-directed antivirals.

Humans↗
PubMed2002

Bunyamwera bunyavirus nonstructural protein NSs counteracts the induction of alpha/beta interferon.

Production of alpha/beta interferons (IFN-alpha/beta) in response to viral infection is one of the main defense mechanisms of the innate immune system. Many viruses therefore encode factors that subvert the IFN system to enhance their virulence. Bunyamwera virus (BUN) is the prototype of the Bunyaviridae family. By using reverse genetics, we previously produced a recombinant virus lacking the nonstructural protein NSs (BUNdelNSs) and showed that NSs is a nonessential gene product that contributes to viral pathogenesis. Here we demonstrate that BUNdelNSs is a strong inducer of IFN-alpha/beta, whereas in cells infected with the wild-type counterpart expressing NSs (wild-type BUN), neither IFN nor IFN mRNA could be detected. IFN induction by BUNdelNSs correlated with activation of NF-kappaB and was dependent on virally produced double-stranded RNA and on the IFN transcription factor IRF-3. Furthermore, both in cultured cells and in mice lacking a functional IFN-alpha/beta system, BUNdelNSs replicated to wild-type BUN levels, whereas in IFN-competent systems, wild-type BUN grew more efficiently. These results suggest that BUN NSs is an IFN induction antagonist that blocks the transcriptional activation of IFN-alpha/beta in order to increase the virulence of Bunyamwera virus.

Animals↗
PubMed2026

Dynamic metabolic modelling of ATP allocation during viral infection.

Viral pathogens, like SARS-CoV-2, hijack the host's macromolecular production machinery, imposing an energetic burden that is distributed across cellular metabolism. To explore the dynamic metabolic tension between the host's survival and viral replication, we developed a computational framework that uses genome-scale models to perform dynamic flux balance analysis of human cell metabolism during virus infections. Relative to previous models, our framework addresses the physiology of viral infections of non-proliferating host cells through two new features. First, by incorporating the lipid content of SARS-CoV-2 biomass, we discovered activation of previously overlooked pathways giving rise to new predictions of possible drug targets. Furthermore, we introduce a dynamic model that simulates the partitioning of resources between the virus and the host cell, capturing the extent to which the competition depletes the human cells from essential ATP. By incorporating viral dynamics into our COMETS framework for spatio-temporal modelling of metabolism, we provide a mechanistic, dynamic and generalizable starting point for bridging systems biology modelling with viral pathogenesis. This framework could be extended to broadly incorporate phage dynamics in microbial systems and ecosystems.

Humans↗
PubMed2025

UHRF1 restricts HCoV-229E infection through epigenetic silencing of the viral receptor APN.

The emergence of SARS-CoV-2 has posed significant threats to global health, particularly for the older population. Similarly, common human coronaviruses, such as HCoV-229E, which typically cause mild cold-like symptoms, can lead to severe diseases, underscoring the need to understand virus-host interactions and identify host factors contributing to viral pathogenesis and disease progression. In this study, we perform a genome-wide CRISPR knockout screen using HCoV-229E and identify UHRF1 as a potent restriction factor. Mechanistically, UHRF1 suppresses HCoV-229E infection by downregulating the expression of its cell entry receptor, APN, through promoter hypermethylation. Focused CRISPR activation screens of UHRF1-downregulated genes confirm the critical role of APN in HCoV-229E infection and identify additional genes (e.g., SIGLEC1, PLAC8, and heparan sulfate biosynthesis genes) contributing to the restrictive functions of UHRF1. Transcriptomic and single-cell RNA sequencing analysis reveal that UHRF1 expression decreases with age, negatively correlating with increased APN expression. This age-related decline in UHRF1 is validated in primary alveolar macrophages from elderly individuals, which exhibit heightened susceptibility to HCoV-229E compared to those from younger individuals. Our findings highlight UHRF1 as a key age-related host defense factor against coronavirus and provide insights into the epigenetic regulation of viral entry receptors.

Animals↗
PubMed2026

Genome-wide CRISPR screen identifies RNF24 as a critical host factor for foot-and-mouth disease virus entry.

BACKGROUND: Foot-and-mouth disease virus (FMDV) causes substantial economic losses in global livestock production; however, the key host factors supporting its early infection process remain poorly characterized. METHODS: In this study, we performed an unbiased genome-wide CRISPR/Cas9 knockout screening using porcine cells to screen and identify host factors involved in FMDV infection. RESULTS: We identified that the E3 ubiquitin ligase RNF24 supports efficient FMDV entry. RNF24 depletion inhibits viral entry and replication, whereas its overexpression enhances viral infectivity. Mechanistically, RNF24 preferentially promotes K27-linked non-degradative polyubiquitination of leupaxin (LPXN) at lysine 162, driving LPXN's trafficking to the plasma membrane. At the membrane, LPXN assembles a ternary integrin-LPXN-VP1 complex that strengthens virus-receptor interactions and promotes viral adsorption and entry. Disruption of this ubiquitination event via the LPXN K162R mutation impairs complex formation and compromises viral entry. CONCLUSION: Together, our study reveals a ubiquitin-dependent RNF24-LPXN regulatory axis that supports FMDV entry, highlights the role of non-degradative ubiquitination in viral pathogenesis, and proposes this interface as a potential target for antiviral intervention.

CRISPR screening↗
PubMed2025

Dysregulation of lung epithelial cell homeostasis and immunity contributes to Middle East respiratory syndrome coronavirus disease severity.

Coronaviruses (CoV) emerge suddenly from animal reservoirs to cause novel diseases in new hosts. Discovered in 2012, the Middle East respiratory syndrome coronavirus (MERS-CoV) is endemic in camels in the Middle East and is continually causing local outbreaks and epidemics. While all three newly emerging human CoVs from the past 20 years (SARS-CoV, SARS-CoV-2, and MERS-CoV) cause respiratory disease, each CoV has unique host interactions that drive differential pathogeneses. To better understand the virus and host interactions driving lethal MERS-CoV infection, we performed a longitudinal multi-omics analysis of sublethal and lethal MERS-CoV infection in mice. Significant differences were observed in body weight loss, virus titers, and acute lung injury among lethal and sub-lethal virus doses. Virus-induced apoptosis of type I and II alveolar epithelial cells suggests that loss or dysregulation of these key cell populations was a major driver of severe disease. Omics analysis suggested differential pathogenesis was multi-factorial with clear differences among innate and adaptive immune pathways as well as those that regulate lung epithelial homeostasis. Infection of mice lacking functional T and B cells showed that adaptive immunity was important in controlling viral replication but also increased pathogenesis. In summary, we provide a high-resolution host response atlas for MERS-CoV infection and disease severity. Multi-omics studies of viral pathogenesis offer a unique opportunity to not only better understand the molecular mechanisms of disease but also to identify genes and pathways that can be exploited for therapeutic intervention all of which is important for our future pandemic preparedness.IMPORTANCEEmerging coronaviruses like SARS-CoV, SARS-CoV-2, and MERS-CoV cause a range of disease outcomes in humans from an asymptomatic, moderate, and severe respiratory disease that can progress to death but the factors causing these disparate outcomes remain unclear. Understanding host responses to mild and life-threatening infections provides insight into virus-host networks within and across organ systems that contribute to disease outcomes. We used multi-omics approaches to comprehensively define the host response to moderate and severe MERS-CoV infection. Severe respiratory disease was associated with dysregulation of the immune response. Key lung epithelial cell populations that are essential for lung function get infected and die. Mice lacking key immune cell populations experienced greater virus replication but decreased disease severity implicating the immune system in both protective and pathogenic roles in response to MERS-CoV. These data could be utilized to design new therapeutic strategies targeting specific pathways that contribute to severe disease.

Animals↗
PubMed2025

Construction and Segmental Reconstitution of Full-Length Infectious Clones of Milk Vetch Dwarf Virus.

The construction of infectious clones (ICs) is essential for studying viral replication, pathogenesis, and host interactions. Milk vetch dwarf virus (MDV), a nanovirus with a multipartite, single-stranded DNA genome, presents unique challenges for IC development due to its segmented genome organization. To enable functional analysis of its genome, we constructed full-length tandem-dimer-based ICs for all eight MDV genomic segments. Each segment was cloned into a binary vector and co-delivered into Nicotiana benthamiana, Nicotiana tabacum, Vicia faba, and Vigna unguiculata plants via Agrobacterium-mediated inoculation. Systemic infection was successfully reconstituted in all host plants, with PCR-based detection confirming the presence of all viral segments in the infected leaves of nearly all tested plants. Segmental accumulation in infected plants was quantified using qPCR, revealing non-equimolar distribution across hosts. This study establishes the first complete IC system for MDV, enabling reproducible infection, replication analysis, and quantitative segment profiling. It provides a foundational tool for future molecular investigations into MDV replication, host interactions, and viral movement, advancing our understanding of nanovirus biology and transmission dynamics.

Nicotiana↗
PubMed2026

Genomic Characterization of Influenza B Victoria Lineage Viruses Circulating in Saudi Arabia During the 2024-2025 Season.

Influenza B viruses contribute substantially to global morbidity and mortality, yet genomic data from the Middle East remain limited. We retrospectively performed whole-genome sequencing of six influenza B virus-positive residual nasopharyngeal specimens collected at King Abdulaziz Medical City, Riyadh, during the 2024-2025 season, including one fatal pediatric case, and described their genomic features alongside clinical outcomes. All six genomes belonged to the B/Victoria lineage and clustered within V1A.3a.2-derived subclades circulating globally during 2024-2025. Five genomes, including the fatal pediatric case, were assigned to subclade C.5.6, whereas one non-fatal case belonged to C.5.7. The Saudi sequences were interspersed among contemporaneous reference strains from Europe, Asia, and North America, without evidence of a distinct local lineage. The fatal isolate did not occupy a distinct phylogenetic position and contained none of the screened virulence-associated markers, including the neuraminidase N342K substitution. These genomes provide regional surveillance data from an underrepresented setting. Given the small sample size and inclusion of a single fatal case, the findings are descriptive and do not permit inference regarding genomic determinants of disease severity. Larger studies integrating viral genomic, clinical, and host data are needed.

Humans↗
PubMed2026

Emerging tick-borne viral diseases in East Asia: pathology-driven insights into pathogenesis and disease causality.

SUMMARYTick-borne viral infections have emerged as a significant and growing public health concern. In East Asia, severe fever with thrombocytopenia syndrome (SFTS) has served as a prototypical disease in which pathological analyses have substantially advanced the understanding of disease pathogenesis. SFTS is characterized by profound immune dysregulation driven by viral tropism for plasmablast-lineage B cells, leading to cytokine storm and hemophagocytic syndrome. Complementary analyses of human clinical specimens and experimental animal models, including cats and ferrets, have provided critical insights into the immunopathogenesis of SFTS. The recent identification of additional tick-borne viruses, including Oz virus (OZV), Yezo virus (YEZV), and Alongshan virus (ALSV), has further expanded the spectrum of emerging infections in this region. Notably, pathological investigation of a fatal human case of OZV infection demonstrated direct viral localization within cardiomyocytes, establishing a causal link between infection and fulminant myocarditis and highlighting a distinct organ-specific pathogenic mechanism. Despite the advances in genomic technologies that enable rapid detection of novel viruses, establishing causal relationships between viral presence and disease remains a major challenge. Tissue-based pathological approaches, particularly in situ localization of viral components, are, therefore, essential for defining disease mechanisms and confirming etiological roles. This review provides a comprehensive synthesis of tick-borne viral infections in East Asia, with particular emphasis on Japan, integrating pathological, virological, and clinical perspectives. It also identifies key knowledge gaps and underscores the importance of a synergistic One Health framework that incorporates both human and veterinary pathology to advance the understanding and control of these emerging diseases.

One Health↗
PubMed2025

Ebola virus VP35 NNLNS motif modulates viral RNA synthesis and MIB2-mediated signaling.

Ebola virus (EBOV) is a nonsegmented, negative-sense virus (NNSV) with a single-stranded RNA genome. EBOV encodes for a limited number of proteins and thus depends on host factors to facilitate viral replication and pathogenesis. Of the virus-encoded proteins, multifunctional EBOV VP35 (eVP35) is necessary for host immune evasion and viral RNA synthesis. Previous proteomics studies identified an interaction between eVP35 and the host E3 ubiquitin ligase Mindbomb 2 (MIB2). Here, we show how an NNLNS (Asn-Asn-Leu-Asn-Ser) motif (residues 201 to 205) within eVP35 serves as a binding site for MIB2. This motif is critical for eVP35-dependent inhibition of MIB2-mediated interferon induction. It is also important for EBOV RNA synthesis as MIB2 binding to eVP35 inhibited EBOV minigenome activity. Altogether, these findings highlight the importance of the eVP35 protein and the role of host factors in EBOV infection.

Ebolavirus↗
PubMed2025

Role of the CTCF binding site in Human T-Cell Leukemia Virus-1 pathogenesis.

During HTLV-1 infection, the virus integrates into the host cell genome as a provirus with a single CCCTC binding protein (CTCF) binding site (vCTCF-BS), which acts as an insulator between transcriptionally active and inactive regions. Previous studies have shown that the vCTCF-BS is important for maintenance of chromatin structure, regulation of viral expression, and DNA and histone methylation. Here, we show that the vCTCF-BS also regulates viral infection and pathogenesis in vivo in a humanized (Hu) mouse model of adult T-cell leukemia/lymphoma. Three cell lines were used to initiate infection of the Hu-mice, i) HTLV-1-WT which carries an intact HTLV-1 provirus genome, ii) HTLV-1-CTCF, which contains a provirus with a mutated vCTCF-BS which abolishes CTCF binding, and a stop codon immediately upstream of the mutated vCTCF-BS which deletes the last 23 amino acids of the p12 gene, and iii) HTLV-1-p12stop that contains the intact vCTCF-BS, but retains the same stop codon in p12 as in the HTLV-1-CTCF cell line. Hu-mice were infected with mitomycin-treated or irradiated HTLV-1 producing cell lines. There was a delay in pathogenicity when Hu-mice were infected with the HTLV-1-CTCF virus compared to mice infected with either HTLV-1-p12 stop or HTLV-1-WT virus. Proviral load (PVL), spleen weights, and CD4 T cell counts were significantly lower in HTLV-1-CTCF infected mice compared to HTLV-1-p12stop infected mice. Furthermore, we found a direct correlation between the PVL in peripheral blood and death of HTLV-1-CTCF infected mice. In cell lines, we found that the vCTCF-BS regulates Tax expression in a time-dependent manner. The scRNAseq analysis of splenocytes from infected mice suggests that the vCTCF-BS plays an important role in activation and expansion of T lymphocytes in vivo. Overall, these findings indicate that the vCTCF-BS regulates Tax expression, proviral load, and HTLV pathogenicity in vivo.

Human T-lymphotropic virus 1↗
PubMed2025

Establishment of reverse genetics systems for Colorado tick fever virus.

The Colorado tick fever virus (CTFV), which has 12-segmented double-stranded RNA genomes, is a pathogenic arbovirus that causes severe diseases in humans. However, little progress has been made in the analysis of replication mechanisms and pathogenicity. This virological constraint is due to the absence of a reverse genetics system for CTFV; therefore, we aimed to establish the system. Initially, the efficacy of CTFV replication was investigated in various cell lines. CTFV was found to grow in many cell types derived from different hosts and organs. Subsequently, BHK-T7 cells stably expressing T7 RNA polymerase were transfected with plasmids encoding each of the 12 CTFV gene segments, expression plasmids encoding all CTFV proteins, and a vaccinia virus RNA-capping enzyme. Following transfection, the cells were co-cultured with Vero or HeLa cells. Using this system, we rescued monoreassortants and recombinant viruses harboring peptide-tagged viral proteins. Furthermore, an improved system using Expi293F cells expressing T7 RNA polymerase was established, which enabled the generation of recombinant reporter CTFVs. In conclusion, these reverse genetics systems for CTFV will greatly contribute to the understanding of viral replication mechanisms, pathogenesis, and transmission, ultimately facilitating the development of rational treatments and candidate vaccines.

Animals↗