Search Results (414)

Plant RNA interference (RNAi) is a fundamental antiviral defense that relies on coordinated activities of DICER-like endonucleases (DCLs), Argonaute proteins (AGOs) and RNA-dependent RNA polymerases (RDRs). Over the past decades, studies using model and crop species have uncovered complex and often redundant roles for DCLs and RDRs in generating and amplifying virus-derived small interfering RNAs (vsiRNAs), in addition to connections with transcriptional gene silencing (TGS) and epigenetic defenses against DNA viruses. Concurrently, plant viruses have evolved diverse counterstrategies—proteinaceous RNA silencing suppressors (RSSs), exoribonuclease (XRN)-resistant noncoding RNAs, and indirect manipulation of host pathways—to evade RNAi. Driven by the co-evolutionary arms race, plants have developed sophisticated counter-countermeasures that modulate or overcome viral anti-RNAi activity. Accumulated evidence suggests that plants encode host factor genes that are activated to degrade or sequester viral components such as RSSs against viral infection. On the other hand, plants have also evolved endogenous host modulators of antiviral RNAi that can either reinforce the antiviral response or be co-opted by viruses to antagonize it, representing a furious dynamic molecular battling mechanism. Here, we review recent advances in the molecular functions of DCLs and RDRs across species, summarize newly discovered viral counter-defenses (including RNA-based suppressors), and discuss host counter-countermeasures. We research key areas—such as the roles of RDRγ-class proteins, RTL1 (RNase three-like 1)-mediated competition with DCLs, and the mechanistic impact of viral noncoding RNAs—and outline translational opportunities for improving virus resistance in crops through breeding, biotechnological approaches, and RNA-based applications. Full article

Curcumin, the major polyphenolic constituent of Curcuma longa, has been widely investigated as a hepatoprotective adjunct due to its antioxidant and immunomodulatory properties. This review evaluates the relevance of curcumin for the prevention and management of liver dysfunction and hepatitis in pigs by synthesizing available porcine evidence and integrating mechanistic insights from translational liver injury models where pig-specific data remain limited. Across experimental hepatic injury contexts, curcumin administration is most consistently associated with reduced biochemical and structural indicators of hepatocellular damage, including decreased aminotransferase activity, attenuation of lipid peroxidation, and enhancement of endogenous antioxidant defenses. These effects are mechanistically linked to suppression of pro-inflammatory signaling pathways, particularly NF-κB-related transcriptional activity and inflammasome-associated responses, together with reduced expression of key cytokines such as TNF-α, IL-1β, and IL-6. Concurrent activation of Nrf2-centered cytoprotective pathways and induction of phase II antioxidant enzymes (including HO-1, GST, and NQO1) appear to constitute a conserved axis supporting hepatic oxidative stress resilience. In swine-relevant infectious settings, available data further support antiviral activity against selected porcine pathogens, including classical swine fever virus and porcine reproductive and respiratory syndrome virus, potentially mediated through interference with lipid-dependent stages of viral replication and modulation of Kupffer cell activation. Although combination strategies with established hepatoprotective approaches are conceptually attractive, current synergy evidence remains heterogeneous and largely extrapolated. Overall, curcumin represents a plausible adjunct candidate for supporting porcine liver health; however, translation into practice will depend on resolving formulation-dependent bioavailability constraints and strengthening the pig-specific evidence base. Full article

NK cells are key components of the innate immune system, capable of recognizing and eliminating tumor or virus-infected cells and able to modulate both innate and adaptive immune responses. This makes NK cells attractive candidates for cancer immunotherapy, through passive approaches such as adoptive NK cell transfer, or active approaches aimed at enhancing endogenous NK cell activity in vivo. Promising results have emerged from preclinical studies and early-phase clinical trials. Nevertheless, the therapeutic efficacy of NK cell-based approaches is often limited by several factors, such as the poor NK cell persistence in vivo, the inefficient tumor infiltration, and the immunosuppressive milieu typical of the tumor microenvironment. The preclinical development of NK cell-based therapies relies largely on animal models. Humanized mouse models have evolved from early immunodeficient strains to more advanced systems incorporating human cytokines, which more effectively support NK cell development, maturation, and function. These models have substantially improved our understanding of human NK cell biology and enabled the evaluation of novel therapeutic strategies. However, further optimization is still required to better recapitulate the tissue-specific heterogeneity of human NK cells and their conditioning by the tumor microenvironment. In this review, we provide an overview of recent advances in the generation of humanized mouse models for NK cell-based cancer immunotherapy, discussing their advantages and limitations and highlighting how emerging technologies may contribute to the development of more predictive preclinical platforms. Full article

Retroviruses are immunosuppressive, and there is evidence that a highly conserved immunosuppressive domain (isu domain) in their transmembrane envelope protein contributes to this activity. Studies have shown that inactivated retroviruses, their purified transmembrane envelope proteins, and synthetic peptides corresponding to the isu domain inhibit mitogen-triggered proliferation of peripheral blood mononuclear cells (PBMCs) and modulate their cytokine and gene expression. This has been demonstrated for human immunodeficiency virus type 1 (HIV-1), as well as for beta- and gammaretroviruses and for both exogenous and endogenous retroviruses, including syncytins. In the case of HIV-1, homopolymers of its isu peptide stimulated an increased release of IL-10, IL-6, and other cytokines from human PBMCs. Up-regulated genes included IL-6, IL-8, and IL-10, as well as MMP-1, TREM-1, and IL-1β. In vivo, in a mouse tumor model, tumor cells that were unable to induce tumors in immunocompetent animals gained the ability to do so when expressing the transmembrane envelope protein or the isu domain of various retroviruses on their surface. Here, we demonstrate that the transmembrane envelope protein p15E of PERV can modulate cytokine expression in human PBMCs. Human 293 cells were transfected with four constructs that express a portion of p15E, including the isu domain, and were cultured in the presence of a selection medium containing hygromycin. The p15E-expressing cells were co-cultured with human PBMCs, leading to the release of IL-6 and IL-10 protein and the modulation of multiple cytokines and other markers, including IL-6, IL-10, IFN-α, TNF-α, MMP1, and SEPP1. Similar, but more pronounced, effects were observed when PERV-producing 293 and pig cells were used in parallel; both expressed higher levels of p15E. Additionally, p15E expression reduced MHC class I expression, and preliminary data indicate that p15E expression could have a protective effect against cellular cytotoxicity. This finding underscores the need for further research to elucidate the dynamics of p15E expression and its immunosuppressive activity. It also contributes to the understanding of the immunosuppressive properties of pathogenic retroviruses. Furthermore, expressing the immunosuppressive p15E of PERV on the surface of a pig xenotransplant may reduce the need for pharmaceutical immunosuppressants. Full article

Gammaretroviruses are ubiquitous pathogens, often associated with the induction of neoplasia, especially leukemia, lymphoma, and sarcoma, and with a propensity to target the germline. The latter trait has left extensive evidence of their infectious competence in vertebrate genomes, the human genome being no exception. Despite the continuing activity of gammaretroviruses in mammals, including Old World monkeys, apes, and gibbons, humans have apparently evaded novel infections by the virus class for the past 30 million years or so. Nevertheless, from the 1970s onward, cell culture studies repeatedly discovered gammaretroviral components and/or virus replication in human samples. The last novel ‘human’ gammaretrovirus, identified in prostate cancer tissue, culminated in the XMRV frenzy of the 2000s. In the end, that discovery was shown to be due to lab contamination with a murine gammaretrovirus. Contamination is also the likely source of the earlier findings. Complementation between genes of partially defective endogenous proviruses could have been another source of the virions observed. However, the capacity of many gammaretroviruses to replicate in human cell lines, as well as the presence of diverse infectious gammaretroviral species in our animal companions, for instance in mice, cats, pigs, monkeys, chickens, and bats, does not make a transmission to humans an improbable scenario. This review will summarize evidence for, or the lack of, gammaretrovirus infections in humans in the past, present, and near future. Aspects linked to the probabilities of novel gammaretrovirus infections in humans, regarding exposure risk in connection to modern lifestyle, geography, diet, and habitat, together with genetic and immune factors, will also be part of the review, as will be the estimated consequences of such novel infections. Full article

This study comprehensively characterizes the PEBP gene family in Cymbidium sinense, an orchid with a prolonged vegetative phase that limits its industrial production. Genome-wide analysis identified six CsPEBPs, classified into FT-like, TFL1-like, and MFT-like subfamilies. Evolutionary, gene structure, and collinearity analyses revealed both conservation and lineage-specific diversification of these genes. CsFTL3, a distinctive FT-like member, displayed notably high expression during the bud undifferentiated stage, followed by a sharp downregulation upon floral initiation. Functional studies identified CsFTL3 as a key floral repressor. Heterologous overexpression in Arabidopsis delayed flowering time from 32.0 days (wild-type) to 63.0–75.3 days (transgenic) and increased rosette leaf number from 12.6 to 33.0–34.5, while its knockdown via virus-induced gene silencing (VIGS) in C. sinense accelerated floral bud development and upregulated flowering-promoter genes. Phylogenetically, CsFTL3 falls within the flowering repressor FT-I clade, and multiple sequence alignment identified critical amino acid substitutions (Y134S, W138L, Q140E) that likely underpin its functional divergence from typical flowering promoters. Furthermore, promoter analysis revealed an enrichment of light-, hormone-, and stress-responsive cis-elements, and its expression was modulated by gibberellin (GA), abscisic acid (ABA), and low-temperature treatments. Predicted protein–protein interaction and transcriptional regulatory networks provide preliminary insights into its complex regulation. We conclude that CsFTL3 acts as a crucial floral inhibitor, integrating environmental and endogenous cues to repress flowering. These findings offer fundamental insights into the molecular mechanisms of flowering in orchids and provide a valuable genetic resource for molecular breeding programs aimed at achieving precise flowering time control. Full article

Technological advancements in blood donor screening have significantly improved blood safety. However, certain testing challenges and limitations continue to face blood banks in donor screening for the hepatitis B virus, resulting in occasional cases of transfusion transmission. These cases are mostly related to donors presenting within the window period and donors with occult hepatitis B infection. There are several other challenges that professionals in transfusion medicine, infectious diseases, gastroenterology, and public health must be aware of. Maintaining the highest test sensitivity is a key parameter for enhancing blood safety, and the review describes current recommendations in this regard, along with relevant advancements. The diversity of viral genotypes and the potential for mutations affecting the surface antigen may negatively affect the performance of both serologic and nucleic acid tests. Serologic tests may also be affected by several interferences, endogenous or exogenous to the sample. A clear understanding of these challenges is necessary to create effective policies and procedures and to properly manage atypical cases. Full article

Plant viral diseases cause significant agricultural losses worldwide and are shaped by complex virus-host and virus-virus interactions. Unlike fungal or bacterial pathogens, viruses cannot be directly controlled with chemicals, and their management relies on insect vector control and the development of virus-resistant plant varieties. Plants deploy endogenous epigenetic (DNA/chromatin-based) and epitranscriptomic (RNA-based) mechanisms to limit viral infections. RNA silencing pathways, particularly post-transcriptional gene silencing (PTGS) mediated by small RNAs, restrict viral replication and shape viral populations. Additional layers, including RNA-directed DNA methylation (RdDM), N6-methyladenosine (m⁶A) RNA modifications, histone modifications and chromatin remodeling, further modulate host–virus interactions. DNA methylation can be inherited and may confer resistance to future generations, although its stability is partial and context-dependent. Virus-derived 24-nt small interfering RNAs (siRNAs) act as mobile signals, inducing systemic gene silencing and potentially influencing viral population dynamics. Understanding these epigenetic and epitranscriptomic mechanisms can improve virus diagnosis, pathogenesis studies and disease management, while also providing insights into viral diversity and co-infection dynamics. This review synthesizes current knowledge of these mechanisms and discusses their implications for developing sustainable antiviral strategies. Full article

Orthoebolavirus zairense is the species name for Zaire Ebola virus (EBOV) within Filoviridae. This group of viruses can cause severe disease in humans, characterized by hemorrhagic shock, coagulation abnormalities, and severe inflammation. While tissue macrophages are critical targets early during EBOV infection, other cell types support viral replication as disease progresses. At late stages of infection, infectious EBOV is found on the surface of the skin, which may be a critical source of infectious virus transmitted between individuals during outbreaks. Human skin contains a number of cellular targets of EBOV, including keratinocytes. Here, we demonstrate EBOV infection of telomerase-immortalized normal human skin keratinocytes (NHSK-1), as well as EBOVΔVP30 infection of NHSK-1 cells that were stably complemented with EBOV transcription factor VP30. Infection with EBOVΔVP30 did not elicit detectable endogenous interferon responses; however, exogenous pre-treatment of NHSK-1 cells with type I, II, and III interferon (IFN) inhibited EBOVΔVP30 infection and infection of an additional low-containment model of EBOV, rVSV/EBOV GP, in a dose-dependent manner. Analysis of the transcriptome of IFN-treated keratinocytes identified multiple genes unique to each IFN and a subset of ISGs upregulated by all three IFNs. Our results indicate that ISGs induced by IFN pre-treatment of keratinocytes can reduce infection, underlining that ISGs may serve as EBOV-targeting therapeutics. Full article

Detection of infectious hypodermal and hematopoietic necrosis virus (IHHNV) in shrimp aquaculture is complicated by endogenous viral elements (EVEs) causing false positives in conventional PCR assays. This study analyzed 277 Penaeus vannamei samples from Ecuador using World Organization for Animal Health (WOAH)-recommended short-fragment primers (IHHNV-309, -389, -392, -77012; ~1.5 kb amplicons) and long-amplicon PCR (LA-PCR; ~3.7 kb, 90% of the genome), complemented by histopathology. Short-fragment primers showed high positivity rates (72.9–83.0% individually; 69.3% combined), while LA-PCR reduced positives to 29.6%, with 95.1% overlap indicating true infections as a subset of conventional results. Approximately 55.6% of samples likely contained EVEs mimicking IHHNV, and 14.8% were true negatives. Histopathology confirmed classic IHHNV lesions (Cowdry A-type inclusions) in only one sample (0.36%), which also showed co-infections (hepatopancreatic atrophy, gregarines, and unidentified viral inclusions), suggesting multifactorial pathology. These findings highlight inflated IHHNV prevalence due to single-primer PCR, particularly in Ecuador, where reliance on WOAH-suggested primers (e.g., 389F/R) fails to distinguish infectious IHHNV from EVEs or confirm subclinical status, risking misattribution of losses to IHHNV while overlooking pathogens like Vibrio spp. We advocate LA-PCR and histopathology to enhance diagnostics and support sustainable shrimp fisheries. Full article

Three main hypotheses have been proposed to explain the origin of viruses: the exogenisation (escape) hypothesis, suggesting that mobile genetic elements gained infectivity and autonomy; the degeneration hypothesis, proposing that viruses arose through gene loss from more complex, possibly cellular ancestors; and the virus-first hypothesis, which argues that viruses are ancient, pre-cellular entities. This review evaluates these models in light of molecular, structural, and ecological evidence. Key considerations include the lack of homologues for many viral proteins, the presence of giant DNA viruses with extensive gene repertoires, the conservation of capsid structures across diverse viruses, and the universal dependence of viruses on living hosts. Also discussed is the vast diversity of the global virosphere revealed by recent metaviromic studies, particularly in marine ecosystems, where viruses play key roles in structuring microbial communities and driving biogeochemical cycles. Such findings highlight that viruses are integral components of biological systems rather than merely parasitic outliers. Although no single hypothesis fully explains the origin of all viruses, their extraordinary genetic and functional complexity suggests a unified evolutionary theory may forever remain elusive. Rather, understanding the origins of viruses requires integrating genomic traits with ecological roles across their wide diversity. Full article

Post-viral neuroinflammatory syndromes, particularly those occurring after SARS-CoV-2 infection, have received increasing attention due to their complex and persistent neurological manifestations. The aim of this narrative review is to integrate current evidence on the molecular and cellular mechanisms underlying chronic neuroinflammation following viral infections, with a focus on dysregulated innate immune responses, macrophage–microglia interactions, oxidative–mitochondrial stress, and impaired inflammation resolution pathways. Our synthesis shows that prolonged activation of macrophages and glial cells promotes the continuous release of pro-inflammatory mediators, while defective phagocytosis and inadequate clearance of cellular debris maintain an inflammatory microenvironment. Mitochondrial dysfunction further amplifies immune activation by stimulating metabolic stress and reactive oxygen species production. In parallel, deficiencies in mediators specialized in inflammation resolution impede the transition from inflammation to resolution, allowing neuroimmune imbalance and nociceptive sensitization to persist long after virus clearance. Key conclusions indicate that these interconnected mechanisms collectively contribute to the long-term neurological symptoms observed in post-viral states, including cognitive impairment, neuropathic pain, and fatigue. Emerging therapeutic strategies targeting cytokine signaling, microglial reactivity, mitochondrial function, and resolution pathways are promising, but remain insufficiently validated in clinical practice. Overall, evidence suggests that post-viral neuroinflammation results from the convergence of sustained immune activation and failure of endogenous resolution mechanisms, highlighting the need for further mechanistic studies and targeted interventions. Full article

Background/Objectives: Chemogenetic excitation of a distinct subset of “effector-neurons” in the brainstem mesopontine tegmental anesthesia area (MPTA) is pro-anesthetic. GABAergic general anesthetics are believed to engage these neurons by disinhibition, thereby inducing loss-of-consciousness (LOC) and enabling pain-free surgery. The transition from wakefulness to LOC, however, does not occur intrinsically within the MPTA. Rather, evidence indicates that LOC is brought about (effected) by ascending and descending axonal projections of MPTA effector-neurons that terminate in a variety of downstream brain targets which, together, generate the various components of anesthesia. Previously we used anterograde and retrograde tracing to delineate the overall axonal trajectories of MPTA projection-neurons, to which targets they project. Effector-neurons, however, represent only a fraction of this neuronal pool. Which of these targets are also innervated by MPTA projecting effector-neurons? Methods: Here we marked MPTA effector-neurons with the adeno-associated virus (AAV) used in the discovery of this neuronal type, with retrograde labelling from the previously identified MPTA target structures, to establish which downstream brain structures receive direct input from effector-neurons. Results: Effector-neurons proved to contribute to all six of the major MPTA projection-targets: the prefrontal cortex, basal forebrain, intralaminar thalamus, zona incerta, rostro-ventromedial medulla and spinal cord. Conclusions: We conclude that a discrete population of projecting effector-neurons, probably representing only about 6% of all MPTA neurons, drive the multiple functional endpoints of surgical anesthesia: analgesia, atonia, amnesia and LOC. Further, we propose that these same neurons, via their associated axonal pathways, may also contribute to endogenous instances of LOC such as natural sleep, fainting, concussion, coma and hibernation. Full article

The open reading frame 3 (ORF3) protein of the swine hepatitis E virus (SHEV) is a critical virulence factor implicated in viral infection, yet its precise mechanisms remain poorly understood. Circular RNAs (circRNAs) have emerged as key regulators of gene expression during viral infections by functioning as miRNA sponges. This study aimed to identify key circRNAs and construct a potential circRNA-miRNA-mRNA regulatory network associated with the viral infection pathway in HepG2 cells expressing genotype IV SHEV ORF3. Based on our previous high-throughput circRNA and transcriptome sequencing data from HepG2 cells with adenovirus-mediated ORF3 overexpression, we screened for differentially expressed circRNAs and mRNAs linked to viral infection pathways. Using bioinformatic tools, we predicted miRNAs targeted by these mRNAs and those that could bind to the circRNAs, ultimately constructing a competing endogenous RNA (ceRNA) network with Cytoscape. We identified 31 differentially expressed circRNAs and 7 mRNAs (HSPA8, HSPA1B, EGR2, CXCR4, SOCS3, NOTCH3, and ZNF527) related to viral infection. A potential ceRNA network comprising 32 circRNAs, 23 miRNAs, and the 7 mRNAs was constructed. Core circRNAs, including ciRNA203, circRNA14936, and circRNA5562, may act as miRNA sponges to regulate the expression of these mRNAs. This network suggests a novel mechanism by which SHEV ORF3 might modulate host cell functions to facilitate viral infection. Full article

Mosquito-borne viruses like West Nile virus (WNV) and Usutu virus (USUV) present growing public health concerns, especially with climate change and expanding vector ranges. This study describes the development and validation of a duplex Real-Time RT-PCR assay targeting β-actin (ACTB) mRNA as an endogenous control and a conserved 92 bp region shared by WNV and USUV genomes. Degenerate primers for ACTB ensure RNA extraction quality and PCR performance while enabling simultaneous detection of both viruses. A total of 1002 mosquito pools collected in Piedmont, Italy, during the 2024 vector season under the National Surveillance Plan for Arboviruses (PNA), were tested. The assay showed 100% accuracy—ACTB mRNA was detected in all pools, and six pools tested positive for WNV or USUV (three each). Diagnostic specificity was confirmed on 40 horse and bovine serum samples. Sanger sequencing confirmed ACTB identity across multiple mosquito species. The assay also demonstrated reproducibility across different operators and thermocyclers. The limit of detection (LOD) evaluation showed that the assay is capable of detecting viral RNA at very low concentrations, confirming its high analytical sensitivity. The duplex RT-PCR here developed is a reliable, sensitive, and specific tool for arbovirus surveillance, combining pathogen detection with internal quality control of RNA extraction and amplification, thus improving early warning and rapid response to mosquito-borne disease threats. Full article