Search Results (2,528)

Background: Hepatitis B virus (HBV) infection remains highly endemic in sub-Saharan Africa, where hepatitis delta virus (HDV) co-infection substantially worsens liver disease outcomes. Mauritania has long been suspected to be a high-burden setting for HBV-HDV co-infection, yet contemporary data describing its clinical and virological impact remain limited. Methods: We conducted a hospital-based cross-sectional study at the National Institute of Hepato-Virology (INHV) in Nouakchott, including 401 HBsAg-positive patients. Demographic, clinical, biological, and virological data were collected. HDV serology and RNA testing were performed when available. Liver disease severity, including cirrhosis and hepatocellular carcinoma (HCC), was assessed using clinical, biological, and imaging criteria. Results: HDV antibodies were detected in 31.9% of HBsAg-positive patients, confirming Mauritania as a hyper-endemic area for HDV. HDV co-infection was strongly associated with advanced liver disease, with HDV antibodies present in 86.4% of cirrhotic patients and 82.4% of those with HCC. Patients with HDV infection frequently exhibited suppressed HBV DNA levels, reflecting viral interference. A substantial proportion of patients presented with decompensated cirrhosis or HCC at diagnosis, and nearly 70% were treatment-naïve. Overall, HDV co-infection emerged as the principal driver of severe liver disease in this cohort. Conclusions: HBV/HDV co-infection is highly prevalent in Mauritania and is associated with a wide clinical spectrum ranging from asymptomatic infection to decompensated cirrhosis and hepatocellular carcinoma. HDV co-infection is the principal driver of severe liver disease, often occurring despite low or undetectable HBV DNA levels. Systematic HDV screening among all HBsAg-positive individuals is urgently needed to improve risk stratification, guide therapeutic decisions, and reduce liver-related morbidity and mortality. Full article

Bovine viral diarrhea virus (BVDV) is a critical pathogen affecting the global cattle industry, causing severe economic losses primarily through persistent infection, immunosuppression, and reproductive failure. The virus exhibits substantial genetic diversity, with marked geographic variation in circulating subtypes, which complicates effective disease control. BVDV evades host immune responses by suppressing type I interferon signaling, impairing neutrophil function, and reprogramming host cellular metabolism, ultimately leading to the generation of persistently infected (PI) animals that serve as the principal reservoir for viral transmission. Current prevention and control strategies rely mainly on the identification and elimination of PI animals in combination with vaccination. However, conventional vaccines, including inactivated vaccines (IVs) and modified live vaccines (MLVs), have notable limitations, such as suboptimal subtype matching, interference by maternal antibodies, and safety concerns associated with MLV use in pregnant cattle. Emerging vaccine platforms, including mRNA vaccines, subunit vaccines, and multi-epitope vaccines, offer promising alternatives owing to their improved safety profiles, rapid design and production, and potential to elicit broad and robust immune responses. Future BVDV vaccine development should integrate artificial intelligence-driven design strategies with high-throughput sequencing and molecular epidemiological surveillance to enable the rational development of multivalent and multi-epitope vaccines. In addition, coordinated implementation of strain monitoring, PI animal clearance, and enhanced biosecurity practices will be essential for establishing a comprehensive and sustainable BVDV prevention and control framework. Full article

Nuclear receptor HR97 is considered as a non-insect arthropod–specific receptor, but its roles in decapod reproduction remain poorly understood. Here, we identified and characterized an HR97 ortholog from the swimming crab Portunus trituberculatus (PtHR97) and verified its placement within the NR1L nuclear receptor family by phylogenetic analysis. PtHR97 encodes a canonical nuclear receptor with a conserved DNA-binding domain (DBD) and ligand-binding domain (LBD). Quantitative PCR revealed predominant PtHR97 expression in the ovary and stage-dependent changes during ovarian development. Using an ovarian explant culture system, we found that arachidonic acid (AA) consistently suppressed PtHR97 transcript levels, while methyl farnesoate (MF) and pyriproxyfen (P) had no significant effect, indicating a potential inhibitory role for AA in PtHR97 expression. RNA interference of HR97 caused significant changes in ovarian development, including reduced GSI, smaller oocytes, and uneven eosinophilic granule distribution. Transcriptomic profiling of HR97-silenced ovaries indicated that the major responses involved genes associated with substrate transport/exchange, cell boundary–related signaling and transduction, and disturbed nuclear transcriptional regulation. Short-term in vivo perturbations (HR97 RNAi and AA treatment) further supported these expression changes and revealed that AA- and HR97 RNAi–elicited transcriptional responses only partially overlapped. Taken together, these results suggest that HR97 contributes to ovarian development, potentially through broad transcriptional responses related to transport, signaling, and gene regulation. Although AA may suppress HR97 expression, HR97 does not fully explain AA-mediated regulation of ovarian development. Full article

Insect insulin signaling plays a central role in regulating development, metamorphosis, and reproduction, yet its mechanistic functions in the tomato leafminer, Tuta absoluta, a globally significant pest, remain poorly understood. This study aimed to elucidate the role of the serine/threonine kinase Akt (TaAkt) in coordinating metamorphosis and female reproductive processes. The TaAkt gene was cloned and characterized, and its spatiotemporal expression was analyzed across various developmental stages and tissues. RNA interference (RNAi) was employed to knock down TaAkt in late pupae and newly emerged females, followed by assessment of pupal-adult eclosion, chitin metabolism, 20-hydroxyecdysone (20E) titer, ovarian development, juvenile hormone (JH) levels, vitellogenin synthesis, and fecundity. Knockdown of TaAkt significantly reduced 20E titers and downregulated the expression of ecdysone biosynthesis and signaling genes, leading to pupal mortality, defective molting, and reduced chitin content. In adult females, TaAkt silencing impaired ovarian growth, decreased JH levels, suppressed vitellogenin production, and reduced egg number and hatching rates. These findings demonstrate that TaAkt exerts pleiotropic control over both metamorphic and reproductive processes in T. absoluta. The study identifies TaAkt as a promising molecular target for RNAi-based pest management strategies, offering a potential approach to simultaneously suppress survival and reproductive capacity in this economically important pest. Full article

To explore the function of the period gene (Ec-per) in Exopalaemon carinicauda, we cloned the gene of 4611 bp with a 5′UTR of 201 bp, a 3′UTR of 813 bp, and an ORF of 3597 bp encoding 1198 amino acids. The predicted protein includes two PAS and one PERIOD domain. qPCR analysis revealed that Ec-per was expressed across all tissues tested at different developmental stages and during both embryonic and larval stages. Moreover, Ec-per oscillated rhythmically under different conditions of light-to-dark (L:D) ratios, including continuous darkness (0 L:24 D), where changes in the photoperiod influenced amplitude and phase shifts. The knockdown of Ec-per mRNA significantly reduced the expression of the circadian-related genes timeless (tim) and cryptochrome 1 (cry1) (p < 0.05). This suggests that Ec-per is an endogenous clock gene that may participate in molecular feedback loops and synergistically regulate the circadian rhythms through interacting with tim and cry1. RNA interference of Ec-per also markedly downregulated ecdysone receptor mRNA (p < 0.05), suggesting a positive role in the ovarian development of E. carinicauda. In situ hybridization further demonstrated that Ec-per is involved in oocyte proliferation and the accumulation of exogenous nutrients. This study provides new insights for promoting ovarian development and artificial breeding in crustaceans through optimized light-cycle management. Full article

Carotenoid-based pigmentation is crucial for the ornamental and commercial value of the cherry shrimp (Neocaridina denticulata sinensis). While several genes are known to influence carotenoid metabolism, the genetic basis for specific color strains remains largely unexplored. Here, we functionally characterized NinaB-like, a homolog of a carotenoid oxygenase, in cherry shrimp pigmentation. We employed qPCR to gain gene expression profiles, utilized RNAi technology to analysize the relation between its expression level and carotenoid accumulation, and performed GT-seq to identify genotypes of different color strains. Significant differential expression of NinaB-like was observed not only across distinct color strains but also during embryonic development of cherry shrimp (p < 0.05), peaking at the red strain and post-larval stage of cherry shrimp. RNA interference-mediated knockdown of NinaB-like resulted in a marked increase in red pigment deposition at the metanauplius and pre-zoea stages, confirming its role as a negative regulator of carotenoid accumulation. Importantly, we identified two tightly linked, non-synonymous SNPs (927C > A and 935A > C) within the NinaB-like coding region that exhibited a strong association with body color. Our study provides the first functional evidence that NinaB-like is a negative regulator of carotenoid degradation and a major genetic determinant for body color in cherry shrimp, providing new insights for genetic breeding and biological research. Full article

The role of extracellular vesicle non-coding RNAs in host–parasite interactions remains poorly understood, particularly for human liver flukes. Although tRNA-derived small RNAs (tsRNAs) are emerging as new regulatory molecules in parasite exosomes, they have not yet been characterized for the liver flukes. We performed small RNA sequencing to profile tsRNAs in the exosome-like vesicles derived from the liver fluke Opisthorchis felineus. Transcriptomic data from human cholangiocytes were analyzed to assess the enrichment of the predicted target genes among differentially expressed genes. We identified 247 functional tRNA genes in the O. felineus genome. Exosome-like vesicles were highly enriched for particular tsRNAs: derived from tRNA-Asp-GTC, tRNA-Ile-AAT, tRNA-Lys, tRNA-His, and tRNA-Tyr. This enrichment was independent of both genomic tRNA copy number and the amino acid composition of the trematode proteome. In silico prediction revealed that these tsRNAs target human genes involved in cell cycle, migration, and proliferation. Notably, these predicted target genes were significantly enriched among the differentially expressed genes in treated cholangiocytes. Our study provides the first evidence that O. felineus exosomes carry a specific repertoire of tsRNAs with the potential to regulate host gene networks. We propose that tsRNAs may contribute to host cell manipulation during O. felineus infection. Full article

RNA viruses pose a persistent global threat due to their high mutation rates, zoonotic potential, and rapid adaptability. Emergence events have risen steadily, as demonstrated by major outbreaks caused by Influenza A, Ebola, Zika, and Chikungunya viruses, followed by the coronavirus epidemics of Severe Acute Respiratory Syndrome coronavirus (SARS-CoV-1) and Middle East Respiratory Syndrome Coronavirus (MERS-CoV) and culminating in the COVID-19 pandemic. These characteristics frequently compromise the durability of existing vaccines and antiviral therapies, highlighting the urgent need for new antiviral agents. Alkaloids, a structurally diverse class of nitrogen-containing natural compounds, have gained attention for their ability to interfere with multiple stages of the viral life cycle, including entry, replication, protein synthesis, and host immune modulation. To our knowledge, this review compiles all currently reported alkaloids with antiviral activity against RNA viruses and summarizes their proposed mechanisms of action, distinguishing evidence from in vitro, in vivo, and in silico studies. Quaternary alkaloids are discussed separately because their permanent ionic charge enables distinctive interactions with membranes and host pathways. Although many findings are promising, clinical translation remains limited by incomplete mechanistic validation, scarce in vivo data, suboptimal bioavailability, narrow therapeutic windows, and inconsistent experimental methodologies. To advance the field, future research should prioritize RT-qPCR–based antiviral evaluation to accurately quantify viral replication, incorporate mechanistic assays to clarify modes of action, apply structure–activity relationship (SAR) approaches for rational optimization, and expand in vivo pharmacokinetic and efficacy studies to assess therapeutic feasibility. Overall, alkaloids represent a promising yet underdeveloped reservoir for next-generation antiviral discovery against rapidly evolving RNA viruses. Full article

The soybean mosaic virus (SMV), a significant viral pathogen impacting soybean cultivation, leads to substantial yield losses and diminishes seed quality. In a prior study, we developed a targeted silencing vector using RNA interference (RNAi) technology targeting the CP gene, which codes for the viral coat proteins in the SMV genome. This vector was delivered into soybean plants through Agrobacterium-mediated transformation. In our current research, we utilized ongoing molecular characterization and resistance screening to identify four genetically pure lines that display moderate to high resistance to SMV. Additionally, the transgenic plants exhibited resistance to three other potyviruses: the bean common mosaic virus, the recombinant soybean mosaic virus, and the watermelon mosaic virus. Greenhouse and field trials conducted with these lines demonstrated that RNAi-mediated silencing of the CP gene significantly enhanced disease resistance. It is noteworthy that, in comparison to the receptor plants, the transgenic plants exhibited no significant differences in maturity, plant height, branching number, node number, pod number, or 100-seed weight. These results offer valuable genetic resources and theoretical support for molecular breeding strategies aimed at combating SMV in soybeans, as well as for RNAi-based methods to control plant viral infections. Full article

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

Background/Objectives: Angelman syndrome is a neurodevelopmental disorder resulting from a deficiency of the maternally inherited UBE3A gene. In mature neurons, UBE3A expression is restricted to the maternal allele due to tissue-specific genomic imprinting, while the paternal allele is silenced in cis by the UBE3A antisense transcript (UBE3A-ATS). To date, numerous strategies have been employed to activate paternal UBE3A expression. In this study, we utilized RNA interference (RNAi) to investigate the downregulation of UBE3A-ATS in mouse primary neurons and human induced pluripotent stem cell (iPSC)-derived neurons. Methods: To induce paternal UBE3A expression, we employed small interfering RNA (siRNA) oligonucleotides (20 mouse candidates and 47 human candidates) and lentiviral short hairpin RNA (LV-shRNA) targeting SNORD115 to suppress UBE3A-ATS expression in both mouse primary neurons and iPSCs. Subsequently, we assessed the expression levels of Angelman syndrome-related neighboring and target genes at the transcript and, where applicable, protein levels. Results: Following treatment with siSnord115 or LV-shSnord115, we observed a reduction in Ube3a-ATS and a corresponding activation of paternal Ube3a RNA and protein expression in both Ube3a^P-YFP/m+ and Ube3a^p+/m− mouse primary neurons. A similar effect was observed upon treatment with LV-shSNORD115s in human iPSC-derived neurons. Conclusions: shRNA-mediated inhibition of Ube3a-ATS by targeting Snord115 effectively restores Ube3a/UBE3A expression in both mouse neurons and human iPSCs. While promising, the mild reduction in Snord116 raises concerns about potential off-target effects. AAV-based delivery of shRNA shows potential, but its translational applicability remains to be evaluated in vivo. Full article

There is increasing evidence that exposure to environmental toxicants may impact fertility, especially during critical windows of reproductive axis development. Hypothalamic gonadotropin-releasing hormone (GnRH) neurons, essential for puberty onset and fertility, originate from the olfactory placode and migrate toward the hypothalamus during development, making them particularly vulnerable to environmental insults. Cadmium (Cd), a widespread heavy metal, is well known for its gonadotoxicity, but its impact on human hypothalamic neuron development remains unclear. Using human fetal GnRH neuroblasts (FNCB4) we investigated the effects of Cd exposure on their morpho-functional and developmental features. Cd induced oxidative stress and COX2 mRNA upregulation, indicative of inflammatory pathway activation, which was accompanied by reduced cell migration and downregulation of motility-related genes. These effects were associated with F-actin disassembly and altered expression of adhesion molecules. Electrophysiological analyses showed that Cd altered membrane potential, increased capacitance and permeability, and disrupted gap junctional communication, as also confirmed by connexin-43 delocalization. Moreover, Cd significantly reduced the expression of specific GnRH neuronal markers, suggesting impaired functional maturation. Overall, our findings provide the first evidence that Cd may interfere with mechanisms crucially involved in human GnRH neuron development, adding new mechanistic insights into the comprehension of how early-life exposure to Cd may contribute to fertility concerns. Full article

Spray-induced gene silencing (SIGS) represents a transformative paradigm in sustainable pest management, utilizing the exogenous application of double-stranded RNA (dsRNA) to achieve sequence-specific silencing of essential genes in arthropod pests. Unlike transgenic approaches, sprayable RNA interference (RNAi) biopesticides offer superior versatility across crop systems, flexible application timing, and a more favorable regulatory and public acceptance profile. The 2023 U.S. EPA registration of Ledprona, the first sprayable dsRNA biopesticide targeting Leptinotarsa decemlineata, marks a significant milestone toward the commercialization of non-transformative RNAi technologies. Despite the milestone, large-scale field deployment faces critical bottlenecks, primarily environmental instability, enzymatic degradation by nucleases, and variable cellular uptake across pest taxa. This review critically analyzes the mechanistic basis of spray-applied RNAi and synthesizes the recent technological breakthroughs designed to overcome physiological and environmental barriers. We highlight advanced delivery strategies, including nuclease inhibitor co-application, liposome encapsulation, and nanomaterial-based formulations that enhance persistence on plant foliage and uptake efficiency. Furthermore, we discuss how innovations in microbial fermentation have drastically reduced synthesis costs, rendering industrial-scale production economically viable. Finally, we outline the roadmap for broad adoption, addressing essential factors such as biosafety assessment, environmental fate, resistance management protocols, and the path toward cost-effective manufacturing. Full article

In the filamentous fungus Neurospora crassa, a gene not having a pairing partner during meiosis is seen as a potential intruder and is targeted by a mechanism called meiotic silencing by unpaired DNA (MSUD). MSUD employs core RNA interference (RNAi) components such as the SMS-2 Argonaute, which uses small interfering RNAs (siRNAs) as guides to seek out mRNAs from unpaired genes for silencing. In Drosophila melanogaster, the heat shock protein 70 (Hsp70) chaperone system facilitates the conformational activation of an Argonaute and allows it to load siRNAs. Here, our results demonstrate that an Hsp70 protein in Neurospora interacts with SMS-2 and mediates the silencing of unpaired genes. Full article

A 19 nt fragment that spans the SARS-CoV-2 furin cleavage site (FCS) is identical to the reverse complement of a proprietary human DNA repair gene sequence. Rather than interpreting this overlap as evidence of a laboratory event, this article uses it as a theoretical springboard to explore underappreciated biorisk concerns, specifically in the context of cancer research. Although they are RNA viruses, coronaviruses are capable of hijacking host DNA damage response (DDR) pathways, exploiting nuclear functions to enhance replication and evade innate immunity. Under selective pressures (antivirals, DDR antagonists, or large-scale siRNA libraries designed to silence critical host genes), escape mutants may arise with fitness advantages. Parallel observations involving in vivo RNA interference via chimeric viruses lend plausibility to some of the key aspects underlying unappreciated biorisks. The mechanistic insights that incorporate DNA repair mechanisms, CoVs in the nucleus, specifics of viruses in cancer research, anticancer drugs, automated gene silencing experiments, and gene sequence overlaps identify gaps in biorisk policies, even those unaccounted for by the potent “Sequences of Concern” paradigm. Key concerning attributes, including genome multifunctionality, such as NLS/FCS in SARS-CoV-2, antisense sequences, and their combination, are further described in more general terms. The article concludes with recommendations pairing modern technical safeguards with enduring ethical principles. Full article