Search Results (245)

Herpesviruses are prevalent infectious agents in humans, with complex structures and life cycles. The viability and detail of a model of capsid assembly and maturation can now be examined against the recently available mature herpesvirus capsids structures. The first large assembly product is the icosahedral procapsid with an outer shell composed of major capsid proteins (MCPs) connected by triplexes (heterotrimers composed of one Tri1 protein and two Tri2 proteins), and an inner shell of scaffold proteins. The asymmetric triplexes have specific and conserved orientations, suggesting a key role in assembly. In the mature capsid structures, triplexes bound to three MCPs may represent an assembly unit where, in most cases, the N-terminus of one MCP wraps around the E-loop of another MCP. The model accommodates the incorporation of a portal into capsid, required for genome encapsidation and viral viability. Cleavage of the scaffold triggers maturation of procapsid. Each of the MCPs rotates mostly as a rigid body, except for the flexible peripheral parts that remodel to close the capsid inner surface. Angularization of the capsid shifts the portal outward to a better contact with the capsid shell. Understanding these events in the herpesvirus life cycle to atomic detail could facilitate the development of drugs that uniquely target assembly and maturation. Full article

Human DEAD-box helicase 3 (DDX3) is a multifunctional RNA helicase implicated in mRNA unwinding and the regulation of gene expression. While DDX3 has been extensively studied in the context of RNA virus replication, its role in DNA virus replication remains less understood. In this study, we explore the involvement of DDX3 in the life cycle of Herpes Simplex Virus type 2 (HSV-2), a double-stranded DNA virus. Silencing of DDX3 expression with siRNA significantly impaired HSV-2 replication, indicating that DDX3 supports viral propagation. Unexpectedly, HSV-2 infection led to a marked reduction in cellular DDX3 protein levels during in vitro replication in human cells, particularly at 24 h post-infection, corresponding to the peak of viral production. Notably, this decrease was not accompanied by a reduction in DDX3 mRNA levels, nor was it prevented by proteasome inhibition, suggesting an alternative mechanism of DDX3 depletion. Further analysis revealed substantial amounts of DDX3 protein within HSV-2 virions, supporting the hypothesis that DDX3 is packaged into viral particles during replication. We propose that HSV-2 exploits host DDX3 by incorporating it into progeny virions to facilitate early stages of infection in newly infected cells. However, no evidence linking DDX3 to the assembly process of HSV-2 particles was found. These findings expand the known functional repertoire of DDX3 and highlight its potential as a host factor co-opted by DNA viruses, suggesting a broader relevance in antiviral strategies. Full article

Background: Monkeypox virus, the etiological agent of Mpox, is a double-stranded DNA virus belonging to the Orthopoxvirus genus that has attracted increasing attention due to sporadic outbreaks in humans. In 2022, it was responsible for the largest Mpox outbreak outside the African continent, infecting over 117,000 individuals worldwide. In Brazil, since the first confirmed case in June 2022, more than 13,000 people have been diagnosed with the virus. Methods: In July 2022, we developed the first molecular test for the detection of monkeypox virus in the Midwest region of the country, allowing the diagnosis of the disease in various patients, mainly residents of the Federal District. Thus, in this work, we present the validation of a laboratory-developed qPCR test (LDT) for monkeypox virus detection, as well as a retrospective epidemiological analysis based on laboratory results. Results: The developed qPCR test demonstrated 100% accuracy, with a detection limit of 21.25 copies per reaction, and was validated for samples from swabbed pustule exudates and lesion crusts. To date, 295 tests have been conducted, with 88 (30%) returning positive. The positivity rate was 41.15% in male patients and 2.41% in female patients. A peak in positivity was observed in August 2022. From 2023 to 2024, there was a marked decline in test demand with occasional positive results. Conclusions: The rapid implementation of the test by our laboratory allowed for an immediate response to patients and provided important data for understanding the dynamics of monkeypox virus spread in Brazil, particularly in the Midwest region. Full article

Epstein–Barr virus (EBV), a double-stranded DNA virus, is implicated in nasopharyngeal carcinoma (NPC), with particularly high incidence in regions such as southern China and Hong Kong. Although NPC is typically treated with radio- and chemotherapy, outcomes remain poor for advanced-stage diagnoses, highlighting the need for targeted therapies. This study explores the potential of CRISPR/CRISPR-associated protein 13 (Cas13) technology to target essential EBV RNA in NPC cells. Previous research demonstrated that CRISPR/Cas9 could partially reduce EBV load, but suppression was incomplete. Here, the combination of CRISPR/Cas13 with CRISPR/Cas9 shows enhanced viral clearance. Long-term EBNA1 suppression via CRISPR/Cas13 reduced the EBV genome, improved CRISPR/Cas9 effectiveness, and identified suitable AAV serotypes for delivery. Furthermore, cotreatment increased NPC cell sensitivity to 5-fluorouracil and cisplatin. These findings underscore the potential of CRISPR/Cas13 as an anti-EBV therapeutic approach, effectively targeting latent EBV transcripts and complementing existing treatments. The study suggests a promising new direction for developing anti-EBV strategies, potentially benefiting therapies for NPC and other EBV-associated malignancies. Full article

Tomato spotted wilt virus (TSWV) is a highly destructive plant pathogen and transmitted by several thrips including the western flower thrips, Frankliniella occidentalis. A structural N protein encoded in the viral genome represents the nucleocapsid protein by binding to the viral RNA genome. However, it remains unknown how the RNA-binding protein specifically interacts with the viral RNA from host RNAs in the target cells. To study the molecular basis of N function, we produced the protein in Escherichia coli and the resulting purified recombinant protein was used to investigate the protein–RNA interactions. The recombinant N protein migrated on agarose gel to the anode in the electric field due to its high basic isoelectric point. This electrostatic property led N protein to bind to DNA as well as RNA. It also bound to both single-stranded (ssRNA) and double-stranded RNA (dsRNA). However, when the total RNA was extracted from plant tissues collected from TSWV-infected host, the RNA extract using the recombinant N protein was much richer in the TSWV genome compared to that without the protein. To investigate the specificity of N protein to ssRNA, the three-dimensional structure was predicted using the AlphaFold program and showed its trimeric oligomerization with the binding pocket for ssRNA. This was supported by the differential susceptibility of N protein with ssRNA and dsRNA against RNase attack. Furthermore, a thermal shift assay to analyze the RNA and protein interaction showed that ssRNA strongly interacted with N protein compared to dsRNA. In addition, the N gene was expressed along with the multiplication of the viral RNA genome segments from the segment-specific fluorescence in situ hybridization analysis in different tissues during different developmental stages of the virus-infected F. occidentalis. These results suggest that the functional trimeric N proteins bind to the viral RNA to form a basic nucleocapsid structure at a specific virus-replicating compartment within the host cells. Full article

Endometrial cancer (EC) is the fourth-most frequent cancer among the female population and a leading cause of death. Multiple factors are susceptible to causing tumorigenesis, including obesity, lack of physical activity, diabetes mellitus, high concentration of estrogen during menopause, unopposed exposure to estrogen, duration of menses, nulliparity and infertility. Human papillomavirus (HPV) is a double-stranded DNA virus, with certain genotypes exclusively human. HPV plays a major role in some cancers (cervical cancer, head and neck cancer, lung cancer, and anogenital cancers). Given the intricate correlation between HPV and cervical cancer, the scientific community conjectured that HPV may be implicated in the carcinogenesis of the endometrium. In this review, we will direct our interest towards previous studies that focused on the expression of HPV on EC samples and cover how both conditions might connect to each other. Full article

Kaposi’s sarcoma-associated herpesvirus (KSHV) is an oncogenic double-stranded DNA virus. There are no vaccines or antiviral therapies for KSHV. Identifying the cellular metabolic pathways that KSHV manipulates can broaden the knowledge of how these pathways contribute to sustaining lytic infection, which can be targeted in future therapies to prevent viral spread. In this study, we performed an untargeted metabolomic analysis of KSHV infected telomerase-immortalized gingival keratinocytes (TIGK) cells at 4 h post-infection compared to mock-infected cells. We found that the metabolomic landscape of KSHV-infected TIGK differed from that of the mock. Specifically, a total of 804 differential metabolic features were detected in the two groups, with 741 metabolites that were significantly upregulated, and 63 that were significantly downregulated in KSHV-infected TIGK cells. The differential metabolites included ornithine, arginine, putrescine, dimethylarginine, orotate, glutamate, and glutamine, and were associated with pathways, such as the urea cycle, polyamine synthesis, dimethylarginine synthesis, and de novo pyrimidine synthesis. Overall, our untargeted metabolomics analysis revealed that KSHV infection results in marked rapid alterations in the metabolic profile of the oral epithelial cells. We envision that a subset of these rapid metabolic changes might result in altered cellular functions that can promote viral lytic replication and transmission in the oral cavity. Full article

The peptide TAT-I24, a fusion of the TAT peptide (amino acids 48–60) and the 9-mer peptide I24, has been previously shown to neutralize several double-stranded (ds) DNA viruses in vitro. We have now extended the testing to potentially sensitive RNA viruses and analyzed the antiviral effect of the peptide against Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). In Vero E6 cells, TAT-I24 neutralized the human 2019-nCoV isolate (Wuhan variant) in a dose-dependent manner, while it was unable to neutralize two SARS-CoV-2 variants of concern, Delta and Omicron. Moreover, TAT-I24 could not significantly neutralize any of the SARS-CoV-2 variants in the human lung carcinoma cell line Calu-3, which provides an alternative entry route for SARS-CoV-2 by direct membrane fusion. Therefore, a possible dependence on virus uptake by endocytosis was investigated by exposing Vero E6 cells to chloroquine (CQ), an inhibitor of endosomal acidification. The Wuhan variant was highly sensitive to inhibition by CQ, an effect which was further enhanced by TAT-I24, while the Delta variant was less sensitive to inhibition by higher concentrations of CQ compared to the Wuhan variant. The microscopic analysis of COS-7 cells using a rhodamine-labeled TAT-I24 (Rho-TAT-I24) showed the endosomal localization of fluorescent TAT-I24 and co-localization with transfected GFP-Rab14 but not GFP-Rab5. As these proteins are found in distinct endosomal pathways, our results indicate that the virus entry pathway determines sensitivity to the peptide. Full article

Polyomaviruses (PyVs) are non-enveloped double-stranded DNA viruses that can cause significant morbidity in allogeneic hematopoietic stem cell transplant (allo-HSCT) recipients, particularly BK polyomavirus (BKPyV) and JC polyomavirus (JCPyV). BKPyV is primarily associated with hemorrhagic cystitis (HC), while JCPyV causes progressive multifocal leukoencephalopathy (PML). The pathogenesis of these diseases involves viral reactivation under immunosuppressive conditions, leading to replication in tissues such as the kidney, bladder, and central nervous system. BKPyV-HC presents as hematuria and urinary symptoms, graded by severity. PML, though rare after allo-HSCT, manifests as neurological deficits due to JCPyV replication in glial cells. Diagnosis relies on nucleic acid amplification testing for DNAuria or DNAemia as well as clinical criteria. Management primarily involves supportive care, as no antiviral treatments have proven consistently effective for either virus and need further research. This review highlights the virology, clinical presentations, and management challenges of PyV-associated diseases post-allo-HSCT, emphasizing the need for improved diagnostic tools and therapeutic approaches to mitigate morbidity and mortality in this vulnerable population. Full article

Since the advent of the clustered regularly interspaced short palindromic repeats (CRISPR) system in the gene editing field, diverse CRISPR-based gene editing tools have been developed for treating genetic diseases. Of these, base editors (BEs) are promising because they can carry out precise gene editing at single-nucleotide resolution without inducing DNA double-strand breaks (DSBs), which pose significant risks of genomic instability. Despite their outstanding advantages, the clinical application of BEs remains challenging due to their large size, which limits their efficient delivery, particularly in adeno-associated virus (AAV)-based systems. To address this issue, various strategies have been explored to reduce the size of BEs. These approaches include truncating the nonessential domains and replacing the bulky components with smaller substitutes without compromising the editing efficiency. In this review, we highlight the importance of downsizing BEs for therapeutic applications and introduce recent advances in size-reduction strategies. Additionally, we introduce the ongoing efforts to overcome other limitations of BEs, providing insights into their potential for improving in vivo gene editing. Full article

Varicella-zoster virus is an α-herpes virus with a double-stranded DNA genome, which causes two main clinical pictures: varicella or chickenpox and herpes zoster. Chickenpox is the primary infection, predominantly affecting children, and it presents with fever and a cutaneous eruption consisting of a vesicular, pruritic, and painful rash. Herpes zoster is a viral infection that typically develops in adulthood as a result of the reactivation of the varicella-zoster virus. If acquired during pregnancy, chickenpox may be responsible for serious complications for the mother, the fetus, or the newborn. The most frequent complication of primary varicella-zoster virus infection in mothers is varicella pneumonia, while encephalitis and hepatitis are rare. The effects on the fetus due to chickenpox infection depend on the stage of pregnancy when the mother becomes infected. If the infection occurs during the first trimester, it does not increase the risk of miscarriage. However, if the infection occurs during the first or second trimester, it may cause fetal varicella syndrome or congenital varicella syndrome. During pregnancy, if the varicella-zoster virus reactivates, it usually does not cause harm to the fetus or lead to any birth defects. However, it may increase maternal morbidity due to herpes zoster and its complications. In the case of primary varicella-zoster virus infection in pregnant women, about 20% of newborns may get neonatal or infantile herpes zoster without any complications. However, it is recommended to start early treatment of herpes zoster in pregnant women as it is believed to accelerate the healing process of skin lesions and alleviate pain, reducing both its duration and severity. Through this narrative review, we discuss the approach to the optimal management of varicella-zoster virus infection during pregnancy. Full article

Banana streak GF virus (BSGFV) is the extremely dangerous monopartite badnavirus (genus, Badnavirus; family, Caulimoviridae) of banana (Musa acuminata AAA Group) that imposes a serious threat to global banana production. The BSGFV causes a devastating pandemic in banana crops, transmitted by deadly insect pest mealybug vectors and replicated through an RNA intermediate. The BSGFV is a reverse-transcribing DNA virus that has a monopartite open circular double-stranded DNA (dsDNA) genome with a length of 7325 bp. RNA interference (RNAi) is a natural mechanism that has revolutionized the target gene regulation of various organisms to combat virus infection. The current study aims to locate the potential target binding sites of banana-encoded microRNAs (mac-miRNAs) on the BSGFV-dsDNA-encoded mRNAs based on three algorithms, RNA22, RNAhybrid and TAPIR. Mature banana (2n = 3x = 33) miRNAs (n = 32) were selected and hybridized to the BSGFV genome (MN296502). Among the 32 targeted mature locus-derived mac-miRNAs investigated, two banana mac-miRNA homologs (mac-miR162a and mac-miR172b) were identified as promising naturally occurring biomolecules to have binding affinity at nucleotide positions 5502 and 9 of the BSGFV genome. The in silico banana-genome-encoded mac-miRNA/mbg-miRNA-regulatory network was developed with the BSGFV—ORFs using Circos software (version 0.69-9) to identify potential therapeutic target proteins. Therefore, the current work provides useful biological material and opens a new range of opportunities for generating BSGFV-resistant banana plants through the genetic manipulation of the selected miRNAs. Full article

The SARS-CoV-2 virus can cause hyperstimulation of the immune system, sometimes leading to the production of various autoantibodies and increased levels of interferons and interleukins in blood plasma. Background/Objectives: Only a few studies are currently focusing on the dynamics of immunological indices after any transferred infectious disease encountered by an organism for the first time. The attention of researchers and clinicians is captured by the dynamics of antibody titers and immunologic markers (interferons and interleukins), as well as the correlation of immunologic indices with changes in the symptomatology of long COVID. This paper discusses the association of antibodies against various autoantigens with rheumatological and neurological manifestations of COVID-19. Our study patient was a 36-year-old man diagnosed with polyneuropathy, which developed after COVID-19. We conducted a dynamic follow-up of the patient for two years. Methods: The blood plasma samples collected were analyzed by ELISA for different autoantigens, IFN-γ, and a variety of interleukins. Results: An association between rheumatologic and neurologic markers in patients with long COVID symptoms was considered. Antibody titers for myelin basic protein (MBP), double-stranded DNA (dsDNA), single-stranded DNA (dsDNA), and IFN-γ, IL-1, IL-6, and IL-10 levels significantly increased during the posthospital period when the patient reported persistent symptoms of long COVID, with complaints decreasing after the symptoms were resolved. Conclusions: The findings of this study shed light on the dynamic alterations of immunological factors, and elucidate the mechanism by which SARS-CoV-2 infection disrupts immunotolerance and eventually restores equilibrium, leading to the rheumatological pathology. Significantly, the notable rise in antibody titers for various autoantigens was transient and did not lead to the progression of autoimmune pathology. Full article

The tripartite-motif protein 56 (TRIM56) is a RING-type E3 ubiquitin ligase whose functions were recently beginning to be unveiled. While the physiological role(s) of TRIM56 remains unclear, emerging evidence suggests this protein participates in host innate defense mechanisms that guard against viral infections. Interestingly, TRIM56 has been shown to pose a barrier to viruses of distinct families by utilizing its different domains. Apart from exerting direct, restrictive effects on viral propagation, TRIM56 is implicated in regulating innate immune signaling pathways that orchestrate type I interferon response or autophagy, through which it indirectly impacts viral fitness. Remarkably, depending on viral infection settings, TRIM56 either operates in a canonical, E3 ligase-dependent fashion or adopts an enzymatically independent, non-canonical mechanism to bolster innate immune signaling. Moreover, the recent revelation that TRIM56 is an RNA-binding protein sheds new light on its antiviral mechanisms against RNA viruses. This review summarizes recent advances in the emerging roles of TRIM56 in innate antiviral immunity. We focus on its direct virus-restricting effects and its influence on innate immune signaling through two critical pathways: the endolysosome-initiated, double-stranded RNA-sensing TLR3-TRIF pathway and the cytosolic DNA-sensing, cGAS-STING pathway. We discuss the underpinning mechanisms of action and the questions that remain. Further studies understanding the complexity of TRIM56 involvement in innate immunity will add to critical knowledge that could be leveraged for developing antiviral therapeutics. Full article

Bats are mammals with high biodiversity and wide geographical range. In Brazil, three haematophagous bat species are found. Desmodus rotundus is the most documented due to its role as a primary host of rabies virus in Latin America. Bats are known to harbor various emerging viruses causing severe human diseases. Beyond zoonotic viruses, these animals also harbor a diversity of non-zoonotic viruses. Papillomaviruses are circular double-stranded deoxyribonucleic acid (dsDNA) viruses that infect the epithelial and mucosal cells of many vertebrates, occasionally causing malignant lesions. High-throughput sequencing has enabled papillomaviruses discovery in different bat species. Here, 22 D. rotundus samples were collected through the rabies eradication program in Rio Grande do Sul. The DNA extracted from pooled intestines was amplified by the rolling-circle amplification (RCA) method and sequenced using the Illumina^® MiSeq platform (San Diego, CA, USA).Analysis revealed three contigs corresponding to the Papillomaviridae family, representing three novel viruses named DrPV-1, DrPV-2, and DrPV-3. Phylogenetic analysis suggests DrPV-1 may constitute a new species within the Dyophipapillomavirus genus, while DrPV-2 and DrPV-3 may represent different types within the same species from a novel genus. This is the first description of a papillomavirus in the D. rotundus species, contributing to the characterization of PVs in the Chiropteran order. Full article