Viruses that infect single-celled algae strongly regulate microalgae growth and community composition through cell lysis, enable nutrient recycling in marine ecosystems, and offer valuable insights into early stages of viral evolution. One major group, the Bacilladnaviridae family of single-stranded DNA viruses, infects diatoms in marine environments. Here, we present the capsid structure of Chaetoceros lorenzianus DNA virus (ClorDNAV, Protobacilladnavirus chaelor) determined at 2.2 Å resolution, thereby expanding the known structural diversity within the Cressdnaviricota phylum. The ClorDNAV capsid protein (CP) contains a conserved jelly-roll fold and a surface-exposed projection domain, with both N- and C-termini oriented toward the capsid interior. A low-resolution reconstruction of the genome revealed a spooled arrangement of the outer DNA layer, similar to that observed in Chaetoceros tenuissimus DNA virus type II (CtenDNAV-II). Structural comparison with CtenDNAV-II revealed five key CP differences: the absence of surface-exposed C-terminal tails in ClorDNAV, the presence of a helical domain, differences in the projection domain conformation, variation in the number of β-strands in the jelly-roll fold, and the lack of ion-attributed densities at subunit interfaces. Together with the genome reconstruction, these findings underscore the importance of experimentally determined structures for understanding viral architecture and evolution. To complement these results, we analyzed AlphaFold3-predicted CPs from all classified Bacilladnaviridae genera. These models confirmed the conservation of the jelly-roll fold across the family while revealing variability in the surface-exposed and terminal regions, likely reflecting host-specific adaptations and genome packaging strategies. Together, the experimental and predicted structures provide a comprehensive view of structural conservation and divergence in Bacilladnaviridae. Furthermore, the results provide additional structural evidence for the evolution of ssDNA Bacilladnaviridae from a noda-like ssRNA virus ancestor and suggest a shared genome organization resembling that of double-stranded viruses.

Hepatitis E virus (HEV) is an emerging zoonosis that can lead to chronic hepatitis in immunocompromised individuals. While HEV genotype 3 circulates in Argentina, data on pediatric populations, especially those immunosuppressed, are scarce. We hypothesized that immunosuppressed children in a region with known zoonotic HEV circulation would show higher seroprevalence compared to healthy controls.

Cell-free DNA (cfDNA) has emerged as a relevant biomarker reflecting disease severity in hospitalised COVID-19 patients, correlating with respiratory failure and mortality. However, its utility has not yet been evaluated in general practitioner setting.

At present, the Monkeypox virus (MPXV) outbreak has become a significant public health concern, and its severity is increasing based on different clades globally, which, combined, are leading to severe complications. However, it was observed that MPXV infection was highly expressed in individuals with Human Immunodeficiency Virus (HIV), and the mechanism of cross-talk has not been explored.

Bovine coronavirus (BCoV) causes neonatal calf diarrhea (CD), winter dysentery in young cattle (WD), and respiratory system infections in cattle of all ages worldwide. The aim of this study was the detection, isolation, and investigation of the frequency, and molecular characterization of circulating BCoVs in cattle in the Thrace district of Türkiye. It was also aimed to determine genotypes and variants to include in vaccine and vaccination strategies.

We explored laboratory marker patterns in patients diagnosed with severe fever with thrombocytopenia syndrome (SFTS) and evaluated their relationships with disease severity and clinical outcomes.

Mesenchymal stromal cells (MSCs) are a population of undifferentiated, non-hematopoietic fibroblast-like cells isolated from several tissues with multipotent differentiation capacity in vitro. This study focused on the establishment and characterization of a mesenchymal stromal cell line derived from ovine peripheral blood mononuclear cells (PBMCs).

Hepatitis E virus (HEV) is a major cause of viral hepatitis in low- and middle-income countries, particularly in South Asia, where poor sanitation facilitates its fecal-oral transmission. Nepal, Bangladesh, and Pakistan experience a significant HEV burden, with severe outcomes in high-risk groups like pregnant women and hepatic patients, who face elevated mortality rates. This systematic review and meta-analysis aimed to estimate HEV seroprevalence in these countries, focusing on the general population, pregnant women, and hepatic patients, to inform public health strategies.

Amidst rising antimicrobial resistance, bacteriophage (phage) therapy has re-emerged as a pivotal weapon against multidrug-resistant pathogens. Jumbo phages, distinguished by large genomes, show particular therapeutic promise. Yet current understanding of jumbo phages is still lacking.

The Rabbit Hemorrhagic Disease Virus (RHDV) represents a significant threat to rabbit populations globally, affecting both wild and domesticated rabbits, with mortality rates ranging from 50% to 90%. Despite its severity, there is currently no specific treatment available for RHDV. This study investigates the potential of natural compounds derived from Nigella sativa as antiviral agents against RHDV. Molecular docking analysis was conducted to explore the interaction between eleven compounds from Nigella sativa and the two key proteins of RHDV, viral protein genome-linked (VPg) and RNA-dependent RNA polymerase (RdRP), as key proteins involved in viral replication. Explicit-solvent MD (100 ns, 310 K) was performed for four top complexes (VPg/RdRP with nigellidine and dithymoquinone), tracking backbone/ligand RMSD, radius of gyration, H-bond counts, and per-residue RMSF, with equilibrated frames analyzed by PCA and MM-GBSA. The results revealed successful docking of all compounds from Nigella sativa to both VPg and RdRP proteins. From Nigella sativa compounds, Nigellidine and Dithymoquinone displayed strong interactions with VPg and RdRP and formed various hydrogen bonds and hydrophobic interactions, indicating their potential as inhibitors of viral replication. Interestingly, all ligands demonstrated favorable drug-likeness properties, adhering to Lipinski's Rule of Five and exhibiting desirable pharmacokinetic profiles. Thymohydroquinone and nigellidine displayed the highest lipophilicity, suggesting their potential for efficient tissue penetration and distribution. Complexes remained stable and retained poses, with reduced pocket flexibility, favorable MM-GBSA ΔG_bind, and tighter PCA clustering-supporting sustained binding and pocket stabilization. These findings suggest that compounds from Nigella sativa show promise as natural antiviral agents against RHDV. Nevertheless, additional experimental validation through in vitro and in vivo studies is essential to confirm the effectiveness and safety of these compounds for treating RHDV infection.

Since its emergence in late 2019, SARS-CoV-2 has evolved into multiple variants with distinct genetic and clinical features. Among them, the Omicron variant (B.1.1.529) and its sublineages BA.2.75, JN.1.8, and KP.2 have shown enhanced transmissibility and immune evasion, while generally exhibiting reduced lower respiratory tract pathogenicity compared to earlier variants, thereby continuing to pose significant challenges to public health. In India, these variants have significantly shaped the trajectory of the pandemic, necessitating focused evaluation of their biological and clinical impact. This review aims to provide a comprehensive study on the virology, pathophysiology, and systemic manifestations of Omicron and its emerging subvariants upto July 2025. We discuss their mechanisms of entry and replication, interaction with ACE2 and TMPRSS2 receptors, and evasion of host immune responses. Particular emphasis is placed on multi-organ involvement beyond the respiratory system, including neuro-respiratory dysregulation, cardiovascular complications, hepatic injury, gastrointestinal disturbances, and renal dysfunction. Furthermore, we evaluate the effectiveness of available vaccines, antiviral therapies, and diagnostic tools, alongside emerging clinical strategies such as vagus nerve stimulation, thermal modulation, and respiratory muscle training. By integrating molecular insights with clinical outcomes, this review highlights the multifaceted and systemic nature of Omicron-induced disease. We underscore the urgent need for variant-specific immunisation, early intervention strategies, and robust genomic surveillance to mitigate long-term sequelae and guide preparedness for future outbreaks.

Viral meningitis is a frequent cause of central nervous system (CNS) inflammation, typically presenting with headache, fever, photophobia, and neck stiffness. While enteroviruses and herpes simplex virus are the most common etiologies, Human Herpesvirus 7 (HHV-7), a rarely recognized cause, is increasingly implicated in aseptic meningitis, particularly in immunocompetent adults. HHV-7 is a T-lymphotropic virus that primarily affects CD4 + T lymphocytes, and it is globally prevalent, with over 95% of adults seropositive for the virus. Though traditionally associated with mild childhood diseases like exanthems and febrile seizures, HHV-7 has been linked to neurological complications, including meningitis, encephalitis, and myelitis. A 37-year-old Italian female with a 10-year history of vegetarianism and a 2-year history of pap smear-diagnosed Human Papillomavirus (HPV)-associated low-grade squamous intraepithelial dysplasia was admitted for a 3-day history of progressive worsening lower back pain radiating to bilateral posterior lower limbs and soles paresthesia. Physical examination shows bilateral positive Lasegue sign, bilateral pain upon palpation of 4/4 Valleix's points, and absence of ankle reflexes, otherwise intact. Initial blood laboratory investigations reveal mild leukocytosis (10.92 G/L) with normal C-reactive protein (CRP), folate, and cobalamin. Cerebrospinal fluid (CSF) analysis shows 441 white blood cells/mm³, elevated protein (1.073 g/L), and positive Pandy reaction. HHV-7 was detected via CSF polymerase chain reaction (PCR); other bacterial and viral pathogens were negative. Patient demonstrates remarkable recovery after 5 days, along with pain control.

Feline leukemia virus (FeLV) significantly impacts feline health worldwide. Although several FeLV antigen rapid tests are available, selecting an accurate diagnostic tool remains a clinical challenge. In this paper, we present a novel and robust point-of-care assay that enables the precise diagnosis of FeLV antigen in blood, plasma, and serum and directly compared it with five other commercially available rapid FeLV antigen tests. Among the evaluated assays, Vet Expert and SNAP demonstrated 100% sensitivity, specificity, and accuracy, equaling gold-standard performance. Results demonstrate Vet Expert's superior diagnostic accuracy and practical applicability in both veterinary practice and disease control strategies.

Giant virus discovery in 2003 revolutionized the virus paradigm. In 2015, we introduced a new host, Vermamoeba vermiformis, that led to the discovery of Faustovirus, Orpheovirus and two giant viruses (Clandestinovirus and a faustovirus) having distinct cytopathic effects despite being co-isolated from the same environmental sample and culture. This raised concerns about the possibility that the most "discreet" virus be overlooked. Here we report on Usurpativirus, a new giant virus closely related to Clandestinovirus and co-isolated with Faustovirus LCD7 in V. vermiformis. Its non-lytic replicative cycle was primarily overlooked in presence of the lytic Faustovirus. The Usurpativirus genome encode two tRNAs and 758 predicted proteins, and share 707 and 202 orthologs with Ushikuvirus and Clandestinovirus, respectively. We detected four histone-like proteins that further challenge the compaction of DNA from these large genomes into icosahedral capsids of approximately 240 nm, as well as four capsid-associated proteins, but we did not detect any predicted proteins involved in entry/fusion that could explain the special replication strategy of this virus. Scanning electron microscopy revealed two distinct morphologies for amoebae infected with Usurpativirus, which became either rounded with a smooth surface or more flattened with a wavy surface. In addition, virions were observed attached to the outside of the amoebae, which most often had a smooth surface and rarely an undulating surface after 6 days of infection. Finally, such co-infection with two distantly-related giant viruses questions on the possible interactions between each other.

Okutama tick virus (OKTV) is a novel tick-borne RNA virus that has been reported in Japan and China. In the present study, an OKTV was detected in Haemaphysalis flava that had bitten a raccoon dog in South Korea by reverse transcription polymerase chain reaction using viral family-specific primers. Whole-genome sequencing revealed that the South Korean OKTV strain contains L and S segments with lengths of 6,529 and 1,890 nucleotides, respectively. Phylogenetic analyses revealed that OKTV strains formed two clusters based on the L segment and three clusters based on the S segment, with the South Korean strain forming a common cluster with three Chinese strains (SDQDH01, SDQDH04, and SDQDR04). Sequence comparisons showed high conservation among OKTV strains, with nucleotide identities of at least 97.74% and amino acid identities of at least 98.53% for both the L and N genes. Notably, the South Korean strain exhibited the highest amino acid similarity with the Chinese strain SDQDH04 (99.86% similarity in RdRP and 100% similarity in N protein). Selection pressure analyses revealed low dN/dS ratios for the L (0.0326) and N (0.0927) genes, with no sites detected under positive selection. Collectively, this study provides the first genomic characterization of OKTV in South Korea, expanding its geographical distribution and contributing to our genetic understanding of this virus. Although infectivity in animal hosts has not been established, further studies are needed to assess the zoonotic potential of OKTV.

Dengue is one of the fastest spreading arboviral infection with no specific antiviral treatment, making vaccination a significant preventive approach. Several dengue vaccines have been developed, but their efficacy, safety, and serotype-specific protection remain areas of concern. Over the past five years, new clinical data have emerged, influencing vaccine recommendations and deployment strategies. This systematic review analyses recent dengue vaccine data, assessing their effectiveness, and safety profiles.

Nucleotide (nt) deletions in the VP1 region of poliovirus are extremely rare. However, as early as 2012, we detected a natural type 2 poliovirus strain in sewage, originating from the Sabin 2, which exhibited such deletions. Whole-genome analysis revealed that the virus genome is 7,436 nt in length, with three nucleotide deletions in positions 16-18 of the VP1 region (2,497-2,499 nt), resulting in a deletion of the amino acid at position six of the VP1 capsid protein. Notaly, the missing amino acids are not located at known attenuation or neutralization sites. In addition, the important attenuated sites at positions 481 and 2,909 remained unchanged. Only one substitution was observed at the known neutralizing antigen site: VP3-61 (Arg to Lys) on NAg3a. Recombinant analysis showed that the virus is a type 2/3 recombinant virus, with the crossover site located between nucleotides 6,981 and 7,439, spanning the 3D region and the 3' untranslated region (UTR). The protein structure simulation showed that VP1 capsid protein of the PV-2 deletion variant was very similar to Sabin 2. In the VP1 region, the PV-2 deletion variant has only a triple nucleotide deletion, with no other mutations, indicates that the virus was in an early stage of evolution before being isolated from sewage. Furthermore, this variant is only a type 2/3 recombinant, not recombined with other non-polio enteroviruses, suggesting a short transmission and circulation time of the virus in the population. Therefore, we speculate that the nucleotide deletion in VP1 region of poliovirus may occur in the early evolutionary stage. Although the virus has not yet spread widely among humans, these findings highlight the importance of continuous environmental monitoring of poliovirus.

To identify early predictive factors for hepatitis B surface antigen (HBsAg) clearance at week 48 following pegylated interferon (Peg-IFN) therapy in inactive HBsAg carriers (IHC), and to develop an early machine learning-based model to assist clinical decision-making.

Rabies, a lethal viral encephalitis caused by Rabies virus (RabV), is transmitted via bites, scratches, or mucosal contact with infected animals, as well as through inhalation of aerosolized particles, ingestion of contaminated raw animal products, or transplantation of infected organs. It's near-universal fatality, diverse transmission routes, and marked clinical variability significantly impede timely diagnosis, highlighting the demand for a rapid and precise diagnostic approach.

Human immunodeficiency viruses (HIV-1 and HIV-2), are the causative agents of the acquired immunodeficiency syndrome (AIDS), that share substantial genomic and structural similarities, yet differ in replication dynamics and disease progression. While HIV-1 primarily enters host cells via CD4 and the chemokine co-receptors CCR5 and CXCR4, HIV-2 engages a broader range of chemokine receptors. The transferrin receptor (TFRC/CD71), a membrane protein essential for iron uptake and immune function, has recently been implicated in viral entry by other pathogens. In this study, we investigated the modulation of TFRC expression following transduction with HIV-1 and HIV-2 pseudovirions.

Nudix enzymes constitute a family of hydrolases that share a conserved Nudix motif, which catalyzes the hydrolysis of nucleoside diphosphates linked to another moiety X. Some members are cellular and viral decapping enzymes that hydrolyze the 5´ cap structure on an mRNA molecule. Unlike vaccinia virus, which encodes two Nudix enzymes, orf virus (ORFV) encodes only a single Nudix-containing gene, ORFV071 (OV71). This study investigates the biochemical properties of recombinant OV71 protein and its role in viral replication.