Objectives: To investigate the profile of Th1- and Th2-type cytokines in response to Epstein–Barr virus (EBV) antigens and to correlate this immune signature with clinical relapses in Multiple Sclerosis (MS). Specifically, we aimed to evaluate the cellular and humoral immune response following stimulation with a pool of lytic and latent EBV proteins. Methods: We employed ELISpot and ELISA to quantify Interferon-gamma (IFN-γ), Interleukin-18 (IL-18), Interleukin-10 (IL-10), and the B-cell activation marker soluble CD23 (sCD23). Measurements were performed on peripheral blood mononuclear cells (PBMCs) from MS patients and controls following stimulation with EBV peptide antigens. Results: MS patients exhibited significantly higher levels of all tested cytokines compared to controls. A statistically significant positive correlation was noted between IL-10 and sCD23 levels (p < 0.03), with significant correlations also found between IL-10 and IFN-γ (r = −0.56) and between IFN-γ and IL-18 (p < 0.02), a finding that warrants cautious interpretation. Crucially, both IL-10 and sCD23 levels strongly correlated with the Expanded Disability Status Scale (EDSS) score (p = 0.0003 and p = 0.0001, respectively). Conclusions: Our findings suggest a chronic, dysregulated immune response to EBV antigens in MS patients, characterized by the co-activation of inflammatory Th1 pathways and robust B-cell activation. These results support a pathogenetic model where the EBV-specific immune response, perpetuated by infected B-cells, may directly contribute to the immunopathological processes driving central nervous system (CNS) damage and clinical relapses.

Viral infections in humans and animals are increasing, and retrospective studies using formalin-fixed, paraffin-embedded (FFPE) samples reveal recurring outbreaks over past decades. However, the impact of pre-analytical factors like fixation and autolysis on immunohistochemistry (IHC) remains insufficiently understood. To examine how autolysis, fixation duration (6–72 h) and formalin concentration (2.5–25%) influence histology and IHC of canine distemper virus (CDV, Morbillivirus canis), interferon-β (IFN-β), and selected IFN-stimulated genes (ISGs), the study was conducted using an in vitro model based on persistently CDV-infected and non-infected DH82 cells (canine histiocytic sarcoma cell line). Autolysis led to a progressive loss of cell morphology, whereas formalin fixation had minimal impact. CDV nucleoprotein, ISG15, and myxovirus resistance protein (Mx) showed stable immunohistochemical signals across all fixation conditions and remained detectable after prolonged autolysis. CDV infection upregulated ISG15 and Mx. In contrast, IFN-β and phosphorylated protein kinase R (pPKR) exhibited variable staining and did not distinguish infected from non-infected samples. Overall, autolysis had a stronger negative impact on IHC signal quality than fixation parameters. Despite the limitations of the in vitro model, the robustness of CDV, ISG15, and Mx under suboptimal conditions highlights their potential utility as virus-sensing markers in FFPE material.

Dendritic cells (DCs) are among the first immune cells to detect viral invasion and play a central role in initiating and shaping antiviral immune responses. Many innate and adaptive immune functions of DCs are regulated by cathepsins, proteolytic enzymes primarily found in acidic endolysosomal compartments. Different DC subsets exhibit distinct cathepsin expression patterns, influencing their functional capacities and interactions with viruses. In DCs, cathepsins contribute to virus sensing through innate receptors, regulate cytokine production and DC migration, and are essential for viral antigen degradation and loading onto MHC molecules for T-cell activation. Many viruses, however, have evolved mechanisms to alter cathepsin expression and activity, thereby subverting DC function and promoting their own persistence. Indeed, cathepsins can facilitate viral entry into DCs, promote viral replication, and support immune evasion strategies. In this review, we summarize recent advances in understanding the role of cathepsins in DC–virus interactions, emphasizing both how DCs exploit cathepsins to generate protective immune responses and how viruses manipulate cathepsin activity to their advantage. We particularly focus on clinically relevant viral pathogens, including HIV, influenza virus, hepatitis C virus, human cytomegalovirus, Ebola virus, and SARS-CoV-2, to illustrate the multifaceted influence of cathepsins on DC biology during viral infection.

Detection of cross-reactivity of antibodies to the N proteins of feline morbillivirus and canine distemper virus in Japanese cat plasma samples.

Decoding long COVID-associated cardiovascular dysfunction: Mechanisms, models, and new approach methodologies.

Evaluation of optimized ELISA to detect anti-cytomegalovirus antibodies against immunogenic proteins.

HBV antigen as a tumour antigen in adoptive TCR-T cell therapy for HBV-related HCC: rationale and clinical effectiveness.

The persistence of HIV latent reservoir is the major challenge to HIV cure because latent viruses serve as sources for viral rebound upon ART cessation. Mechanisms regulating viral persistence are not well understood; thus, there is a compelling need for research focusing on addressing the knowledge gap related to HIV persistence. The present study focuses on the effect of extracellular condensates (ECs) on latent HIV/SIV reactivation in the brain in the context of HIV infection using the SIV-infected rhesus macaque model. We used in vitro model systems of post-integration latency and primary peripheral blood mononuclear cells isolated from HIV-infected ART-suppressed donors to explore the role of basal ganglia (BG) isolated extracellular condensates (ECs) in reprogramming HIV latent cells. We found that BG ECs from uninfected macaques (VEH) and SIV infected macaques (VEH | SIV) activated latent HIV transcription in various model systems. VEH | SIV ECs significantly increased the expression and production of viral antigen in latently infected cells. Activation of viral transcription, antigen expression, and latency reactivation was inhibited by ECs from the brain of macaques treated with Delta-9-tetrahydrocannabinol (THC) and infected with SIV (THC | SIV). Virus produced by latently infected cells treated with VEH | SIV ECs potentiated cell-cell and cell-free HIV transmission. VEH | SIV ECs also reversed dexamethasone-mediated inhibition of HIV transcription while TNFα-mediated reactivation of latency was reversed by THC | SIV ECs. Transcriptome and secretome analyses of total RNA and supernatants from latently infected cells treated with ECs revealed significant alterations in gene expression and cytokine secretion. THC | SIV ECs increased secretion of Th2 and decreased secretion of proinflammatory cytokines. Most strikingly, while VEH/SIV ECs robustly induced expression of HIV RNA in latently HIV-infected cells, increased the frequency of HIV gag p24 expressing cells in HIV-infected CD4 + T cells within PBMCs, and production of extracellular HIV gag p24, long-term low-dose THC administration enriched ECs with anti-inflammatory cargo that significantly diminished their ability to reactivate latent HIV, an indication that ECs are endogenous host factors that may regulate HIV persistence.

Hemorrhagic fever viruses have been shown to localize to immune-privileged sites, including the reproductive tract, raising important questions about long-term persistence and the potential for sexual transmission. Anecdotal evidence of sexual transmission of Crimean-Congo hemorrhagic fever virus (CCHFV) has been reported, and in vivo studies suggest that CCHFV can localize to reproductive tissues; however, to date, this phenomenon has not been explicitly investigated. We evaluated histopathology and viral loads (viral RNA, viral antigen, and infectious viral titers) in reproductive tissues obtained from lethal and survivor mouse models of CCHFV during acute and convalescent phases of infection. Viral loads in urogenital swabs were also evaluated to assess the potential for virus transmission. Although no evidence of long-term persistence was observed in the survivor model of CCHF, our data indicate a potential for sexual transmission during acute infection, even in cases of mild disease, as infectious virus was isolated from urogenital swabs. These data support the importance of sampling human patients to better define the risk of sexual transmission and potential viral persistence in reproductive tissues during and after recovery from CCHF.

The pathogenic mechanisms underlying autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy (GFAP-A), a central nervous system disorder associated with GFAP autoimmunity, remain controversial. The present study aimed to investigate the potential role of the intrathecal reactivation of Epstein-Barr virus (EBV) in patients with GFAP-A. EBV-DNA levels were measured in the cerebrospinal fluid (CSF) and blood samples of 14 patients with GFAP-A and 28 patients with other disorders. IgM and IgG antibodies against EBV viral capsid antigen (VCA) and IgG antibodies against early antigen (EA) were also measured in serum samples. EBV-DNA was detected in the CSF samples in 10 of the 14 patients with GFAP-A and in 1 of the 28 patients in the disease control group, with a significant difference between the two groups (71.4% vs 3.6%; p<0.0001). Conversely, EBV-DNA was not detected in the blood of the 13 patients with GFAP-A. In patients with GFAP-A, the CSF-EBV-DNA level was significantly associated with the worst modified Rankin scale score during the acute phase (rs=0.6143, p=0.0194). Serum antibody profiling revealed evidence of past EBV infection, with VCA-IgG positivity and VCA-IgM and/or EA-IgG negativity observed in 92.9% of the patients with GFAP-A. The study findings suggest that GFAP autoimmunity is associated with intrathecal EBV reactivation.

Detection of Torque Teno Sus Virus1 by an RNA in situ hybridization assay.

BackgroundCross-species transmission of several viral neuropathogens may lead to fatal disease in incidental hosts. The newly discovered rustrela virus (RusV) as well as Borna disease virus 1 (BoDV-1), tick-borne encephalitis virus (TBEV), and highly pathogenic avian influenza virus (HPAIV) of hemagglutinin subtype H5 may cause fatal lymphocytic meningoencephalitis in a broad range of mammalian species after crossing species borders. Here, we tested brain tissue samples from 191 animals representing 19 mammalian species diagnosed with lymphocytic meningoencephalitis from 1989 to 2024 for these four neuropathogens by RT-qPCR. Positive samples were analysed for cell-associated viral RNA or viral antigen by RNA in situ hybridisation or immunohistochemistry, respectively.ResultsFor the first time RusV was detected in one out of two tested maned wolves (50%). Further, two out of 50 cats (4.0%) and the only tested donkey were infected. BoDV-1 and TBEV were found in three out of eight horses (37.5%) and one out of 78 dogs (1.3%), respectively. Neurons were the main target cells for all three pathogens. Partial genomic RusV and BoDV-1 sequences matched with the predominant virus types in the study region. Influenza A virus RNA was not detected in any of the samples.ConclusionsThe host range of RusV was extended to Canidae, represented by a fatal case of a maned wolf. Both RusV and BoDV-1 seem to be important pathogens causing lymphocytic meningoencephalitis in other mammalian species and their distribution should be monitored closely.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12917-025-05132-w.

Influenza virus elicits respiratory tract disease and is a threat to global human health. Vaccination is considered an effective tool for reducing the morbidity and mortality caused by influenza disease. The only licensed live-attenuated influenza vaccine that has been proven safe and effective is FluMist. In this study, we isolated an attenuated influenza mutant virus with a Lys471 single amino acid substitution in PB1, which displayed a temperature-sensitive and a low-pathogenicity phenotype. By applying the PB1-Lys471 substitution to the vaccine mother strain or the circulating influenza virus using reverse genetic technology, a high-performance and safe live-attenuated vaccine carrying the viral antigens of the vaccine-targeted strain can be developed.

Hepatitis B virus (HBV) is a hepatotropic DNA virus that infects over 250 million people worldwide and causes serious liver diseases. HBV infection can modulate host cellular processes, potentially inducing proteomic changes in hepatocytes. In this study, we investigated how acute HBV infection alters the proteome and secretome of primary human hepatocytes, a physiologically relevant in vitro model that retains essential liver-specific functions. Protein-level changes in cell lysates and culture supernatants were quantified 8 days post-infection using data-independent acquisition MS. We used HBV infection in the presence of the entry inhibitor bulevirtide as a control to separate the effects of productive infection from those caused by inoculum-associated components. Despite robust infection, active HBV replication induced only subtle changes in host protein levels. Orthogonal validation of MS-identified candidates confirmed reticulocalbin-2 as a novel host factor downregulated during productive HBV infection. The functional role of candidate proteins identified by MS was assessed in vitro by siRNA-mediated knockdown and measurement of viral replication markers. Knockdown had no impact on viral RNA or antigen levels, suggesting that the observed proteomic changes may reflect stress responses or broader modulation of the hepatic microenvironment. Our findings support the concept of HBV as a stealth virus and underscore the importance of carefully controlled experimental systems for studying host responses to infection in vitro.

Predictors of antiviral treatment in Chronic Hepatitis -B (CHB) population.

ABSTRACTThe emergence of SARS‐CoV‐2 posed a major global public health threat, necessitating urgent development of therapeutics. Despite vaccine availability, continuous emergence of viral variants with enhanced transmissibility and immune escape capabilities, and consequential impacts on health services, requires effective antiviral therapeutics. Drug repurposing offers an expeditious strategy to identify therapeutics with established safety profiles. We implemented a comprehensive three‐tiered validation approach, screening 2,570 compounds against SARS‐CoV‐2 in vitro, followed by ex vivo validation in well‐differentiated primary human bronchial epithelial cell (WD‐PBEC) cultures, and rigorous in vivo assessment. This methodical progression identified Azatadine‐Dimaleate, a H1‐receptor antagonist, as an exceptional candidate with consistent efficacy across all systems. Azatadine‐Dimaleate demonstrated potent antiviral activity‐ EC50: 4.0 µM (95% CI: 3.2–4.8 µM), reducing viral replication by ~5,000‐fold at 25 µM in epithelial cultures and lowering peak viral titers in WD‐PBECs by 1.4 log10, and 2.33 log10 at 48 and 96 hpi, respectively, compared to controls. There was also a concomitant reduction in expression of interferons and pro‐inflammatory genes, including IL‐6. Combination with Remdesivir synergistically enhanced antiviral activity, reducing the EC50 of both drugs by > 60%. In the K18‐hACE2 transgenic mouse model, Azatadine‐Dimaleate significantly reduced weight loss (4% vs. 12%, p ≤ 0.05), decreased viral loads, and halved viral antigen expression in lung tissues. Unlike many candidates that faltered in complex models, Azatadine‐Dimaleate maintained efficacy across all platforms. These findings support its clinical evaluation, alone or in combination with Remdesivir, as a versatile therapeutic with strong potential to address current and emerging SARS‐CoV‐2 variants.

Analysis of antiviral functions, differences and apoptotic effects of two novel MHC-Iα genotypes in orange-spotted grouper (Epinephelus coioides).

The dairy industry in India is emerging as one of the key agribusiness sectors, significantly contributing to the national economy. However, despite its high significance, the dairy business is vulnerable to various diseases. The bovine respiratory syncytial virus (BRSV) is the most common viral infection affecting the respiratory system, especially in calves. The association of BRSV with the development of pneumonia is well-established globally; however, only limited research has been conducted on its prevalence and associated pathology in India. This study aims to investigate the pathology and prevalence of BRSV among bovine calves under one year of age. Thirty calves necropsied from June 1st, 2021, to June 30th, 2022, were included in the research to investigate BRSV pathology using cytological, gross, histopathological, and immunohistochemical examinations. A total of 228 samples were collected for BRSV detection, comprising 30 tissue samples from necropsy, 130 samples from clinically ill calves (121 nasal and 9 ocular swabs), and 68 nasal swabs from apparently healthy calves. In cases where BRSV was detected, the main gross findings during necropsy were cranioventral consolidation, rubbery and non-collapsing lungs having rib impressions. Histopathologically, necrotising bronchiolitis and bronchitis, thickening of the interalveolar septa, and multiple numbers of syncytial cells in the alveolar lumen, along with the infiltration of inflammatory cells, mainly lymphocytes, were evident. The cytological examination revealed multi-nucleated cells along with the infiltration of inflammatory cells, mainly lymphocytes. Immunohistochemical examination revealed the presence of viral antigen in syncytial cells along with cells from the bronchial and bronchiolar epithelium, including inflammatory cells, predominantly macrophages. The prevalence of BRSV was found to be 50% (15/30; 95% CI: 33.2-66.8) in necropsied samples and 23.73% (47/198; 95% CI: 18.0-30.3) in clinical samples tested by nested RT-PCR targeting the nucleoprotein (N) gene having an amplicon size of 435bp. This study concludes that BRSV causes significant morbidity and mortality in bovine calves and requires timely diagnosis and management to prevent heavy economic losses.

SARS-CoV-2 infection is associated with long-lasting neuropsychiatric and cognitive symptoms, collectively referred to as neuro-PASC. Emerging studies indicates that accelerate brain aging and cellular senescence in COVID brain could lead to altered neuroimmune responses and neurodegenerative outcomes. However, little is known about how cellular senescence is development in neuro-PASC. Here, we examined the role of spike protein subunit S1, a persistent viral antigen, in driving the development of cellular senescence in primary human astrocytes. We have demonstrated that S1 enters endolysosomes and induces endolysosome dysfunction and cellular senescence. Moreover, the multibasic motif is critical for such S1-induced damaging effects. Importantly, we identified Toll-like receptor 7 (TLR7), an endolysosome-resident pattern recognition receptor, as a critical mediator of S1-induced damaging effects. Mechanistically, S1 interacts with TLR7 at the site of the endolysosome lumen and activates p38 MAPK signaling of downstream of TLR7, which drive the development of cellular senescence. Together, these findings suggest that TLR7 mediates S1-induced endolysosome dysfunction and cellular senescence, and that TLR7 represents a therapeutic target for mitigating neuro-PASC.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12974-025-03586-1.

A single-chain mRNA vaccine co-expressing GPC and NP provides complete protection against lethal Dabie bandavirus challenge in mice