Search Results (1,047)

Requirements for novel effective antiviral agents against SARS-CoV-2 emphasizes the importance of robust in vitro screening platforms. We developed a test system based on spike-pseudotyped lentiviruses, carrying either luc+ or EGFP reporter genes as a payload, and a human non-small cell lung carcinoma (NSCLC) cell line, overexpressing ACE2 (H1299-hACE2). The cell origin makes our system resemble lung epithelium infection. Transmission electron microscopy confirmed that the spike glycoproteins on the pseudotyped lentiviral particles resemble native SARS-CoV-2 spike glycoproteins, thus validating their use in inhibitor screening. H1299-hACE2 cells showed significantly higher infection rate (p < 0.005) with spike-pseudotyped lentiviruses compared to parental H1299 cells, as determined by luciferase and fluorescence assays. The susceptibility of the stable H1299-hACE2 cell line to a broad panel of SARS-CoV-2 variants (Wuhan, Beta, Delta, Omicron) was assessed here for the first time in a unified experimental setting. Infection of H1299-hACE2 cells with SARS-CoV-2 induced cell fusion and syncytium formation with subsequent cell death. The developed pseudovirus-based assay was further used for assessment of the antiviral properties of derivatives of 1,7,7-trimethyl-[2.2.1]-bicycloheptane-potential spike protein inhibitors, which possess moderate activity against lentiviral particles. The H1299-hACE2/spike-pseudotyped lentivirus assay is, therefore, a reliable, high-efficiency platform for screening spike-mediated entry inhibitors. The cell line obtained during the development of the platform can be used to isolate and study new variants of SARS-CoV-2. Full article

Respiratory viruses such as SARS-CoV-2, influenzas A and B, respiratory syncytial virus (RSV), human metapneumovirus (hMPV), human parainfluenza virus type 3 (HPIV-3), and rhinoviruses remain major causes of global morbidity. Their rapid evolution, high transmissibility, and limited therapeutic options, together with the absence of approved vaccines for several pathogens, highlight the need for broad-acting and pathogen-independent antiviral strategies. Nitric oxide exhibits antiviral activity through redox-dependent mechanisms, including S-nitrosylation of cysteine-containing viral proteins and disruption of redox-sensitive structural domains. Clinical studies conducted during the SARS-CoV-2 pandemic demonstrated that a nitric oxide nasal spray (NONS) rapidly reduced nasal viral load and transmission. In this study, we evaluated the in vitro virucidal activity of the NONS against a panel of clinically relevant respiratory viruses representing four major virus families. Virus suspensions of approximately 10⁴ CCID₅₀ were exposed to a full-strength NONS for contact times ranging from 5 s to 2 min at room temperature, followed by neutralization and quantification of residual infectivity using endpoint dilution assays. The NONS rapidly reduced viral infectivity across all viruses tested, achieving >3 log₁₀ reductions within 2 min. SARS-CoV-2 variants including Alpha, Beta, Gamma, Delta, Omicron BA.1, and XBB 2.0 were reduced to levels at or below the assay detection limit within 30 s to 2 min. Influenza A and B viruses showed the fastest loss of infectivity, reaching detection limits within 10–15 s. RSV, hMPV, HPIV-3, and human rhinovirus 14 were similarly inactivated within 1–2 min. These findings demonstrate that the NONS exhibits rapid and broad-spectrum virucidal activity against diverse respiratory viruses and supports its potential role in pandemic preparedness but also seasonal use. Full article

COVID-19 has raised significant concern regarding its neurological impact, particularly during the early pandemic waves when severe systemic inflammation and neuroimmune dysregulation were more common. Although SARS-CoV-2 has been extensively studied, the precise mechanisms underlying its neurological effects remain incompletely understood, and much of the available evidence is derived from early variants with higher pathogenicity. Current research indicates that neuroinflammatory processes—driven primarily by systemic cytokine elevation, microglial activation, and blood–brain barrier dysfunction—contribute to a wide range of neurological symptoms. Severe complications such as encephalopathy, stroke, and cognitive impairment were predominantly reported in critically ill patients infected with the Wuhan, Alpha, or Delta variants, while such manifestations are considerably less frequent in the Omicron era. Most proposed mechanisms, including ACE2-mediated viral entry into the central nervous system, are supported mainly by experimental or preclinical studies rather than definitive human evidence. Biomarkers such as IL-6 and TNF-α, along with neuroimaging modalities including MRI and PET, offer useful but indirect indicators of neuroinflammation. Therapeutic approaches continue to focus on controlling systemic inflammation through immunomodulatory agents, complemented by targeted non-pharmacological strategies—such as physical rehabilitation, cognitive support, and psychological interventions—for the minority of patients with persistent neurological deficits. Overall, current evidence supports a variant-dependent neuroinflammatory profile and underscores the need for longitudinal, mechanism-focused studies to better characterize long-term neurological outcomes and refine therapeutic strategies. Full article

Background: Casirivimab–imdevimab (REGEN-COV) is a neutralizing antibody cocktail that has been shown to prevent the progression of COVID-19 and serious adverse outcomes in patients with COVID-19 disease. During the period preceding the emergence of the Omicron variant, REGEN-COV demonstrated clinical activity against several circulating SARS-CoV-2 variants. The delta variant was dominant worldwide during much of the study period. Aim: This retrospective observational study aimed to show the single centre’s results in treating patients with REGEN-COV. Methods: This study included adult patients who received REGEN-COV at our COVID-19 centre from 01 June 2021 to 31 January 2022 (REGEN-COV group) and a comparison group that included patients who did not meet the eligibility criteria for REGEN-COV (non-REGEN-COV group). The primary end-point was the need for hospitalization. The secondary end-point was all-cause mortality. Intensive care unit admission was also evaluated. Results: This study included 206 patients, of whom 69 received REGEN-COV, and 137 comprised the non-REGEN-COV group. During follow-up, 128 patients (62%) required hospitalization, including 11 (15.9%) in the REGEN-COV group and 117 (85.4%) in the non-REGEN-COV group (p < 0.001). Mortality occurred in 2 patients (2.9%) treated with REGEN-COV compared with 30 patients (21.9%) in the non-REGEN-COV group. In the propensity score-matched analysis, the average marginal absolute risk difference for mortality between the groups was −4.0% (95% CI −9.8 to 1.8), p = 0.178; however, Kaplan–Meier survival analysis demonstrated a significant difference in survival between groups (log-rank p < 0.001). Conclusions: Our study showed that in high-risk patients, with specific variants of SARS-CoV-2, the use of REGEN-COV was associated with a lower risk of hospitalization, and it was associated with better disease outcomes. One of the limitations of this study was the variant-specific effectiveness of REGEN-COV, which may limit generalizability. Full article

Background/Objectives: COVID-19 mRNA vaccines protect against hospitalization, but less is known about real-world vaccine effectiveness (VE) against other severe outcomes. Methods: We enrolled adults hospitalized with acute respiratory illness at two hospitals in Atlanta, Georgia, USA from May 2021 to January 2023. Participants were eligible if they had standard-of-care COVID-19 testing or provided an upper respiratory swab for analysis. Vaccination status was confirmed through the state registry. mRNA COVID-19 VE among those with severe outcomes was determined using a test-negative case–control design with stepwise logistic regression adjusting for confounding variables. Results: Of 1973 participants eligible for analysis, 886 (44.9%) were unvaccinated, 641 (32.5%) received a primary series, and 446 (22.6%) received a primary series plus ≥ 1 booster. A total of 734 (37.2%) were positive for COVID-19. During the pre-Delta/Delta (2 May 2021–19 December 2021) vs. Omicron (20 December 2021–31 January 2023) eras, adjusted COVID-19 mRNA VE of a primary series compared to no vaccination was 85.5% (95% CI: 77.0%, 90.8%) vs. 38.2% (95% CI: 11.5%, 56.8%) overall, 90.0% (95% CI: 82.6%, 94.2%) vs. 54.4% (95% CI: 9.0%, 77.1%) among those with radiographic pneumonia, and 94.4% (95% CI: 80.5%, 98.4%) vs. 62.5% (95% CI: 19.0%, 82.7%) among those admitted to the ICU. VE against severe outcomes was highest within the 6 months following vaccination and during the pre-Delta/Delta era. A booster dose partially restored VE against Omicron-associated hospitalization and pneumonia. Conclusions: COVID-19 mRNA vaccines were effective at preventing hospitalization and other severe outcomes in adults during periods of pre-Delta/Delta and Omicron variant circulation. Full article

The continuing spread of SARS-CoV-2 and the associated morbidity and mortality, especially in vulnerable populations, highlight the need for the development of antiviral therapeutics. Reverse genetics systems and reporter viruses are valuable for antiviral screening by simplifying methods to detect and quantify virus infections. This study aimed to generate wild-type and Nluc reporter full-length SARS-CoV-2 molecular clones and viruses as tools for high-throughput antiviral assays. The large SARS-CoV-2 genome (~30 kb) makes cDNA cloning and virus rescue technically challenging, so we opted to use cDNA chemical synthesis services to generate full-length wild-type and reporter Delta and Omicron clones. Clone-derived Delta and Omicron wild-type and reporter viruses were successfully rescued and showed replication kinetics comparable to patient-derived isolates. Nluc reporter viruses displayed stable luciferase expression that correlated with viral titres, supporting their reliability as replication substitutes. Antiviral assays measuring replication inhibition by Remdesivir, Molnupiravir, and Nirmatrelvir, based on Nluc expression, yielded IC₅₀ values and selectivity indices consistent with published ranges. Finally, Delta Nluc viruses replicated in primary human bronchial epithelial cells, demonstrating the application of clone-derived viruses in physiologically relevant models. The SARS-CoV-2 cDNA clones and Nluc reporter viruses derived from DNA synthesis services provide a rapid, scalable reverse genetics platform for generating new viruses and developing assays to rapidly assess antiviral compounds against current and emerging SARS-CoV-2 variants or coronaviruses that may emerge in the future. Full article

Background/Objectives: It is critical to monitor real-world COVID-19 vaccine effectiveness (VE) in older adults, as they have been identified as a priority group for vaccination. This is the first study that aims to estimate national absolute vaccine effectiveness (aVE) against severe COVID-19 outcomes among Canadian older adults aged ≥50 years. Methods: The screening method (SM) was implemented using standard and spline-based logistic regression models to estimate aVE and 95% confidence intervals (CIs) by outcome, age group, vaccination status, time since last dose, vaccine schedules, and variant of concern (VOC) period. Results: From 1 August 2021 to 30 November 2023, there were 103,822 severe COVID-19 cases, of which 72.9% were hospitalized, 8.2% were admitted to ICU, and 18.9% had died. A total of 23.1% of these cases were unvaccinated against COVID-19, 21.9% completed a primary series only, and 55.0% received at least one additional/booster dose. National aVE against severe COVID-19 outcomes remained moderate to high during Delta and original Omicron VOC predominance periods. Monthly age-specific aVE of at least two additional/booster doses remained stable during recombinant XBB.1.5/EG.5 VOC predominance, ranging from 61.0% (95% CI: 51.9–68.4%) to 69.8% (95% CI: 67.5–72.0%) against hospitalization, and 71.0% (95% CI: 62.8–77.4%) to 77.2% (95% CI: 74.2–79.9%) against ICU admission/death. Adjusted aVE was higher for last booster doses received within the past six months and with heterologous mRNA vaccine schedules. Conclusions: The SM is a useful method to estimate aVE in near real-time, enabling the assessment of temporal changes in aVE, guiding vaccine policy, and building vaccine confidence among populations at higher risk of severe outcomes. Full article

Background/Objectives: The rise of immune escape variants of the SARS-CoV-2 virus has prompted the development of vaccines based on the variant’s spike antigen sequence. Since variant-specific SARS-CoV-2 vaccines are mostly administered as boosters to individuals previously vaccinated with reference (Ref.) strain-based vaccines, a better understanding of their immunogenicity in this context is essential. Protein subunit vaccines have a well-established track record of safety. Herein, we assessed the ability of variant-specific protein subunit vaccine formulations to boost pre-existing Ref. strain-specific immune responses compared to boosting with a Ref. strain-specific formulation in young and aged female Balb/c mice. Methods: Following a priming vaccination series with Ref. spike protein adjuvanted with sulfated lactosyl archaeol (SLA) archaeosomes on days 0 and 21, immune responses were evaluated in young and aged female Balb/c mice. On day 91, mice received a third immunization with Ref., Beta, or Delta spike protein formulations, with or without SLA archaeosomes. Antibody titers, neutralization activity, and cellular immune responses were measured to assess the impact of the booster formulation. Results: Aged mice exhibited lower antibody titers throughout the study and a decline over time compared to young mice. After a third immunization, responses were boosted by all vaccine formulations (Ref., Beta, or Delta), with or without adjuvant. However, variant-specific antigen formulations did not overcome immune imprinting from the priming series or increase neutralization activity against the corresponding SARS-CoV-2 variants in either age group. Conclusions: Variant-specific protein subunit vaccines enhanced immune responses but did not overcome immune imprinting induced by the Ref. strain’s priming. The inclusion of SLA archaeosomes improved cellular immunity, supporting their potential role in optimizing booster vaccine performance, particularly in aged populations. Full article

Wastewater-based surveillance is an effective method to monitor community health by detecting pathogens excreted from large populations. Traditionally, wastewater analyses are considered privacy-preserving since samples are pooled. However, advances in molecular resolution may challenge this assumption. This study investigated whether a rare SARS-CoV-2 variant detected in a hospital sewershed could be linked to a specific patient. During 2023, wastewater samples were collected weekly and analyzed for SARS-CoV-2 concentrations and variant composition using droplet digital PCR (ddPCR) and tiled sequencing. During the same period, nasal swab samples from hospital patients were sequenced for comparison. While wastewater was dominated by Omicron lineages, several weeks showed a sharp increase in SARS-CoV-2 concentrations, with over 80% belonging to the Delta lineage AY.25—rare globally since 2022. Nasal swab sequencing identified one patient carrying AY.25, whose admission and discharge coincided with the emergence and disappearance of AY.25 in the hospital’s wastewater. The temporal pattern and sequence similarity suggest that the Delta signal might have originated from this single patient, with sequence differences potentially reflecting intrahost divergence. These findings indicate that, under certain conditions, wastewater signals can be attributed to individuals, highlighting the need to keep in mind the ethical considerations surrounding privacy and data use while benefiting the community through wastewater surveillance. Full article

Exosome-based vaccines represent a transformative platform in modern vaccinology, combining nanoscale delivery, biocompatibility, and potent immunogenicity. Among these, the StealthX platform developed by Capricor, Inc. has demonstrated exceptional versatility, enabling antigen presentation at nanogram level doses without the need for adjuvants. Preclinical studies using StealthX have shown strong humoral and cellular immune responses against SARS-CoV-2 variants, including Delta and Omicron, as well as broader applications against influenza and RSV antigens. The platform’s ability to accommodate multiple antigens within a single formulation addresses the challenges of viral variation and facilitates multivalent “mix-and-match” immunization strategies. This review offers an in-depth evaluation of the StealthX vaccine platform, covering the biological mechanisms underlying exosome function, the engineering approaches used to load antigens, and preclinical results demonstrated across three pivotal studies. By synthesizing current evidence, this review underscores the platform’s applicability for emerging infectious diseases and explores the strategic value of multivalent exosome-based vaccines in global immunization efforts as an emerging next-generation vaccine technology. Full article

SARS-CoV-2, the virus responsible for COVID-19, disrupts human cellular pathways through complex protein–protein interaction, contributing to disease progression. As the virus has evolved, emerging variants have exhibited differences in transmissibility, immune evasion, and pathogenicity, underscoring the need to investigate their distinct molecular interactions with host proteins. In this study, we constructed a comprehensive SARS–CoV–2–human protein–protein interaction network and analyzed the temporal evolution of pathway perturbations across different variants. We employed computational approaches, including network-based clustering and functional enrichment analysis, using our custom-developed Python (v3.13) pipeline, BioEnrichPy, to identify key host pathways perturbed by each SARS-CoV-2 variant. Our analyses revealed that while the early variants predominantly targeted respiratory and inflammatory pathways, later variants such as Delta and Omicron exerted more extensive systemic effects, notably impacting neurological and cardiovascular systems. Comparative analyses uncovered distinct, variant-specific molecular adaptations, underscoring the dynamic and evolving nature of SARS-CoV-2–host interactions. Furthermore, we identified host proteins and pathways that represent potential therapeutic vulnerabilities, which appear to have co-evolved with viral mutations. Full article

Background: The GRIA3 gene encodes the GluA3 subunit of AMPA-type glutamate receptors, which are crucial for excitatory neurotransmission in the central nervous system. Pathogenic GRIA3 variants cause X-linked neurodevelopmental disorders of varying severity, including developmental delay, behavioral abnormalities, and epilepsy. Case Summary: Here, we present the case of a seven-year-old female patient presenting with developmental delay, spastic gait, and non-convulsive status epilepticus (NCSE), who was found to carry a novel de novo GRIA3 missense variant (c.1969A > G; p.Thr657Ala). The EEG revealed high-amplitude diffuse rhythmic theta/delta activity consistent with NCSE. A brain MRI showed transient cortical and thalamic T2-FLAIR hyperintensities, likely postictal. Metabolic investigations were unremarkable. Following intensive treatment with levetiracetam and midazolam, the patient gradually recovered to her baseline neurological status. Genetic Finding: Whole-exome sequencing (WES) identified a novel de novo variant in GRIA3, c.1969A > G; p.Thr657Ala, involving the replacement of threonine with alanine at position 657 within the coding region. Significance: This case expands the clinical and molecular spectrum of GRIA3-related disorders, demonstrating that females with de novo variants may experience severe epilepsy. This is the first reported case of NCSE in a female patient with a GRIA3 variant. Full article

Background/Objectives: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can naturally infect a broad spectrum of animal species, with cats, minks, and ferrets being highly susceptible. There is a potential risk that infected animals could transmit viruses to humans. Moreover, SARS-CoV-2 continues to evolve via mutation and genetic recombination, resulting in the continuous emergence of new variants that have triggered a wave of reinfection. Therefore, safe and effective corona virus disease 2019 (COVID-19) vaccines for animals are still being sought. Methods: We generated three recombinant Modified vaccinia virus Ankara (MVAs) expressing the prefusion-stabilized S proteins, S6P, DS6P, and BA2S6P, targeting the full-length S protein genes of the ancestral, Delta, and Omicron BA.2 strains of SARS-CoV-2. Subsequently, the safety, immunogenicity, and protective efficacy of these MVA-based oral COVID-19 vaccine candidates were assessed in mice, minks, and cats. Results: These recombinant MVAs are safe in mice, minks, and cats. Oral or intramuscular vaccination with rMVA-S6P induced a robust SARS-CoV-2 neutralizing antibody (NA) response and conferred complete protection against the SARS-CoV-2 challenge in mice. Meanwhile, oral or intramuscular administration of these recombinant MVAs in combination induced a potent and durable NA response against homotypic SARS-CoV-2 pseudovirus in mice, minks, and cats, respectively. Conclusions: These findings suggest that the MVA-vectored vaccines are promising oral COVID-19 vaccine candidates for animals, and that the combined vaccination approach is an effective administration strategy for such vaccines. Full article

The coronavirus disease 2019 (COVID-19) pandemic in Tocantins, Brazil, exhibited distinct phases between 2020 and 2025, with high mortality concentrated in 2020–2021 and subsequent stabilization at residual levels. Using epidemiological data, statistical modeling, and genomic surveillance, we show that the crisis peaked in 2021, coinciding with the circulation of Gamma and Delta, when health system capacity was severely strained. From 2022 onwards, the spread of Omicron led to record incidence but proportionally low mortality, reflecting accumulated immunity, vaccination, and improved clinical management. Vaccination represented the turning point, reducing hospitalizations and deaths by over 90% and driving a clear decoupling between incidence and severity. Interrupted time-series and generalized additive model (GAM) analyses confirmed sustained reductions in transmission and severity associated with mass immunization. Genomic sequencing of 3941 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genomes identified 166 lineages and successive variant replacements, culminating in the predominance of LP.8.1.4 in 2025. To our knowledge, this is one of the few integrated, long-term analyses (2020–2025) combining epidemiological and genomic data, capturing the full succession of variants up to LP.8.1.4 and highlighting Tocantins as a strategic “variant corridor” linking Brazil’s North and Central-West regions. These findings underscore the dual role of vaccination and genomic surveillance in shaping the epidemic trajectory and the importance of sustaining both strategies to mitigate future health crises. Full article

The continuous emergence of SARS-CoV-2 variants with enhanced transmissibility and immune escape capability underscores the urgent need for mutation-independent anti-viral strategies. SARS-CoV-2 non-structural protein 12 (NSP12), which encodes the RNA-dependent RNA polymerase (RdRp), is an essential component of the viral replication complex and represents a highly conserved target for therapeutic intervention. In this study, we developed RNA aptamers, composed of 2′-hydroxyl nucleotides or 2′-fluoro pyrimidines, targeting NSP12 using the SELEX (Systematic Evolution of Ligands by EXponential enrichment) approach. SELEX was performed with purified NSP12 protein derived from the Omicron variant, leading to the identification of aptamer candidates with high binding ability. RNA–protein pull-down assays confirmed binding between representative aptamers and NSP12 with high affinity. Competition assays supported binding specificity between aptamers and NSP12. Of note, functional evaluation using a primer extension assay revealed that the aptamers effectively inhibited NSP12 RdRp activity in vitro. Furthermore, the aptamers consistently bound to and inhibited NSP12 variants from wild-type, Alpha, Delta, and Omicron strains. These results suggest that the selected RNA aptamers are potential as broad-spectrum inhibitors targeting a conserved region of NSP12 and may serve as a promising platform for the development of anti-viral agents against current and emerging SARS-CoV-2 variants, as well as other RNA viruses. Full article