Search Results (2,717)

Background: Long COVID—defined as the persistence of symptoms or the development of new symptoms beyond four weeks after acute SARS-CoV-2 infection—affects an estimated 10–30% of individuals recovering from COVID-19, posing a significant public health burden. Emerging evidence suggests that type I interferons (IFNs) (a critical group of cytokines in the antiviral defense) and hematologic alterations, such as lymphopenia and elevated inflammatory markers, are linked to both the severity of acute COVID-19 and the likelihood of developing long-term symptoms. The aim of this study is to explore the association between type I IFN signatures and long COVID. A second aim is to examine the relationship between laboratory findings during acute infection and long COVID. Methods: The study included 61 patients investigated for the presence of long COVID symptoms 16.5 ±1.5 months after acute infection. Patients were divided into two groups of higher symptom burden of long COVID and those with milder symptoms based on demographic, laboratory, and clinical data as well as type I IFN-inducible gene expression (MX-1, IFIT-1, and IFI-44) measured in peripheral blood by real-time PCR. Data collected during acute infection were recorded. Peripheral blood samples were collected during the acute phase of infection, within the first 48 h of hospital admission. IFN-inducible gene expression was measured prospectively at that time, and RNA was extracted immediately for subsequent analysis. Results: History of intubation emerged as a significant associated factor of severe long COVID, with 75% of intubated patients reporting >8 persistent symptoms approximately 16 months post-infection. Higher white blood cell (WBC) and neutrophil counts but lower eosinophil and monocyte counts in acute infection were found to be associated with a high burden of long COVID symptoms. Interestingly, absolute monocyte count was found to independently correlate with higher long COVID symptom burden. Lactate dehydrogenase (LDH) and serum glutamic-oxaloacetic transaminase (SGOT) also differed significantly between groups, with higher levels correlating with a high burden of long COVID symptoms. Notably, MX-1 transcript levels in peripheral blood at the time of acute infection were reduced in patients with a high burden of long COVID symptoms, suggesting that dysregulated immune responses during the acute phase may contribute to persistent symptoms. Conclusions: These findings suggest the potential association of hematological and immune markers with long COVID severity, as well as the importance of monitoring these parameters to identify at-risk patients for early interventions. Full article

Neutralizing antibodies (nAbs) are key indicators of protection against SARS-CoV-2, and their measurement remains essential for monitoring vaccine responses and population immunity. While the plaque reduction neutralization test (PRNT) is the gold standard, it relies on replicative viruses and is not suited for high-throughput applications. Here, both an in-house and a commercial pseudovirus-based neutralization (PBN) assay were standardized and compared with PRNT to assess performance and concordance. The in-house PBN employed a VSV-ΔG pseudovirus encoding NanoLuc and displaying the SARS-CoV-2 Spike from the Wuhan or Omicron BA.1 variants in HEK293T-hACE2 cells, whereas the commercial assay (Integral Molecular, Philadelphia, PA, USA) used a lentiviral backbone with Renilla or GFP reporters and Wuhan or Omicron XBB.1.5/XBB.1.9 Spikes in Vero E6-ACE2-TMPRSS2 cells. Both assays showed strong correlations with PRNT, the commercial assay; moreover, they offered superior reproducibility and scalability, while the in-house version provided a cost-effective alternative suitable for BSL-2 settings. A total of 600 serum samples from vaccinated individuals were analyzed by commercial PBN at collection time points, from pre-vaccination to twelve months post–second dose, enabling large-scale screening, revealing marked differences in neutralization between Wuhan and Omicron XBB.1.5/1.9, and allowing unbiased classification of low, medium, and high responders using k-means clustering. The geometric mean titers (log₁₀ GMT) highlighted a ~1.5 log₁₀ (eightfold) reduction in neutralizing activity against Omicron, reflecting antibody waning and antigenic drift. Altogether, this study integrates assay standardization, PRNT comparison, and large-scale immune profiling, establishing a robust framework for harmonized pseudovirus-based neutralization testing. Full article

Throughout human history, contagious infectious diseases have significantly impacted societies, shaping the fate of great dynasties and challenging economic and political systems, social relations, and the overall well-being of the human species. The SARS-CoV-2 pandemic brought unprecedented challenges, emerging in the context of extreme globalization and rapid technological development. The speed of viral spread, the highest absolute mortality rate caused by a viral agent in the last 100 years, and the severe economic and social consequences imposed an urgent need for vaccine development on a previously unimaginable timescale. The proven safety and efficacy of inactivated vaccines enabled the development and large-scale application of the first immunizer against SARS-CoV-2 in less than a year after the World Health Organization (WHO) declared the pandemic. In this review, we discuss the importance of inactivated antiviral vaccines and their historical impact in containing highly harmful diseases affecting humanity. We also explore the cellular mechanisms by which inactivated vaccines may induce immunogenic responses against viral pathogens. In addition, we bring to light a discussion about a fast, cost-effective, potentially efficient technology for large-scale immunizer production: High hydrostatic pressure (HHP), a method long supported by decades of preclinical studies and which is especially effective in the context of enveloped viruses. Finally, we discuss the role of inactivated antiviral vaccines in the face of advances in biotechnology and, therefore, the emergence of vaccines that use genetic engineering in their production, such as RNA, DNA and viral vaccines, which have gained special prominence during the COVID-19 pandemic. Full article

Background: Intranasal (I.N.) vaccination holds promise to elicit mucosal immunity that counters respiratory pathogens at the site of infection. For subunit protein vaccines, immunostimulatory adjuvants are typically required. Methods: We screened a panel of 22 lipid-phase adjuvants to identify which ones elicited antigen-specific IgA with I.N. immunization of liposome-displayed SARS-CoV-2 receptor-binding domain (RBD). Results: Initial screening showed the TLR-4 agonist Kdo2-Lipid A (KLA) effectively elicited RBD-specific IgA. A second round of screening identified further inclusion of the invariant NKT cell ligands α-Galactosylceramide (α-GalCer) and its synthetic analog 7DW8-5 as complementary adjuvants for I.N. immunization, resulting in orders-of-magnitude-greater mucosal IgA response relative to intramuscular (I.M.) immunization. The inclusion of cationic lipids conferred capacity for mucosal adhesion and maintained immune responses. In K18 hACE2 transgenic mice, vaccination significantly reduced viral replication and prevented mortality from SARS-CoV-2 challenge. Conclusions: These results point towards the potential for the use of KLA and α-GalCer for I.N. subunit vaccines. Full article

Since its discovery in 2019, SARS-CoV-2 has continued to be detected in both humans and animals worldwide. Currently there is limited research focusing on serological surveillance of wildlife under human care. Here we tested 230 serum samples of 134 animals from two zoological institutions collected between 2015 and 2024. To assess prior exposure and antibody responses from natural infection or vaccination, we used three serological assays: a nucleocapsid protein-based ELISA (N-ELISA), a surrogate virus neutralization test (sVNT) for spike (S) protein and a neutralization assay with S-pseudotyped viral particles. Among the 114 samples collected from 58 animals at Fort Wayne Zoo in Indiana, 37 samples from 20 vaccinated animals were sVNT-positive, and 2 of the positive animals had 2 samples prior to vaccination that tested positive by N-ELISA. Of the 116 samples from 76 animals at Brookfield Zoo in Illinois, 20 samples of 20 animals were sVNT-positive, and 19 of the positive animals had been vaccinated. Among these 20 sVNT-positive samples, only one sample from a South American Tapir was positive from prior to vaccination and 1 sample from a sloth bear was also positive by N-ELISA, marking the first documented cases of SARS-CoV-2 exposure in both species. Neutralization assays with S-pseudotyped virus revealed that some of the sVNT-positive samples have strong activity against the WH1-S pseudovirus but showed significantly reduced neutralization against the Omicron LP.8.1-S pseudovirus. These results underscore the need for updated vaccines tailored to emerging variants. Overall, our findings highlight the importance of continued serological surveillance across multiple species to detect new SARS-CoV-2 exposures and monitor vaccine-induced immunity in captive animal populations. Full article

The continuous evolution of SARS-CoV-2 and its variants poses persistent challenges to global public health. As a sublineage of the XDV.1 variant, NB.1.8.1 has rapidly emerged as a dominant strain worldwide, triggering a new wave of infections. Representing a product of viral adaptation, this variant has acquired several critical amino acid mutations—including A435S and T478I—which enhance its transmissibility and immune evasion capabilities compared to the ancestral XDV.1 lineage. This review systematically summarizes the genomic characteristics, epidemiological features, and immune escape potential of NB.1.8.1. It emphasizes that sustained genomic surveillance and serological assessments are crucial for informing public health response strategies, guiding vaccine development, and optimizing containment measures. Full article

Background: While host immune responses to SARS-CoV-2 vaccination are routinely assessed through IgG measurements, less is known about the temporal dynamics of vaccine-induced cellular immunity, particularly in individuals who fail to develop detectable IgG antibodies after COVID-19 vaccination. Objective: To investigate the development and timing of T-cell immunity following SARS-CoV-2 vaccination in antibody-non-responders to COVID-19 vaccination. Methods: A cross-sectional analysis was conducted on COVID-19-naive individuals who had received full SARS-CoV-2 vaccination, categorized by SARS-CoV-2 IgG serostatus. T-cell response was evaluated using the IGRA methodology T-SPOT^®.COVID (Oxford Immunotec, Abingdon, Oxfordshire, UK). T-cell response rates and levels were compared between SARS-CoV-2 seropositive and seronegative groups, and a temporal cutoff analysis was applied to examine trends in T-cell response over time. Results: Within the seronegative group, IgG levels showed a strong negative correlation with time since vaccination (Spearman ρ = −0.65, p < 0.001), while T-cell response levels exhibited a weak positive time-dependent trend (ρ = 0.15, p = 0.019). Temporal cutoff analysis identified a critical time-point beginning at 80 days post-vaccination, after which both T-cell response rates and levels were significantly higher. Specifically, individuals tested after 80 days showed increased median T-cell response levels (U = 4205, p < 0.001) and higher positive T-cell response rate (67% vs. 38%, Χ² = 17.06, p < 0.001). Conclusions: Cellular immunity response against SARS-CoV-2 may emerge later than expected in antibody-non-responders to COVID-19 vaccination, with the 80-day post-vaccination mark emerging as a critical time point. Our results support the inclusion of cellular assays in post-vaccination monitoring and emphasize the need to reconsider the timing and criteria for evaluating vaccine response. Full article

Background/Objectives: The anti-spike (S) SARS-CoV-2 antibodies confer neutralizing properties and their concentration may be related to COVID-19 protection. Anti-nucleocapsid (N) SARS-CoV-2 antibodies in mRNA COVID-19 vaccine recipients indicate infection. The aim of this study was to analyze the anti-S and anti-N titers 3 years after COVID-19 vaccination. Methods: Ninety-nine vaccinated healthcare workers provided blood samples in 2024 and filled out questionnaires about their COVID-19 history and boosters acceptance. Anti-spike and anti-nucleocapsid IgG were assessed with commercially available immunoassays, DiaSorin’s SARS-CoV-2 TrimericS IgG and Abbott’s SARS-CoV-2 IgG, respectively. Results: Three years after the primary COVID-19 vaccination, the anti-S SARS-CoV-2 antibody concentration was still high. However, it dropped in comparison to the data obtained a year before (3600 vs. 2040 BAU/mL), possibly due to the lack of boosters. In contrast, the percentage of anti-N seropositive individuals grew from 34% two years after vaccination to 40.4% after three years. Subjects with SARS-CoV-2 infection within a year prior to the antibody measurements had statistically significantly higher median anti-S concentrations than those with tentatively no contact with SARS-CoV-2 (2940 vs. 1930 BAU/mL). Conclusions: Overall, our data indicates that although the booster vaccinations’ acceptance decreases, the circulating SARS-CoV-2 stimulates humoral immunity, resulting in high anti-S antibody concentrations even three years after the vaccination. Full article

Background/Objectives: Although SARS-CoV-2 infection often follows a self-limiting course, its public health impact remains persistent. Older adults exhibit unique susceptibility to infection due to immunosenescence. Therefore, in order to offer recommendations for improving management options for older persons, this study intends to examine the immunological properties of NAb in the elderly population. Methods: Elderly patients aged 60 years and older infected during the prevalence of BF.7 and EG.5 variants were enrolled. The patterns of NAb responses in infected patients under both natural and vaccine-induced immunity were explored using bead-based proteomics techniques. The associations between NAb and IgG antibody levels, clinical characteristics, and traditional inflammatory indicators were evaluated using systematic analysis. Based on NAb levels, SARS-CoV-2 strains were immunologically classified. Results: There was a positive correlation between the severity of the disease and the strength of the NAb response. Because of more extensive immune activation, severe instances in elderly patients showed higher levels of NAb responses. When compared to the uninfected group, people who had received two doses of vaccination exhibited greater NAb levels. Additionally, there was a link between NAb and IgG levels, but as the virus evolved, this correlation progressively diminished. Three serotypes of SARS-CoV-2 were identified based on NAb response characteristics: pre-Omicron, Omicron, and XBB serotypes. Conclusions: The results show the features of NAb responses in older patients, which could help with the creation of future vaccines and public health initiatives. Full article

Background: In response to the emergence of immune-evasive variants of SARS-CoV-2, this study explores a novel heterologous vaccination strategy using a microparticulate formulation approach that is delivered via oral dissolving film (ODF) formulations into the buccal cavity. Heterologous administration has the potential to generate cross-reactive antibodies, which can be especially beneficial against viruses with ever-mutating variants. Moreover, the microparticulate oral dissolving film-based vaccine approach is a non-invasive vaccine delivery platform. Methods: The vaccine design incorporated whole inactivated Delta and Omicron variants of the virus, administered at prime and booster doses, respectively, effectively encapsulated in a Poly(lactic-co-glycolic) acid (PLGA) polymer matrix, and adjuvanted with Alum to enhance immune activation. Following vaccination, serum, mucosal, and tissue samples were analyzed to evaluate humoral and cellular immune responses against the model antigen, as well as other variants such as Alpha and Beta variants, to understand the cross-reactive response. Result: In vitro evaluations confirmed the vaccine’s safety and its ability to stimulate immune responses. On administering microparticulate oral dissolving films to mice, whole inactivated delta and omicron variant-specific antibodies were observed in serum samples along with neutralizing titers in terminal week. The formulated vaccine showed significant secretory IgA antibody levels in mucosal samples. Moreover, CD4⁺ and CD8a cellular responses were observed in tissue samples of spleen and lymph nodes, along with antibodies (IgG, IgA, and IgM) detected in lung supernatant samples. Humoral and cellular cross-reactive antibodies were observed in the samples. Conclusions: This approach offers a promising platform for developing next-generation vaccines capable of inducing broad immunity. Full article

Immunosuppressive therapies used in clinics to reduce the risk of rejection in transplanted patients unfortunately also decrease the response of the immune system to the pathogens. Previous data has shown that the most diffuse SARS-CoV-2 variants of concern between 2020 and 2021 showed a different modulation of the host immune response in healthy subjects, with the Delta B.1.617.2 variant leading to a failure in the activation of the adaptive immune response. In this study, the transcriptomic profiles of monocyte-derived macrophages (MDM), isolated from four immunosuppressed kidney transplant patients and exposed to SARS-CoV-2 VOCs, were analyzed and compared with previously published data gathered from immune-competent subjects. Human monocytes were isolated from peripheral blood mononuclear cells (PBMCs) of four kidney transplant patients admitted to the IRCCS Policlinico San Matteo of Pavia (Italy), differentiated into macrophages, and exposed to the active and the UV-inactivated particles of the different SARS-CoV-2 VOCs (D614G, Alpha B.1.1.7, Gamma P.1, Delta B.1.617.2 and Omicron BA.1). Bulk RNA-Seq was performed and significant transcripts were assessed based on Student’s t-test (p-value < 0.05) and Fold change > 2. RNA-Seq data analyses of immunosuppressed MDMs showed that SARS-CoV-2 VOCs, although transcriptionally active, did not induce strong alterations in the transcriptomic profiles of these cells, while a strong down-regulation of key genes involved in the innate immunity pathways was observed when comparing these data to the ones obtained from immunocompetent participants. Overall, this study suggests that patients under immunosuppressive therapies do have an altered macrophage response to SARS-CoV-2 viral infection. Full article

Dengue and COVID-19 are viral diseases characterized by coagulopathies, with Dengue associated with fibrinolysis and COVID-19 with prothrombotic events. Furthermore, cross-reactivity between anti-SARS-CoV-2 and anti-DENV antibodies may confer protective immunity or exacerbate disease severity. Our investigation explored the impact of prior COVID-19 exposure on the immunopathogenesis of Dengue, focusing on hemostatic parameters. We quantified nitrites, procoagulant, anticoagulant, and fibrinolytic mediators in the plasma of Dengue patients before and after the COVID-19 pandemic. We also evaluated the influence of plasma from dengue patients on platelet activation in vitro using platelets from healthy donors exposed to DENV-2. Hemorrhagic manifestations were more frequent in pre-COVID-19 Dengue, while nitrite levels were elevated in post-COVID-19 Dengue patients, particularly among those without hemorrhagic signs. Among procoagulant factors, tissue factor (TF) levels were increased in post-COVID-19 Dengue, whereas Factor XIII was higher in pre-COVID-19 Dengue. In contrast, antithrombin (an anticoagulant) and plasminogen (a profibrinolytic factor) were more elevated in pre-COVID-19 Dengue than in post-COVID-19 cases. In vitro, DENV-2-infected platelets exposed to plasma of Dengue patients before and after COVID-19 showed decreased nitrite production in relation to DENV-2 alone. These findings suggest that prior COVID-19 exposure may influence hemostatic responses in Dengue, potentially modulating disease pathophysiology and opening new avenues for research and therapeutic strategies. Full article

Background/Objectives: Dendritic cell vaccines are a promising cancer immunotherapy. AV-OVA-1 is a patient-specific vaccine consisting of autologous dendritic cells (DCs) loaded with autologous tumor antigens (ATA) from a lysate of irradiated self-renewing cells enriched for tumor-initiating cells (TICs). A multicenter, double-blind, randomized phase 2 trial was designed to determine manufacturing feasibility, safety, and efficacy. Methods: Patients had newly diagnosed stage 3 or 4 ovarian cancer. Short-term cell cultures were established from freshly resected tumor specimens. Patients were screened for randomization seven months after initial diagnosis, after completing neoadjuvant and/or adjuvant chemotherapy and surgery. Eligibility included a successful cell culture, cryopreservation of sufficient monocyte numbers for differentiation into DCs, and good performance status. Patients were stratified by whether they had persistent disease; then, they were randomized 2:1 to AV-OVA-1 or autologous monocytes (MC). Cryopreserved doses of AV-OVA-1 and MC were thawed and admixed with granulocyte–macrophage colony-stimulating factor just before subcutaneous injections at weeks 1, 2, 3, 8, 12, 16, 20, and 24. Results: Study accrual was terminated early during the SARS-CoV-2 pandemic. Manufacturing success rates for TICs, monocyte intermediate products, and AV-OVA-1 were 70/72 (97.2%) and 47/50 (94.0%), and 29/30 (96.7%), respectively. A total of 29 participants were treated with AV-OVA-1 and 15 with MC. Patients received an average of 7.4 injections. Adverse-event frequencies were similar in both arms, mild to moderate in severity, and self-limited. T-cell immune responses increased only after AV-OVA-1. There were no survival differences in this underpowered study. Conclusions: AV-OVA-1 was manufactured reliably and injections were well tolerated. Full article

SARS-CoV-2 infection remains a global health concern, with its impact on host immune responses not fully understood. In a case–control study, we examined how COVID-19 affects DNA methylation patterns in the upper respiratory airway of hospitalized individuals. DNA methylation arrays were performed on nasopharyngeal samples at inclusion/hospitalization and 6 weeks post-inclusion. We found a distinct DNA methylation pattern in COVID-19 patients compared to healthy controls, identifying 510,099 differentially methylated CpGs. Within the transcription start sites (TSSs) and gene body, COVID-19 patients displayed a higher number of genes/CpGs with elevated methylation levels. Enrichment analysis of TSS-methylated genes revealed effects of SARS-CoV-2 on genes associated with type I interferons, anti-viral and inflammatory responses, and immune functions. Some CpG methylations were transient, and normalized at group level by 6 weeks post-inclusion. Several IFN-regulated genes, including OAS1, OAS3, IFIT3, and MX1, were identified. Among the top regulators were IL17A and ERK1/2, both involved in inflammatory processes. Networks nodes included IGF1 and EGF, associated with processes including tissue repair and activation of immune responses. Overall, our data suggests that COVID-19 can impact the upper airway by modifying gene methylation patterns. This could have implications for conditioning of the airways, how individuals respond to future airway infections, and therapeutic interventions. Full article

Long COVID (LC) is characterized by a wide range of symptoms, the causes of which remain unclear. We investigated associations between inflammatory and coagulation factors, adaptive immune response to SARS-CoV-2, and LC. We enrolled 196 unvaccinated individuals with SARS-CoV-2 (March–June 2020). Blood samples were collected at three (T3M) and twelve (T12M) months post infection. Plasma concentrations of coagulation factors (D-Dimer, E-Selectin, ICAM-1, VCAM-1) and inflammatory markers (IL-6, IL-8, TNF-α, IL-1β) were measured by ELISA, and SARS-CoV-2-specific T-cell response was assessed by Elispot. LC occurred in 66/196 patients (34%); 77.8% had been hospitalized. Respiratory symptoms were present in 54%, fatigue in 30%, and neuropsychological symptoms in 14%. At T3M, hospitalized patients exhibited higher levels of ICAM-1, VCAM-1, and IL-6, along with increased immunoreactivity. LC patients exhibited elevated IL-8 and TNF-α and enhanced immunoreactivity at T3M, though these differences were not observed at T12M. Inflammatory and coagulation markers were altered at three months after acute infection, with some changes persisting at one year, suggesting a long-term immunological impact of SARS-CoV-2 on the inflammatory response. A SARS-CoV-2-specific T-cell response was still detectable at T12M, albeit at a lower level than at T3M, suggesting the persistence of protective memory T-cells beyond the acute phase. Full article