Search Results (27)

Background: Understanding immune response is essential for preparing for public health crises. COVID-19 vaccination provides robust immunity against SARS-CoV-2, but immunocompromised populations may have weaker immune responses. We assessed SARS-CoV-2 spike (trimer) total IgG/IgM/IgA (total Ig) to investigate immune response to COVID-19 vaccination in people living with HIV (PLWH), considering CD4⁺ T cell count, viral load, substance use, and comorbidities. Methods: This cross-sectional study was conducted in Miami, Florida, between May 2021 and December 2021 as part of the NIH Rapid Acceleration of Diagnostics-Underserved Populations (RADx-UP) initiative (3U01DA040381-05S1) and the Miami Adult Studies on HIV (MASH) cohort (U01DA040381). Blood samples were collected and SARS-CoV-2 spike (trimer) total Ig was quantified. HIV serostatus, viral load, CD4⁺ T cell count, and COVID-19 vaccinations were abstracted from medical records. Substance use (tobacco, alcohol, and drug use [marijuana, cocaine, heroin, fentanyl, methamphetamine, amphetamine, hallucinogens, ecstasy, or misuse of prescription drugs]), and comorbidities (hypertension, diabetes, autoimmune disease, obesity, chronic kidney disease, and substance use disorders) were assessed via validated questionnaires. Drug use was confirmed via urine toxicology. Multivariable linear regression was conducted. Results: Median age (n = 1317) was 57.8 years, 49.8% were male, 50% were Black non-Hispanic, 66.2% had received ≥1 dose of a COVID-19 vaccine, and 29.6% were PLWH (71.3% virally suppressed and median CD4⁺ T cell count > 500 cells/µL). PLWH, compared to people without HIV, were more likely to have received ≥1 dose of a COVID-19 vaccine (76.2% vs. 62.0%, p < 0.001) and present with substance use (77.2% vs. 42.9%, p < 0.001) and comorbidities (72.8% vs. 48.2%, p < 0.001). Vaccinated PLWH, compared to unvaccinated PLWH, had higher CD4⁺ T cell counts (577.5 vs. 517.5, p = 0.011) and were more likely to be virally suppressed (76.4% vs. 54.8%, p < 0.001). A lower CD4⁺ T cell count (<200 vs. ≥500, β = −0.400, p = 0.033) and higher HIV viral load (≥200–<5000 vs. <200, β = −0.275, p < 0.001) were associated with lower spike (trimer) total Ig titers, indicating a diminished response to COVID-19 vaccination. Conclusions: A lower CD4⁺ T cell count and higher HIV viremia were linked to reduced SARS-CoV-2 immunogenicity in racial/ethnic minority PLWH, a population underrepresented in vaccine clinical trials. HIV care providers should target efforts to maintain viral suppression to avoid diminished responses to COVID-19 vaccination. Full article

Background/Objectives: COVID-19 vaccines effectively prevent severe disease, but unequal distribution, especially in low- and middle-income countries, has led to vaccine-resistant strains. This highlights the urgent need for alternative vaccine platforms that are safe, thermostable, and easy to distribute. This study evaluates the immunogenicity, stability, and scalability of a dissolved microneedle array patch (MAP) delivering the rS1RS09 subunit vaccine, comprising the SARS-CoV-2 S1 monomer and RS09, a TLR-4 agonist peptide. Methods: The rS1RS09 vaccine was administered via MAP or intramuscular injection in murine models. The immune responses of the MAP with and without gamma irradiation as terminal sterilization were assessed at doses of 5, 15, and 45 µg, alongside neutralizing antibody responses to Wuhan, Delta, and Omicron variants. The long-term storage stability was also evaluated through protein degradation analyses at varying temperatures. Results: The rS1RS09 vaccine elicited stronger immune responses and ACE2-binding inhibition than S1 monomer alone or trimer. The MAP delivery induced sgnificantly higher and longer-lasting S1-specific IgG responses for up to 70 weeks compared to intramuscular injections. Robust Th2-prevalent immune responses were generated in all the groups vaccinated via the MAP and significant neutralizing antibodies were elicited at 15 and 45 µg, showing dose-sparing potential. The rS1RS09 in MAP has remained stable with minimal protein degradation for 19 months at room temperature or under refrigeration, regardless of gamma-irradiation. After an additional month of storage at 42 °C, cit showed less than 3% degradation, ompared to over 23% in liquid vaccines Conclusions: Gamma-irradiated MAP-rS1RS09 is a promising platform for stable, scalable vaccine production and distribution, eliminating cold chain logistics. These findings support its potential for mass vaccination efforts, particularly in resource-limited settings. Full article

During the COVID-19 pandemic, diabetic and obese patients experienced higher rates of hospital admissions, severe illness, and mortality. However, vaccinations failed to provide those vulnerable populations the same level of protection against COVID-19 severity as those without diabetic and obese phenotypes. Our study aimed to investigate how diabetes mellitus (DM) impacts the immune response following vaccination including the artificially designed trimeric SARS-CoV-2 spike (S)-protein. By using two diabetic mouse models, ob/ob mice (obese, hyperglycemic, and insulin-resistant) and STZ-treated mice (insulin-deficient and hyperglycemic), we observed a significant reduction in S-protein-specific IgG antibody titer post-vaccination in both diabetic models compared to wild-type (WT) mice. Both diabetic mouse models exhibited significant abnormalities in spleen tissue, including marked reductions in splenic weight and the size of the white pulp regions. Furthermore, the splenic T-cell and B-cell zones were notably diminished, suggesting an underlying immune dysfunction that could contribute to impaired antibody production. Notably, vaccination with the S-protein, when paired with an optimal adjuvant, did not exacerbate diabetic cardiomyopathy, blood glucose levels, or liver function, providing reassurance about the vaccine′s safety. These findings offer valuable insights into potential mechanisms responsible for the decreased persistence of antibody production in diabetic patients. Full article

This study follows 99 subjects vaccinated with Pfizer/BioNTech COVID-19 vaccines over two years, with particular focus on the last year of observation (between days 360 and 720). The response to the vaccination was assessed with Diasorin’s SARS-CoV-2 TrimericSpike IgG. Screening for SARS-CoV-2 infection was performed with Abbott’s SARS-CoV-2 Nucleocapsid IgG immunoassay. Data from questionnaires were also analyzed. Two years after the first vaccine dose administration, 100% of the subjects were positive for anti-spike SARS-CoV-2 IgG and the median antibody level was still high (3600 BAU/mL), dropping insignificantly over the last year. Simultaneously, a substantial increase in seropositivity in anti-nucleocapsid SARS-CoV-2 IgG was noted, reaching 33%. There was no statistically significant agreement between anti-N seropositivity and reported COVID-19. Higher anti-spike concentrations and lower COVID-19 incidence was seen in the older vaccinees. It was noted that only subjects boosted between days 360 and 720 showed an increase in anti-spike IgG concentrations. The higher antibody concentrations (median 7440 BAU/mL) on day 360 were noted in participants not infected over the following year. Vaccination, including booster administrations, and natural, even unrecognized, contact with SARS-CoV-2 entwined two years after the primary vaccination, leading to high anti-spike antibody concentrations. Full article

Little is known about the long-term durability of the induced immune response in subjects with obesity, particularly in those with an abdominal distribution of adipose tissue. We evaluated SARS-CoV-2-specific antibody responses after BNT162b2 vaccine booster dose, comparing individuals with and without abdominal obesity (AO), discerning between individuals previously infected or not. IgG-TrimericS were measured in 511 subjects at baseline, on the 21st day after vaccine dose 1, and at 1, 3, 6, and 9 months from dose 2, and at 1 and 3 months following the booster dose. To detect SARS-CoV-2 infection, nucleocapsid antibodies were measured at baseline and at the end of the study. Multivariable linear regression evaluated the three-month difference in the absolute variation in IgG-TrimericS levels from booster dose, showing AO and SARS-CoV-2 infection status interactions (p = 0.016). Regardless of possible confounding factors and IgG-TrimericS levels at the booster dose, AO is associated with a higher absolute change in IgG-TrimericS in prior infected individuals (p = 0.0125). In the same regression model, no interaction is highlighted using BMI (p = 0.418). The robust response in the development of antibodies after booster dose, observed in people with AO and previous infection, may support the recommendations to administer a booster dose in this population group. Full article

Mucosal vaccination appears to be suitable to protect against SARS-CoV-2 infection. In this study, we tested an intranasal mucosal vaccine candidate for COVID-19 that consisted of a cationic liposome containing a trimeric SARS-CoV-2 spike protein and CpG-ODNs, a Toll-like receptor 9 agonist, as an adjuvant. In vitro and in vivo experiments indicated the absence of toxicity following the intranasal administration of this vaccine formulation. First, we found that subcutaneous or intranasal vaccination protected hACE-2 transgenic mice from infection with the wild-type (Wuhan) SARS-CoV-2 strain, as shown by weight loss and mortality indicators. However, when compared with subcutaneous administration, the intranasal route was more effective in the pulmonary clearance of the virus and induced higher neutralizing antibodies and anti-S IgA titers. In addition, the intranasal vaccination afforded protection against gamma, delta, and omicron virus variants of concern. Furthermore, the intranasal vaccine formulation was superior to intramuscular vaccination with a recombinant, replication-deficient chimpanzee adenovirus vector encoding the SARS-CoV-2 spike glycoprotein (Oxford/AstraZeneca) in terms of virus lung clearance and production of neutralizing antibodies in serum and bronchial alveolar lavage (BAL). Finally, the intranasal liposomal formulation boosted heterologous immunity induced by previous intramuscular vaccination with the Oxford/AstraZeneca vaccine, which was more robust than homologous immunity. Full article

CD40L is expressed in activated T cells, and it plays a major role in immune response and is a major therapeutic target for inflammation. High IgM syndrome type 1 (HIGM1) is a congenital functional defect in CD40L/CD40 signaling due to defective CD40L. CD40L is also stored in platelet granules and transported to the surface upon platelet activation. Platelet integrin αIIbβ3 is known to bind to fibrinogen and activation of αIIbβ3 is a key event that triggers platelet aggregation. Also, the KGD motif is critical for αIIbβ3 binding and the interaction stabilizes thrombus. Previous studies showed that CD40L binds to and activates integrins αvβ3 and α5β1 and that HIGM1 mutations are clustered in the integrin-binding sites. However, the specifics of CD40L binding to αIIbβ3 were unclear. Here, we show that CD40L binds to αIIbβ3 in a KGD-independent manner using CD40L that lacks the KGD motif. Two HIGM1 mutants, S128E/E129G and L155P, reduced the binding of CD40L to the classical ligand-binding site (site 1) of αIIbβ3, indicating that αIIbβ3 binds to the outer surface of CD40L trimer. Also, CD40L bound to the allosteric site (site 2) of αIIbβ3 and allosterically activated αIIbβ3 without inside-out signaling. Two HIMG1 mutants, K143T and G144E, on the surface of trimeric CD40L suppressed CD40L-induced αIIbβ3 activation. These findings suggest that CD40L binds to αIIbβ3 in a manner different from that of αvβ3 and α5β1 and induces αIIbβ3 activation. HIGM1 mutations are clustered in αIIbβ3 binding sites in CD40L and are predicted to suppress thrombus formation and immune responses through αIIbβ3. Full article

COVID-19 convalescent plasma (CCP) with high neutralizing antibodies has been suggested in preventing disease progression in COVID-19. In this study, we investigated the relationship between clinical donor characteristics and neutralizing anti-SARS-CoV-2 antibodies in CCP donors. COVID-19 convalescent plasma donors were included into the study. Clinical parameters were recorded and anti-SARS-CoV-2 antibody levels (Spike Trimer, Receptor Binding Domain (RBD), S1, S2 and nucleocapsid protein) as well as ACE2 binding inhibition were measured. An ACE2 binding inhibition < 20% was defined as an inadequate neutralization capacity. Univariate and multivariable logistic regression analysis was used to detect the predictors of inadequate neutralization capacity. Ninety-one CCP donors (56 female; 61%) were analyzed. A robust correlation between all SARS-CoV-2 IgG antibodies and ACE2 binding inhibition, as well as a positive correlation between donor age, body mass index, and a negative correlation between time since symptom onset and antibody levels were found. We identified time since symptom onset, normal body mass index (BMI), and the absence of high fever as independent predictors of inadequate neutralization capacity. Gender, duration of symptoms, and number of symptoms were not associated with SARS-CoV-2 IgG antibody levels or neutralization. Neutralizing capacity was correlated with SARS-CoV-2 IgG antibodies and associated with time since symptom onset, BMI, and fever. These clinical parameters can be easily incorporated into the preselection of CCP donors. Full article

The role and durability of the immunogenicity of the BNT162b2 mRNA vaccine against severe acute respiratory virus 2 (SARS-CoV-2), in cancer patients one year after receiving the third dose have to be elucidated. We have prospectively evaluated the long-term immunogenicity of the third dose of the SARS-CoV-2 BNT162b2 mRNA vaccine in 55 patients undergoing active treatment. Neutralizing antibody (NT Ab) titers against Omicron variants and total anti-trimeric S IgG levels were measured one year after the third dose. Heparinized whole-blood samples were used for the assessment of the SARS-CoV-2 interferon-γ release assay (IGRA). Thirty-seven patients (67.3%) showed positive total anti-trimeric S IgG one year after the third dose. Looking at the T-cell response against the spike protein, the frequency of responder patients did not decrease significantly between six and twelve months after the third dose. Finally, less than 20% of cancer patients showed an undetectable NT Ab titer against BA.1 and BA.5 variants of concern (VOCs). Underlying therapies seem to not affect the magnitude or frequency of the immune response. Our work underlines the persistence of humoral and cellular immune responses against BNT162b2 in a cohort of cancer patients one year after receiving the third dose, regardless of the type of underlying therapy. Full article

Accurate studies on the dynamics of Pfizer-Biontech BNT162b2-induced antibodies are crucial to better tailor booster dose administration depending on age, comorbidities, and previous natural infection with SARS-CoV-2. To date, little is known about the durability and kinetics of antibody titers months after receiving a booster dose. In this work, we studied the dynamic of anti-Trimeric Spike (anti-TrimericS) IgG titer in the healthcare worker population of a large academic hospital in Northern Italy, in those who had received two vaccine doses plus a booster dose. Blood samples were collected on the day of dose 1, dose 2, then 1 month, 3 months, and 6 months after dose 2, the day of the administration of the booster dose, then 1 month and 3 months after the booster dose. The vaccination immunogenicity was evaluated by dosing anti-TrimericS IgG titer, which was further studied in relation to SARS-CoV-2 infection status, age, and sex. Our results suggest that after the booster dose, the anti-TrimericS IgG production was higher in the subjects that were infected only after the completion of the vaccination cycle, compared to those that were infected both before and after the vaccination campaign. Moreover, the booster dose administration exerts a leveling effect, mitigating the differences in the immunogenicity dependent on sex and age. Full article

We sought to assess pre-vaccination and post-vaccination seroprevalences of anti-SARS-CoV-2 antibodies in Kuwait and to compare antibody levels between vaccine types. In phase 1 (pre-vaccination period, n = 19,363), blood samples were collected before the launch of COVID-19 vaccination in Kuwait between 1 September and 31 December 2020. Blood samples for phase 2 (post-vaccination period, n = 4973) were collected between 1 September and 30 November 2021. We tested subjects for anti-SARS-CoV-2 antibodies using the DiaSorin LIAISON^® SARS-CoV-2 IgM and Trimeric S IgG tests. In the pre-vaccination period, the prevalence of SARS-CoV-2 IgM and IgG was 14.50% (95% CI: 14.01–15.00) and 24.89% (95% CI: 24.29–25.50), respectively. The trend of seropositivity increased with age and was higher for females and non-Kuwaiti participants (p < 0.0001). Interestingly, seroprevalence was significantly higher for those who had received one dose of BNT162b2 (95.21%) than those who had received one dose of ChAdOx1-nCov-19 (92.86%). In addition, those who reported receiving two doses had higher seroprevalence, 96.25%, 95.86%, and 94.93% for ChA-dOx1-nCov-19/AstraZeneca, mix-and-match, and BNT162b2 recipients, respectively. After the second dose, median spike-specific responses showed no significant difference between ChAdOx1-nCov-19 and BNT162b2. Furthermore, statistical analysis showed no significant difference between median anti-trimeric S antibody levels of vaccinated individuals according to sex, age, or nationality (p > 0.05). In contrast, a negative correlation between age and anti-trimeric S IgG titers of BNT162b2-vaccinated subjects was observed (r = −0.062, p = 0.0009). Antibody levels decreased with time after vaccination with both vaccines. Our findings indicate that seroprevalence was very low during the pre-vaccination period (25%) in the general population and was greater than 95% in the vaccinated population in Kuwait. Furthermore, ChAdOx1-nCov-19 and BNT162b2 are effective in generating a similar humoral response. Full article

This study pictures the humoral response of 100 vaccinees to Pfizer/BioNTech COVID-19 vaccine over a year, with particular focus on the influence of a booster shot administered around 10 months after the primary immunization. The response to the vaccination was assessed with Diasorin’s SARS-CoV-2 TrimericSpike IgG. Abbott’s SARS-CoV-2 Nucleocapsid IgG immunoassay was used to identify SARS-CoV-2 contact, even asymptomatic. In contrast to the gradual decline of the anti-spike IgG between 30 and 240 days after the first dose, an increase was noted between days 240 and 360 in the whole cohort. However, a statistically significant rise was seen only in boosted individuals, and this effect of the booster decreased over time. An increase was also observed in non-boosted but recently infected participants and a decrease was reported in non-boosted, non-infected subjects. These changes were not statistically significant. On day 360, a percentage of new SARS-CoV-2 infections was statistically lower in the boosted vs. non-boosted subgroups. The booster immunization is the most efficient way of stimulating production of anti-spike, potentially neutralizing antibodies. The response is additionally enhanced by the natural contact with the virus. Individuals with a low level of anti-spike antibodies may benefit the most from the booster dose administration. Full article

Staphylococcus aureus protein A (SpA) is an IgG Fc-binding virulence factor that is widely used in antibody purification and as a scaffold to develop affinity molecules. A cyclized SpA Z domain could offer exopeptidase resistance, reduced chromatographic ligand leaching after single-site endopeptidase cleavage, and enhanced IgG binding properties by preorganization, potentially reducing conformational entropy loss upon binding. In this work, a Z domain trimer (Z3) was cyclized using protein intein splicing. Interactions of cyclic and linear Z3 with human IgG₁ were characterized by differential scanning fluorimetry (DSF), surface plasmon resonance (SPR), and isothermal titration calorimetry (ITC). DSF showed a 5 ℃ increase in IgG₁ melting temperature when bound by each Z3 variant. SPR showed the dissociation constants of linear and cyclized Z3 with IgG₁ to be 2.9 nM and 3.3 nM, respectively. ITC gave association enthalpies for linear and cyclic Z3 with IgG₁ of −33.0 kcal/mol and −32.7 kcal/mol, and −T∆S of association 21.2 kcal/mol and 21.6 kcal/mol, respectively. The compact cyclic Z3 protein contains 2 functional binding sites and exhibits carboxypeptidase Y-resistance. The results suggest cyclization as a potential approach toward more stable SpA-based affinity ligands, and this analysis may advance our understanding of protein engineering for ligand and drug development. Full article

We investigated the spike IgG levels of HIV+ patients on antiretroviral therapy six months after they received their second dose (T2) and six months after the third dose (T3) of the BNT162b2 mRNA vaccine, as well as the influence of different levels of plasma HIV viremia of overall CD4+ cell count and nadir value on the humoral time course. One hundred eighty-four patients were enrolled. The median age was 55 years, the median CD4+ cell count was 639 cells/mm³ and the median nadir value was 258 cells/mm³. On the basis of all tests performed during the study period, persistently undetectable plasma HIV RNA (PUD) was found in 66 patients, low-level viremia (LLV) in 57 and ongoing viremia (OV) in 61. Serum levels of IgG antibodies against a trimeric S-protein antigen were tested with DiaSorin Liaison SARS-CoV-2 TrimericS IgG and the response was classified as optimal (>75th percentile), intermediate (50th–25th percentile) and low (<25th percentile). The frequencies of the three different patterns of plasma HIV viremia (PUD, LLV and OV) were comparable in patients with low, intermediate and optimal IgG response evaluated at T2, with no difference in overall CD4+ cell count or nadir count. At T3, 92.9% of patients achieved an optimal response: T2 response proved to be the most important factor in predicting T3 optimal response in patients with LLV and OV.A nadir value ≤ 330 cells/mm³ had 100% sensitivity in predicting a non-optimal response. In conclusion, we demonstrated the persistence of anti-spike IgG, with high serum levels occurring in most patients six months after the third dose of the BNT162b2 mRNA vaccine and a predictive role of humoral response at T2 in subjects with detectable plasma HIV viremia. Immunological alterations related to past immunodeficiency may persist despite immune reconstitution, and the nadir value could be a useful tool for elaborating personalized vaccine schedules. Full article

Healthcare workers (HCWs) are a vulnerable and critical population in the ongoing response to the SARS-CoV-2 pandemic. We aimed to estimate the seroprevalence in HCWs considering all of their previous contacts with the SARS-CoV-2 virus and/or the immunity acquired through their immunization against COVID-19 before the advent of the Omicron variants BA.4/BA.5. Serum samples were collected from 28 March to 10 June 2022. We covered 25% out of all the people who worked in some of the government healthcare centers (primary, secondary, and tertiary level) across the entire Autonomous Province of Vojvodina (Northern Serbia). Two serological tests (Anti-SARS-CoV-2 QuantiVac ELISA and LIAISON^® SARS-CoV-2 TrimericS) were used to detect anti-spike IgG antibodies. The overall prevalence of the SARS-CoV-2 antibody among the 6936 HCWs was 92.96% [95% CI 92.33–93.55]. Regarding the type of serological test, there was a statistically significant (p = 0.0079) difference of the seropositivity obtained by the LIAISON^® SARS-CoV-2 TrimericS (93.87%, 95% CI 92.97–94.69) and Anti-SARS-CoV-2 QuantiVac ELISA (92.23%, 95% CI 91.34–93.06) tests. Seropositivity to SARS-CoV-2 significantly (p < 0.0001) increased with the number of SARS-CoV-2 infections combined with the number of doses of the SARS-CoV-2 vaccines received. A vast majority of the HCWs in Vojvodina had detectable levels of antibodies to the spike protein of SARS-CoV-2, but despite this high seropositivity, it is unknown whether this herd immunity among HCWs is protective against the new variants of concern. Further research should evaluate the rates of reinfections and the associated severity of COVID-19 caused by the Omicron sublineages and/or new variants of SARS-CoV-2 among HCWs. Full article