Search Results (68)

Objectives: The durability and breadth of neutralizing antibodies following SARS-CoV-2 mRNA vaccination remain incompletely understood. This study aimed to investigate how longitudinal changes in antibody isotype composition impact neutralization against structurally diverse SARS-CoV-2 variants. Methods: After screening a broader cohort of mRNA-vaccinated sera, time-matched samples collected one month (1 mpv) and three months post-vaccination (3 mpv) were selected for detailed analysis. Neutralization assays against live virus variants, enzyme-linked immunosorbent assays (ELISA), and immunogold electron microscopy were performed to assess antibody titers, isotype levels, and virion morphology. Results: Neutralization titers declined markedly at 3 mpv, particularly against immune-evasive variants. Notably, the Lambda variant showed disproportionately high sensitivity to early-phase sera despite its divergence from the vaccine strain. Antibody isotyping showed that IgA and IgM decreased over time, while IgG levels were relatively more sustained. Electron microscopy revealed broader virion size heterogeneity in Lambda (50–200 nm) compared to Wuhan (80–120 nm), potentially enhancing multivalent antibody engagement. Consistently, ELISA under reduced spike density conditions showed that IgA and IgM retained stronger binding than IgG. Conclusions: These findings indicate that the decline of IgA and IgM compromises neutralization breadth, especially against structurally divergent variants such as Lambda. Sustaining dynamic multivalent isotype responses that adapt to diverse spike morphologies may be critical for broad cross-variant immunity. Full article

Food allergies result from dysregulated immune responses to dietary antigens. IgE antibodies are key in triggering allergic reactions through binding to high-affinity receptors on mast cells and triggering mast cell activation when crosslinked by allergens. In contrast, IgG antibodies—particularly IgG4—are linked to immunomodulation and tolerance. Allergen-specific memory B cells, especially IgG1+ cells, undergo class-switching to IgE, and IgE plasma cells underlie allergy persistence. Although there is no cure, allergen-specific immunotherapy (AIT) aims to achieve sustained unresponsiveness by gradually increasing allergen exposure. Oral immunotherapy (OIT), a form of AIT, induces a shift from a TH2-skewed response to a more regulated immune profile, characterized by a switch from IgE to IgG4 and IgA isotypes. This review outlines current insights into AIT’s cellular and humoral mechanisms, with implications for improving long-term outcomes and developing predictive biomarkers. Full article

The aim of the paper was to characterize rheumatoid factor IgA, IgG, and IgM isotypes in patients with Sjögren’s syndrome (SS) subsets, based on the absence or presence of joint complaints of different etiologies. In total, 164 SS patients were grouped based on whether they had polyarthritis as an extraglandular manifestation (n = 73, SS+pa), rheumatoid arthritis as an associated autoimmune disorder (n = 46, SS+RA), or Sjögren’s syndrome without inflammatory joint pain (n = 45, SS). The highest IgA rheumatoid factor isotype levels were detected in SS patients, whereas the lowest levels were found in the SS+RA group, without a significant difference. Neither IgG nor IgM RF differed significantly between the patient subclasses. In addition to other disease-specific markers, seropositive patients who were seropositive for any RF isotype were significantly more frequently anti-Ro/SS-A and anti-La/SS-B positive and had higher ESSDAI levels. In SS and SS+pa patients, a strong negative correlation was observed between IgA RF and age, whereas a strong positive correlation was found between IgA RF and ESSDAI, RF, IgA, IgG, anti-Ro/SS-A, and anti-La/SS-B levels. High total IgG levels together with high IgA RF levels occurred most frequently in SS patients (p = 0.05), whereas the combination of normal IgG and high IgM RF was significantly more frequent in the SS+RA group. The co-occurrence of high total IgG and normal IgM RF did not differ significantly between the patient subsets; however, this was the combination with the highest sensitivity (94.5%) for SS+pa patients. Based on our findings, rheumatoid factor isotypes have an additive value in the differentiation of non-erosive polyarthritis and erosive rheumatoid arthritis during the disease course of patients with Sjögren’s syndrome. All rheumatoid factor isotypes predict a more severe disease course, but IgA RF may serve as a candidate for being an early, poor prognostic factor for SS patients. Full article

Parainfluenza viruses are a common cause of respiratory illness in many species. In this study, experimental, alphavirus-derived RNA particle vaccines either with or without adjuvant were evaluated against porcine parainfluenza virus 1 (PPIV1) challenge and compared to live virus exposure. Groups of ten, three-week-old pigs were vaccinated intramuscularly with an adjuvanted RNA particle (RPAdj/C) or non-adjuvanted RP (RP/C) or administered an intranasal live exposure (LE/C) dose of PPIV1 at 0- and 21-days post vaccination (DPV) followed by challenge with PPIV1 at 40 DPV. In addition, two groups were included as non-vaccinated, non-challenged (NV/NC) and non-vaccinated, challenged (NV/C) controls. Intranasal virus exposure and RP vaccination, regardless of adjuvant, reduced PPIV1 shedding in nasal swabs by 5 days post inoculation (DPI). All vaccinated or exposed pigs seroconverted as shown by enzyme-linked immunosorbent assay and serum virus neutralization. The antibody isotype detected in bronchoalveolar lavage fluid (BALF) LE/C was predominantly IgA while RP vaccination induced an IgG response. Reduced PPIV1 antigen was observed in the LE/C, RP/C and RPAdj/C groups in lung, trachea, or nasal turbinate epithelium. Additionally, the RPAdj vaccine significantly reduced nasal shedding compared to NV/C pigs although not as much as LE/C pigs. These results suggest vaccination could mitigate PPIV1 infection in commercial systems. Full article

Previous studies have shown that high-dose vitamin supplements can improve vaccine-induced immune responses and pathogen protection in the context of vitamin deficiencies. To further elucidate the influence of vitamin supplements on immune responses toward pediatric vaccines, we performed a randomized controlled clinical trial (PCVIT) of 20 healthy children 1–4 years of age in Memphis, Tennessee. Study participants received a booster vaccine for pneumococcus and a primary vaccine for hepatitis A virus with or without a high-dose, oral, liquid supplement of 10,000 IU retinyl palmitate. We found that the children enrolled in PCVIT had higher baseline vitamin levels than previously described older children and adults living in Memphis. Only one child in PCVIT had a serum retinol level of less than 0.3 µg/mL. The children frequently consumed milk and baby foods that were likely vitamin-fortified, providing an explanation for the relatively high vitamin levels. Most children in PCVIT responded well to pneumococcus and hepatitis A vaccines by pathogen-specific antibody upregulation. The one child with a serum retinol level below 0.3 µg/mL did not receive a vitamin supplement and exhibited the lowest fold-change in antibody responses toward pneumococcal serotypes. A correlation matrix encompassing demographics, vitamin levels, vaccine-induced immune responses, C-reactive protein, and total serum immunoglobulin isotypes, including IgG2 and IgA, identified variables associated with vaccination outcomes. Perhaps because children were predominantly retinol-sufficient at baseline, the high-dose vitamin A supplement exhibited no benefit to vaccine-induced immune responses. In fact, when vitamin supplemented and vitamin unsupplemented groups were compared among participants with the highest baseline retinol levels, there was a trend toward weaker vaccine-induced immune responses in the vitamin supplemented group. Results encourage the performance of larger clinical studies before high-dose vitamin supplements are recommended for populations that are otherwise vitamin-replete. Full article

Rheumatoid factor (RF) is the first autoantibody identified in rheumatoid arthritis (RA) which targets the fragment crystallizable (Fc) region of immunoglobulin (Ig) G. Although IgM isotype is predominant, other Ig isotypes, including IgG and IgA, also exist. While RF is not specific to RA, it remains a valuable serological test for diagnosing the disease, as evidenced by its inclusion in the 2010 classification criteria for RA based on elevated serum RF levels. RF is also associated with RA severity, including joint damage and extra-articular manifestations, serving as a poor prognostic factor and aiding in the identification of difficult-to-treat RA. Recent studies have demonstrated that high serum RF levels are associated with a reduced response to tumor necrosis factor (TNF) inhibitors. In contrast, anti-TNF antibodies lacking the Fc portion have shown stable efficacy in RA patients regardless of baseline RF levels. These findings reaffirm the clinical significance of RF measurement, 80 years after its initial discovery. This review explores the diagnostic and prognostic significance of RF and its impact on treatment selection in RA management. Full article

Multiple sclerosis (MS) is a chronic immune-mediated neurological disorder, characterized by progressive demyelination and neuronal cell loss in the central nervous system. Many possible causes of MS have been proposed, including genetic factors, environmental triggers, and infectious agents. Recently, Clostridium perfringens epsilon toxin (ETX) has been incriminated in MS, based initially on the isolation of the bacteria from a MS patient, combined with an immunoreactivity to ETX. To investigate a putative causative role of ETX in MS, we analyzed the pattern of antibodies reacting to the toxin using a sensitive qualitative assay. This prospective observational study included one hundred patients with relapsing remitting multiple sclerosis (RRMS), all untreated, and ninety matched healthy controls. By assessing the isotypic pattern and serum concentration of ETX-reacting antibodies, our study shows a predominant IgM response over IgG and IgA antibody responses both in MS patients and controls, and significantly higher levels of IgM reacting to ETX in MS patients compared to the control group. A longitudinal follow-up of ETX-specific antibody response in a subgroup of MS patients did not show any correlation with disease evolution. Overall, these unexpected findings are not compatible with a specific recognition of ETX by serum antibodies from MS patients. They rather argue for a cross immunological reactivity with an antigen, possibly an autoantigen, mimicking ETX. Thus, our data argue against the hypothesis of a causal relationship between C. perfringens ETX and MS. Full article

Plague, caused by Yersinia pestis, poses a public health threat not only due to sporadic outbreaks across the globe but also due to its potential as a biothreat agent. Ironically, among the seven deadliest pandemics in global history, three were caused by Y. pestis. Pneumonic plague, the more contagious and severe form of the disease, is difficult to contain, requiring either prophylactic antibiotic treatment or vaccination. However, no vaccine (live attenuated or subunit) is currently approved by the Food and Drug Administration, requiring rigorous preclinical studies in different animal models, thus forming the basis of this study. Objectives: The aim of this study was to evaluate the efficacy and immune responses of two live attenuated vaccines (LAVs), LMA and LMP, either alone or in combination with a trivalent adenoviral vector-based vaccine (Ad5-YFV), in IL-17A-depleted and IgG control mice by using an anti-IL-17A monoclonal antibody (mAb) or its matched isotype IgG, respectively. Methods: IL-17A mAb or IgG isotype control was administered to mice twice per week to their respective groups during the course of immunization. Serum, spleens, and broncho-alveolar lavage fluid (BALF) were collected for assessing immunological responses, and another cohort of mice was intranasally challenged with a lethal dose of parental Y. pestis CO92. Results: Robust humoral and cellular immune responses followed by complete protection were observed in all vaccinated animals against highly lethal intranasal challenge doses of parental Y. pestis CO92. Serum IgG titers to YscF and overall mucosal IgA titers to all three antigens of the Ad5-YFV vaccine were significantly lower, with slightly reduced serum LcrV-neutralizing antibodies when IL-17A was depleted compared to IgG control animals during the course of immunization. A remarkable reduction in Th1 (IFNγ or IL-2) and Th17 cell populations was observed in IL-17A-depleted mice compared to IgG controls in response to vaccination. On the other hand, B cell activities in germinal centers, overall activated antigen-specific T cells, and memory B and T cells remained at comparable levels in both vaccinated IL-17A-depleted and IgG control mice. Conclusions: These data demonstrated the effectiveness of our vaccines even under the reduced levels of both Th1 and Th17 responses and thus should be suitable for those individuals associated with certain immune deficiencies. Full article

SARS-CoV-2 infection induces a humoral immune response, producing virus-specific antibodies such as IgM, IgG, and IgA. IgA antibodies are present at mucosal sites, protecting against respiratory and other mucosal infections, including SARS-CoV-2, by neutralizing viruses or impeding attachment to epithelial cells. Since SARS-CoV-2 spreads through the nasopharynx, the specific IgAs of SARS-CoV-2 are produced quickly after infection, effectively contributing to virus neutralization. Dimeric IgA has been reported to be 10 to 15 times more potent than its equivalent IgG, suggesting that this isotype may be particularly interesting in developing new monoclonal antibodies and/or new vaccines efficiently neutralizing the virus at the mucosal sites. It is still unclear whether IgA antibodies in BAL might play a role in the disease course and if their presence may have a prognostic significance. However, a harmful effect on diseases with high IgA titers has been reported. This study evaluated mucosal-specific IgA and IgG profiles in BAL of patients with COVID-19 acute respiratory failure admitted to the ICU. We included 57 patients (41 males and 16 females), admitted to the ICU of the University of Foggia. We used a commercially available ELISA assay to evaluate the presence of SARS-CoV-2 IgG and IgA antibodies in plasma and BAL of the 57 hospitalized patients with severe COVID-19 respiratory failure. However, 40/57 BAL and plasma from infected patients were available for the ELISA test; the remaining specimens were unsuitable. IgG and IgA antibodies against SARS-CoV-2 were detectable in 37 (92.5%) and 40 (100%) plasma specimens, respectively. IgG antibodies were found in a single sample, while IgAs were detected in 19 of 40 BAL samples analyzed. Correlations between these parameters and patient outcomes reveal a signature associated with survival. Interestingly, a statistically significant inverse correlation was found between the mortality rate and the presence of IgA to SARS-CoV-2 in BAL specimens. None of the 19 patients with a positive IgA died, compared to 7 out of 12 patients with a negative IgA-BAL (p: <0.0004). Despite being limited in size, this study suggests a significant protective effect of mucosal immunity in COVID-19 patients, even in advanced disease stages, and a role of IgA in the defense against the virus, as well as the possible use of effective vaccines and therapeutic strategies based on IgA antibodies. Full article

Background/Objectives: In a previous study, we described elevated anti-Anisakis IgG levels in septic patients in relation to disease severity. In this study, our objective was to analyze the evolution of anti-Anisakis immunoglobulins in septic patients during hospital admission and their association with αβ and γδ T cell subsets. Methods: We recruited 80 subjects: 40 patients with sepsis and 40 controls. αβ and γδ T cells were analyzed using flow cytometry. Apoptosis was also assessed, and anti-Anisakis antibodies were measured by ELISA in the sera of patients with sepsis and controls. Results: In the second analysis (7–10 after sepsis evolution), an increase in all specific antibody isotypes was identified in individuals with septic shock, except IgE. The levels of anti-Anisakis IgG and IgA were higher in the subjects with sepsis in the first analysis and continued to increase in the second analysis compared with the healthy control subjects. There was an increase in anti-Anisakis IgG and IgA levels in surviving patients and an increase in IgA levels in non-surviving patients. A rise in specific IgG and IgE levels was noted in the second analysis of patients with sepsis with αβ CD3+ T cell deficiency. Patients without γδ T cell deficiency had increased anti-Anisakis IgA levels 7–10 days after admission. Conclusions: Our results suggest a previous infection by Anisakis that could be involved in the subsequent septic process and be related to patients who have negative cultures in which the pathogen causing sepsis has not been identified. Full article

Background/Objectives: Schizophrenia (SZ) is a complex psychiatric disorder with increasing evidence pointing to an autoimmune component, including the presence of antiphospholipid antibodies (aPLs). This study aims to assess the prevalence of anticardiolipin (aCL) and anti-beta-2 glycoprotein I (aβ2GPI) antibodies, particularly the IgG, IgA, and IgM isotypes, in drug-free SZ patients compared to healthy controls, and explore their possible involvement in the disease’s pathophysiology. Methods: Eighty SZ patients meeting DSM-IV criteria were recruited, along with 80 matched healthy controls. Serum samples were analyzed using enzyme-linked immunosorbent assays (ELISA) to quantify IgG, IgA, and IgM isotypes of aCL and aβ2GPI. Results: SZ patients exhibited significantly higher levels of aCL-IgM and aCL-IgA (p < 0.05), as well as elevated aβ2GPI-IgA (22.5%, p < 0.001), compared to controls. No significant differences were observed in the aCL-IgG isotype. Interestingly, 72% of aPL-positive SZ patients were positive for aβ2GPI-IgA, with some also co-expressing multiple isotypes, suggesting a potential link between SZ and antiphospholipid syndrome (APS). Conclusions: This study is the first to report a high prevalence of aCL-IgA and aβ2GPI-IgA in SZ patients, highlighting a possible autoimmune involvement in the disease. The presence of multiple aPL isotypes, particularly IgA, suggests a need for further investigation into their role in SZ pathogenesis and their potential association with APS. Full article

Background/Objectives. The presence of anti-citrullinated peptide/protein antibodies (ACPAs), anti-carbamylated peptide/protein antibodies (anti-CarPs), and anti-acetylated peptide/protein antibodies (AAPAs), collectively termed as anti-modified peptide/protein antibodies (AMPAs), is a hallmark of rheumatoid arthritis. These autoantibodies play a crucial role in the complex autoimmune responses observed in patients. Understanding the interplay between them is essential for early diagnosis and effective management of the disease. Methods. In this work, we investigate IgG, IgM, and IgA levels of ACPAs, anti-CarPs, and AAPAs in two cohorts: patients with established RA disease and healthy blood donors, using a unique peptide antigenic backbone. Results. Our results showed that antibody levels of anti-citrullinated peptide (CFFCP) and anti-homocitrullinated peptide (CFFHP) were significantly higher in RA patients compared to healthy blood donors in the three isotypes analyzed, IgG, IgA, and IgM. Fine specificities were more frequent when using the CFFCP antigen. Regarding the reactivity to the acetyl-lysine modified peptide (CFFAP), the correlation between IgA and IgG/IgM was very weak. CCFAP was highly specific for isotypes IgG and IgA, but its sensitivity was low for both isotypes. Anti-CarP and AAPA are significant in the context of RA, particularly concerning their IgA isotypes. Conclusions. Their inclusion in diagnostics assessments for RA, especially for anti-citrulline negative cases, presents a potential advance in the field; however, they do not replace yet traditional markers like rheumatoid factor (RF) and ACPAs. Full article

Vaccination strategies are used to manage Salmonella in chickens. Salmonella-killed vaccines are considered safer since they are inactivated. However, little is known regarding the cellular immune activities at the site of vaccine administration of Salmonella-killed vaccines. The growing feather (GF) cutaneous test has been shown to be an effective bioassay to monitor local tissue/cellular responses. We assessed local and systemic antibody responses initiated by intradermal injection of Salmonella-killed vaccines into GF-pulps of 14–15-week-old pullets. Treatments consisted of two autogenous Salmonella-killed vaccines (SV1 and SV2), S. Enteritidis (SE) lipopolysaccharide (SE-LPS), and the water-oil-water (WOW) emulsion vehicle. GF-pulps were collected before (0 h) and at 6, 24, 48, and 72 h post-GF-pulp injection for leukocyte population analysis, while heparinized blood samples were collected before (0 d) and at 3, 5, 7, 10, 14, 21, and 28 d after GF-pulp injections to assess plasma levels (a.u.) of SE-specific IgM, avian IgY (IgG), and IgA antibodies using an ELISA. Injection of GF-pulps with SV1, SV2, or SE-LPS, all in a WOW vehicle, initiated inflammatory responses characterized by the recruitment of heterophils, monocytes/macrophages, and a few lymphocytes. The WOW vehicle emulsion alone recruited more lymphocytes than vaccines or SE-LPS. The SV1 and SV2 vaccines stimulated Salmonella-specific IgM and IgA early, while IgG levels were greatly elevated later during the primary response. Overall, SV1 and SV2 stimulated a heterophil and macrophage-dominated local inflammatory- and SE-specific humoral response with an isotype switch from IgM to IgG, characteristic of a T-dependent primary antibody response. This study provides comprehensive information on innate and adaptive immune responses to autogenous Salmonella-killed vaccines and their components that will find application in the management of Salmonella in poultry. Full article

Background/Objectives: Enzyme-linked immunosorbent assays (ELISAs) have been used to measure anti-human-papillomavirus (HPV) immunoglobulin IgG. The goal of this study was to evaluate the reproducibility of ELISAs measuring different HPV immunoglobulin isotypes, IgG1, 2, 3, and 4, IgA, and IgM, against HPV16. Methods: Seventy-two serum samples collected from participants in the Costa Rica HPV Vaccine Trial (CVT) and immunized with bivalent HPV vaccine (2vHPV) were used for reproducibility assessment. IgG2 and IgG4 levels were too low to be detected. Levels of IgG1, IgG3, IgA, and IgM were measured, and the data were used to calculate intraclass correlation coefficients (ICCs) and coefficients of variation (CVs). Results: CVs were assessed between technicians (12.8–22.7%) and across days (6.2–30.6%). The overall CVs ranged from 7.7–31.1%. IgM ELISA showed higher CVs (15.8–31.1%) than IgG1, IgG3, and IgA (6.2–22.7%). All ICC values were >98.7%. IgG3 was detected in all samples, while IgG1 and IgA had >86.3% detectability and IgM had 62.1% detectability. Pearson correlational analyses between different antibodies all showed significant correlations (p ≤ 0.001), except when comparing IgGs or IgA to IgM (p = 0.29–0.53). Conclusions: Our data showed that these ELISAs are reproducible and detect isotype antibodies to HPV16 L1 across a range of concentrations in 2vHPV-vaccinated participants. Full article

Increasing the effectiveness of vaccines against respiratory viruses is particularly relevant for the elderly, since they are prone to develop serious infections due to comorbidities and the senescence of the immune system. The addition of saponin-based adjuvants is an interesting strategy to increase the effectiveness of vaccines. We have previously shown that ISCOM matrices from Q. brasiliensis (IMXQB) are a safe and potent adjuvant. In this study, we evaluated the use of IMXQB as an adjuvant for the seasonal trivalent influenza vaccine (TIV) in an aged mice model. Herein, we show that subcutaneous injection of the adjuvanted vaccine promoted higher titers of IgM, IgG (and isotypes), and serum hemagglutination inhibition titers (HAI). Notably, aged mice immunized by intranasal route also produced higher IgG (and isotypes) and IgA titers up to 120 days after priming, as well as demonstrating an improvement in the HAI antibodies against the TIV. Further, experimental infected aged mice treated once with sera from adult naïve mice previously immunized with TIV-IMXQB subcutaneously successfully controlled the infection. Overall, TIV-IMXQB improved the immunogenicity compared to TIV by enhancing systemic and mucosal immunity in old mice conferring a faster recovery after the H1N1pdm09-like virus challenge. Thus, IMXQB nanoparticles may be a promising platform for next-generation viral vaccines. Full article