Monitoring SARS-CoV-2 IgA, IgM and IgG antibodies in dried blood and saliva samples using antibody proximity extension assays (AbPEA).

Using a modified proximity extension assay, total and immunoglobulin (Ig) class-specific anti-SARS-CoV-2 antibodies were sensitively and conveniently detected directly from ø1.2 mm discs cut from dried blood and saliva spots (DBS and DSS) without the need for elution. For total Ig detection, antigen probes were prepared by conjugating recombinant spike protein subunit 1 (S1-RBD) to a pair of oligonucleotides. To detect isotype-specific antibody reactivity, one antigen probe was replaced with oligonucleotide-conjugated antibodies specific for antibody isotypes. Binding of pairs of oligonucleotide-conjugated probes to antibodies in patient samples brings oligonucleotides in proximity. An added DNA polymerase uses a transient hybridization between the oligonucleotides to prime synthesis of a DNA strand, which serves as a DNA amplicon that is quantified by real-time PCR. The S1-RBD-specific IgG, IgM, and IgA antibodies in DBS samples collected over the course of a first and second vaccination exhibited kinetics consistent with previous reports. Both DBS and DSS collected from 42 individuals in the autumn of 2023 showed significant level of total S1-RBD antibodies with a correlation of R = 0.70. However, levels in DSS were generally 10 to 100-fold lower than in DBS. Anti-S1-RBD IgG and IgA in DSS demonstrated a correlation of R = 0.6.

The immune response to Covid-19 mRNA vaccination among Lymphoma patients receiving anti-CD20 treatment.

The monoclonal antibody rituximab improves clinical outcome in the treatment of CD20-positive lymphomatous neoplasms, and it is an established drug for treatment of these cancers. Successful mRNA COVID-19 (SARS-CoV-2) vaccination is extremely important for lymphoma patients because they tend to be elderly with comorbidities which leaves them at increased risk of poor outcomes once infected by Coronavirus. Anti-CD20 therapies such as rituximab, deplete B-cell populations and can affect vaccine efficacy. Therefore, a knowledge of the effect of COVID-19 vaccination in this group is critical. We followed a cohort of 28 patients with CD20-positive lymphomatous malignancies treated with rituximab that started prior to their course of COVID-19 vaccination, including boosters. We assayed for vaccine "take" in the humoral (IgG and IgA) and cellular compartment. Here, we show that short-term and long-term development of IgG and IgA antibodies directed toward COVID-19 spike protein are reduced in these patients compared to healthy controls. Conversely, the robustness and breath of underlying T-cell response is equal to healthy controls. This response is not limited to specific parts of the spike protein but spans the spike region, including response to the conserved Receptor Binding Domain (RBD). Our data informs on rational vaccine design and bodes well for future vaccination strategies that require strong induction of T-cell responses in these patients.

SARS-CoV-2 as a trigger of IgA vasculitis: a clinical case and literature review.

Coronavirus Disease 2019 (COVID-19), caused by SARS-CoV-2, has negatively affected global health. COVID-19 has been associated with a variety of autoimmune and inflammatory disorders, complicating its respiratory manifestations. SARS-CoV-2 triggers inflammatory reactions which may involve multiple organs and systems. The proof for IgA involvement in the immune reactions to coronavirus infection is growing, particularly in the case of IgA immune complex deposition diseases such as IgA vasculitis (IgAV) and IgA nephropathy.This report presents a case of IgAV caused by SARS-CoV-2 in a 53-year-old man. His symptoms included papillomatous, bright red rashes, urticaria throughout the body, aphthous stomatitis, pain in all joints and muscles, weakness, malaise, abdominal pain, face swelling, and arterial hypertension (160/100 mmHg). He received intravenous methylprednisolone (250 mg) and then oral methylprednisolone (16 mg) treatment, which improved his condition. This improvement included the disappearance of abdominal and joint pain and skin rashes.This article also provides an overview of published cases of IgAV after SARS-CoV-2. It may alert rheumatologists and allied specialists of clinical features of IgAV and guide them how to diagnose and treat this disease.

The serological diagnostic value of EBV-related IgA antibody panels for nasopharyngeal carcinoma: a diagnostic test accuracy meta-analysis.

BACKGROUND: Nasopharyngeal carcinoma (NPC) is diagnosed relatively late and has a poor prognosis, requiring early detection to reduce the disease burden. This diagnostic test accuracy meta-analysis evaluated the serological diagnostic value of nine EBV-related IgA antibody panels (EBNA1-IgA, VCA-IgA, EA-IgA, Zta-IgA, EBNA1-IgA + VCA-IgA, VCA-IgA + EA-IgA, VCA-IgA + Rta-IgG, EBNA1-IgA + VCA-IgA + Zta-IgA and VCA-IgA + EA-IgA + Rta-IgG), aiming to identify suitable serological detection biomarkers for NPC screening. METHODS: PubMed, Embase, China National Knowledge Infrastructure and Chinese BioMedical Literature Database were searched from January 1st, 2000 to September 30th, 2023, with keywords nasopharyngeal carcinoma, IgA, screening, early detection, early diagnosis, sensitivity and specificity. Articles on the diagnostic value of serum EBV-related IgA antibody panels for NPC were included. Study selection, data extraction, and quality assessment were performed independently by two researchers, and a third researcher was consulted in the case of disagreement. Bivariate models were used for statistical analysis. The quality of included studies was evaluated through Quality Assessment of Diagnostic Accuracy Studies tool (QUADAS-2). RESULTS: A total of 70 articles were included, involving 11 863 NPC cases and 34 995 controls. Among the nine EBV-related IgA antibody panels, EBNA1-IgA + VCA-IgA [0.928 (0.898, 0.950)], VCA-IgA + Rta-IgG [0.925 (0.890, 0.949)], EBNA1-IgA + VCA-IgA + Zta-IgA [0.962 (0.909, 0.985)] and VCA-IgA + EA-IgA + Rta-IgG [0.945 (0.918, 0.964)] demonstrated higher pooled sensitivity (95%CI). In terms of diagnostic odds ratio (DOR) (95%CI), EBNA1-IgA + VCA-IgA [107.647 (61.173, 189.430)], VCA-IgA + Rta-IgG [105.988 (60.118, 186.857)] and EBNA1-IgA + VCA-IgA + Zta-IgA [344.450 (136.351, 870.153)] showed superior performance. Additionally, the SROC curves for EBNA1-IgA + VCA-IgA and VCA-IgA + Rta-IgG were more favorable. However, publication bias was detected for VCA-IgA (P = 0.005) and EBNA1-IgA + VCA-IgA (P = 0.042). CONCLUSIONS: In general, parallel detection of serum EBNA1-IgA, VCA-IgA and Zta-IgA antibodies using ELISA demonstrates better pooled sensitivity and DOR among the studied panels. In the cases where fewer indicators are used, serum VCA-IgA and EBNA1-IgA/Rta-IgG antibody panel exhibits a comparable performance. TRIAL REGISTRATION: The International Prospective Register of Systematic Reviews registration number: CRD42023426984, registered on May 28, 2023.

Longitudinal proteome-wide antibody profiling in Marburg virus survivors identifies wing domain immunogen for vaccine design.

Limited knowledge exists on the quality of polyclonal antibody responses generated following Marburg virus (MARV) infection and its evolution in survivors. In this study, we evaluate MARV proteome-wide antibody repertoire longitudinally in convalescent phase approximately every six months for five years following MARV infection in ten human survivors. Differential kinetics were observed for IgM vs IgG vs IgA epitope diversity, antibody binding, antibody affinity maturation and Fc-receptor interaction to MARV proteins. Durability of MARV-neutralizing antibodies is low in survivors. MARV infection induces a diverse epitope repertoire with predominance against GP, VP40, VP30 and VP24 that persisted up to 5 years post-exposure. However, the IgM and IgA repertoire declines over time. Within MARV-GP, IgG recognize antigenic sites predominantly in the amino-terminus, wing domain and GP2-heptad repeat. Interestingly, MARV infection generates robust durable FcɣRI, FcɣRIIA and FcɣRIIIA IgG-Fc receptor interactions. Immunization with immunodominant MARV epitopes reveals conserved wing region between GP1 and GP2, induces neutralizing antibodies against MARV. These findings demonstrate that MARV infection generates a diverse, long-lasting, non-neutralizing, IgG antibody repertoire that perturbs disease by FcɣR activity. This information, along with discovery of neutralizing immunogen in wing domain, could aid in development of effective therapeutics and vaccines against Marburg virus.

Understanding antibody magnitude and durability following vaccination against SARS-CoV-2.

Vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) results in transient antibody response against the spike protein. The individual immune status at the time of vaccination influences the response. Using mathematical models of antibody decay, we determined the dynamics of serum immunoglobulin G (IgG) and serum immunoglobulin A (IgA) over time. Data fitting to longitudinal IgG and IgA titers was used to quantify differences in antibody magnitude and antibody duration among infection-naïve and infection-positive vaccinees. We found that prior infections result in more durable serum IgG and serum IgA responses, with prior symptomatic infections resulting in the most durable serum IgG response and prior asymptomatic infections resulting in the most durable serum IgA response. These findings can guide vaccine boosting schedules.

Post-Hoc Analysis of Potential Correlates of Protection of a Recombinant SARS-CoV-2 Spike Protein Extracellular Domain Vaccine Formulated with Advax-CpG55.2-Adjuvant.

SpikoGen® vaccine is a subunit COVID-19 vaccine composed of an insect cell expressed recombinant spike protein extracellular domain formulated with Advax-CpG55.2™ adjuvant. A randomized double-blind, placebo-controlled Phase II clinical trial was conducted in 400 adult subjects who were randomized 3:1 to receive two intramuscular doses three weeks apart of either SpikoGen® vaccine 25 µg or saline placebo, as previously reported. This study reports a post hoc analysis of the trial data to explore potential immune correlates of SpikoGen® vaccine protection. A range of humoral markers collected pre- and post-vaccination, including spike- and RBD-binding IgG and IgA, surrogate (sVNT), and conventional (cVNT) virus neutralization tests were compared between participants who remained infection-free or got infected over three months of follow-up. From 2 weeks after the second vaccine dose, 21 participants were diagnosed with SARS-CoV-2 infection, 13 (4.2%) in the SpikoGen® group and 8 (9%) in the placebo group. Those in the vaccinated group who experienced breakthrough infections had significantly lower sVNT titers (GMT 5.75 µg/mL, 95% CI; 3.72-8.91) two weeks after the second dose (day 35) than those who did not get infected (GMT 21.06 µg/mL, 95% CI; 16.57-26.76). Conversely, those who did not develop SARS-CoV-2 infection during follow-up had significantly higher baseline sVNT, cVNT, spike-binding IgG and IgA, and RBD-binding IgG, consistent with a past SARS-CoV-2 infection. SpikoGen® further reduced the risk of re-infection (OR 0.29) in baseline seropositive (previously infected) as well as baseline seronegative participants. This indicates that while SpikoGen vaccine is protective in seronegative individuals, those with hybrid immunity have the most robust protection.

Isotype deficiencies (IgG subclass and selective IgA, IgM, IgE deficiencies).

Background: Immunoglobulin G (IgG) subclass deficiencies and isolated IgA, IgM, IgE deficiencies have all been described in the literature with variable prevalence. Methods: These isotype deficiencies have a variable presentation from asymptomatic to recurrent infections resistant to prophylactic antibiotics. Results: Atopic disorders and autoimmune diseases are common comorbidities. IgE deficiency has been associated with impaired vaccine response and an increased risk of malignancy, particularly in patients with no allergic comorbidities and those with non-common variable immunodeficiency (CVID) humoral immunodeficiency, IgM deficiency, IgG2 deficiency, and CD4 lymphopenia. Conclusion: Close monitoring for malignancy should be strongly considered for these patients who are at risk. Treatment is variable and may include antimicrobial therapies for illnesses and prophylactic antibiotics in select patients, and immunoglobulin replacement can be considered for patients with refractory, recurrent infections.

Unlocking epitope similarity: A comparative analysis of the American manatee (Trichechus manatus) IgA and human IgA through an immuno-informatics approach.

The American manatee (Trichechus manatus), experiencing population declines due to various threats, is the focus of conservation efforts that include the capture, rehabilitation, and release of orphaned calves when their mothers are unable to care for them. These efforts are compromised by the use of commercially available milk substitutes that lack essential components found in natural manatee breast milk, particularly immunoglobulin A (IgA). IgA plays a crucial role in nurturing the immune mucosal system and fostering a healthy microbiota. However, research on IgA in non-maternally fed manatees is limited due to the lack of species-specific reagents. To address this gap, our study employs immuno-informatics analysis to compare IgA sequences from manatees with those from other species, aiming to explore epitope similarity and sharing. We compared the protein sequence of manatee IgA with available IgA sequences, assessing similarity at the sequence, 3D structures, and epitope levels. Our findings reveal that human IgA exhibits the highest similarity in terms of sequence and 3D structure. Additionally, epitope analysis shows high conservation, identity, and similarity of predicted epitopes compared to human IgA. Future studies should focus on functional analysis using human IgA polyclonal reagents to detect manatee IgA in breast milk. Our findings highlight the potential of comparative analysis in advancing the understanding of immunology in non-human animals and overcoming challenges associated with the scarcity of species-specific reagents.

Salivary immune responses after COVID-19 vaccination.

mRNA-based COVID-19 vaccines have played a critical role in reducing severe outcomes of COVID-19. Humoral immune responses against SARS-CoV-2 after vaccination have been extensively studied in blood; however, limited information is available on the presence and duration of SARS-CoV-2 specific antibodies in saliva and other mucosal fluids. Saliva offers a non-invasive sampling method that may also provide a better understanding of mucosal immunity at sites where the virus enters the body. Our objective was to evaluate the salivary immune response after vaccination with the COVID-19 Moderna mRNA-1273 vaccine. Two hundred three staff members of the U.S. Centers for Disease Control and Prevention were enrolled prior to receiving their first dose of the mRNA-1273 vaccine. Participants were asked to self-collect 6 saliva specimens at days 0 (prior to first dose), 14, 28 (prior to second dose), 42, and 56 using a SalivaBio saliva collection device. Saliva specimens were tested for anti-spike protein SARS-CoV-2 specific IgA and IgG enzyme immunoassays. Overall, SARS-CoV-2-specific salivary IgA titers peaked 2 weeks after each vaccine dose, followed by a sharp decrease during the following weeks. In contrast to IgA titers, IgG antibody titers increased substantially 2 weeks after the first vaccine dose, peaked 2 weeks after the second dose and persisted at an elevated level until at least 8 weeks after the first vaccine dose. Additionally, no significant differences in IgA/IgG titers were observed based on age, sex, or race/ethnicity. All participants mounted salivary IgA and IgG immune responses against SARS-CoV-2 after receiving the mRNA-1273 COVID-19 vaccine. Because of the limited follow-up time for this study, more data are needed to assess the antibody levels beyond 2 months after the first dose. Our results confirm the potential utility of saliva in assessing immune responses elicited by immunization and possibly by infection.

A mouse protozoan boosts antigen-specific mucosal IgA responses in a specific lipid metabolism- and signaling-dependent manner.

IgA antibodies play an important role in mucosal immunity. However, there is still no effective way to consistently boost mucosal IgA responses, and the factors influencing these responses are not fully understood. We observed that colonization with the murine intestinal symbiotic protozoan Tritrichomonas musculis (T.mu) boosted antigen-specific mucosal IgA responses in wild-type C57BL/6 mice. This enhancement was attributed to the accumulation of free arachidonic acid (ARA) in the intestinal lumen, which served as a signal to stimulate the production of antigen-specific mucosal IgA. When ARA was prevented from undergoing its downstream metabolic transformation using the 5-lipoxygenase inhibitor zileuton or by blocking its downstream biological signaling through genetic deletion of the Leukotriene B4 receptor 1 (Blt1), the T.mu-mediated enhancement of antigen-specific mucosal IgA production was suppressed. Moreover, both T.mu transfer and dietary supplementation of ARA augmented the efficacy of an oral vaccine against Salmonella infection, with this effect being dependent on Blt1. Our findings elucidate a tripartite circuit linking nutrients from the diet or intestinal microbiota, host lipid metabolism, and the mucosal humoral immune response.

Assessment of immune responses to a Comirnaty® booster following CoronaVac® vaccination in healthcare workers.

BACKGROUND: The immunological response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and immunisation is variable. OBJECTIVES: To describe the humoral immune response by correlating IgA and IgG antibodies with NAbs titration following CoronaVac® immunisation and an mRNA (Comirnaty®) booster among healthcare workers (HCWs) and to compare the cytokine and interleukin profiles between HCWs vaccinated with CoronaVac and coronavirus disease 2019 (COVID-19) infected patients. METHODS: Samples from 133 HCWs collected at 20 (T1) and 90 (T2) days after CoronaVac immunisation and 15 (T3) days after a booster dose with the Comirnaty vaccine were analysed for IgA and IgG EIA and neutralisation assay. Cytokine levels from vaccinated individuals at T1 day and COVID-19 patients were compared. FINDINGS: Neutralising antibodies (NAbs) were observed in 81.7% of participants at T1, but only 49.2% maintained detectable NAbs after 90 days. The booster dose increased NAbs response in all participants. The cytokines with the highest levels post-vaccination were IL-6 and MCP-1. The MCP-1, IL-18, and IFN- γ levels were higher in COVID-19 patients than in vaccinated HCWs, while IL-22 levels increased in the vaccinated HCWs group. MAIN CONCLUSIONS: The neutralisation titres in the T2 samples decreased, and antibody levels detected at T2 showed a more significant reduction than the neutralisation. The higher IL-22 expression in immunised individuals compared to those with COVID-19 suggests that IL-22 may be beneficial in protecting against severe disease.

Humoral immune responses primed by the alteration of gut microbiota were associated with galactose-deficient IgA1 production in IgA nephropathy.

Introduction: Galactose-deficient IgA1 (GdIgA1) is critical in the formation of immunodeposits in IgA nephropathy (IgAN), whereas the origin of GdIgA1 is unknown. We focused on the immune response to fecal microbiota in patients with IgAN. Methods: By running 16S ribosomal RNA gene sequencing, we compared IgAN samples to the control samples from household-matched or non-related individuals. Levels of plasma GdIgA1 and poly-IgA complexes were measured, and candidate microbes that can either incite IgA-directed antibody response or degrade IgA through specific IgA protease activities were identified. Results: The IgAN group showed a distinct composition of fecal microbiota as compared to healthy controls. Particularly, high abundance of Escherichia-Shigella was associated with the disease group based on analyses using receiver operating characteristic (area under curve, 0.837; 95% CI, 0.738-0.914), principle coordinates, and the linear discriminant analysis effect size algorithm (linear discriminant analysis score, 4.56; p < 0.001). Accordingly, the bacterial levels directly correlated with high titers of plasma GdIgA1(r = 0.36, p < 0.001), and patients had higher IgA1 against stx2(2.88 ± 0.46 IU/mL vs. 1.34 ± 0.35 IU/mL, p = 0.03), the main antigen of Escherichia-Shigella. Conversely, the healthy controls showed relatively higher abundance of the commensal bacteria that produce IgA-degrading proteases. Particularly, the abundance of some intestinal bacteria expressing IgA proteases showed an inverse correlation with the levels of plasma GdIgA1 in IgAN. Conclusion: Our data suggest that mucosal IgA production, including those of GdIgA1, is potentially linked to the humoral response to gut Escherichia-Shigella as one of the sources of plasma GdIgA1. Conversely, the IgA protease-producing microbiota in the gut are suppressed in patients with IgAN.

Orally dissolving film as a potential vaccine delivery carrier to prevent influenza virus infection.

Orally dissolving films (ODF) are designed to be dissolved on the tongue and absorbed in the mouth. It offers multiple advantages over the commonly used needle-based vaccines, especially in terms of convenience allowing safe, painless, and easy self-administration. As the efficacy of ODF-encapsulated influenza vaccines has not been demonstrated, we assessed the protection elicited by inactivated influenza virus (A/PR/8/34, H1N1) vaccine delivered using ODFs in mice. Trehalose and pullulan components of the ODF ensured that the HA antigens of the inactivated PR8 virus retained their stability while ensuring the rapid release of the vaccines upon exposure to murine saliva. Mice were immunized thrice by placing the PR8-ODF on the tongues of mice at 4-week intervals, and vaccine-induced protection was evaluated upon lethal homologous challenge infection. The PR8-ODF vaccination elicited virus-specific serum IgG and IgA antibody responses, hemagglutinin inhibition (HAI), and viral neutralization. Upon challenge infection, ODF vaccination showed higher levels of IgG and IgA antibody responses in the lungs and antibody-secreting cell (ASC) responses in both lung and spleen compared to unimmunized controls. These results corresponded with the enhanced T cell and germinal center B cell responses in the lungs and spleens. Importantly, ODF vaccination significantly reduced lung virus titers and inflammatory cytokines (IFN-γ, IL-6) production compared to unvaccinated control. ODF vaccination ensured 100% survival and prevented weight loss in mice. These findings suggest that influenza vaccine delivery through ODFs could be a promising approach for oral vaccine development.

Moderate Aerobic Exercise Induces Homeostatic IgA Generation in Senile Mice.

A T-cell-independent (TI) pathway activated by microbiota results in the generation of low-affinity homeostatic IgA with a critical role in intestinal homeostasis. Moderate aerobic exercise (MAE) provides a beneficial impact on intestinal immunity, but the action of MAE on TI-IgA generation under senescence conditions is unknown. This study aimed to determine the effects of long-term MAE on TI-IgA production in young (3 month old) BALB/c mice exercised until adulthood (6 months) or aging (24 months). Lamina propria (LP) from the small intestine was obtained to determine B cell and plasma cell sub-populations by flow cytometry and molecular factors related to class switch recombination [Thymic Stromal Lymphopoietin (TSLP), A Proliferation-Inducing Ligand (APRIL), B Cell Activating Factor (BAFF), inducible nitric oxide synthase (iNOS), and retinal dehydrogenase (RDH)] and the synthesis of IgA [α-chain, interleukin (IL)-6, IL-21, and Growth Factor-ß (TGF-ß)]; and epithelial cells evaluated IgA transitosis [polymeric immunoglobulin receptor (pIgR), tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), IL-4] by the RT-qPCR technique. The results were compared with data obtained from sedentary age-matched mice. Statistical analysis was computed with ANOVA, and p < 0.05 was considered to be a statistically significant difference. Under senescence conditions, MAE promoted the B cell and IgA+ B cells and APRIL, which may improve the intestinal response and ameliorate the inflammatory environment associated presumably with the downmodulation of pro-inflammatory mediators involved in the upmodulation of pIgR expression. Data suggested that MAE improved IgA and downmodulate the cytokine pro-inflammatory expression favoring homeostatic conditions in aging.

Requirement of a Wnt5A-microbiota axis in the maintenance of gut B-cell repertoire and protection from infection.

We investigated the influence of a Wnt5A-gut microbiota axis on gut B-cell repertoire and protection from infection, having previously demonstrated that Wnt5A in association with gut commensals helps shape gut T-cell repertoire. Accordingly, Wnt5A heterozygous mice, which express less than wild-type level of Wnt5A, and their isolated Peyer's patches (PPs) were studied in comparison with the wild-type counterparts. The percentages of IgM- and IgA-expressing B cells were quite similar in the PP of both sets of mice. However, the PP of the Wnt5A heterozygous mice harbored significantly higher than wild-type levels of microbiota-bound B cell-secreted IgA, indicating the prevalence of a microbial population therein, which is significantly altered from that of wild-type. Additionally, the percentage of PP IgG1-expressing B cells was appreciably depressed in the Wnt5A heterozygous mice in comparison to wild-type. Wnt5A heterozygous mice, furthermore, exhibited notably higher than the wild-type levels of morbidity and mortality following infection with Salmonella typhimurium, a common gut pathogen. Differences in morbidity/mortality correlated with considerable disparity between the PP-B-cell repertoires of the Salmonella-infected Wnt5A heterozygous and wild-type mice, in which the percentage of IgG1-expressing B1b cells in the PP of heterozygous mice remains significantly low as compared to wild-type. Overall, these results suggest that a gut Wnt5A-microbiota axis is intrinsically associated with the maintenance of gut B-cell repertoire and protection from infection.IMPORTANCEAlthough it is well accepted that B cells and microbiota are required for protection from infection and preservation of gut health, a lot remains unknown about how the optimum B-cell repertoire and microbiota are maintained in the gut. The importance of this study lies in the fact that it unveils a potential role of a growth factor termed Wnt5A in the safeguarding of the gut B-cell population and microbiota, thereby protecting the gut from the deleterious effect of infections by common pathogens. Documentation of the involvement of a Wnt5A-microbiota axis in the shaping of a protective gut B-cell repertoire, furthermore, opens up new avenues of investigations for understanding gut disorders related to microbial dysbiosis and B-cell homeostasis that, till date, are considered incurable.

The Healthcare Study Examines the Humoral Anti-S1 Antibody Response Following mRNA Vaccination, Comparing Individuals with and without Prior SARS-CoV-2 Infection.

Vaccines targeting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been pivotal in curtailing the spread of infection. Health care workers, as frontline responders, were among the first to receive vaccination to mitigate coronavirus disease in 2019 (COVID-19) transmission. This study aimed to assess the humoral response elicited by mRNA vaccines, specifically measuring antibodies against the spike S1 protein, a marker of immune response. A cohort of 649 health care workers received three doses of mRNA vaccine, with antibody levels evaluated before and after each dose within a 2- to 3-week interval. Participants were stratified into groups based on prior exposure to the virus: those without prior contact (440 individuals) and those with a history of infection (209 individuals). Among the latter, cases of SARS-CoV-2 infection ranged from asymptomatic (92 individuals) to mild symptomatic (117 individuals). Participants with a history of infection exhibited elevated levels of IgG antibodies against the S1 protein prior to vaccination. Notably, both immunoglobulin IgA class (IgA) and immunoglobulin IgG class (IgG) antibody responses increased significantly post-vaccination, peaking after the second dose for IgG and after the third dose for IgA. Interestingly, the immune response to the vaccine did not vary significantly based on the symptomatic or asymptomatic nature of prior infection. Furthermore, the study findings indicate that completion of the vaccination regimen led to sustained antibody production lasting between 6 months and 9 months. This study underscores the robust and enduring humoral response elicited by mRNA vaccines, particularly among health care workers, irrespective of prior SARS-CoV-2 exposure.

Immunogenicity and safety of an Entamoeba histolytica adjuvanted protein vaccine candidate (LecA+GLA-3M-052 liposomes) in rhesus macaques.

Entamoeba histolytica, the causative agent of amebiasis, is one of the top three parasitic causes of mortality worldwide. However, no vaccine exists against amebiasis. Using a lead candidate vaccine containing the LecA fragment of Gal-lectin and GLA-3M-052 liposome adjuvant, we immunized rhesus macaques via intranasal or intramuscular routes. The vaccine elicited high-avidity functional humoral responses as seen by the inhibition of amebic attachment to mammalian target cells by plasma and stool antibodies. Importantly, antigen-specific IFN-γ-secreting peripheral blood mononuclear cells (PBMCs) and IgG/IgA memory B cells (BMEM) were detected in immunized animals. Furthermore, antigen-specific antibody and cellular responses were maintained for at least 8 months after the final immunization as observed by robust LecA-specific BMEM as well as IFN-γ+ PBMC responses. Overall, both intranasal and intramuscular immunizations elicited a durable and functional response in systemic and mucosal compartments, which supports advancing the LecA+GLA-3M-052 liposome vaccine candidate to clinical testing.

A mucosal vaccine formulation against tuberculosis by exploiting the adjuvant activity of S100A4-A damage-associated molecular pattern molecule.

Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), remains one of the top three causes of death. Currently, the only licensed vaccine against TB is the bacillus Calmette-Guerin (BCG), which lacks efficacy in preventing and controlling pulmonary TB in adults. We aimed to evaluate a nasal TB vaccine formulation composed of the Mtb-specific vaccine antigen ESAT-6, an Mtb-associated protein that can trigger protective immune responses, and S100A4, a recently characterized novel mucosal adjuvant. Mice were intranasally given recombinant ESAT-6 in the presence or absence of S100A4 as an adjuvant. We have provided experimental evidence demonstrating that S100A4 admixed to ESAT-6 could induce Mtb-specific adaptive immune responses after intranasal immunization. S100A4 remarkably augmented the levels of anti-ESAT-6 IgG in serum and IgA in mucosal sites, including lung exudates, bronchoalveolar lavage fluid (BALF) and nasal lavage. Furthermore, in both lung and spleen tissues, S100A4 strongly promoted ESAT-6-specific expansion of CD4 T cells. Both CD4 and CD8 T cells from these tissues expressed increased levels of IFN-γ, TNF-α, and IL-17, cytokines critical for antimicrobial activity. Antigen-reencounter-induced T cell proliferative responses, a key vaccine performance indicator, were augmented in the spleen of S100A4-adjuvanted mice. Furthermore, CD8 T cells from the spleen and lung tissues of these mice expressed higher levels of granzyme B upon antigen re-stimulation. S100A4-adjuvanted immunization may predict good mucosal protection against TB.