IgA Titers Research Articles

Nasal mucosal IgA levels against SARS-CoV-2 and seasonal coronaviruses are low in children but boosted by reinfection

Repeated coronavirus infections in childhood drive progressive maturation of systemic immune responses into adulthood. Analyses of immune responses in children have focused primarily upon systemic assessment but the importance of mucosal immunity is increasingly recognised. We studied virus-specific antibody responses in contemporaneous nasal swabs and blood samples from 99 children (4-15 years) and 28 adults (22-56 years), all of whom had prior SARS-CoV-2 infection. Whilst mucosal IgA titres against Influenza and Respiratory Syncytial virus were comparable between children and adults, those against all coronaviruses, including SARS-CoV-2, were lower in children. Mucosal IgA antibodies demonstrated comparable relative neutralisation capacity in both groups and retained activity against recent omicron variants such as XBB.1 which are highly evasive of IgG neutralisation. SARS-CoV-2 reinfection preferentially enhanced mucosal IgA responses whilst the impact of vaccination was more modest. Nasal IgA levels against coronaviruses thus display a pattern of incremental response to reinfection which likely determines the natural history of reinfection. This highlights the particular significance of developing mucosal vaccines against coronaviruses in children.

Follow up and comparative assessment of IgG, IgA, and neutralizing antibody responses to SARS-CoV-2 between mRNA-vaccinated naïve and unvaccinated naturally infected individuals over 10 months

BackgroundEvidence on the effectiveness of vaccination-induced immunity compared to SARS-CoV-2 natural immunity is warranted to inform vaccination recommendations. AimIn this study, we aimed to conduct a comparative assessment of antibody responses between vaccinated naïve (VN) and unvaccinated naturally infected individuals (NI) over 10 Months. MethodThe study comprised fully-vaccinated naïve individuals (VN; n = 596) who had no history of SARS-CoV-2 infection, and received two doses of either BNT162b2 or mRNA-1273, and naturally infected individuals who had a documented history of SARS-CoV-2 infection and no vaccination record (NI cohort; n = 218). We measured the levels of neutralizing total antibodies (NtAbs), anti-S-RBD IgG, and anti-S1 IgA titers among VN and NI up to ∼10 months from administration of the first dose, and up to ∼7 months from SARS-CoV-2 infection, respectively. To explore the relationship between the antibody responses and time, Spearman's correlation coefficient was computed. Furthermore, correlations between the levels of NtAbs/anti-S-RBD IgG and NtAbs/anti-S1 IgA were examined through pairwise correlation analysis. ResultsUp to six months, VN individuals had a significantly higher NtAb and anti-S-RBD IgG antibody responses compared to NI individuals. At the 7th month, there was a significant decline in antibody responses among VN individuals, but not NI individuals, with a minimum decrease of 3.7-fold (p < 0.001). Among VN individuals, anti-S1 IgA levels began to decrease significantly (1.4-fold; p = 0.007) after two months, and both NtAb and S-RBD IgG levels began to decline significantly (NtAb: 2.0-fold; p = 0.042, S-RBD IgG: 2.4-fold; p = 0.035) after three months. After 10 months, the most significant decline among VN individuals was observed for S-RBD-IgG (30.0-fold; P < 0.001), followed by NtAb (15.7-fold; P < 0.001) and S-IgA (3.7-fold; P < 0.001) (most stable). Moreover, after 5 months, there was no significant difference in the IgA response between the two groups. ConclusionThese findings have important implications for policymakers in the development of vaccination strategies, particularly in the consideration of booster doses to sustain long-lasting protection against COVID-19.

Phase III Pivotal comparative clinical trial of intranasal (iNCOVACC) and intramuscular COVID 19 vaccine (Covaxin®)

One of the most preferable characteristics for a COVID-19 vaccine candidate is the ability to reduce transmission and infection of SARS-CoV-2, in addition to disease prevention. Unlike intramuscular vaccines, intranasal COVID-19 vaccines may offer this by generating mucosal immunity. In this open-label, randomised, multicentre, phase 3 clinical trial (CTRI/2022/02/40065; ClinicalTrials.gov: NCT05522335), healthy adults were randomised to receive two doses, 28 days apart, of either intranasal adenoviral vectored SARS-CoV-2 vaccine (BBV154) or licensed intramuscular vaccine, Covaxin®. Between April 16 and June 4, 2022, we enrolled 3160 subjects of whom, 2971 received 2 doses of BBV154 and 161 received Covaxin. On Day 42, 14 days after the second dose, BBV154 induced significant serum neutralization antibody titers against the ancestral (Wuhan) virus, which met the pre-defined superiority criterion for BBV154 over Covaxin®. Further, both vaccines showed cross protection against Omicron BA.5 variant. Salivary IgA titers were found to be higher in BBV154. In addition, extensive evaluation of T cell immunity revealed comparable responses in both cohorts due to prior infection. However, BBV154 showed significantly more ancestral specific IgA-secreting plasmablasts, post vaccination, whereas Covaxin recipients showed significant Omicron specific IgA-secreting plasmablasts only at day 42. Both vaccines were well tolerated. Overall reported solicited reactions were 6.9% and 25.5% and unsolicited reactions were 1.2% and 3.1% in BBV154 and Covaxin® participants respectively.

Durable Anti-Vi IgG and IgA Antibody Responses in 15-Month-Old Children Vaccinated With Typhoid Conjugate Vaccine in Burkina Faso.

We assessed anti-Vi IgG/IgA responses to typhoid conjugate vaccine (TCV) in children enrolled in a double-blind randomized controlled, phase 2 trial in Burkina Faso. Anti-Vi IgG seroconversion and anti-Vi IgA titers were higher in TCV than control recipients at 30-35 months post-vaccination. TCV induces durable immunity in Burkinabe children vaccinated at 15 months.

Similarities in rotavirus vaccine viral shedding and immune responses in pairs of twins.

Intestinal rotavirus (RV) vaccine replication and host immune response are suggested to be affected by several factors, including maternal antibodies, breastfeeding history, and gut microbiome, which are thought to be similar in pairs of twins. The aim of this study was to determine whether viral shedding from the fecal RV vaccine strain Rotarix® (RV1) and IgG and IgA responses to RV show similarity in pairs of twins. Quantitative reverse transcription polymerase chain reaction specific to RV vaccine strain RV1 was used to monitor fecal RV1 viral shedding. RV IgG and IgA titers were measured using an in-house enzyme-linked immunosorbent assay. Fecal RV1 viral shedding and immune responses were compared between twins and singletons with mixed effects and fixed effects models. A total of 347 stool and 54 blood samples were collected from four pairs of twins and twelve singletons during the observation period. Although the kinetics of fecal RV1 viral shedding and immune responses differed among vaccinated individuals, they appeared to be similar within twin pairs. RV shedding after the first dose (P=0.049) and RV IgG titers during the entire observation period (P=0.015) had a significantly better fit in the fixed effect model that assumed that twins have the same response versus the model that assumed that twins have a different response. The similarity of RV vaccine viral replication in intestine and host immune responses in twin pairs was demonstrated using statistical analysis.

Lactobacillus plantarum surface-displayed Eimeria tenella profilin antigens with FliC flagellin elicit protection against coccidiosis in chickens

Coccidiosis is a parasitic disease in the intestine caused by the genus Eimeria that poses a substantial economic threat to the broiler breeding industry. The misuse of chemoprophylaxis and live oocyst vaccines has a negative impact on chicken reproductivity. Therefore, there is a pressing need to develop safe, convenient, and effective vaccines. Lactic acid bacteria can be used as a means to deliver mucosal vaccines against intestinal pathogens, which is a promising strategy. In this study, a recombinant Lactobacillus plantarum (L. plantarum) with surface-expressed antigens constructed from the fusion of Eimeria tenella (E. tenella) antigen profilin and the Salmonella enterica serovar Typhimurium flagellin protein FliC was created. After oral immunization with the recombinant L. plantarum, T-cell differentiation was analyzed by flow cytometry, and specific antibody levels were determined via indirect ELISA. Oocyst shedding, body weight, and cecum lesions were assessed as measures of protective immunity after challenge with E. tenella. The results of this study demonstrate the effectiveness of recombinant L. plantarum as an immunization agent for chickens. Specific IgA titers in the intestine and specific IgG antibody titers in the serum were significantly higher in chickens immunized with recombinant L. plantarum (P < 0.001). Additionally, the levels of IL-2 (P < 0.05) and IFN-γ (P < 0.01) in the serum were markedly increased. Recombinant L. plantarum induced T-cell differentiation, resulting in a higher proportion of CD4+ and CD8+ T cells in splenocytes (P < 0.001). Fecal oocyst shedding in the immunized group was significantly reduced (P < 0.001). Additionally, recombinant L. plantarum significantly relieved pathological damage in the cecum, as evidenced by lesion scores (P < 0.01) and histopathological cecum sections. In conclusion, the present study provides evidence to support the possibility of using L. plantarum as a promising carrier for the delivery of protective antigens to effectively protect chickens against coccidiosis.

Assessment of Adverse Reactions, Antibody Patterns, and 12-month Outcomes in the Mother-Infant Dyad After COVID-19 mRNA Vaccination in Pregnancy

Longitudinal data on COVID-19 messenger RNA (mRNA) vaccine reactogenicity and immunogenicity in pregnancy and for the mother-infant dyad are needed. To examine COVID-19 mRNA vaccine reactogenicity and immunogenicity in pregnancy and observe longitudinal maternal and infant outcomes. This prospective cohort study of pregnant individuals enrolled in the COVID-19 Vaccination in Pregnancy and Lactation study from December 1, 2020, through December 31, 2021, with follow-up through March 31, 2022, was conducted at a large academic medical center in an urban metropolitan area in California. Pregnant individuals receiving COVID-19 mRNA vaccines (mRNA-1273 [Moderna] and BNT162b2 [Pfizer-BioNTech]) were eligible. Of 81 participants enrolled, 5 were excluded after enrollment: 1 terminated pregnancy, 1 received the third vaccine dose prior to delivery, and 3 delivered prior to completing the initial vaccine series. COVID-19 mRNA vaccination at any time during pregnancy. The primary outcomes were vaccine response as measured by blood Immunoglobulin G (IgG) titers after each vaccine dose and self-reported postvaccination symptoms. Patients' IgG titers were measured in cord blood and in infant blood at intervals up to 1 year of life; IgG and IgA titers were measured in maternal milk. Clinical outcomes were collected from medical records. Of 76 pregnant individuals included in final analyses (median [IQR] maternal age, 35 [29-41] years; 51 [67.1%] White; 28 [36.8%] primigravid; 37 [48.7%] nulliparous), 42 (55.3%) received BNT162b2 and 34 (44.7%) received mRNA-1237. There were no significant differences in maternal characteristics between the 2 vaccine groups. Systemic symptoms were more common after receipt of the second vaccine dose than after the first dose (42 of 59 [71.2%] vs 26 of 59 [44.1%]; P = .007) and after mRNA-1237 than after BNT162b2 (25 of 27 [92.6%] vs 17 of 32 53.1%; P = .001). Systemic symptoms were associated with 65.6% higher median IgG titers than no symptoms after the second vaccine dose (median [IQR], 2596 [1840-4455] vs 1568 [1114-4518] RFU; P = .007); mean cord titers in individuals with local or systemic symptoms were 6.3-fold higher than in individuals without symptoms. Vaccination in all trimesters elicited a robust maternal IgG response. The IgG transfer ratio was highest among individuals vaccinated in the second trimester. Anti-SARS-CoV-2 IgG was detectable in cord blood regardless of vaccination trimester. In milk, IgG and IgA titers remained above the positive cutoff for at least 5-6 months after birth, and infants of mothers vaccinated in the second and third trimesters had positive IgG titers for at least 5 to 6 months of life. There were no vaccine-attributable adverse perinatal outcomes. The findings of this cohort study suggest that mRNA COVID-19 vaccination in pregnancy provokes a robust IgG response for the mother-infant dyad for approximately 6 months after birth. Postvaccination symptoms may indicate a more robust immune response, without adverse maternal, fetal, or neonatal outcomes.

Unveiling a New Perspective on Distinguishing Omicron Breakthrough Cases and Postimmune COVID-19-Naive Individuals: Insights from Antibody Profiles.

In the situation of mass vaccination against COVID-19, few studies have reported on the early kinetics of specific antibodies (IgG/IgM/IgA) of vaccine breakthrough cases. There is still a lack of epidemiological evidence about the value of serological indicators in the auxiliary diagnosis of COVID-19 infection, especially when the nucleic acid results were undetectable. Omicron breakthrough cases post-inactivated vaccination (n = 456) and COVID-19-naive individuals with two doses of inactivated vaccination (n = 693) were enrolled. Blood samples were collected and tested for SARS-CoV-2 antibody levels based on the magnetic chemiluminescence enzyme immunoassay. Among Omicron breakthrough cases, the serum IgG antibody level was 36.34 Sample/CutOff (S/CO) (95% confidence interval [CI], 31.89 to 40.79) in the acute phase and 88.45 S/CO (95% CI, 82.79 to 94.12) in the recovery phase. Serum IgA can be detected in the first week post-symptom onset (PSO) and showed an almost linear increase within 5 weeks PSO. Compared with those of breakthrough cases, IgG and IgA titers of the postimmune group were much lower (4.70 S/CO and 0.46 S/CO, respectively). Multivariate regression showed that serum IgG and IgA levels in Omicron breakthrough cases were mainly affected by the weeks PSO (P < 0.001). Receiver operating characteristic ROC0 curve analysis showed that the area under the curve (AUC) was 0.744 and 0.806 when the cutoff values of IgA and IgG were 1 S/CO and 15 S/CO, respectively. Omicron breakthrough infection can lead to a further increase in IgG and IgA levels relative to those of the immunized population. When nucleic acid real-time PCR was negative, we would use the kinetics of IgG and IgA levels to distinguish the breakthrough cases from the immunized population. IMPORTANCE This study fills a gap in the epidemiological evidence by investigating the value of serological indicators, particularly IgG and IgA levels, in the auxiliary diagnosis of COVID-19 infections when nucleic acid results are undetectable. The findings reveal that among Omicron breakthrough cases, both IgG and IgA antibody levels exhibit significant changes. Serum IgG levels increase during the acute phase and rise further in the recovery phase. Serum IgA can be detected as early as the first week post-symptom onset (PSO), showing a consistent linear increase within 5 weeks PSO. Furthermore, receiver operating characteristic (ROC) curve analysis demonstrates the potential of IgG and IgA cutoff values as diagnostic markers. The study's conclusion underscores the importance of monitoring IgG and IgA kinetics in distinguishing Omicron breakthrough cases from vaccinated individuals. These findings contribute to the development of more accurate diagnostic approaches and help inform public health strategies during the ongoing COVID-19 pandemic.

Intranasal Single-Replication Influenza Vector Induces Cross-Reactive Serum and Mucosal Antibodies against SARS-CoV-2 Variants.

Current SARS-CoV-2 vaccines provide protection for COVID-19-associated hospitalization and death, but remain inefficient at inhibiting initial infection and transmission. Despite updated booster formulations, breakthrough infections and reinfections from emerging SARS-CoV-2 variants are common. Intranasal vaccination to elicit mucosal immunity at the site of infection can improve the performance of respiratory virus vaccines. We developed SARS-CoV-2 M2SR, a dual SARS-CoV-2 and influenza vaccine candidate, employing our live intranasal M2-deficient single replication (M2SR) influenza vector expressing the receptor binding domain (RBD) of the SARS-CoV-2 Spike protein of the prototype strain, first reported in January 2020. The intranasal vaccination of mice with this dual vaccine elicits both high serum IgG and mucosal IgA titers to RBD. Sera from inoculated mice show that vaccinated mice develop neutralizing SARS-CoV-2 antibody titers against the prototype and Delta virus strains, which are considered to be sufficient to protect against viral infection. Moreover, SARS-CoV-2 M2SR elicited cross-reactive serum and mucosal antibodies to the Omicron BA.4/BA.5 variant. The SARS-CoV-2 M2SR vaccine also maintained strong immune responses to influenza A with high titers of anti H3 serum IgG and hemagglutination inhibition (HAI) antibody titers corresponding to those seen from the control M2SR vector alone. With a proven safety record and robust immunological profile in humans that includes mucosal immunity, the M2SR influenza viral vector expressing key SARS-CoV-2 antigens could provide more efficient protection against influenza and SARS-CoV-2 variants.

Immunosuppressive therapy selectively modulates B‐cell responses in patients with rheumatic and musculoskeletal diseases receiving the inactivated COVID‐19 vaccine

AbstractBackgroundImmunosuppressive medication reduces the immunogenicity of the coronavirus disease 2019 (COVID‐19) vaccines in patients with rheumatic and musculoskeletal diseases (RMDs). However, the underlying mechanism remains unclear. The primary aim of our study was to dissect the impact of immunosuppressive medication on cellular and humoral immune responses in RMD patients receiving the inactivated COVID‐19 vaccine.MethodsA total of 28 RMD patients and five healthy controls (HCs) receiving two doses of the inactivated COVID‐19 vaccine (Sinovac‐CoronaVac) were prospectively enrolled. Blood samples were collected before the primary vaccination (Week 0) and one week after the second vaccination (Week 5). Neutralizing antibody (nAb) titers and autoantibody titers were measured by a pseudovirus‐based neutralization assay and enzyme‐linked immunosorbent assay, respectively. CD4+ T‐cell and CD19+ B‐cell subsets and serum cytokines were analyzed by flow cytometry.ResultsThe inactivated COVID‐19 vaccine was immunogenic in RMD patients and HCs after the second vaccination, but the nAb titers were lower in RMD patients than those in HCs. Only patients with systemic lupus erythematosus (SLE) had notably increased nAb titers. Remarkably, IgG+CD27+, IgG+IgG1+, and IgG+IgG1− B cells were reduced, whereas IgG−IgG1+ B cells, and total IgA and IgG titers were markedly increased. However, Tfh cell and Tfr cell subsets and cytokines produced by Tfh cells were not increased. The flare rate was low in RMD patients with comparable autoantibody titers, unchanged CD4+ T cell subsets and serum pro‐inflammatory cytokines (interleukin [IL]‐6, IL‐17, interferon‐γ, and tumor necrosis factor‐α) after the second vaccination.ConclusionsImmunosuppressive therapy decreased the immunogenicity of the vaccine and maintained a low flare rate by selectively modulating B cell but not CD4+ T cell responses in RMD patients receiving the inactivated COVID‐19 vaccine. Optimization of the treatment regimen might ensure a durable and robust COVID‐19 vaccination response.

Detection of anti-SARS-CoV-2 antibodies in tears: Ocular surface immunity to COVID-19

PurposeTo evaluate the presence of SARS-COV-2 specific IgA and IgG antibodies in tears of unvaccinated and anti-COVID-19 vaccinated subjects with previous history of SARS-COV-2 infection. To compare results in tears with those in saliva and serum and correlate with clinical data and vaccination regimens. MethodsCross-sectional study including subjects with a previous history of SARS-CoV-2 infection, both unvaccinated and vaccinated against COVID-19. Three samples were collected: tears, saliva and serum. IgA and IgG antibodies against S-1 protein of SARS-CoV-2 were analyzed with a semi-quantitative ELISA. Results30 subjects, mean age 36.4 ± 10, males 13/30 (43.3%) with history of mild SARS-CoV-2 infection were included. 13/30 (43.3%) subjects had received a 2-dose regimen and 13/30 (43.3%) a 3-dose regimen of anti-COVID-19 vaccine, 4/30 (13.3%) subjects were unvaccinated. All the participants with full anti-COVID-19 vaccination (2-or 3-doses) presented detectable anti-S1 specific IgA in all three biofluids, tears, saliva and serum. Among unvaccinated subjects, specific IgA was detected in 3/4 subjects in tears and saliva, whereas IgG was not detected. Considering IgA and IgG antibodies titers, no differences were observed between the 2- and 3-dose vaccination regimen. ConclusionsSARS-CoV-2-specific IgA and IgG antibodies were detected in tears after mild COVID-19, highlighting the role of the ocular surface as a first line of defense against infection. Most naturally infected unvaccinated individuals exhibit long-term specific IgA in tears and saliva. Hybrid immunization (natural infection plus vaccination) appears to enhance mucosal and systemic IgG responses. However, no differences were observed between the 2- and 3-dose vaccination schedule.

Detección de anticuerpos anti-SARS-CoV-2 en lágrimas: inmunidad de la superficie ocular frente a COVID-19

PurposeTo evaluate the presence of SARS-CoV-2 specific IgA and IgG antibodies in tears of unvaccinated and anti-COVID-19 vaccinated subjects with previous history of SARS-CoV-2 infection. To compare results in tears with those in saliva and serum and correlate with clinical data and vaccination regimens. MethodsCross-sectional study including subjects with a previous history of SARS-CoV-2 infection, both unvaccinated and vaccinated against COVID-19. Three samples were collected: tears, saliva and serum. IgA and IgG antibodies against S-1 protein of SARS-CoV-2 were analyzed with a semi-quantitative ELISA. ResultsThirty subjects, mean age 36.4±10, males 13/30 (43.3%) with history of mild SARS-CoV-2 infection were included. 13/30 (43.3%) subjects had received a 2-dose regimen and 13/30 (43.3%) a 3-dose regimen of anti-COVID-19 vaccine, 4/30 (13.3%) subjects were unvaccinated. All the participants with full anti-COVID-19 vaccination (2-or 3-doses) presented detectable anti-S1 specific IgA in all 3biofluids, tears, saliva and serum. Among unvaccinated subjects, specific IgA was detected in 3/4 subjects in tears and saliva, whereas IgG was not detected. Considering IgA and IgG antibodies titers, no differences were observed between the 2- and 3-dose vaccination regimen. ConclusionsSARS-CoV-2-specific IgA and IgG antibodies were detected in tears after mild COVID-19, highlighting the role of the ocular surface as a first line of defense against infection. Most naturally infected unvaccinated individuals exhibit long-term specific IgA in tears and saliva. Hybrid immunization (natural infection plus vaccination) appears to enhance mucosal and systemic IgG responses. However, no differences were observed between the 2- and 3-dose vaccination schedule.

TFR cell-mediated regulation of IgA and gut microbiota in food allergy

Abstract About two grams of secretory Immunoglobulin A (sIgA) are secreted daily into the intestine, where it serves as the first line of defense against pathogens and protects the host's commensals by coating them, ensuring mucosal immune system homeostasis. Gut microbiota (Mb)-specific IgA can be generated via T cell-dependent (TD) or T cell-independent (TI) pathways. However, the TD route is required to generate high-affinity, pathogen-specific antibodies (Abs). T follicular helper (Tfh) cells are essential for germinal center (GC) development, promoting B cells expansion. Nevertheless, the role of T follicular regulatory (Tfr) cells in Mb-reactive IgA production is unclear. Unpublished results and a prior work demonstrated that deleting Tregs or Tfr cells in mice increased antigen-specific IgA titers, indicating that these cells negatively control IgA response. Thus, we hypothesized that TFR cells regulate gut Mb-reactive IgA via the regulation of high-affinity IgA production against gut Mb. To test this hypothesis, TFR cell-deficient Bcl6FC (Foxp3 cre-Bcl6 fl/fl) and WT mice were primed with peanut plus cholera toxin through oral gavage in a food allergy model. Then, we stained fecal Mb with anti-mouse IgA, sorted commensals into IgA +and IgA −populations and sequence 16S rRNA gene of the sorted bacteria (IgA-seq) to evaluate the Mb-reactive IgA response. Flow cytometry data showed significantly higher IgA-coated bacteria in Bcl6FC than in WT mice, showing TFR cells adversely modulate IgA response to gut Mb. Our current experiments will dissect if the higher Mb-reactive IgA secreted in the absence of TFR cells were non-specific and polyreactive or were specific towards certain members of gut commensals. R21 AI172087 NIH

Comparison of Clinical, Biochemical and Histological Features between Adult Celiac Patients with High and Low Anti-Transglutaminase IgA Titer at Diagnosis and Follow-Up

In adults, celiac disease (CD) diagnosis is based on specific serology (anti-transglutaminase IgA-anti-tTG) and duodenal histology. Evidence is raising the possibility of perform CD diagnosis based only on high anti-tTG titer in children. We aimed to evaluate clinical, histological and biochemical differences between adult patients with high tTG IgA titer (HT) and those with low titer (LT) at CD diagnosis and follow-up. This retrospective study included consecutive adult CD patients divided into two groups: HT (anti-tTG &gt; 10 × ULN) and LT (anti-tTG &lt; 10 × ULN). Clinical, biochemical and histological features were compared between groups at CD diagnosis and at follow-up. A total of 291 patients were included (HT: 47.1%; LT: 52.9%). At CD diagnosis, HT patients showed a non ‘classical’ presentation (p = 0.04), Marsh 3C (p = 0.005), hypoferritinaemia (p = 0.006) and osteopenia/osteoporosis (p = 0.04) more frequently than LT patients. A total of 216 patients (HT: 48.6%; LT: 51.4%) performed a follow-up after a median Gluten-free diet of 14 months; HT patients had persistent antibodies positivity (p = 0.001) more frequently and GI symptoms (p = 0.04) less frequently than LT patients. In conclusion, HT patients presented severe histological damage more frequently at diagnosis, recovering similarly to LT patients after the start of the Gluten-free diet. At follow-up, anti-tTG persisted positive in HT more frequently compared to LT patients, without differences regarding histological recovery and clinical improvement.

Vaccination and Omicron BA.1/BA.2 Convalescence Enhance Systemic but Not Mucosal Immunity against BA.4/5.

Rising breakthrough infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron BA.4/5 led to the performance of various studies investigating systemic immunity and neutralizing antibodies in sera, but mucosal immunity remains understudied. In this cohort study, the humoral immune responses, including immunoglobulin levels and the presence of virus-neutralizing antibodies, of 92 vaccinated and/or BA.1/BA.2 convalescent individuals were investigated. Cohorts received two doses of ChAdOx1, BNT162b2, or mRNA-1273 and subsequent booster vaccination with either BNT162b2 or mRNA-1273, following BA.1/BA.2 infection. In addition, vaccinated and nonconvalescent or unvaccinated and BA.1 convalescent individuals were studied. Serum and saliva samples were used to determine SARS-CoV-2 spike-specific IgG and IgA titers and neutralizing activity against replication-competent SARS-CoV-2 wild-type virus and the Omicron BA.4/5 variant. Vaccinated/convalescent cohorts demonstrated strongest neutralization against BA.4/5, with 50% neutralization titer (NT50) values reaching 174.2; however, neutralization was reduced up to 11-fold, compared to wild-type virus. Both BA.1 convalescent and vaccinated nonconvalescent cohorts displayed the weakest neutralization against BA.4/5, with NT50 values being reduced to 4.6, accompanied by lower numbers of positive neutralizers. Additionally, salivary neutralization against wild-type virus was strongest in vaccinated and BA.2 convalescent subjects, but this elevated neutralization efficiency was lost when challenged with BA.4/5. Our data support the contention that current coronavirus disease 2019 (COVID-19) vaccines efficiently induce humoral immunity. However, antiviral effectiveness in serum and saliva is greatly reduced against novel variants of concern. These results suggest an adjustment of current vaccine strategies to an adapted or alternative vaccine delivery, such as mucosal booster vaccinations, which might establish enhanced or even sterilizing immunity against novel SARS-CoV-2 variants. IMPORTANCE Rising incidences of breakthrough infections caused by SARS-CoV-2 Omicron BA.4/5 have been observed. Although various studies were conducted investigating neutralizing antibodies in sera, mucosal immunity was barely evaluated. Here, we investigated mucosal immunity, since the presence of neutralizing antibodies at mucosal entry sites plays a fundamental role in disease limitation. We found strong induction of serum IgG/IgA, salivary IgA, and neutralization against SARS-CoV-2 wild-type virus in vaccinated/convalescent subjects but detected 10-fold reduced (albeit positive) serum neutralization against BA.4/5. Interestingly, vaccinated and BA.2 convalescent patients demonstrated the greatest serum neutralization against BA.4/5, but this advantageous neutralizing effect was not observed in the saliva. Our data support the contention that current COVID-19 vaccines are very efficient against severe/critical disease progression. Moreover, these results suggest an adjustment of the current vaccine strategy to adapted and alternative vaccine delivery, such as mucosal booster vaccinations, to establish robust sterilizing immunity against novel SARS-CoV-2 variants.

Concordance of adenosine deaminase with immunoglobulins and lymphocyte subsets in EBV-related diseases

BackgroundClinical manifestations of Epstein–Barr virus (EBV) infection are diverse. This study aimed to explore the immune response in EBV-related diseases and the correlation between immune cells and adenosine deaminase (ADA) levels.MethodsThis study was conducted at the Children’s Hospital of Soochow University. In total, 104 patients with EBV-associated respiratory tract infection (EBV-RTI), 32 patients with atypical EBV infection, 54 patients with EBV-associated infectious mononucleosis (IM1, with normal alanine aminotransferase [ALT] levels), 50 patients with EBV-IM2 (with elevated ALT levels), 50 patients with acute respiratory infection (AURI, with other pathogens), and 30 healthy controls were enrolled in this study. Indicators of ADA, immunoglobulins (Igs), and lymphocyte subsets were analyzed for EBV-related diseases.ResultsDifferences in the white blood cell, lymphocyte counts, ADA levels, IgA, IgG and IgM titers, percentage of CD3+, CD3+CD4+, CD3+CD8+, CD16+CD56+, CD3−CD19+, and CD19+CD23+ lymphocytes, and CD4+/CD8+ ratio between EBV-related disease groups were all statistically significant (P < 0.01). ADA levels in the EBV-related disease groups were significantly higher than those in the control group (P < 0.01). The lymphocyte count, ADA levels, IgA and IgG titers, and percentage of CD3+ and CD3+CD8 + lymphocytes in the atypical EBV infection, EBV-IM1, and EBV-IM2 groups were significantly higher than those in the EBV-RTI, AUTI, and control groups (P < 0.01), whereas the percentage of CD3+CD4+, CD3−CD19+, and CD19+CD23+ lymphocytes and CD4+/CD8+ ratio showed the opposite trend. ADA levels were consistent with and closely related to the viral load and cellular and humoral immunity in EBV-related diseases.ConclusionsADA levels, humoral immunity, and cellular immunity were diverse in EBV-related diseases, and ADA was closely related to Igs and lymphocyte subsets.

Comparative Analyses of IgA Antibody Response of Non-COVID-19 Infected People Over 60 Years Old Following CoronaVac and Pfizer-BioNTech COVID-19 Vaccination

The formation rate, magnitude, and duration of the antibody-mediated humoral immune response that develops against different viral proteins of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) are considered important in vaccine success. It is known that the response to vaccinations decreases due to immunosenescence in older adults. This study was aimed to investigate the levels of serum IgA response at 1st and 3rd month after vaccination of people over 60 years old who were immunized with CoronaVac and Pfizer-BioNTech. A total of 35 people living in the North Cyprus who have not previously had COVID-19 infection were included in the study. After the 2nd dose of vaccination, serum IgA levels were measured after the 1st and 3rd month with the anti-SARS-CoV-2 IgA (Euroimmun, Lubeck, Germany) kit. The statistical significance was determined as 0.05 in the whole study. SPSS and GraphPad Prism software were used for calculations, analyses and graphs. The possible effect of demographic variables on serum IgA level was compared between the vaccine groups and it was found that there was no statistically significant difference between them. For the IgA titer-positive individuals who had been vaccinated with the Pfizer-BioNTech vaccine, for both 1st and 3rd months were observed to be higher than CoronaVac vaccinated IgA titer-positive individuals. In individuals who received the CoronaVac vaccine, there was a statistically significant change in serum IgA levels between 1st and 3rd months, but there was no statistically significant change in the Pfizer-BioNTech vaccine administered group. When the Pfizer/BioNTech and CoronaVac vaccines were compared with each other in terms of serum IgA antibody titers, it was found that the mean serum IgA levels of the individuals in the Pfizer/BioNTech group were statistically higher at the 1st and 3rd months than the CoronaVac group. Serum IgA titers in both vaccine groups were statistically significantly decreased from 1st month to 3rd month. This study showed that the Pfizer/BioNTech vaccine induced higher SARS-CoV-2 specific serum IgA antibodies than the CoronaVac vaccine and remained seropositive for a longer time in individuals aged 60 years and older. It is believed that the serum IgA levels that were determined may not reflect the serum IgA levels. However, these findings support the studies in other literature, showing that the Pfizer-BioNTech mRNA vaccine induces higher SARS-CoV-2 specific serum IgA antibodies than the inactive CoronaVac vaccine and that it remains seropositive for a longer period of time. This study is important as it is the first study to compare the SARS-CoV-2 IgA antibody responses of individuals over 60 years of age in the Turkish Republic of Northern Cyprus in two different vaccine groups.

Complexity of the Immune Response Elicited by Different COVID-19 Vaccines, in the Light of Natural Autoantibodies and Immunomodulatory Therapies.

Despite the abundance of data on the COVID-19 vaccine-induced immune activation, the impact of natural autoantibodies (nAAbs) on these processes is less well defined. Therefore, we investigated potential connections between vaccine efficacy and nAAb levels. We were also interested in the impact of immunomodulatory therapies on vaccine efficacy. Clinical residual samples were used for the assessment of the COVID-19 vaccine-elicited immune response (IR) (n=255), as well as for the investigation of the immunization-associated expansion of the nAAb pool (n=185). In order to study the potential interaction between immunomodulatory therapies and the vaccine-induced IR, untreated, healthy individuals and patients receiving anti-TNFα or anti-IL-17 therapies were compared (n total =45). In-house ELISAs (anticitrate synthase, anti-HSP60 and-70) and commercial ELISAs (anti-SARS-CoV-2 ELISAs IgG, IgA, NeutraLISA and IFN-γ release assay 'IGRA') were applied. We found significant differences in the IR given to different vaccines. Moreover, nAAb levels showed plasticity in response to anti-COVID-19 immunization. We conclude that our findings may support the theorem about the non-specific beneficial 'side effects' of vaccination, including the broadening of the nAAb repertoire. Considering immunomodulation, we suggest that anti-TNFα and anti-IL17 treatments may interfere negatively with MALT-associated IR, manifested as decreased IgA titers; however, the modest sample numbers of the herein presented model might be a limiting factor of reaching a more comprehensive conclusion.

Retrospective analyses of antibody titers in the diagnosis of pediatric Celiac Disease

Objective: We aimed to evaluate the relationship between Tissue Transglutaminase IgA titer (tTGIgA) and Endomisium antibody (EMA) positivity and the stage of duodenal mucosal damage at Celiac disease (CD). Material and Methods: The study group consisted of 233 children (2-18 years old) who were diagnosed with CD and admitted to our XXX Hospital, Pediatric Gastroenterology Outpatient Clinic, between September 2017 and November 2022. All patients underwent an endoscopy, and a histopathological diagnosis was made. In upper gastrointestinal endoscopy, one biopsy sample were taken from the duodenum bulb and four samples from the second part of the duodenum. Histological patterns were evaluated according to the Marsh-Oberhuber classification. Results: A total 233 patients with CD were included in the study. The mean age of the patients at the time of diagnosis was 97.0 ± 57.1 months. The patients' mean tissue transglutaminase (tTG) IgA value was 172 ± 133. The most common Marsh-Oberhuber classification was found to be Marsh 3b (47.6%) in CD patients. According to the Marsh-Oberhuber classification, the mean tTGIgA values were significantly different compared to the groups. Conclusion: We recommend starting a diet with a diagnosis of CD without endoscopy for patients with a tTGIgA value of 10 X ULN (upper limit of normal) or more recommended by ESPGAN, and we even support randomized prospective studies to reduce this value to 7-10 times or less.

Antibody response in children with multisystem inflammatory syndrome related to COVID-19 (MIS-C) compared to children with uncomplicated COVID-19.

To comprehensively analyze the quality of the antibody response between children with Multisystem inflammatory syndrome (MIS-C) and age-matched controls at one month after SARS-CoV-2 exposure, and infected in the same time-period. Serum from 20 MIS-C children at admission, and 14 control children were analyzed. Antigen specific antibody isotypes and subclasses directed against various antigens of SARS-CoV-2 as well as against human common coronavirus (HCoVs) and commensal or pathogenic microorganisms were assessed by a bead-based multiplexed serological assay and by ELISA. The functionality of these antibodies was also assessed using a plaque reduction neutralization test, a RBD-specific avidity assay, a complement deposition assay and an antibody-dependent neutrophil phagocytosis (ADNP) assay. Children with MIS-C developed a stronger IgA antibody response in comparison to children with uncomplicated COVID-19, while IgG and IgM responses are largely similar in both groups. We found a typical class-switched antibody profile with high level of IgG and IgA titers and a measurable low IgM due to relatively recent SARS-CoV-2 infection (one month). SARS-CoV-2-specific IgG antibodies of MIS-C children had higher functional properties (higher neutralization activity, avidity and complement binding) as compared to children with uncomplicated COVID-19. There was no difference in the response to common endemic coronaviruses between both groups. However, MIS-C children had a moderate increase against mucosal commensal and pathogenic strains, reflecting a potential association between a disruption of the mucosal barrier with the disease. Even if it is still unclear why some children develop a MIS-C, we show here that MIS-C children produce higher titers of IgA antibodies, and IgG antibodies with higher functionality, which could reflect the local gastro-intestinal mucosal inflammation potentially induced by a sustained SARS-CoV-2 gut infection leading to continuous release of SARS-CoV-2 antigens.