Specific IgA Levels Research Articles

Immunogenicity and protective efficacy of a recombinant lactococcus lactis vaccine against HSV-1 infection

BackgroundHerpes simplex virus type 1 (HSV-1) is a major cause of viral encephalitis, genital mucosal infections, and neonatal infections. Lactococcus lactis (L. lactis) has been proven to be an effective vehicle for delivering protein antigens and stimulating both mucosal and systemic immune responses. In this study, we constructed a recombinant L. lactis system expressing the protective antigen glycoprotein D (gD) of HSV-1.ResultsTo improve the stability and persistence of antigen stimulation of the local mucosa, we inserted the immunologic adjuvant interleukin (IL)-2 and the Fc fragment of IgG into the expression system, and a recombinant L. lactis named NZ3900-gD-IL-2-Fc was constructed. By utilizing this recombinant L. lactis strain to elicit an immune response and evaluate the protective effect in mice, the recombinant L. lactis vaccine induced a significant increase in specific neutralizing antibodies, IgG, IgA, interferon-γ, and IL-4 levels in the serum of mice. Furthermore, in comparison to the mice in the control group, the vaccine also enhanced the proliferation levels of lymphocytes in response to gD. Moreover, recombinant L. lactis expressing gD significantly boosted nonspecific immune reactions in mice through the activation of immune-related genes. Furthermore, following the HSV-1 challenge of the murine lung mucosa, mice inoculated with the experimental vaccine exhibited less lung damage than control mice.ConclusionOur study presents a novel method for constructing a recombinant vaccine using the food-grade, non-pathogenic, and non-commercial bacterium L. lactis. The findings indicate that this recombinant vaccine shows promise in preventing HSV-1 infection in mice.

A novel bacterium-like particles platform displaying antigens by new anchoring proteins induces efficacious immune responses.

Bacterium-like particles (BLP) are the peptidoglycan skeleton particles of lactic acid bacteria, which have high safety, mucosal delivery efficiency, and adjuvant effect. It has been widely used in recent years in the development of vaccines. Existing anchoring proteins for BLP surfaces are few in number, so screening and characterization of new anchoring proteins are necessary. In this research, we created the OACD (C-terminal domain of Escherichia coli outer membrane protein A) to serve as an anchoring protein on the surface of BLP produced by the immunomodulatory bacteria Levilactobacillus brevis 23017. We used red fluorescent protein (RFP) to demonstrate the novel surface display system's effectiveness, stability, and ability to be adapted to a wide range of lactic acid bacteria. Furthermore, this study employed this surface display method to develop a novel vaccine (called COB17) by using the multi-epitope antigen of Clostridium perfringens as the model antigen. The vaccine can induce more than 50% protection rate against C. perfringens type A challenge in mice immunized with a single dose and has been tested through three routes. The vaccine yields protection rates of 75% for subcutaneous, 50% for intranasal, and 75% for oral immunization. Additionally, it elicits a strong mucosal immune response, markedly increasing levels of specific IgG, high-affinity IgG, specific IgA, and SIgA antibodies. Additionally, we used protein anchors (PA) and OACD simultaneous to show several antigens on the BLP surface. The discovery of novel BLP anchoring proteins may expand the possibilities for creating mucosal immunity subunit vaccines. Additionally, it may work in concert with PA to provide concepts for the creation of multivalent or multiple vaccines that may be used in clinical practice to treat complex illnesses.

Serum and Salivary IgG and IgA Response After COVID-19 Messenger RNA Vaccination

There is still considerable controversy in the literature regarding the capacity of intramuscular messenger RNA (mRNA) vaccination to induce a mucosal immune response. To compare serum and salivary IgG and IgA levels among mRNA-vaccinated individuals with or without previous SARS-CoV-2 infection. In this cohort study, SARS-CoV-2-naive participants and those with previous infection were consecutively included in the CoviCompare P and CoviCompare M mRNA vaccination trials and followed up to day 180 after vaccination with either the BNT162b2 (Pfizer-BioNTech) vaccine or the mRNA-1273 (Moderna) vaccine at the beginning of the COVID-19 vaccination campaign (from February 19 to June 8, 2021) in France. Data were analyzed from October 25, 2022, to July 13, 2023. An ultrasensitive digital enzyme-linked immunosorbent assay was used for the comparison of SARS-CoV-2 spike-specific serum and salivary IgG and IgA levels. Spike-specific secretory IgA level was also quantified at selected times. A total of 427 individuals were included in 3 groups: participants with SARS-CoV-2 prior to vaccination who received 1 single dose of BNT162b2 (Pfizer-BioNTech) (n = 120) and SARS-CoV-2-naive individuals who received 2 doses of mRNA-1273 (Moderna) (n = 172) or 2 doses of BNT162b2 (Pfizer-BioNTech) (n = 135). The median age was 68 (IQR, 39-75) years, and 228 (53.4%) were men. SARS-CoV-2 spike-specific IgG saliva levels increased after 1 or 2 vaccine injections in individuals with previous infection and SARS-CoV-2-naive individuals. After vaccination, SARS-CoV-2-specific saliva IgA levels, normalized with respect to total IgA levels, were significantly higher in participants with previous infection, as compared with the most responsive mRNA-1273 (Moderna) recipients (median normalized levels, 155 × 10-5 vs 37 × 10-5 at day 29; 107 × 10-5 vs 54 × 10-5 at day 57; and 104 × 10-5 vs 70 × 10-5 at day 180 [P < .001]). In contrast, compared with day 1, spike-specific IgA levels in the BNT162b2-vaccinated SARS-CoV-2-naive group increased only at day 57 (36 × 10-5 vs 49 × 10-5 [P = .01]). Bona fide multimeric secretory IgA levels were significantly higher in individuals with previous infection compared with SARS-CoV-2-naive individuals after 2 antigenic stimulations (median optical density, 0.36 [IQR, 0.16-0.63] vs 0.16 [IQR, 0.10-0.22]; P < .001). The findings of this cohort study suggest that mRNA vaccination was associated with mucosal immunity in individuals without prior SARS-CoV-2 infection, but at much lower levels than in previously infected individuals. Further studies are needed to determine the association between specific saliva IgA levels and prevention of infection or transmission.

Specific IgA, But Not IgG, in Human Milk From COVID-19-Infected Mothers Neutralizes SARS-CoV-2.

This study highlights the importance of human milk in providing anti-severe acute respiratory syndrome coronavirus 2 immunity to newborns. The highest protective activity of human milk against COVID-19 was found in colostrum from infected mothers. Neutralizing activity was associated with high levels of specific IgA. Depletion of IgA, but not IgG, from milk samples completely abolished the ability of human milk to neutralize severe acute respiratory syndrome coronavirus 2.

Dynamics of humoral immunity during natural SARS-CoV-2 infection and/or after vaccination with the ‘Sputnik V’ vaccine

Comprehensive analysis of adaptive immune response to SARS-CoV-2 is critical for epidemiological monitoring, as well as for tracking immune response stages and vaccination strategies. Understanding the differences between immunity formed after COVID-19 infection and vaccine-induced immunity is a specific task within this problem. Moreover, the obvious task is to assess the effect of repeated antigenic stimulation on immunological defense against SARS-CoV-2. The aim of present study was a comparative analysis of humoral immunity (anti-SARS-CoV-2 IgA and IgG) developing after natural infection with SARS-CoV-2 and/or after vaccination with anti-COVID vaccine “Sputnik V”. The study involved 36 volunteers. 21 of them had COVID-19 and were vaccinated 8-10 months later (group 1). In 15 primarily vaccinated persons, previous SARS-CoV-2 infection was excluded by means of regular PCR screening and serological testing (group 2). Results: Intensity of humoral immune response to the primary natural SARS-CoV-2 infection and similar indexes of antiviral adaptive immunity after vaccination with “Sputnik V” vaccine were similar in both groups. However, both maximal values of anti-SARS-CoV-2 IgA and IgG and the rates of post-vaccination humoral immune response differed significantly between the persons who have previously had COVID-19 and those who have not previously been infected with SARS-CoV-2. We’ve got statistically significant differences between two groups of participants using Student’s t test comparing the average maximum IgA levels after vaccination (p &lt; 0.05). For IgG levels, these differences are less pronounced. In the first group, the average maximal values of specific IgA and IgG levels after natural infection with SARS-CoV-2 and after subsequent vaccination differed by more than 2 times. The time intervals for reaching maximal antibody levels after vaccination proved to be significantly shorter in the subjects who had a story of COVID-19, than in persons who did not report a clinical COVID-19 infection. Concerning the terms of arising IgG antibody response after vaccination versus cases of COVID-19 in the first group, we obtained a statistically significant difference by the Student’s t-test (p &lt; 0.05). Hence, the persons with a previous natural COVID-19 infection develop a faster, stronger and more durable response to the “Sputnik V” vaccine than the subjects who had no such infection in their history

Chloroplast display of subunit vaccines and their efficacy via oral administration

As a safe and natural “capsule,” plants have several advantages over mammals and microorganisms for the production of oral vaccines. In this study, we innovatively utilized the transmembrane region of the pea Translocase of chloroplast 34 (TOC34) protein to display two subunit vaccines, capsid protein VP2 of Porcine parvovirus (PPV) and the heat-labile enterotoxin B (LTB) of Escherichia coli, on the surface of chloroplasts. Unlike microbial display techniques, chloroplast display circumvents antigen degradation in the stomach while retaining the size characteristic of microorganisms. Additionally, a co-expressed peptide adjuvant, antimicrobial peptide protegin-1 (PG1), was used to enhance the strength of oral immunization. Immunohistochemistry and trypsin digestion of chloroplast surface proteins confirmed the successful localization of both antigens on the chloroplast surface. In stable transgenic tobacco plants, the expression level of VP2-TOC34 ranged from 0.21 to 6.83 μg/g FW, while LTB-TOC34 ranged from 2.42 to 10.04 μg/g FW. By contrasting the digestive characteristics of plant materials with different particle sizes, it was observed that plant materials with diameters around 1 mm exhibited more prominent advantages in terms of chloroplast release and antigen exposure compared to both larger and smaller particles. Oral immunization resulted in significantly increased levels of specific IgG and secretory IgA in the mice compared to the control, with similar effects observed between the groups receiving oral immunization alone and those receiving a combination of initial injection and subsequent oral immunization. Challenge experiments further demonstrated the effective protection against infection in mice using this approach. These findings highlight the potential of chloroplast display technology for the development of effective oral vaccines.

Comparative Immune Response after Vaccination with SOBERANA® 02 and SOBERANA® plus Heterologous Scheme and Natural Infection in Young Children.

(1) Background: In children, SARS-CoV-2 infection is mostly accompanied by mild COVID-19 symptoms. However, multisystem inflammatory syndrome (MIS-C) and long-term sequelae are often severe complications. Therefore, the protection of the pediatric population against SARS-CoV-2 with effective vaccines is particularly important. Here, we compare the humoral and cellular immune responses elicited in children (n = 15, aged 5-11 years) vaccinated with the RBD-based vaccines SOBERANA® 02 and SOBERANA® Plus combined in a heterologous scheme with those from children (n = 10, aged 4-11 years) who recovered from mild symptomatic COVID-19. (2) Methods: Blood samples were taken 14 days after the last dose for vaccinated children and 45-60 days after the infection diagnosis for COVID-19 recovered children. Anti-RBD IgG and ACE2-RBD inhibition were assessed by ELISA; IgA, cytokines, and cytotoxic-related proteins were determined by multiplex assays. Total B and T cell subpopulations and IFN-γ release were measured by multiparametric flow cytometry using a large panel of antibodies after in vitro stimulation with S1 peptides. (3) Results: Significant higher levels of specific anti-RBD IgG and IgA and ACE2-RBD inhibition capacity were found in vaccinated children in comparison to COVID-19 recovered children. Th1-like and Th2-like CD4+ T cells were also significantly higher in vaccinated subjects. IFN-γ secretion was higher in central memory CD4+ T cells of COVID-19 recovered children, but no differences between both groups were found in the CD4+ and CD8+ T cell effector, terminal effector, and naïve T cell subpopulations. In contrast to low levels of IL-4, high levels of IL-2, IL-6, IFN-γ, and IL-10 suggest a predominant Th1 cell polarization. Cytotoxic-related proteins granzyme A and B, perforin, and granulin were also found in the supernatant after S1 stimulation in both vaccinated and recovered children. (4) Conclusions: Vaccination with the heterologous scheme of SOBERANA® 02/SOBERANA® Plus induces a stronger antibody and cellular immune response compared to natural infections in young children.

Differential levels of anti-Mycobacterium tuberculosis-specific IgAs in saliva of household contacts with latent tuberculosis infection.

Mucosal immunity is strongly elicited in early stages of many respiratory and enteric infections; however, its role in tuberculosis pathogenesis has been scarcely explored. We aimed to investigate Mycobacterium tuberculosis (Mtb) specific IgA levels in saliva in different stages of latent Tuberculosis Infection (TBI). A multiplex bead-based Luminex immunoassay was developed to detect specific IgA against 12 highly immunogenic Mtb antigens. A prospective cohort of household contacts (>14 years) of pulmonary TB cases was established in Santiago, Chile. Contacts were classified as Mtb-infected or not depending on serial interferon-γ release assay results. Saliva samples were collected and tested at baseline and at a 12-week follow-up. Mtb-specific IgA was detectable at all visits in all participants (n = 168), including the "non-Mtb infected" (n = 64). Significantly higher median levels of IgA were found in the "Mtb infected" compared to the uninfected for anti-lipoarabinomannan (LAM) (110 vs. 84.8 arbitrary units (AU), p < 0.001), anti-PstS1 (117 vs. 83 AU, p < 0.001), anti-Cell Membrane Fraction (CMF) (140 vs. 103 AU, p < 0.001) and anti-Culture Filtrate Proteins (CFP) (median 125 vs. 96 AU, p < 0.001), respectively. Nonetheless, the discriminatory performance of these specific mucosal IgA for TBI diagnosis was low. Saliva holds Mtb-specific IgA against several antigens with increased levels for anti-LAM, anti-PstS1, anti-CMF and anti-CFP found in household contacts with an established TBI. The role of these mucosal antibodies in TB pathogenesis, and their kinetics in different stages of Mtb infection merits further exploring.

A nasal vaccine with inactivated whole-virion elicits protective mucosal immunity against SARS-CoV-2 in mice.

Vaccinations are ideal for reducing the severity of clinical manifestations and secondary complications of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2); however, SARS-CoV-2 continues to cause morbidity and mortality worldwide. In contrast to parenteral vaccines such as messenger RNA vaccines, nasal vaccines are expected to be more effective in preventing viral infections in the upper respiratory tract, the primary locus for viral infection and transmission. In this study, we examined the prospects of an inactivated whole-virion (WV) vaccine administered intranasally against SARS-CoV-2. Mice were immunized subcutaneously (subcutaneous vaccine) or intranasally (nasal vaccine) with the inactivated WV of SARS-CoV-2 as the antigen. The spike protein (S)-specific IgA level was found to be higher upon nasal vaccination than after subcutaneous vaccination. The level of S-specific IgG in the serum was also increased by the nasal vaccine, although it was lower than that induced by the subcutaneous vaccine. The nasal vaccine exhibited a stronger defense against viral invasion in the upper respiratory tract than the subcutaneous vaccine and unimmunized control; however, both subcutaneous and nasal vaccines provided protection in the lower respiratory tract. Furthermore, we found that intranasally administered inactivated WV elicited robust production of S-specific IgA in the nasal mucosa and IgG in the blood of mice previously vaccinated with messenger RNA encoding the S protein. Overall, these results suggest that a nasal vaccine containing inactivated WV can be a highly effective means of protection against SARS-CoV-2 infection.

SARS-CoV-2 antibody dynamics over time and risk factors associated with infection and long COVID-19 symptoms in large working environments.

Factors influencing SARS-CoV-2 antibody dynamics, transmission, waning and long COVID-19 symptomatology are still not fully understood. In the Danish section of the Novo Nordisk Group, we performed a prospective seroepidemiological study during the first and second waves of the COVID-19 pandemic. All employees and their household members (>18 years) were invited to participate in a baseline (June-August 2020), 6-month follow-up (December 2020-January 2021), and 12-month follow-up (August 2021) sampling. In total, 18,614 accepted and provided at least one blood sample and completed a questionnaire regarding socioeconomic background, health status, previous SARS-CoV-2 infection, and persistent symptoms. Total antibody and specific IgM, IgG and IgA levels against recombinant receptor binding domain were tested. At baseline, the SARS-CoV-2-antibody seroprevalence was 3.9%. At the 6-month follow-up, the seroprevalence was 9.1%, while at the 12-month follow-up, the seroprevalence was 94.4% (after the vaccine rollout). Male sex and younger age (18-40 years) were significant risk factors for seropositivity. From baseline to the 6-month sampling, we observed a substantial waning of IgM, IgG and IgA levels (p<0.001), regardless of age, sex and initial antibody level. An increased antibody level was found in individuals infected prior to vaccination compared to vaccinated infection naïves (p<0.0001). Approximately a third of the seropositive individuals reported one or more persistent COVID-19 symptoms, with anosmia and/or ageusia (17.5%) and fatigue (15.3%) being the most prevalent. In conclusion, this study provides a comprehensive insight into SARS-CoV-2 antibody seroprevalence following infection and vaccination, waning, persistent COVID-19 symptomatology and risk factors for seropositivity in large working environments. This article is protected by copyright. All rights reserved.

Mannose facilitates Trichinella spiralis expulsion from the gut and alleviates inflammation of intestines and muscles in mice

Trichinellosis is a major zoonotic parasitosis which is a vital risk to meat food safety. It is requisite to exploit new strategy to interdict food animal Trichinella infection and to obliterate Trichinella from food animals to ensure meat safety. Mannose is an oligosaccharide that specifically binds to the carbohydrate-recognition domain of C-type lectin; it has many physiological functions including reliving inflammation and regulating immune reaction. The purpose of this study was to investigate the suppressive role of mannose on T. spiralis larval invasion and infection, its effect on intestinal and muscle inflammation, and immune responses after challenge. The results showed that compared to the saline-treated infected mice, the mannose-treated infected mice had less intestinal adult and muscle worm burdens, mild inflammation of intestine and muscle of infected mice. The levels of specific anti-Trichinella IgG (IgG1/IgG2a), IgA and sIgA in mannose-treated infected mice were obviously inferior to saline-treated infected mice (P < 0.01). Furthermore, the levels of two cytokines (IFN-γ and IL-4) in mannose-treated infected mice were also significantly lower than the saline-treated infected mice (P < 0.01). The protective effect of the mannose against Trichinella infection might be not related to specific antibody and cellular immune responses. The above results demonstrated that mannose could be considered as a novel adjuvant therapeutic agent for anti-Trichinella drugs to block larval invasion at early stage of Trichinella infection.

Safety and Immunogenicity of a Chimeric Subunit Vaccine against Shiga Toxin-Producing Escherichia coli in Pregnant Cows.

Shiga toxin-producing Escherichia coli (STEC) is a zoonotic pathogen that causes gastroenteritis and Hemolytic Uremic Syndrome. Cattle are the main animal reservoir, excreting the bacteria in their feces and contaminating the environment. In addition, meat can be contaminated by releasing the intestinal content during slaughtering. Here, we evaluated the safety and immunogenicity of a vaccine candidate against STEC that was formulated with two chimeric proteins (Chi1 and Chi2), which contain epitopes of the OmpT, Cah and Hes proteins. Thirty pregnant cows in their third trimester of gestation were included and distributed into six groups (n = 5 per group): four groups were administered intramuscularly with three doses of the formulation containing 40 µg or 100 µg of each protein plus the Quil-A or Montanide™ Gel adjuvants, while two control groups were administered with placebos. No local or systemic adverse effects were observed during the study, and hematological parameters and values of blood biochemical indicators were similar among all groups. Furthermore, all vaccine formulations triggered systemic anti-Chi1/Chi2 IgG antibody levels that were significantly higher than the control groups. However, specific IgA levels were generally low and without significant differences among groups. Notably, anti-Chi1/Chi2 IgG antibody levels in the serum of newborn calves fed with colostrum from their immunized dams were significantly higher compared to newborn calves fed with colostrum from control cows, suggesting a passive immunization through colostrum. These results demonstrate that this vaccine is safe and immunogenic when applied to pregnant cows during the third trimester of gestation.

P124 Cryptococcus neoformans-and Cryptococcus gattii-specific antibodies vary among children and adults with cryptococcosis and healthy from Colombia

Poster session 1, September 21, 2022, 12:30 PM - 1:30 PMBackground Cryptococcus neoformans (Cn), predominantly, and Cryptococcus gattii (Cg) cause cryptococcosis, a life-threatening systemic mycosis of global distribution affecting mainly immunocompromised adults.ObjectivesThis study aimed to determine total and specific antibodies against C. neoformans and C. gattii antigens in sera from patients with cryptococcosis and from healthy individuals from Colombia, which will help to elucidate sero-epidemiological variations in the incidence of the disease in the country.MethodsSera from child and adult patients with cryptococcosis (n = 109) and sera from healthy children and adults from Colombia (n = 119) were studied. Using ELISA, total and Cn- and Cg-specific levels of immunoglobulin (Ig)G, IgA, and IgM were determined in sera.ResultsTotal IgG, IgA, and IgM levels were higher in HIV + compared with HIV− patients with cryptococcosis. Specific IgG, IgA, and IgM levels tended to be higher in cryptococcosis patients than in healthy controls and to be higher in adults than in children, with a positive correlation between antibody reactivity and age. All serum immunoglobulins were more reactive against Cn-proteins than Cg-proteins. Including all samples, a positive correlation between total and specific IgG, IgA, and IgM levels was found.ConclusionsIn cryptococcosis patients from Colombia, serum immunoglobulins levels differ depending on HIV status, as reported previously. However, this study shows for the first-time variations in immunoglobulin production among adults and children with cryptococcal disease and between Cn and Cg-protein antigens. The observation of differential antibody reactivity with cryptococcal proteins encourages further studies of the humoral immunity for host defense against cryptococcosis.

Microscopic and submicroscopic infection by Plasmodium falciparum: Immunoglobulin M and A profiles as markers of intensity and exposure.

Assessment of serological Plasmodium falciparum–specific antibodies in highly endemic areas provides valuable information about malaria status and parasite exposure in the population. Although serological evidence of Plasmodium exposure is commonly determined by Plasmodium-specific immunoglobulin G (IgG) levels; IgM and IgA are likely markers of malaria status that remain relatively unexplored. Previous studies on IgM and IgA responses have been based on their affinity for single antigens with shortage of immune responses analysis against the whole Plasmodium proteome. Here, we provide evidence of how P. falciparum infection triggers the production of specific IgM and IgA in plasma and its relationship with parasite density and changes in hematological parameters. A total of 201 individuals attending a hospital in Breman Asikuma, Ghana, were recruited into this study. Total and P. falciparum–specific IgM, IgA, and IgG were assessed by ELISA and examined in relation to age (0–5, 14–49, and ≥50 age ranges); infection (submicroscopic vs. microscopic malaria); pregnancy and hematological parameters. Well-known IgG response was used as baseline control. P. falciparum–specific IgM and IgA levels increased in the population with the age, similarly to IgG. These data confirm that acquired humoral immunity develops by repeated infections through the years endorsing IgM and IgA as exposure markers in endemic malaria regions. High levels of specific IgA and IgM in children were associated with microscopic malaria and worse prognosis, because most of them showed severe anemia. This new finding shows that IgM and IgA may be used as diagnostic markers in this age group. We also found an extremely high prevalence of submicroscopic malaria (46.27% on average) accompanied by IgM and IgA levels indistinguishable from those of uninfected individuals. These data, together with the observed lack of sensitivity of rapid diagnostic tests (RDTs) compared to PCR, invoke the urgent need to implement diagnostic markers for submicroscopic malaria. Overall, this study opens the potential use of P. falciparum–specific IgM and IgA as new serological markers to predict malaria status in children and parasite exposure in endemic populations. The difficulties in finding markers of submicroscopic malaria are highlighted, emphasizing the need to explore this field in depth.

Low rate of asymptomatic carriage and salivary immunoglobulin A response to Group A Streptococci in the healthy adult population in Finland

Streptococcus pyogenes, also called group A streptococcus (GAS), is a human pathogen causing a wide range of infections ranging from mild tonsillitis to severe, life threatening conditions such as bacteraemia, necrotizing fasciitis, and streptococcal toxic shock syndrome. GAS may also colonise the oropharynx without causing any signs of disease which is known as asymptomatic carriage. This study aims to investigate IgA responses against GAS and oral streptococci from saliva samples collected from healthy Finnish adults. In addition, asymptomatic throat GAS carriage was studied. The study participants consisted of healthy adult volunteers who provided one saliva sample, a throat swab, and a background questionnaire. Total salivary IgA, and GAS specific IgA were analysed from the saliva samples using enzyme-linked immunosorbent assays (ELISA) and the results were compared to oral streptococci specific IgA levels. Asymptomatic GAS throat carriers were identified by bacterial culture, and the isolates were emm typed. Samples from a total of 182 individuals were analysed. The median salivary IgA concentration was 62.9 µg/ml (range 17.3–649.9 µg/ml), and median GAS and oral streptococcal specific IgA concentrations 2.7 and 3.3 arbitrary units (AU, range 1.4–7.4 AU and 1.6–12.0 AU), respectively. Three individuals with asymptomatic GAS throat carriage were identified.

Induction of Severe Eosinophilic Esophagitis and Multi-Organ Inflammation by Airborne Allergens is Associated with IL-4/IL-13 and CCL11 but Not IgE in Genetic Susceptible Mice.

BackgroundEosinophilic Esophagitis (EoE) is an increasingly common chronic inflammatory disease. The pathological mechanisms underlying EoE are largely unknown.ObjectiveWe sought to understand the mechanisms underlying aeroallergen-induced EoE in Sharpin gene deficient (Sharpin-/-) mice that is prone to inflammatory response.MethodsSharpin-/-mice were exposed with Aspergillus fumigatus and ovalbumin intranasally every alternate day for 4 weeks. Wild type (WT) naïve mice, WT exposed, and un-exposed Sharpin-/- mice were controls. Histopathological analysis was performed by H&E, trichrome and major basic protein staining. Total and specific IgE, IgG, and IgA levels were measured by ELISA and Th2 cytokine and CCL11 chemokine gene expression were determined.ResultsAirborne allergen exposed Sharpin-/- mice showed severe eosinophilic inflammation in the esophagus (p < 0.001), and markedly increased epithelial thickening (p < 0.0001) compared to WT normal controls, whereas airborne allergen exposed WT mice and unexposed Sharpin-/- mice only showed mild eosinophilic inflammation in the esophagus. These exposed Sharpin-/- mice also showed over 7-fold increase in blood eosinophils (p < 0.0001), 60-fold increase in eosinophils in bronchoalveolar lavage fluid (p < 0.0001) and 4-fold increase in eosinophils in the skin (p < 0.0001) compared to normal controls. Surprisingly, exposed Sharpin-/- mice did not show elevation of serum total or antigen-specific IgE levels but reduced total IgA and IgG levels than normal controls There was a marked increase in IL-4, IL-13 and CCL11 gene expression in esophageal tissue (p < 0.001) in exposed Sharpin-/- mice compared to WT normal mice.ConclusionTh2 cytokines and chemokines, but not IgE may play an important pathologic role in aeroallergen-induced EoE. This study may provide insight into new therapeutics for EoE.

Immunologic changes during desensitization with cow's milk: How it differs from natural tolerance or nonallergic state?

BackgroundOral immunotherapy (OIT) is a novel allergen-specific treatment for food allergies. ObjectiveTo investigate the effect of OIT on blocking antibodies, T cell regulation, and cytokine response during immunoglobulin (Ig)E-mediated cow's milk allergy (CMA) treatment. MethodsA total of 59 children with IgE-mediated CMA who were followed in pediatric allergy outpatient clinic and 18 healthy children were included. The children were evaluated in the following 4 groups: OIT group, elimination group (patients receiving dairy elimination diet), tolerance group (patients who developed tolerance), and healthy control group. Milk-specific IgE, IgG4, and IgA levels, cow's milk induration diameters in skin prick test, CD4 + CD25 + FoxP3 + Treg cell percentages, messenger RNA (mRNA) expressions, and interleukin (IL)-10, transforming growth factor-beta (TGF-β), IL-2, IL-4, and IL-13 cytokine levels were compared between the groups. ResultsThe mean age of the patients was 42.6 ± 39 (6-201) months, and 63.6% (n = 49) of the patients were girls. We observed an increase in total IgE levels (P = .02), a decrease in cow's milk sIgE (P = .08, NS), and an increase in cow's milk component (β-lactoglobulin and casein) specific IgA (P < .05) and IgG4 (P < .001) levels at 2 months after the maintenance phase of OIT. In addition, the immune response after OIT treatment, which had a 100% clinical success rate, was notable for similar CD4 + CD25 + FoxP3 + cell percentages (P = .8), and increased IL-10 (P = .04) levels and increased but statistically nonsignificant TGF-β levels (P = .17) compared with those before treatment. FoxP3 mRNA expression was similar to that of patients who developed natural tolerance. Pretreatment and post-treatment FoxP3 mRNA-FoxP3 flow cytometric expressions were positively correlated with TGF-β concentrations in the OIT group. ConclusionA successful immune response to OIT was found, possibly through the blockage of IgE-mediated allergen presentation by blocking antibodies, marked IL-10 cytokine response, and TGF-β response. FoxP3 mRNA expression was similar to the natural tolerance mechanism, but more studies are needed.

Immunogenicity evaluation after BNT162b2 booster vaccination in healthcare workers

Waning of the immune response upon vaccination in SARS-CoV-2 infection is an important subject of evaluation in this pandemic, mostly in healthcare workers (HCW) that are constantly in contact with infected samples and patients. Therefore, our study aimed to establish the specific humoral response of specific IgG and IgA antibodies upon vaccination, during the second year of pandemic and evaluating the booster shot with the same vaccine type. A group of 103 HCW with documented exposure to the virus were monitored for specific IgG and IgA levels prior to vaccination, after the first vaccination round, during the following 8 months and after the booster shot with the same vaccine type. After 8 months post-vaccination the humoral response in both IgG and IgA decreased, 2.4 times for IgG, and 2.7 times for IgA. Although the antibodies levels significantly decreased, no documented infection was registered in the group. After the booster shot, the entire group, displayed IgG increased levels, immediately after booster followed by the increase in specific IgA. IgG levels post-second round of vaccination are statistically higher compared to the first round, while IgA is restored at the same levels. Within the vaccination or booster routine for a multiple waves’ pandemic that is generating new virus variants, populational immunity remains an important issue for future implementation of prevention/control measures.

Coronavirus Disease 2019 Vaccine Booster Effects Are Seen in Human Milk Antibody Response.

Infants remain at high risk for severe coronavirus disease 2019 (COVID-19). Human milk contains high levels of protective SARS CoV-2 specific antibodies post-infection and primary vaccine series, but levels decline over time. We hypothesized that the COVID-19 booster vaccine augment antibody production and the protection afforded to human milk-fed infants. We prospectively enrolled pregnant or lactating mothers planning to receive COVID-19 vaccination. We measured human milk IgG, IgA, and IgM antibodies targeting the SARS CoV-2 receptor binding domain within the spike protein and human milk neutralization activity against SARS CoV-2 in 10 lactating mothers from pre-COVID-19 primary series vaccine to post-booster dose. Human milk SARS CoV-2 specific IgG increased significantly from pre- to post-booster levels (median OD 0.33 vs. 2.02, P = 0.002). The IgG levels post-booster were even higher than the peak level after the primary series (2.02 vs. 0.95, P = 0.03). The increase in SARS CoV-2 specific IgA levels was not significant (0.10 vs. 0.33, P = 0.23). There was a strong correlation between paired maternal blood and milk IgG and IgA levels (IgG rho 0.52, P < 0.001, IgA rho 0.31, P = 0.05). Post-booster neutralizing activity was elevated compared to pre-booster levels (66% vs. 12% inhibition, P = 0.002). COVID-19 vaccine booster elicits SARS CoV-2 specific antibodies in human milk at higher levels compared to the initial primary series. This finding suggests that three doses of COVID-19 mRNA vaccination leads to improved mucosal response in human milk and reinforces current guidance recommending all pregnant or lactating mothers receive full COVID-19 vaccine courses with a booster dose.

Oral Immunization of Chickens with Probiotic Lactobacillus crispatus Constitutively Expressing the α-β2-ε-β1 Toxoids to Induce Protective Immunity.

Clostridium perfringens (C. perfringens) is a bacterium that commonly causes zoonotic disease. The pathogenicity of C. perfringens is a result of the combined action of α, β, and ε exotoxins. In this study, Lactobacillus crispatus (pPG-T7g10/L. crispatus) expressing the main toxoids of C. perfringens, α, ε, β1, and β2, with EGFP-labeling, was constructed, and the protective effect was estimated in chickens. The α-β2-ε-β1 toxoid was constitutively expressed for confirmation by laser confocal microscopy and western blotting, and its immunogenicity was analyzed by enzyme-linked immunosorbent assay (ELISA) and immunohistochemical assays. After booster immunization, the probiotic vaccine group showed significantly higher levels (p < 0.05) of specific secretory IgA (sIgA) and IgY antibodies in the serum and intestinal mucus. Furthermore, the levels of cytokines, including interferon (IFN)-γ, interleukin (lL)-2, IL-4, IL-10, IL-12, and IL-17, and the proliferation of spleen lymphocytes in chickens orally immunized with pPG-E-α-β2-ε-β1/L. crispatus increased significantly. Histopathological observations showed that the intestinal pathological changes in chickens immunized with pPG-E-α-β2ε-β1/L. crispatus were significantly alleviated. These data reveal that the probiotic vaccine could stimulate mucosal, cellular, and humoral immunity and provide an active defense against the toxins of C. perfringens, suggesting a promising candidate for oral vaccines against C. perfringens.