Examination of the affinity of anti-SARS-CoV-2 IgA, which is mucosal immunity, for SARS-CoV-2 BA.4 variant and BA.5 variant

Currently, the variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is the mainstream of COVID-19 in the world, are the omicron type SARS-CoV-2 BA.4 variant and BA.5 variant derived from the omicron variant. In Japan, the Pfizer/BioNTech COVID-19 vaccine (BNT162b2) and the Moderna COVID-19 mRNA-1273 vaccine, which were created based on the viral gene of the Wuhan-type SARS-CoV-2 B.1.1.7 variant, have been inoculated. Previous clinical studies have reported that vaccination with these mRNA-based COVID-19 vaccines secretes a large amount of anti-SARSCoV- 2 IgA, which is mucosal immunity, into breast milk. However, recent clinical studies revealed that SARS-CoV-2 BA.4 and BA.5 variants have possessed the ability to successfully circumvent anti-SARS-CoV-2 immune mechanisms conferred by COVID-19 vaccination or prior SARS-CoV-2 infection. Therefore, we investigated the affinity of anti-SARS-CoV-2 IgA (PDB:CV2.1169 and PDB: CR3022) against SARS-CoV-2 B.1.1.7 variant (PDB: 7QEZ_A), SARS-CoV-2 BA.4 variant and BA.5 variant (PDB: 7XNS) by in silico analysis. As a result of the in silico analysis, the affinity of IgA CV2.1169 for each SARS-CoV-2 variant (B.1.1.7 variant, BA.4 variant, BA.5 variant) was -15.92 Kcal/mol, -9.26 Kcal/mol, -8.94 Kcal/ mol. The affinities of IgA CR3022 for each SARS-CoV-2 variant (B.1.1.7 variant, BA.4 variant, BA.5 variant) were -16.35 Kcal/ mol, -9.85 Kcal/mol, and -9.24 Kcal/mol. In addition, IgA derived from individuals vaccinated with the Pfizer/BioNTech COVID-19 vaccine (BNT162b2) or the Moderna COVID- 19 mRNA-1273 vaccine was found to have no high affinity to the omicron type SARS-CoV-2 BA.4 and BA.5 variants. In other words, the anti-SARS-CoV-2 IgA (PDB: CV2.1169 and PDB: CR3022), which has strong binding power to Wuhan type SARS-CoV-2 B.1.1.7 variant, was found not to have a strong affinity for omicron type SARS-CoV- 2 BA.4 variant and the BA.5 variant. In Japan, it has been reported that the COVID-19 vaccine for omicron type SARS-CoV-2 BA.4 variant and BA.5 variant may be approved in November 2022. We hope that the new COVID-19 vaccine will become widespread. Funding(s): This research was performed with research funding from the following: Japan Society for Promoting Science for TH (Grant No. 19K09840), and Japan Science and Technology Agency for TH (Grant No. STSC20001). Acknowledgments: We thank all medical staff for providing medical care to this patient at the National Hospital Organization Kyoto Medical Center.Copyright © 2023 The American Society for Biochemistry and Molecular Biology, Inc.

Sequential Immunization of Updated Covid-19 DNA and Rna Vaccines in Nonhuman Primates

Background: COVID-19 vaccines that expand immunity against emerging variants of concern (VOC) are needed to protect against ongoing viral evolution. We investigated the impact of boosting nonhuman primates pre-immune to the original WA-1 strain with updated VOC vaccines on the breadth and magnitude of mucosal and systemic antibody (Ab) and T cell (Tc) responses. Method(s): Cynomolgus macaques were primed with 2 doses of WA-1 Spike protein encoded by either an IL-12 adjuvanted DNA vaccine administered by gene gun (GG) or a self-amplifying RNA vaccine (repRNA) delivered intramuscularly (IM) with a cationic nanocarrier (LIONTM/IM, HDT Bio) or by GG (FIG 1). A booster dose was administered at week 17 with DNA or repRNA vaccines expressing B.1.351 (Beta) and B.1.617 (Delta) Spike receptor-binding domains (RBDs) fused to influenza HA2 stem domain (SHARP, designed by AIR/ JP) followed by a final Beta + Delta + WA-1 SHARP boost at week 34. Blood and bronchoalveolar lavages (BAL) were collected before and after each dose. Binding and neutralizing Ab to VOCs, including Omicron strains, were measured by ELISA and pseudovirus neutralization assays. Tc responses to Spike protein (WA-1 peptides) were measured by ELISpot. Immune responses were compared between groups and between blood vs lung using non-parametric statistical tests. Result(s): Two doses of WA-1 DNA or repRNA vaccines induced broad Ab against all VOC with the repRNA vaccine inducing the highest titers. Boosting with VOC SHARP significantly increased mucosal and systemic Ab responses against all VOCs tested including Omicron. After final boost, all groups had comparable binding and neutralization Ab titers and Tc responses regardless of method of delivery (GG or LIONTM/IM) or formulation (DNA or repRNA). Tc responses were significantly higher in the BAL vs PBMC after WA-1 Spike doses (p=0.0420) and VOC SHARP boosters (p=0.0009). Conclusion(s): The WA-1 strain primed for broad responses against VOCs that were significantly boosted with updated SHARP vaccines including responses against Omicron, even though this strain was not included in any dose. This suggests that sequential immunization with updated vaccines may broaden mucosal and systemic immunity against future VOCs. The repRNA vaccine initially induced the strongest responses, but there were no differences between RNA and DNA following additional booster doses, a result that supports development of a more cost-effective, room temperature stable DNA vaccine for worldwide boosters. (Figure Presented).

A Single Dose of BNT162b2 mRNA Vaccine Induces Airway Immunity in SARS-CoV-2 Naive and recovered COVID-19 subjects.

BACKGROUND: Mucosal antibodies can prevent virus entry and replication in mucosal epithelial cells and hence virus shedding. Parenteral booster injection of a vaccine against a mucosal pathogen promotes stronger mucosal immune responses following prior mucosal infection compared to injections of a parenteral vaccine in a mucosally naive subject. We investigated whether this was also the case for the BNT162b2 COVID-19 mRNA vaccine. METHODS: Twenty recovered COVID-19 subjects (RCS) and 23 SARS-CoV-2 naive subjects were vaccinated with respectively one and two doses of the BNT162b2 COVID-19 vaccine. Nasal Epithelial Lining Fluid (NELF) and plasma were collected before and after vaccination and assessed for Immunoglobulin (Ig)G and IgA antibody levels to Spike and for their ability to neutralize binding of Spike to ACE-2 receptor. Blood was analyzed one week after vaccination for the number of Spike-specific Antibody Secreting Cells (ASCs) with a mucosal tropism. RESULTS: All RCS had both nasal and blood SARS-CoV-2 specific antibodies at least 90 days after initial diagnosis. In RCS, a single dose of vaccine amplified pre-existing Spike-specific IgG and IgA antibody responses in both NELF and blood against both vaccine homologous and variant strains, including delta. These responses were associated with Spike-specific IgG and IgA ASCs with a mucosal tropism in blood. Nasal IgA and IgG antibody responses were lower in magnitude in SARS-CoV-2 naive subjects after two vaccine doses compared to RCS after one dose. CONCLUSION: Mucosal immune response to the SARS-CoV-2 Spike protein is higher in RCS after a single vaccine dose compared to SARS-CoV-2 naive subjects after two doses.

mRNA vaccination drives differential mucosal neutralizing antibody profiles in naïve and SARS-CoV-2 previously-infected individuals.

Two doses of BNT162b2 mRNA vaccine induces a strong systemic SARS-CoV-2 specific humoral response. However, SARS-CoV-2 airborne transmission makes mucosal immune response a crucial first line of defense. Therefore, we characterized SARS-CoV-2-specific IgG responses induced by BNT162b2 vaccine, as well as IgG responses to other pathogenic and seasonal human coronaviruses in oral fluid and plasma from 200 UK healthcare workers who were naïve (N=62) or previously infected with SARS-CoV-2 (N=138) using a pan-coronavirus multiplex binding immunoassay (Meso Scale Discovery®). Additionally, we investigated the impact of historical SARS-CoV-2 infection on vaccine-induced IgG, IgA and neutralizing responses in selected oral fluid samples before vaccination, after a first and second dose of BNT162b2, as well as following a third dose of mRNA vaccine or breakthrough infections using the same immunoassay and an ACE2 inhibition assay. Prior to vaccination, we found that spike-specific IgG levels in oral fluid positively correlated with IgG levels in plasma from previously-infected individuals (Spearman r=0.6858, p<0.0001) demonstrating that oral fluid could be used as a proxy for the presence of plasma SARS-CoV-2 IgG. However, the sensitivity was lower in oral fluid (0.85, 95% CI 0.77-0.91) than in plasma (0.94, 95% CI 0.88-0.97). Similar kinetics of mucosal and systemic spike-specific IgG levels were observed following vaccination in naïve and previously-infected individuals, respectively. In addition, a significant enhancement of OC43 and HKU1 spike-specific IgG levels was observed in previously-infected individuals following one vaccine dose in oral fluid (OC43 S: p<0.0001; HKU1 S: p=0.0423) suggesting cross-reactive IgG responses to seasonal beta coronaviruses. Mucosal spike-specific IgA responses were induced by mRNA vaccination particularly in previously-infected individuals (71%) but less frequently in naïve participants (23%). Neutralizing responses to SARS-CoV-2 ancestral and variants of concerns were detected following vaccination in naïve and previously-infected participants, with likely contribution from both IgG and IgA in previously-infected individuals (correlations between neutralizing responses and IgG: Spearman r=0.5642, p<0.0001; IgA: Spearman r=0.4545, p=0.0001). We also observed that breakthrough infections or a third vaccine dose enhanced mucosal antibody levels and neutralizing responses. These data contribute to show that a previous SARS-CoV-2 infection tailors the mucosal antibody profile induced by vaccination.

Dynamics of Clinical Symptoms and Secretory Immunoglobulin a in Covid-19 Convalescent Patients

The post-COVID-19 recovery period is characterized by persistence of some symptoms, with immunological alterations being of great importance. Development of preventive measures to normalize mucosal immunity after a coronavirus infection determines the relevance of the current study. The aim was to study dynamics of clinical symptoms and level of secretory immunoglobulin A in individuals after a novel coronavirus infection as well as evaluate effectiveness of using IFN alpha-2b. Materials and methods. A study was conducted with patients aged 18 to 60 years old (n = 130), surveyed 1 to 9 months after post-infection, as well as in apparently healthy individuals lacking COVID-19 (n = 15). Previous novel coronavirus infection and post-COVID manifestations were verified based on medical documentation, complaints, anamnesis data, physical examination and questionnaires. The concentration of salivatory and nasopharyngeal mucosal sIgA was measured dynamically prior to and after administration of local therapy with IFN alpha-2b (gel applied intranasally twice a day for 30 days). Results. The acute period of COVID-19 was characterized by fever, anosmia, severe asthenia (fatigue and weakness), muscle and joint pain. Among the post-COVID manifestations at early period (1-3 months), pain in the joints and muscles (75.0%) as well as elevated body temperature (21.2%) were reliably detected, whereas in the long period (6-9 months) there were revealed dominance with the same frequency of shortness of breath, muscle and joint pain (75.8%, respectively). Based on examination data in healthy subjects, there was determined an arbitrary normal range of secretory IgA in saliva - 6.45 +/- 1.81 mg/ml and nasal swabs - 13.43 +/- 3.24 mg/ml. In the group of patients 1-3 months post-infection, therapy with IFN alpha-2b one month later resulted in significantly increased level of secretory IgA in saliva (from 1.84 +/- 0.28 to 5.78 +/- 1.96 mg/ml) and in nasal swabs (from 28.61 +/- 3.0 to 39.83 +/- 3.85 mg/ml) by more than 3-and 1.5-fold, respectively. In the group of patients without therapy was featured with stably sustained decline in sIgA level up to 9 months after COVID-19. In particular, the level of saliva sIgA ranged from 2.36 +/- 0.56 down to 2.16 +/- 0.66 mg/ml, and in nasal smears - from 15.66 +/- 1.32 to 10.23 +/- 1.07 mg/ml that differed insignificantly compared to baseline level. The rate of respiratory diseases prevailed in this group (27.6% of cases), which fully lacked in the group of topically administered IFN alpha-2b. Conclusion. In the post-COVID period, multiple organ disorders persist and reduced sIgA level is registered. Intranasally applied IFN alpha-2b made possible to normalize sIgA level and prevent accumulation of respiratory infectious pathologies.

Intramuscular mRNA BNT162b2 vaccine against SARS-CoV-2 induces neutralizing salivary IgA.

Intramuscularly administered vaccines stimulate robust serum neutralizing antibodies, yet they are often less competent in eliciting sustainable "sterilizing immunity" at the mucosal level. Our study uncovers a strong temporary neutralizing mucosal component of immunity, emanating from intramuscular administration of an mRNA vaccine. We show that saliva of BNT162b2 vaccinees contains temporary IgA targeting the receptor-binding domain (RBD) of severe acute respiratory syndrome coronavirus-2 spike protein and demonstrate that these IgAs mediate neutralization. RBD-targeting IgAs were found to associate with the secretory component, indicating their bona fide transcytotic origin and their polymeric multivalent nature. The mechanistic understanding of the high neutralizing activity provided by mucosal IgA, acting at the first line of defense, will advance vaccination design and surveillance principles and may point to novel treatment approaches and new routes of vaccine administration and boosting.

Mucosal vaccines for SARS-CoV-2: triumph of hope over experience.

Currently approved COVID-19 vaccines administered parenterally induce robust systemic humoral and cellular responses. While highly effective against severe disease, there is reduced effectiveness of these vaccines in preventing breakthrough infection and/or onward transmission, likely due to poor immunity elicited at the respiratory mucosa. As such, there has been considerable interest in developing novel mucosal vaccines that engenders more localised immune responses to provide better protection and recall responses at the site of virus entry, in contrast to traditional vaccine approaches that focus on systemic immunity. In this review, we explore the adaptive components of mucosal immunity, evaluate epidemiological studies to dissect if mucosal immunity conferred by parenteral vaccination or respiratory infection drives differential efficacy against virus acquisition or transmission, discuss mucosal vaccines undergoing clinical trials and assess key challenges and prospects for mucosal vaccine development.

High dietary iodine intake may contribute to the low death rate from COVID-19 infection in Japan with activation by the lactoperoxidase system

We draw the attention of readers and governments to the death rate from coronavirus disease 2019 in Japan, continuing as a fraction of that experienced by many other developed nations. We think this is due to the activity of the powerful, protective lactoperoxidase system (LPO) which prevents serious airborne infections. The LPO system requires iodine, which is liberally provided by the typical Japanese diet but lacking in many others. One might consider the Japanese experience an incredibly large, open-label study exhibiting the preventative power of a high-iodine diet. We predict this favourable trend will continue for Japan because deadly variants of the severe, acute respiratory syndrome coronavirus 2 will be with us, forever.Copyright © 2023 The Scandinavian Foundation for Immunology.

Advances and challenges in intranasal vaccines development for respiratory infectious diseases

The great challenge to prevent transmission makes widespread of respiratory infectious diseases easily occur. Intranasal immunization is considered to be a promising route of vaccination to prevent it. Different from parenteral vaccines, intranasal vaccines can induce mucosal immune in respiratory tracts in addition to systemic immune, which provide the first line of defense against respiratory pathogen infection and further prevent transmission. Safe and effective intranasal spray flu vaccines have been licensed. Since the outbreak of COVID-19, intranasal administration has been applied in different vaccine platforms. This article has reviewed the progress of intranasal vaccines for respiratory infectious diseases that have been licensed or are under evaluation in the clinical trials, meanwhile discusses its unique advantages and challenges faced. © 2023, Publication Centre of Anhui Medical University. All rights reserved.

Intranasal administration of adenoviral vaccines expressing SARS-CoV-2 spike protein improves vaccine immunity in mouse models.

The ongoing SARS-CoV-2 pandemic is controlled but not halted by public health measures and mass vaccination strategies which have exclusively relied on intramuscular vaccines. Intranasal vaccines can prime or recruit to the respiratory epithelium mucosal immune cells capable of preventing infection. Here we report a comprehensive series of studies on this concept using various mouse models, including HLA class II-humanized transgenic strains. We found that a single intranasal (i.n.) dose of serotype-5 adenoviral vectors expressing either the receptor binding domain (Ad5-RBD) or the complete ectodomain (Ad5-S) of the SARS-CoV-2 spike protein was effective in inducing i) serum and bronchoalveolar lavage (BAL) anti-spike IgA and IgG, ii) robust SARS-CoV-2-neutralizing activity in the serum and BAL, iii) rigorous spike-directed T helper 1 cell/cytotoxic T cell immunity, and iv) protection of mice from a challenge with the SARS-CoV-2 beta variant. Intramuscular (i.m.) Ad5-RBD or Ad5-S administration did not induce serum or BAL IgA, and resulted in lower neutralizing titers in the serum. Moreover, prior immunity induced by an intramuscular mRNA vaccine could be potently enhanced and modulated towards a mucosal IgA response by an i.n. Ad5-S booster. Notably, Ad5 DNA was found in the liver or spleen after i.m. but not i.n. administration, indicating a lack of systemic spread of the vaccine vector, which has been associated with a risk of thrombotic thrombocytopenia. Unlike in otherwise genetically identical HLA-DQ6 mice, in HLA-DQ8 mice Ad5-RBD vaccine was inferior to Ad5-S, suggesting that the RBD fragment does not contain a sufficient collection of helper-T cell epitopes to constitute an optimal vaccine antigen. Our data add to previous promising preclinical results on intranasal SARS-CoV-2 vaccination and support the potential of this approach to elicit mucosal immunity for preventing transmission of SARS-CoV-2.

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.

A new hope? Possibilities of therapeutic IgA antibodies in the treatment of inflammatory lung diseases.

Inflammatory lung diseases represent a persistent burden for patients and the global healthcare system. The combination of high morbidity, (partially) high mortality and limited innovations in the last decades, have resulted in a great demand for new therapeutics. Are therapeutic IgA antibodies possibly a new hope in the treatment of inflammatory lung diseases? Current research increasingly unravels the elementary functions of IgA as protector against infections and as modulator of overwhelming inflammation. With a focus on IgA, this review describes the pathological alterations in mucosal immunity and how they contribute to chronic inflammation in the most common inflammatory lung diseases. The current knowledge of IgA functions in the circulation, and particularly in the respiratory mucosa, are summarized. The interplay between neutrophils and IgA seems to be key in control of inflammation. In addition, the hurdles and benefits of therapeutic IgA antibodies, as well as the currently known clinically used IgA preparations are described. The data highlighted here, together with upcoming research strategies aiming at circumventing the current pitfalls in IgA research may pave the way for this promising antibody class in the application of inflammatory lung diseases.

DYNAMICS OF CLINICAL SYMPTOMS AND SECRETORY IMMUNOGLOBULIN A IN COVID-19 CONVALESCENT PATIENTS.

The post-COVID-19 recovery period is characterized by persistence of some symptoms, with immunological alterations being of great importance. Development of preventive measures to normalize mucosal immunity after a coronavirus infection determines the relevance of the current study. The aim was to study dynamics of clinical symptoms and level of secretory immunoglobulin A in individuals after a novel coronavirus infection as well as evaluate effectiveness of using IFNalpha-2b. Materials and methods. A study was conducted with patients aged 18 to 60 years old (n = 130), surveyed 1 to 9 months after post-infection, as well as in apparently healthy individuals lacking COVID-19 (n = 15). Previous novel coronavirus infection and post-COVID manifestations were verified based on medical documentation, complaints, anamnesis data, physical examination and questionnaires. The concentration of salivatory and nasopharyngeal mucosal sIgA was measured dynamically prior to and after administration of local therapy with IFNalpha-2b (gel applied intranasally twice a day for 30 days). Results. The acute period of COVID-19 was characterized by fever, anosmia, severe asthenia (fatigue and weakness), muscle and joint pain. Among the post-COVID manifestations at early period (1-3 months), pain in the joints and muscles (75.0%) as well as elevated body temperature (21.2%) were reliably detected, whereas in the long period (6-9 months) there were revealed dominance with the same frequency of shortness of breath, muscle and joint pain (75.8%, respectively). Based on examination data in healthy subjects, there was determined an arbitrary normal range of secretory IgA in saliva - 6.45+/-1.81 mg/ml and nasal swabs - 13.43+/-3.24 mg/ml. In the group of patients 1-3 months post-infection, therapy with IFNalpha-2b one month later resulted in significantly increased level of secretory IgA in saliva (from 1.84+/-0.28 to 5.78+/-1.96 mg/ml) and in nasal swabs (from 28.61+/-3.0 to 39.83+/-3.85 mg/ml) by more than 3- and 1.5-fold, respectively. In the group of patients without therapy was featured with stably sustained decline in sIgA level up to 9 months after COVID-19. In particular, the level of saliva sIgA ranged from 2.36+/-0.56 down to 2.16+/-0.66 mg/ml, and in nasal smears - from 15.66+/-1.32 to 10.23+/-1.07 mg/ml that differed insignificantly compared to baseline level. The rate of respiratory diseases prevailed in this group (27.6% of cases), which fully lacked in the group of topically administered IFNalpha-2b. Conclusion. In the post-COVID period, multiple organ disorders persist and reduced sIgA level is registered. Intranasally applied IFNalpha-2b made possible to normalize sIgA level and prevent accumulation of respiratory infectious pathologies.Copyright © 2022 Saint Petersburg Pasteur Institute. All rights reserved.

Features of secretory immunoglobulin A in patients after COVID-19 infection.

Secretory immunoglobulin A, as a marker of the immune response in the mucous membrane, is an available indicator for detecting changes in the local immunity of mucous patients who have undergone COVID-19. Objective. To evaluate the dynamics of changes in the level of sIgA in saliva samples and the effectiveness of the use of interferon alpha-2b in individuals after a coronavirus infection. Patients and methods. Patients aged 18 to 60 years after COVID-19 infection (group 1 on therapy, n = 65;group 2 without therapy, n = 65) and conditionally healthy individuals (control group, n = 15) were monitored. The material is saliva samples, where the sIgA level was determined initially and after a month. The drug - interferon alpha-2b, in the form of a gel for topical use (Viferon, dosage 36,000 IU/g) was administered intranasally 2 times a day, for 1 month. Results. In all groups of patients who underwent COVID-19, the level of saliva sIgA was lower compared to the conditional norm of healthy individuals (6,45 +/- 1,81 mg/ml). A month after the administration of interferon alpha-2b the best effect was observed in patients in the time interval of 1-3 months from the infection, where sIgA was noted a statistically significant increase from 1,84 +/- 0,28 to 5,78 +/- 1,96 mg/ml. In the groups of patients with later terms, a moderate increase in sIgA was determined (3-6 months: 2,83 +/- 0,71 to 3,33 +/- 1,78 mg/ml;6-9 months: 3,53 +/- 0,45 to 4,76 +/- 2,3 mg/ml) and the absence of infectious diseases during rehabilitation period. In the group without therapy, in all temporal aspects, a persistent decrease in sIgA indicators below normal values was revealed, and the frequency of incidence of respiratory viral infections was noted in 9,2% of cases. Conclusions. During the rehabilitation period, the greatest changes in sIgA in saliva were observed in patients in the first 3 months after the COVID infection. The administration of interferon alpha-2b to patients in the post-COVID period is accompanied by the normalization of sIgA and prevents the development of respiratory infections. In similar groups, after COVID-19 without therapy, the indicator tends to decrease, and this category of people is at a higher risk of developing other infectious pathologies.Copyright © 2022, Dynasty Publishing House. All rights reserved.

Mucosal immune responses in COVID19 - a living review.

COVID-19 was initially characterized as a disease primarily of the lungs, but it is becoming increasingly clear that the SARS-CoV2 virus is able to infect many organs and cause a broad pathological response. The primary infection site is likely to be a mucosal surface, mainly the lungs or the intestine, where epithelial cells can be infected with virus. Although it is clear that virus within the lungs can cause severe pathology, driven by an exaggerated immune response, infection within the intestine generally seems to cause minor or no symptoms. In this review, we compare the disease processes between the lungs and gastrointestinal tract, and what might drive these different responses. As the microbiome is a key part of mucosal barrier sites, we also consider the effect that microbial species may play on infection and the subsequent immune responses. Because of difficulties obtaining tissue samples, there are currently few studies focused on the local mucosal response rather than the systemic response, but understanding the local immune response will become increasingly important for understanding the mechanisms of disease in order to develop better treatments.

Advances and challenges in intranasal vaccines development for respiratory infectious diseases.

The great challenge to prevent transmission makes widespread of respiratory infectious diseases easily occur. Intranasal immunization is considered to be a promising route of vaccination to prevent it. Different from parenteral vaccines, intranasal vaccines can induce mucosal immune in respiratory tracts in addition to systemic immune, which provide the first line of defense against respiratory pathogen infection and further prevent transmission. Safe and effective intranasal spray flu vaccines have been licensed. Since the outbreak of COVID-19, intranasal administration has been applied in different vaccine platforms. This article has reviewed the progress of intranasal vaccines for respiratory infectious diseases that have been licensed or are under evaluation in the clinical trials, meanwhile discusses its unique advantages and challenges faced.Copyright © 2023, Publication Centre of Anhui Medical University. All rights reserved.

Induction of systemic, mucosal, and cellular immunity against SARS-CoV-2 in mice vaccinated by trans-airway with a S1 protein combined with a pulmonary surfactant-derived adjuvant SF-10.

Background: There is a need for vaccines that can induce effective systemic, respiratory mucosal, and cellular immunity to control the COVID-19 pandemic. We reported previously that a synthetic mucosal adjuvant SF-10 derived from human pulmonary surfactant works as an efficient antigen delivery vehicle to antigen presenting cells in the respiratory and gastrointestinal tracts and promotes induction of influenza virus antigen-specific serum IgG, mucosal IgA, and cellular immunity. Methods: The aim of the present study was to determine the effectiveness of a new administration route of trans-airway (TA) vaccine comprising recombinant SARS-CoV-2 spike protein 1 (S1) combined with SF-10 (S1-SF-10 vaccine) on systemic, local, and cellular immunity in mice, compared with intramuscular injection (IM) of S1 with a potent adjuvant AddaS03™ (S1-AddaS03™ vaccine). Results: S1-SF-10-TA vaccine induced S1-specific IgG and IgA in serum and lung mucosae. These IgG and IgA induced by S1-SF-10-TA showed significant protective immunity in a receptor binding inhibition test of S1 and angiotensin converting enzyme 2, a receptor of SARS-CoV-2, which were more potent and faster achievement than S1-AddaS03™-IM. Enzyme-linked immunospot assay showed high numbers of S1-specific IgA and IgG secreting cells (ASCs) and S1-responsive IFN-γ, IL-4, IL-17A cytokine secreting cells (CSCs) in the spleen and lungs. S1-AddaS03™-IM induced IgG ASCs and IL-4 CSCs in spleen higher than S1-SF-10-TA, but the numbers of ASCs and CSCs in lungs were low and hardly detected. Conclusions: Based on the need for effective systemic, respiratory, and cellular immunity, the S1-SF-10-TA vaccine seems promising mucosal vaccine against respiratory infection of SARS-CoV-2.

The Oral Inactivated Porcine Epidemic Diarrhea Virus Presenting in the Intestine Induces Mucosal Immunity in Mice with Alginate-Chitosan Microcapsules.

The porcine epidemic diarrhea virus, PEDV, which causes diarrhea, vomiting and death in piglets, causes huge economic losses. Therefore, understanding how to induce mucosal immune responses in piglets is essential in the mechanism and application against PEDV infection with mucosal immunity. A method of treatment in our research was used to make an oral vaccine that packaged the inactive PEDV with microencapsulation, which consisted of sodium alginate and chitosan, and adapted the condition of the gut in mice. The in vitro release experiment of microcapsules showed that inactive PEDV was not only easily released in saline and acid solutions but also had an excellent storage tolerance, and was suitable for use as an oral vaccine. Interestingly, both experimental groups with different doses of inactive virus enhanced the secretion of specific antibodies in the serum and intestinal mucus, which caused the effective neutralization against PEDV in the Vero cell by both IgG and IgA, respectively. Moreover, the microencapsulation could stimulate the differentiation of CD11b+ and CD11c+ dendritic cells, which means that the microencapsulation was also identified as an oral adjuvant to help phagocytosis of dendritic cells in mice. Flow cytometry revealed that the B220+ and CD23+ of the B cells could significantly increase antibody production with the stimulation from the antigens' PEDV groups, and the microencapsulation could also increase the cell viability of B cells, stimulating the secretion of antibodies such as IgG and IgA in mice. In addition, the microencapsulation promoted the expression of anti-inflammatory cytokines, such as IL-10 and TGF-ß. Moreover, proinflammatory cytokines, such as IL-1, TNF-α, and IL-17, were inhibited by alginate and chitosan in the microencapsulation groups compared with the inactivated PEDV group. Taken together, our results demonstrate that the microparticle could play the role of mucosal adjuvant, and release inactivated PEDV in the gut, which can effectively stimulate mucosal and systemic immune responses in mice.

The Future of Epidemic and Pandemic Vaccines to Serve Global Public Health Needs.

This Review initiates a wide-ranging discussion over 2023 by selecting and exploring core themes to be investigated more deeply in papers submitted to the Vaccines Special Issue on the "Future of Epidemic and Pandemic Vaccines to Serve Global Public Health Needs". To tackle the SARS-CoV-2 pandemic, an acceleration of vaccine development across different technology platforms resulted in the emergency use authorization of multiple vaccines in less than a year. Despite this record speed, many limitations surfaced including unequal access to products and technologies, regulatory hurdles, restrictions on the flow of intellectual property needed to develop and manufacture vaccines, clinical trials challenges, development of vaccines that did not curtail or prevent transmission, unsustainable strategies for dealing with variants, and the distorted allocation of funding to favour dominant companies in affluent countries. Key to future epidemic and pandemic responses will be sustainable, global-public-health-driven vaccine development and manufacturing based on equitable access to platform technologies, decentralised and localised innovation, and multiple developers and manufacturers, especially in low- and middle-income countries (LMICs). There is talk of flexible, modular pandemic preparedness, of technology access pools based on non-exclusive global licensing agreements in exchange for fair compensation, of WHO-supported vaccine technology transfer hubs and spokes, and of the creation of vaccine prototypes ready for phase I/II trials, etc. However, all these concepts face extraordinary challenges shaped by current commercial incentives, the unwillingness of pharmaceutical companies and governments to share intellectual property and know-how, the precariousness of building capacity based solely on COVID-19 vaccines, the focus on large-scale manufacturing capacity rather than small-scale rapid-response innovation to stop outbreaks when and where they occur, and the inability of many resource-limited countries to afford next-generation vaccines for their national vaccine programmes. Once the current high subsidies are gone and interest has waned, sustaining vaccine innovation and manufacturing capability in interpandemic periods will require equitable access to vaccine innovation and manufacturing capabilities in all regions of the world based on many vaccines, not just "pandemic vaccines". Public and philanthropic investments will need to leverage enforceable commitments to share vaccines and critical technology so that countries everywhere can establish and scale up vaccine development and manufacturing capability. This will only happen if we question all prior assumptions and learn the lessons offered by the current pandemic. We invite submissions to the special issue, which we hope will help guide the world towards a global vaccine research, development, and manufacturing ecosystem that better balances and integrates scientific, clinical trial, regulatory, and commercial interests and puts global public health needs first.