COVID-19 virus: the immune reaction to vaccines

The immune system is developed to preserve its hosts from an ever-expanding cluster of pathogenic microbes. The elimination of toxic substances, allergens, or any other harmful existences that come in, passing the mucosal surfaces, is as well the responsibility of this special system. Its ability to distinguish self (our bodies' functioning cells and tissues) from non-self is the key aspect to its ability to mobilize some reaction to an invasion initiated by the stranger substances listed above. To identify and kill unsafe microorganisms, the host applies both natural and versatile systems, our innate and adaptive immune systems. Vaccines are used to combat the current SARS-CoV-2 strain by utilizing immune system mechanisms, specifically the adaptive immune system. Vectored vaccines, protein vaccines, genetic vaccine, and monoclonal antibody for passive vaccination are among the vaccine platforms under consideration for SARS-CoV-2. Each vaccine has its own benefits and drawbacks. This paper is written to describe the three major forms of COVID-19 vaccines, as well as the unique mechanisms of elements of the immune system associated with the virus. © 2023 SPIE.

Changes in Kawasaki disease incidence and phenotype during the COVID-19 pandemic

INTRODUCTION. The aetiology of Kawasaki disease (KD) remains unknown. Changes in infectious exposure during the COVID-19 pandemic owing to infection prevention measures may have affected the incidence of KD, supporting the pathogenic role of an infectious trigger. The purpose of this study was to evaluate the incidence, phenotype and outcome of KD before and during the COVID-19 pandemic in Denmark. METHODS. This was a retrospective cohort study based on patients diagnosed with KD at a Danish paediatric tertiary referral centre from 1 January 2008 to 1 September 2021. RESULTS. A total of 74 patients met the KD criteria of whom ten were observed during the COVID-19 pandemic in Denmark. Alof these patients were negative for SARS-CoV-2 DNA and antibodies. A high KD incidence was observed during the first six months of the pandemic, but no patients were diagnosed during the following 12 months. Clinical KD criteria were equally met in both groups. The fraction of intravenous immunoglobulin (IVIG) non-responders was higher in the pandemic group (60%) than in the in the pre-pandemic group (28.3%), although the rate of timely administered IVIG treatment was the same in both groups (>= 80%). Coronary artery dilation was observed in 21.9% in the pre-pandemic group compared with 0% in KD patients diagnosed during the pandemic. CONCLUSION. Changes in KD incidence and phenotype were seen during the COVID-19 pandemic. Patients diagnosed with KD during the pandemic had complete KD, higher liver transaminases and significant IVIG resistance but no coronary artery involvement.Copyright © 2023, Almindelige Danske Laegeforening. All rights reserved.

Current Status of Intranasal COVID-19 Vaccine, its Usage and Efficacy: A Narrative Review

The creation of a vaccine against Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) has received top focus worldwide. The majority of the COVID-19 vaccine candidates created is given Intramuscularly (IM). Intranasal (IN) vaccines offer a great benefit due to the first involvement of mucosa of the nasal cavity in the due course of disease, also SARS-CoV-2 is spread through respiratory secretions which are infectious, and mucosal immunity due to IN vaccination could contribute significantly to controlling this disease. IN vaccination has been shown in preclinical and clinical investigations to produce significant levels of neutralising antibodies, mucosal IgA, and T-cell responses that protect against SARS-CoV-2 infection in the respiratory pathway. Blocking Coronavirus Disease-2019 (COVID-19) infection and transmission requires the immune system response at the initial infection site of the virus. Many IN vaccines are currently under trial for their safety and efficacy, while some are recently approved for use in specific conditions in India and are proven to be protective against the virus and safe also. In this context, this review will provide knowledge of the IN vaccines for their effectiveness and application. [ FROM AUTHOR] Copyright of Journal of Clinical & Diagnostic Research is the property of JCDR Research & Publications Private Limited and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)

Cellular and Molecular Atlas of Peripheral Blood Mononuclear Cells from a Pregnant Woman after Recovery from COVID-19

Objective This study aimed to investigate the immune response of a pregnant woman who recovered from the coronavirus disease 2019 (COVID_RS) by using single-cell transcriptomic profiling of peripheral blood mononuclear cells (PBMCs) and to analyze the properties of different immune cell subsets. Methods PBMCs were collected from the COVID_RS patient at 28 weeks of gestation, before a cesarean section. The PBMCs were then analyzed using single-cell RNA sequencing. The transcriptional profiles of myeloid, T, and natural killer (NK) cell subsets were systematically analyzed and compared with those of healthy pregnant controls from a published single-cell RNA sequencing data set. Results We identified major cell types such as T cells, B cells, NK cells, and myeloid cells in the PBMCs of our COVID_RS patient. The increase of myeloid and B cells and decrease of T cells and NK cells in the PBMCs in this patient were quite distinct compared with that in the control subjects. After reclustering and Augur analysis, we found that CD16 monocytes and mucosal-Associated invariant T (MAIT) cells were mostly affected within different myeloid, T, and NK cell subtypes in our COVID_RS patient. The proportion of CD16 monocytes in the total myeloid population was increased, and the frequency of MAIT cells in the total T and NK cells was significantly decreased in the COVID-RS patient. We also observed significant enrichment of gene sets related to antigen processing and presentation, T-cell activation, T-cell differentiation, and tumor necrosis factor superfamily cytokine production in CD16 monocytes, and enrichment of gene sets related to antigen processing and presentation, response to type II interferon, and response to virus in MAIT cells. Conclusion Our study provides a single-cell resolution atlas of the immune gene expression patterns in PBMCs from a COVID_RS patient. Our findings suggest that CD16-positive monocytes and MAIT cells likely play crucial roles in the maternal immune response against severe acute respiratory syndrome coronavirus 2 infection. These results contribute to a better understanding of the maternal immune response to severe acute respiratory syndrome coronavirus 2 infection and may have implications for the development of effective treatments and preventive strategies for the coronavirus disease 2019 in pregnant women.Copyright © Wolters Kluwer Health, Inc. All rights reserved.

Oral and nasal vaccination: current prospects, challenges, and impact of nanotechnology-based delivery systems

Abstract Currently, mucosal vaccine administration has stood out as an easier and non-invasive application method. It can also be used to induce local and systemic immune responses. In the COVID-19 pandemic context, nasal and oral vaccines have been developed based on different technological platforms. This review addressed relevant aspects of mucosal vaccine administration, with emphasis on oral and nasal vaccinations, in addition to the importance of using nanotechnology-based delivery systems to enable these strategies.

A deficient immune response to SARS-CoV-2 in the nasopharynx is associated with severe COVID-19 pneumonia.

OBJECTIVES: We analyzed the expression of inflammatory and antiviral genes in the nasopharynx of SARS-CoV-2 infected patients and their association with the severity of COVID-19 pneumonia. METHODS: We conducted a cross-sectional study on 223 SARS-CoV-2 infected patients. Clinical data were collected from medical records, and nasopharyngeal samples were collected in the first 24 hours after admission to the emergency room. The gene expression of eight proinflammatory/antiviral genes (plasminogen activator urokinase receptor [PLAUR], interleukin [IL]-6, IL-8, interferon [IFN]-ß, IFN-stimulated gene 15 [ISG15], retinoic acid-inducible gene I [RIG-I], C-C motif ligand 5 [CCL5], and chemokine C-X-C motif ligand 10 [CXCL10]) were quantified by real-time polymerase chain reaction. Outcome variables were: (i) pneumonia; (ii) severe pneumonia or acute respiratory distress syndrome. Statistical analysis was performed using multivariate logistic regression analyses. RESULTS: We enrolled 84 mild, 88 moderate, and 51 severe/critical cases. High expression of PLAUR (adjusted odds ratio [aOR] = 1.25; P = 0.032, risk factor) and low expression of CXCL10 (aOR = 0.89; P = 0.048, protective factor) were associated with pneumonia. Furthermore, lower values of ISG15 (aOR = 0.88, P = 0.021), RIG-I (aOR = 0.87, P = 0.034), CCL5 (aOR = 0.73, P <0.001), and CXCL10 (aOR = 0.84, P = 0.002) were risk factors for severe pneumonia/acute respiratory distress syndrome. CONCLUSION: An unbalanced early innate immune response to SARS-CoV-2 in the nasopharynx, characterized by high expression of PLAUR and low expression of antiviral genes (ISG15 and RIG-I), and chemokines (CCL5 and CXCL10), was associated with COVID-19 severity.

Enhancing respiratory comfort with fan respirators: Computational analysis of carbon dioxide reduction, temperature regulation, and humidity control

Respirators provide protection from inhalation exposure to dangerous substances, such as chemicals and infectious particles, including SARS-COVID-laden droplets and aerosols. However, they are prone to exposure to stale air as masks create a microclimate influenced by the exhaled air. As a result, exhaled air from lungs accumulating in the mask produces a warm and humid environment that has a high concentration of carbon dioxide (CO2), unsuitable for re-inhalation. Fans are a favorable option for respirators to ventilate the mask and remove the stale air. This study utilized computational fluid dynamics simulation consisting of a hybrid Reynolds-averaged Navier-Stokes-large eddy simulation turbulence method to compare the inhalation flow properties for different fan locations (bottom, top, and side) with regular respirator breathing. Three mask positions, top, side, and bottom, were evaluated under two breathing cycles (approximately 9.65 s of breathing time). The results demonstrated that adding a fan respirator significantly decreased internal mask temperature, humidity, and CO2 concentration. The average CO2 concentration decreased by 87%, 67%, and 73% for locations bottom, top, and side, respectively. While the top and side fan locations enhanced the removal of the exhaled gas mixture, the bottom-fan respirator was more efficient in removing the nostril jet gas mixture and therefore provided the least barrier to respiratory function. The results provide valuable insight into the benefits of fan respirators for long-term use for reducing CO2 concentration, mask temperature, and humidity, improving wearer safety and comfort in hazardous environments, especially during the COVID-19 pandemic.

A non-transmissible live attenuated SARS-CoV-2 vaccine.

Live attenuated vaccines (LAVs) administered via the mucosal route may offer better control of the COVID-19 pandemic than non-replicating vaccines injected intramuscularly. Conceptionally, LAVs have several advantages, including presentation of the entire antigenic repertoire of the virus, and the induction of strong mucosal immunity. Thus, immunity induced by LAV could offer superior protection against future surges of COVID-19 cases caused by emerging SARS-CoV-2 variants. However, LAVs carry the risk of unintentional transmission. To address this issue, we investigated whether transmission of a SARS-CoV-2 LAV candidate can be blocked by removing the furin cleavage site (FCS) from the spike protein. The level of protection and immunity induced by the attenuated virus with the intact FCS was virtually identical to the one induced by the attenuated virus lacking the FCS. Most importantly, removal of the FCS completely abolished horizontal transmission of vaccine virus between cohoused hamsters. Furthermore, the vaccine was safe in immunosuppressed animals and showed no tendency to recombine in vitro or in vivo with a SARS-CoV-2 field strain. These results indicate that removal of the FCS from SARS-CoV-2 LAV is a promising strategy to increase vaccine safety and prevent vaccine transmission without compromising vaccine efficacy.

Management of Acquired von Willebrand Syndrome During Prolonged VV-ECMO

Acquired von Willebrand syndrome (AVWS) contributes to bleeding during extracorporeal membrane oxygenation (ECMO) support. Although it is recognized that AVWS rapidly resolves after ECMO decannulation, this approach may often be clinically unsuitable. In such cases, optimal AVWS management during ECMO support is not well established. We report our approach to managing AVWS in a patient on veno-venous (VV) ECMO for 59 days. A 19-year-old male developed hypoxemic respiratory failure from SARS-CoV-2 pneumonia. Following intubation, he progressed to VV-ECMO support for refractory hypoxemia and was started on bivalirudin for systemic anticoagulation. Two days later, he developed refractory gastrointestinal and oro-nasopharyngeal bleeding despite blood product transfusions and discontinuing bivalirudin. He was started on pantoprazole along with infusions of octreotide and aminocaproic acid. Upper endoscopy on ECMO day 5 revealed an ulcerative bleeding vessel in the duodenum that was clipped. Recurrent mucosal bleeding precluded resumption of systemic anticoagulation. On ECMO day 23, AVWS was diagnosed based on elevated von Willebrand factor (VWF) activity (207%, normal 55-189%) and antigen (234%, normal 50-210%) levels with abnormally low VWF high-molecular-weight multimers. Factor VIII complex was administered twice over the following week. Between doses, the ECMO circuit was exchanged to empirically mitigate suspected shear-related VWF consumption from the fibrin burden, and a repeat endoscopy controlled additional intestinal bleeding with local hemostatic agents. He received 36 units of red blood cells, 2 units of platelets, 2 units of plasma, and 7 pooled units of cryoprecipitate over 31 days leading into these combined interventions. In the 28 days afterwards, he received 3 units of red blood cells, 3.5 pooled units of cryoprecipitate, and no additional platelets or plasma. Our patient was maintained off systemic anticoagulation for 54 of 59 days of VV-ECMO support without any thrombotic complications occurring. With no subsequent clinical evidence of bleeding, repeat VWF testing was done two months post-decannulation and showed near-normal VWF activity (54%) and normal multimer distribution. Our patient rehabilitated well without any neurologic deficits and on discharge was requiring supplemental oxygen with sleep and strenuous activity. Avoiding systemic anticoagulation, repleting VWF, maintaining circuit integrity, and providing local hemostasis, when possible, may be a safe and effective management strategy of AVWS on ECMO support when decannulation is not a viable option.

Establishment and applications of a duplex quantitative real-time RT-PCR assay for simultaneous detection of bovine rhinitis A virus and bovine rhinitis B virus

Bovine rhinitis virus (BRV) is an important pathogen responsible for the bovine respiratory disease complex (BRDC) and can be divided into two genotypes (BRAV and BRBV). To establish a duplex quantitative real-time RT-PCR assay for simultaneous detection of BRAV and BRBV, specific primers and TaqMan probes targeting the 5'NTR of BRAV and 3'NTR of BRBV were designed. A duplex quantitative real- time RT- PCR assay for simultaneous detecting BRAV and BRBV was preliminarily established by optimizing reaction conditions for each step. The assay specifically detects BRAV and BRBV, and no crossreaction with other common bovine respiratory pathogens, including IDV, BCoV, BVDV-1, BRSV, BPIV-3, BAdV-3, mycoplasma bovis, Pasteurella multocida, Mannheimia haemolytica, Escherichia coli, and Salmonella, was observed. In addition, the sensitivity test showed that the detection limits of this assay were 3.2x101 copies/L for both BRAV and BRBV plasmid standards. Besides, the repeatability test showed that the variation coefficients of this assay were less than 0.05 from both lot-to-lot and intra-lot. These results showed that the assay has high specificity, extreme sensitivity, and good repeatability. Moreover, a total of 43 nasal swabs of BRDC cattle were tested by our assay and four other quantitative real-time RT-PCR assays, including 3 BRAV assays and 4 BRBV assays. The results showed that the detection rates of our assay were 32.56%(14/43) for BRAV and 30.23%(13/43) for BRBV, and the detection rates of other quantitative real-time RT-PCR assays were 0(0/43), 2.33%(1/43), 23.26%(10/43) for BRAV and 27.91% (12/43), 27.91%(12/43), 27.91%(12/43), 27.91%(12/43) for BRBV, indicating that our assay has a more substantial detection capability than other assays. This study firstly established a duplex quantitative real-time RT-PCR assay for simultaneous detection of BRAV and BRBV, and the assay exhibited high specificity, sensitivity, and stability. Moreover, the study firstly confirmed the existence of BRAV in China, contributing to the prevention and control of BRDC.

Mucosa-Associated Lymphoid Tissue Lymphoma of the Rectum Incidentally Found in a Patient with Ulcerative Colitis

Introduction: Mucosa-associated lymphoid tissue (MALT) lymphomas are extra-nodal marginal zone B-cell lymphomas, most commonly found in the stomach, associated with Helicobacter pylori infections, and generally not linked with inflammatory bowel disease. Rectal MALT lymphoma is very uncommon and often associated with painful defecation, change in bowel habits, or rectal pressure/prolapse. Here, we present a rare case of an asymptomatic female with ulcerative colitis (UC) found to have benign-appearing rectal polyps during a routine screening colonoscopy. Case Description/Methods: The patient is a 56-year-old female with a history of left-sided UC, diagnosed in 1993, with one flare after receiving the 2nd dose of the Moderna COVID-19 vaccine, taking oral Olsalazine 500 mg twice daily, low-dose Prednisone, and mesalamine suppositories as needed presenting for screening colonoscopy. The patient was asymptomatic, citing regular non-bloody bowel movements and normal stool consistency. Colonoscopy revealed two 7 mm sessile, non-bleeding rectal polyps, surrounded by congested, erythematous, friable, and ulcerated mucosa in the rectosigmoid colon. Cold forceps biopsies were taken. Hematopathology evaluation of the routine colon biopsy samples revealed chronic nonspecific colitis while pathology of the rectal polyps showed marked lymphoplasmacytic infiltrate and extra-nodal marginal zone lymphoma of MALT. Ancillary studies, immunohistochemistry, and molecular studies for B-cell gene rearrangement confirmed extra-nodal marginal zone lymphoma of MALT with prominent plasmacytic differentiation. The patient was informed and close follow-up in Gastroenterology clinic was arranged. (Figure) Discussion: Rectal MALT lymphoma is rare with unclear management options. Treatments of UC include watchful waiting, surgical resection, endoscopic mucosal resection, radiation, and/or chemotherapy. Helicobacter pylori infections, though strongly linked with gastric MALT lymphoma, have not been shown to be strongly correlated with rectal MALT lymphoma. Given that patients with UC have chronic UCassociated colonic inflammation, lymphoma is often difficult to distinguish visually during colonoscopy, frequently masked by ulcerations and pseudo-polyps. In cases like these, more definitive treatments such as surgical resection could therefore be warranted. Long-term follow-up data is sparse and definitive management remains a clinical conundrum, thus these patients require reliable long-term multidisciplinary close follow-up. (Figure Presented).

Die Kämpfe únd schláchten-the struggles and battles of innate-like effector T lymphocytes with microbes.

The large majority of lymphocytes belong to the adaptive immune system, which are made up of B2 B cells and the αß T cells; these are the effectors in an adaptive immune response. A multitudinous group of lymphoid lineage cells does not fit the conventional lymphocyte paradigm; it is the unconventional lymphocytes. Unconventional lymphocytes-here called innate/innate-like lymphocytes, include those that express rearranged antigen receptor genes and those that do not. Even though the innate/innate-like lymphocytes express rearranged, adaptive antigen-specific receptors, they behave like innate immune cells, which allows them to integrate sensory signals from the innate immune system and relay that umwelt to downstream innate and adaptive effector responses. Here, we review natural killer T cells and mucosal-associated invariant T cells-two prototypic innate-like T lymphocytes, which sense their local environment and relay that umwelt to downstream innate and adaptive effector cells to actuate an appropriate host response that confers immunity to infectious agents.

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).

Repurposing mucosal delivery devices for live attenuated tuberculosis vaccines.

Tuberculosis (TB) remains one of the most lethal infectious diseases globally. The only TB vaccine approved by the World Health Organization, Bacille Calmette-Guérin (BCG), protects children against severe and disseminated TB but provides limited protection against pulmonary TB in adults. Although several vaccine candidates have been developed to prevent TB and are undergoing preclinical and clinical testing, BCG remains the gold standard. Currently, BCG is administered as an intradermal injection, particularly in TB endemic countries. However, mounting evidence from experimental animal and human studies indicates that delivering BCG directly into the lungs provides enhanced immune responses and greater protection against TB. Inhalation therapy using handheld delivery devices is used for some diseases and allows the delivery of drugs or vaccines directly into the human respiratory tract. Whether this mode of delivery could also be applicable for live attenuated bacterial vaccines such as BCG or other TB vaccine candidates remains unknown. Here we discuss how two existing inhalation devices, the mucosal atomization device (MAD) syringe, used for influenza vaccines, and the Respimat® Soft Mist™ inhaler, used for chronic obstructive pulmonary disease (COPD) therapy, could be repurposed for mucosal delivery of live attenuated TB vaccines. We also outline the challenges and outstanding research questions that will require further investigations to ensure usefulness of respiratory delivery devices that are cost-effective and accessible to lower- and middle-income TB endemic countries.

Mucosal immunization with lactiplantibacillus plantarum-displaying recombinant SARS-CoV-2 epitopes on the surface induces humoral and mucosal immune responses in mice.

BACKGROUND: The use of probiotic lactic acid bacteria as a mucosal vaccine vector is considered a promising alternative compared to the use of other microorganisms because of its "Generally Regarded as Safe" status, its potential adjuvant properties, and its tolerogenicity to the host. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease (COVID-19), is highly transmissible and pathogenic. This study aimed to determine the potential of Lactiplantibacillus plantarum expressing SARS-CoV-2 epitopes as a mucosal vaccine against SARS-CoV-2. RESULTS: In this study, the possible antigenic determinants of the spike (S1-1, S1-2, S1-3, and S1-4), membrane (ME1 and ME2), and envelope (E) proteins of SARS-CoV-2 were predicted, and recombinant L. plantarum strains surface-displaying these epitopes were constructed. Subsequently, the immune responses induced by these recombinant strains were compared in vitro and in vivo. Most surface-displayed epitopes induced pro-inflammatory cytokines [tumor necrosis factor alpha (TNF-α and interleukin (IL)-6] and anti-inflammatory cytokines (IL-10) in lipopolysaccharide-induced RAW 264.7, with the highest anti-inflammatory to pro-inflammatory cytokine ratio in the S1-1 and S1-2 groups, followed by that in the S1-3 group. When orally administered of recombinant L. plantarum expressing SARS-CoV-2 epitopes in mice, all epitopes most increased the expression of IL-4, along with induced levels of TNF-α, interferon-gamma, and IL-10, specifically in spike protein groups. Thus, the surface expression of epitopes from the spike S1 protein in L. plantarum showed potential immunoregulatory effects, suggesting its ability to potentially circumvent hyperinflammatory states relevant to monocyte/macrophage cell activation. At 35 days post immunization (dpi), serum IgG levels showed a marked increase in the S1-1, S1-2, and S1-3 groups. Fecal IgA levels increased significantly from 21 dpi in all the antigen groups, but the boosting effect after 35 dpi was explicitly observed in the S1-1, S1-2, and S1-3 groups. Thus, the oral administration of SARS-CoV-2 antigens into mice induced significant humoral and mucosal immune responses. CONCLUSION: This study suggests that L. plantarum is a potential vector that can effectively deliver SARS-CoV-2 epitopes to intestinal mucosal sites and could serve as a novel approach for SARS-CoV-2 mucosal vaccine development.

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.