COVID-19: AFTER TWO YEARS OF IATROGENIC AND BIOLOGIC IMMUNIZATION/ VACCINATION DO WE ACTUALLY NEED FURTHER BOOSTER IMMUNIZATION/ VACCINATION?

BackgroundThe Covid19 pandemic started in late 2019 and went through different phases by spreading from China around the whole globe. During the pandemic different mutation types got predominant from original Wuhan type through Alpha, Delta and Omicron variate BA 1/2 to BA 4/5 with different infectiousity and different potential to harm people´s health status. Immunization/ vaccination program started late 2020, first booster phase started midst of 2021, second booster phase in late 2021/ beginning of 2022 and Omicron specific booster phase midst of 2022.ObjectivesIs there a need of further iatrogenic (booster) immunization/ vaccination after 2 years of immunization/ vaccination program from efficacy driven analysis and safety issues standpoint?MethodsAnalysis of Covid-19 antibody development every three months since August 2021 with comparison of infection rates and assessment of safety parameters by assessing D-Dimers as potential endothelium damage marker in 725 patients (600 female, 125 male, age mean: 62,2 years) of a German rheumatological practice to improve the medical care.ResultsIn 99 % of the patients longstanding immune memory could be shown by analyzing the antibody curves in different exemplary shown biologic and iatrogenic immunization pathways after 2 years of immunization/ vaccination program and biologic immunization, mainly by Delta variate since late 2021 and Omicron variate since beginning of 2022. In 38.5 % of the patients the safety concerns of potential endothelium damage by analysing D-Dimers every 3 months showed a side effect potential of at least 8 months after every MRNA/ Vector immunization, but not after protein based vaccination and even not after infections in that amount.ConclusionOut of the obligation "nil nocere” no further iatrogenic Covid-19 immunization/ vaccination is of need in nearly all (99 %) already immunized people. At present only adult people with very low antibody levels (at least below 64 BAU/ml) (considering the infection or iatrogenic immunization/ vaccination status and time since last spike protein contact) and not yet immunized adult people should be forseen for iatrogenic immunization/ vaccination with protein based or attenuated viral vaccines or in rare cases one Omicron specific MRNA immunization drug. In that case D-Dimer controls for up to 8 months should be obligatory to detect endothelial damage side effect of MRNA (or Vector) technique. Intense cardiovascular monitoring (small vessels) of MRNA/ Vector immunized people in the next 10 – 20 years is necessary.Figure 1.References[1] Pohl C;SAFETY AND EFFICACY ASSESSMENT OF COVID-19 IMMUNIZATIONS/ VACCINATIONS IN PATIENTS OF A GERMAN GENERAL RHEUMATOLOGICAL PRACTICE;EULAR 2022 Poster POS1213;https://doi.org/10.1136/annrheumdis-2022-eular.1389[2] McConeghy KW et al. Effectiveness of a Second COVID-19 Vaccine Booster Dose Against Infection, Hospitalization, or Death Among Nursing Home Residents - 19 States, March 29-July 25, 2022. MMWR Morb Mortal Wkly Rep. 2022 Sep 30;71(39):1235-1238. doi: 10.15585/mmwr.mm7139a2. PMID: 36173757;PMCID: PMC9533729.[3] Bowe, B. Et al. Acute and postacute sequelae associated with SARS-CoV-2 reinfection. Nat Med 28, 2398–2405 (2022). https://doi.org/10.1038/s41591-022-02051-3[4] Hui-Lee Wong et al. Surveillance of COVID-19 vaccine safety among elderly persons aged 65 years and older, Vaccine, Volume 41, Issue 2, 2023, Pages 532-539, ISSN 0264-410X, https://doi.org/10.1016/j.vaccine.2022.11.069.[5] Maher AK et al. Transcriptional reprogramming from innate immune functions to a pro-thrombotic signature by monocytes in COVID-19. Nat Commun. 2022 Dec 26;13(1):7947. doi: 10.1038/s41467-022-35638-y. PMID: 36572683;PMCID: PMC9791976.[6] Erich Freisleben;Sie wollten alles richtig machen – Dokumentation eines verschwiegenen Leidens – Bericht eines Hausarztes über die Nebenwirkungen der Corona Impfungen;Nov 11, 2022;Cajus Verlag[7] Positive Testrate Germany – https://www.rki.de/DE/Content/InfAZ/N/Neuartiges_Coronavirus/Testzahl.htmlAcknowledgementsThanks to my fami y, all my patients and my collegues for supporting me in my research to improve my personal patient care.Disclosure of InterestsNone Declared.

COMPARISON OF HOMOLOGOUS AND HETEROLOGOUS BOOSTER SARS-CoV-2 VACCINATION IN AUTOIMMUNE RHEUMATIC AND MUSCULOSKELETAL PATIENTS

BackgroundVaccine-induced immunity is very important for controlling the COVID-19 infection. The vaccination supports humoral and cellular immunity, and this is one of the main strategy for us. Various vaccines approved in the countries have been shown to reduce infection rates, severity, and mortality.ObjectivesWe aimed to compare humoral and cellular immune responses after homologous or heterologous vaccination among patients with aiRMDs at their third vaccination with BNT162b2 or with two vaccinations followed by COVID-19 infection. We detected the anti-SARS-CoV2 antibody levels and measured the SARS-CoV-2 reactive B-, or T-cell mediated immunity in aiRMDs receiving homologous (Hom.), heterologous (Het.) vaccines or became infected (Inf.).MethodsA single center observational study evaluated immunogenicity and safety of the third dose vaccines or after two-dose regimen of vaccine and COVID infection in patients with aiRMDs. Neutralizing anti-RBD antibodies and specific T-cell response were measured.ResultsWe showed that following 4 months of the booster vaccination with the third dose of mRNA-based vaccine or after COVID infection, the positive (>21.8 BAU/mL) neutralizing anti-RBD IgG antibody response was outstanding in all three patient groups, 95.5%, 100% and 100% of the homologous and heterologous as well as the SARS-CoV-2 infected groups. Taken together booster vaccinations or SARS-CoV-2 infection after completing 2 doses of the vaccination can lead to the production of neutralizing antibodies still protective in RMD cases after 4 months of the third antigen exposition. The booster vaccination reduces the frequency of hospital admissions and mortality with ai RMDs. The vaccinations are effective independently from the type of vaccine, the SARS-CoV-2 specific memory B-cell populations showed a statistically not significant but lower frequency in the infection group. Clinical activity of aiRMDs was not increased following booster vaccination.ConclusionPatients, who received a heterologous booster vaccine had a higher level of peripheral memory B-cells compared to those who had COVID-19 infection. Biologic therapy decreased the level of B-cells. Patients with a disease duration of more than 10 years had higher level of CD8+TNF-α+ and CD8+IFN-γ+ T-cells compared to patients who were diagnosed less than 10 years ago. The third booster mRNA-based vaccine was as much effective as in the homologous and heterologous patients groups compared who had COVID infection.References[1] Szebeni, G.J.;Gemes, N.;Honfi, D.;Szabo, E.;Neuperger, P.;Balog, J.A.;Nagy, L.I.;Szekanecz, Z.;Puskas, L.G.;Toldi, G.;et al. Humoral and Cellular Immunogenicity and Safety of Five Different SARS-CoV-2 Vaccines in Patients With Autoimmune Rheumatic and Musculoskeletal Diseases in Remission or With Low Disease Activity and in Healthy Controls: A Single Center Study. Front. Immunol. 2022, 13, 846248.[2]Honfi, D.;Gémes, N.;Szabó, E.;Neuperger, P.;Balog, J.Á.;Nagy, L.I.;Toldi, G.;Puskás, L.G.;Szebeni, G.J.;Balog, A. Comparison of Homologous and Heterologous Booster SARS-CoV-2 Vaccination in Autoimmune Rheumatic and Musculoskeletal Patients. Int. J. Mol. Sci. 2022, 23, 11411Acknowledgements:NIL.Disclosure of InterestsNone Declared.

GRAd-COV2 vaccine provides potent and durable humoral and cellular immunity to SARS-CoV-2 in randomized placebo-controlled phase 2 trial.

The ongoing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic and heterologous immunization approaches implemented worldwide for booster doses call for diversified vaccine portfolios. GRAd-COV2 is a gorilla adenovirus-based COVID-19 vaccine candidate encoding prefusion-stabilized spike. The safety and immunogenicity of GRAd-COV2 is evaluated in a dose- and regimen-finding phase 2 trial (COVITAR study, ClinicalTrials.gov: NCT04791423) whereby 917 eligible participants are randomized to receive a single intramuscular GRAd-COV2 administration followed by placebo, or two vaccine injections, or two doses of placebo, spaced over 3 weeks. Here, we report that GRAd-COV2 is well tolerated and induces robust immune responses after a single immunization; a second administration increases binding and neutralizing antibody titers. Potent, variant of concern (VOC) cross-reactive spike-specific T cell response peaks after the first dose and is characterized by high frequencies of CD8s. T cells maintain immediate effector functions and high proliferative potential over time. Thus, GRAd vector is a valuable platform for genetic vaccine development, especially when robust CD8 response is needed.

Precise Epitope Organization with Self‐adjuvant Framework Nucleic Acid for Efficient COVID‐19 Peptide Vaccine Construction

Peptide vaccines have advantages in easy fabrication and high safety, but their effectiveness is hampered by the poor immunogenicity of the epitopes themselves. Herein, we constructed a series of framework nucleic acids (FNAs) with regulated rigidity and size to precisely organize epitopes in order to reveal the influence of epitope spacing and carrier rigidity on the efficiency of peptide vaccines. We found that assembling epitopes on rigid tetrahedral FNAs (tFNAs) with the appropriate size could efficiently enhance their immunogenicity. Further, by integrating epitopes from SARS‐CoV‐2 on preferred tFNAs, we constructed a COVID‐19 peptide vaccine which could induce high titers of IgG against the receptor binding domain (RBD) of SARS‐CoV‐2 spike protein and increase the ratio of memory B and T cells in mice. Considering the good biocompatibility of tFNAs, our research provides a new idea for developing efficient peptide vaccines against viruses and possibly other diseases.

MAINTAINING IMMUNOLOGICAL MEMORY TO THE SARS-CoV-2 VIRUS DURING COVID-19 PANDEMIC.

The question on the duration and effectiveness of post-infection vs post-vaccination SARS-CoV-2 immunity remains in the focus of numerous studies. The aim of the work was to examine the duration of maintained post-infection and post-vaccination SARS-CoV-2 immunity as well as formation of hybrid (vaccination after infection) and breakthrough (repeated disease or disease after vaccination) immunity in the context of an ongoing COVID-19 pandemic. 107 adults with mild or moderate COVID-19 3-18 months after the disease and 30 subjects vaccinated twice with the Sputnik V vaccine were examined 1-6 times. Antibodies against SARS-CoV-2 virus were determined by ELISA on the "SARSCoV-2-IgG quantitative-ELISA-BEST" test systems. The antibody avidity was measured by additional incubation with and without denaturing solution. Mononuclear cells were isolated from blood by gradient centrifugation, incubated with and without coronavirus S-protein for 20 hours, stained with fluorescently labeled antibodies, and the percentage of CD8highCD107a+ was counted using FACSCanto II cytometer. It was shown that in the group of convalescent and vaccinated subjects, the level of virus-specific antibodies decreased more deeply in individuals with initially high humoral response, but 9 months later the decrease slowed down and reached a plateau. The antibody avidity rose up to 50% and persisted for 18 months. Cellular immunity in recovered patients did not change for 1.5 years, while in vaccinated patients it gradually decreased 6 months later, but remained at detectable level. After revaccination, a significant increase in the level of antibodies, avidity up to 67.6% and cellular immunity returned to the initial level were noted. Hybrid immunity turned out to be significantly higher than post-infection and post-vaccination immunity. The level of antibodies increased to 1218.2 BAU/ml, avidity - to 69.85%, and cellular immunity - to 9.94%. Breakthrough immunity was significantly higher than that after the first disease. The level of antibodies rose to 1601 BAU/ml, avidity - up to 81.6%, cellular immunity - up to 13.71%. Using dynamic observation of four COVID-19 convalescents, it has been shown that in the context of the ongoing pandemic and active coronavirus mutation, natural boosting occurs both asymptomatically and as a result of a mild re-infection, which prevents disappearance of SARS-CoV-2 humoral and cellular immunity.Copyright © 2023 Saint Petersburg Pasteur Institute. All rights reserved.

CD8+ T CELL CLONES FROM PRIOR SARS-CoV-2 INFECTION PREDOMINATE AFTER mRNA VACCINATION

Background: Hybrid immunity is more protective than vaccination or prior infection alone. To understand the formation of hybrid immunity, we studied how SARS-CoV-2 mRNA vaccines interact with T cell memory by tracking spike (S) specific T cells in cohorts of hospitalized (n = 19) or non-hospitalized (n = 34) COVID-19 convalescents. We hypothesized that S-reactive CD4 and CD8 T cells would increase in response to serial vaccine doses and reflect prior immune exposure at the clonal level. Method(s): After vaccination, we stimulated PBMCs from 12 participants (8M/4F) with peptides spanning S. Activated cells (CD69+CD137+) were sorted and CD4/CD8 phenotype linked with paired TRB-TRA sequences at single cell resolution. S-reactive TRB sequences were mapped within 4-6 serial blood and post-booster nasal TRB repertoires to evaluate S-reactive CD4 and CD8 T cell clonotypic kinetics spanning convalescence to boost. PBMCs from 53 participants were sequenced with the ImmunoSEQ assay to evaluate S-reactive TRB breadth using a database of S-assigned TRB sequences (Adaptive Biotechnologies), comparing S-reactive TRB diagnostic breadth by hospitalization status (Wilcoxon test). Result(s): SARS-CoV-2 mRNA vaccination provoked strong T cell clonal expansion in most participants. At 8-12 months after infection, each primary mRNA dose increased the abundance and diversity of S-specific T cells. Clonal and integrated expansions were larger in CD8 than in CD4 T cells. At the convalescent time point, we observed greater diagnostic S-reactive CD4 T cell breadth in hospitalized vs. non-hospitalized patients (p< 0.01). CD4 T cell S breadth was again higher in previously hospitalized persons after the 2nd primary (p=0.02) and booster (p< 0.01) doses, suggesting that diverse CD4 T cell memory after severe infection leads to increased repertoire diversity after vaccination. S-specific T cells with identical TCRs were detectable in blood and the nasal mucosa, with specificity confirmed using a TRA/TRB transgenic T cell with the matching receptor. Conclusion(s): Although both S-specific CD8 and CD4 T cell memory are established by prior infection, S-specific CD8 T cells predominated in blood after primary vaccination, with some clonotypes showing up to 1000-fold expansion across 1-2 mRNA doses. Vaccine-reactive CD8 clonotypes were present at the barrier nasal site after booster mRNA dosing. Severe disease imprinted a highly diverse S-reactive CD4 repertoire persisting through vaccination.

Trained innate immunity and diseases: Bane with the boon

Emerging research shows that innate immunity can also keep the memory of prior experiences, challenging the long-held notion that immunological memory is only the domain of the adaptive immune cells. However, the absence of immunological memory in innate immune responses has recently been brought into question. Now it is known that after a few transient activations, innate immune cells may acquire immunological memory phenotype, resulting in a stronger response to a subsequent secondary challenge. When exposed to particular microbial and/or inflammatory stimuli, trained innate immunity is characterized by the enhanced non-specific response, which is regulated by substantial metabolic alterations and epigenetic reprogramming. Trained immunity is acquired by two main reprogramming, namely, epigenetic reprogramming and metabolic adaptation/reprogramming. Epigenetic reprogramming causes changes in gene expression and cell physiology, resulting in internal cell signaling and/or accelerated and amplified cytokine release. Metabolic changes due to trained immunity induce accelerated glycolysis and glutaminolysis. As a result, trained immunity can have unfavorable outcomes, such as hyper inflammation and the development of cardiovascular diseases, autoinflammatory diseases, and neuroinflammation. In this review, the current scenario in the area of trained innate immunity, its mechanisms, and its involvement in immunological disorders are briefly outlined.Copyright © 2022

The Role of Active Immunity and its Types

When a pathogen activates B cells and T cells, memory B cells and memory T cells form, and the major immune response happens as a result. These memory cells "remember" every unique pathogen an animal encounters over the course of its lifetime and can develop a potent secondary response if the pathogen is discovered again. Due to the immune system's proactive self-preparation, this sort of immunity is both active and adaptable. The innate immune system and both the cell-mediated and humoral components of immunity are frequently involved in active immunity. Here, Maiorino discusses the naturally and artificially acquired active immunity.

T Cells In Virus Infection And Vaccination: Lessons For Vaccine Development

The current COVID-19 pandemic has highlighted the need for new immunological parameters to assess the vaccine for generating durable protective immunity. Both humoral and cell mediated immunity play crucial role in the vaccine induced protection. Because T cells are essential for killing virus infected cells as well as for the generation of humoral immunity ('neutralizing antibodies and the B cell memory'), the T-cell related parameters may provide crucial information on the immunological effectiveness of a vaccine in early stages of development. The SARS-CoV-2 infection and vaccination in the similar demography provided an opportunity to understand various functional traits of T cells as the quantifiable correlates of protective immunity. Here, we will discuss the lessons learned from the immunological memory studies of the SARS-Co V-2 infection and vaccination in a long-term in Indian population. Moreover, how this knowledge about the physiological process of T-cell response could be utilized to develop new immunological parameters for vaccine evaluation will be discussed in details. Importantly, with an example of intranasal COVID-19 vaccine, we will share our experience on applying these advanced T-cell immunology tools for evaluating a vaccine under human trial.

The Function of Memory CD8+ T Cells in Immunotherapy for Human Diseases.

Memory T (Tm) cells protect against Ags that they have previously contacted with a fast and robust response. Therefore, developing long-lived Tm cells is a prime goal for many vaccines and therapies to treat human diseases. The remarkable characteristics of Tm cells have led scientists and clinicians to devise methods to make Tm cells more useful. Recently, Tm cells have been highlighted for their role in coronavirus disease 2019 vaccines during the ongoing global pandemic. The importance of Tm cells in cancer has been emerging. However, the precise characteristics and functions of Tm cells in these diseases are not completely understood. In this review, we summarize the known characteristics of Tm cells and their implications in the development of vaccines and immunotherapies for human diseases. In addition, we propose to exploit the beneficial characteristics of Tm cells to develop strategies for effective vaccines and overcome the obstacles of immunotherapy.

Patients with B-cell malignancies experience reduced antibody responses with class switching defect following BNT162b2 SARS-CoV-2 vaccination

Vaccines having aided in escaping the majority of the population from immunological naïvety, our strategies are now shifting towards an increased focus on identifying and protecting the extremely vulnerable. We here describe the results of testing 12 patients, those with lymphoid malignancies having been targeted their B-cells for therapy with rituximab-containing regimens or a Bruton tyrosine kinase inhibitor, for anti-SARS-CoV-2 spike antibodies after receiving the BNT162b2 mRNA vaccine doses. The interval from last dosing of B-cell depletion therapy to SARS-CoV-2 vaccination was at median 5.3 (range 3.1–6.6) months. Using the ‘seroprotection' threshold of 775 [BAU/mL] for the anti-spike antibody titer, our finding points out the crucial unresponsiveness of the targeted population with 0/12 (0%) achieving ‘seroprotection'. Although IgG seroconversion was observed in 4/12 (33%), supporting the overall benefit of vaccination, the figures still point out a potential need for optimization of practice. IgA was further less responsive (unsuccessful ‘seroconversion' in 11/12 (92%)), implicating an underlying class switch defect. Those with depletion on B-cells are caught at a dilemma between, being too early and too late on receiving SARS-CoV-2 vaccines. They wish to get over their immunological naïvety at the earliest, while, in order to assure quality immune memory, are also required to hold the patience for their B-cells to repopulate. Although it remains an issue whether intensified vaccine schedules and/or regimens will lead to stronger immunogenicity or more effective boosters for non-responders, we shall take advantage of every increasing evidence in order to optimize current options. © 2022 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases

Boosting compromised SARS-CoV-2-specific immunity with mRNA vaccination in liver transplant recipients.

BACKGROUND & AIMS: Liver transplant recipients (LTRs) demonstrate a reduced response to COVID-19 mRNA vaccination; however, a detailed understanding of the interplay between humoral and cellular immunity, especially after a third (and fourth) vaccine dose, is lacking. METHODS: We longitudinally compared the humoral, as well as CD4+ and CD8+ T-cell, responses between LTRs (n = 24) and healthy controls (n = 19) after three (LTRs: n = 9 to 16; healthy controls: n = 9 to 14 per experiment) to four (LTRs: n = 4; healthy controls: n = 4) vaccine doses, including in-depth phenotypical and functional characterization. RESULTS: Compared to healthy controls, development of high antibody titers required a third vaccine dose in most LTRs, while spike-specific CD8+ T cells with robust recall capacity plateaued after the second vaccine dose, albeit with a reduced frequency and epitope repertoire compared to healthy controls. This overall attenuated vaccine response was linked to a reduced frequency of spike-reactive follicular T helper cells in LTRs. CONCLUSION: Three doses of a COVID-19 mRNA vaccine induce an overall robust humoral and cellular memory response in most LTRs. Decisions regarding additional booster doses may thus be based on individual vaccine responses as well as evolution of novel variants of concern. IMPACT AND IMPLICATIONS: Due to immunosuppressive medication, liver transplant recipients (LTR) display reduced antibody titers upon COVID-19 mRNA vaccination, but the impact on long-term immune memory is not clear. Herein, we demonstrate that after three vaccine doses, the majority of LTRs not only exhibit substantial antibody titers, but also a robust memory T-cell response. Additional booster vaccine doses may be of special benefit for a small subset of LTRs with inferior vaccine response and may provide superior protection against evolving novel viral variants. These findings will help physicians to guide LTRs regarding the benefit of booster vaccinations.

Immune memory after SARS-CoV-2 infection.

The COVID-19 pandemic has become a serious global public health threat with more than 540 million infections and 6.32 million cases of death as of 25 June, 2022.Understanding whether COVID-19 patients can obtain persistent immune protection after recovery is crucial for vaccine development, disease control and epidemic forecast.The persistent immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is mainly derived from the immune memory.Thus, the generation and maintenance of immune memory specifically targeted to the virus were reviewed in this paper. Copyright © 2022 Society of Microbiology and Immunology. All rights reserved.

BNT162b2 booster vaccination elicits cross-reactive immunity against SARS-CoV-2 variants B.1.1.529 and B.1.617.2 in convalescents of all ages

Background: Among the greatest challenges of the current pandemic with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is its ongoing evolution, resulting in variants of interest (VOI) and variants of concern (VOC) with an enhanced capacity for immune escape. The likelihood for the emergence of such variants exponentially rises with the time a host is infected with the virus and the virus is reproduced without being properly controlled by the immune system. Method(s): In this prospective observational cohort study we analyzed cellular and serological immune response parameters against SARS-CoV-2 and current variants of concern (VOC) in 147 COVID-19-convalescent and 39 COVID-19-naive individuals before and after BNT162b2 booster vaccination. End points included anti-SARS-CoV-2 IgG and IgA titers, neutralization capacities against wild type SARS-CoV-2 and the VOCs B.1.1.529 and B.1.617.2 as well as SARS-CoV-2-specific T cell IFN-gamma responses. Result(s): No significant differences regarding immunological response parameters were observed between younger and older individuals. Booster vaccination induced full recovery of both cellular and serological response parameters including IFN-g secretion and anti-spike antibody titers with strong neutralization capacities against wild type SARS-COV-2 and Delta. Surprisingly, even serological neutralization capacity against Omicron was detectable one month after second vaccination and four months before it had been first observed in South Africa. As a result, more than 90% of convalescent individuals exhibited detectable and 75% strong Omicron neutralization capacity after booster vaccination, compared with 72% and 46% of COVID-19-naive individuals. Conclusion(s): Broad and cross-reactive immune memory against SARSCoV- 2 including currently known VOCs can be established by booster vaccination with spike-based mRNA vaccines like BNT162b2, particularly in COVID-19-convalescent individuals of all ages. Nevertheless, especially in COVID-19-naive individuals future variants escaping the memory immune response may require vaccine approaches such as inactivated whole virus vaccines, which include all antigenic components of the virus. (Figure Presented).

Humoral immunity for durable control of SARS-CoV-2 and its variants.

The coronavirus disease 2019 (COVID-19) pandemic is ongoing because of the repeated emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants, highlighting the importance of developing vaccines for variants that may continue to emerge. In the present review, we discuss humoral immune responses against SARS-CoV-2 with a focus on the antibody breadth to the variants. Recent studies have revealed that the temporal maturation of humoral immunity improves the antibody potency and breadth to the variants after infection or vaccination. Repeated vaccination or infection further accelerates the expansion of the antibody breadth. Memory B cells play a central role in this phenomenon, as the reactivity of the B-cell antigen receptor (BCR) on memory B cells is a key determinant of the antibody potency and breadth recalled upon vaccination or infection. The evolution of memory B cells remarkably improves the reactivity of BCR to antigenically distinct Omicron variants, to which the host has never been exposed. Thus, the evolution of memory B cells toward the variants constitutes an immunological basis for the durable and broad control of SARS-CoV-2 variants.

ANTICORPII MONOCLONALI ȘI UTILIZAREA ACESTORA ÎN TERAPIA ȘI IMUNOPROFILAXIA INFECȚIILOR VIRALE - ACTUALITĂȚI ȘI PERSPECTIVE

Anticorpii joacă un rol esenţial în imunitatea antiinfecţioasă, fiind principalele biomolecule instrumentale pentru prevenirea sau modularea specifică a infecţiilor virale. Obiective. Studiul de faţă a urmărit actualizarea informaţiilor ştiinţifice privind anticorpii cu potenţial imunoprofilactic şi terapeutic în viroze de importanţă majoră pentru sănătatea publică (rabie, arboviroze, COVID-19, gripa cu tulpini înalt patogene), precum şi tehnologiile contemporane de obţinere a anticorpilor în laborator, pentru a fitestaţi şi utilizaţi în clinică. Materiale şi metode. Au fost studiate datele din literatura ştiinţifică de specialitate publicate în ultimii 10 ani, cu deosebire cele cu impact ştiinţific şi profesional de excelenţă (grupurile editoriale Nature, Science, Lancet, Elsevier, MDPI etc). Informaţiile au fost filtrate prin experienţa practică de lucru în domeniu a autorului, la nivel naţional şi internaţional. Rezultate şi discuţii. În prezent, pentru a genera anticorpi monoclonali, există o paletă largă de tehnologii care se utilizează în laborator: a) fuzionarea limfocitelor B cu linii de celule de mielom uman sau uman/murin;b) imortalizarea limfocitelor B prin transformare cu virusul Epstein-Barr;c) tehnologia denumită phage display care implică exprimarea regiunilor variabile (VH şi VL) ale imunoglobulinei G pe suprafaţa unor bacteriofagi, care sunt apoi selectaţi iterativ prin legarea la un antigen specific;d) tehnicile de clonare celulară prin sortarea celulelor B de memorie specifice pentru un antigen, cultivarea acestor in vitro cu activare antigen specifică, urmată de amplificarea genică şi clonarea regiunilor variabile ale lanţurilor grele şi uşoare, pornind de la o singură celulă B;ulterior regiunile clonate se exprimă în vectori specifici de expresie proteică. e) tehnologii bazate pe ADN şi ARN mesager. Pe de altă parte, se pot obţine in vitro anticorpi monoclonali, himerici, bispecifici, fragmente de anticorpi, cu proprietăţi funcţionale şi farmacologice particulare. Până la sfarşitul anului 2021 existau aproximativ 100 de tipuri de anticorpi aprobaţi pentru utilizări în clinica infecţiilor virale, la nivel mondial. Concluzii. Îmbunătăţirea şi apariţia noi abordări ale tehnologiilor de clonare celulară şi moleculară, precum şi industrializarea proceselor în condiţii automatizate, conduc la posibilitatea de a dezvolta anticorpi monoclonali cu înaltă eficienţă şi scurtarea considerabilă a timpului necesar de control şi evaluare a acestora pentru înregistrarea punerii pe piaţă. Utilizarea anticorpilor neutralizanţi rămâne una dintre cele mai promiţătoare opţiuni în lupta împotriva infecţiilor virale, fiind o decizie strategică în contextul apariţiei de noi epidemii sau al ameninţărilor bioteroriste. Sursa de finanţare: lucrări desfăşurate în cadrul proiectului PSCD/2022 - VIROMAB H, finanţat de Ministerul Apărării Naţionale.Alternate :Antibodies play an essential role in anti-infective immunity, being the main instrumental biomolecules for the specific prevention or modulation of viral infections. Objectives. The present study aimed to update scientific information regarding antibodies with immunoprophylactic and therapeutic potential in viroses of major importance for public health (rabies, arboviruses, COVID-19, influenza with highly pathogenic strains), as well as contemporary technologies for getting antibodies in the laboratory, in order to be tested and used in the clinic. Materials and methods. Data from specialized scientific literature published in the last 10 years were studied, especially those publications with excellent scientific and professional impact (publishing groups Nature, Science, Lancet, Elsevier, MDPI etc.). The information has been filtered through the author's practical work experience in the field, at national and international level. Results and discussion. Currently, to generate monoclonal antibodies, there is a wide range of te hnologies that are used in the laboratory: a) fusion of B lymphocytes with human or human/murine myeloma cell lines;b) immortalization of B lymphocytes by transformation with the Epstein-Barr virus;c) the phage display technology that involves the expression of the variable regions (VH and VL) of immunoglobulin G on the surface of some bacteriophages, which are then iteratively selected by binding to a specific antigen;d) cell cloning techniques by sorting memory B cells specific for an antigen, in vitro cell cultivation with specific antigen activation, followed by gene amplification and cloning of the variable regions of the heavy and light chains (VH, VL) starting from a single B cell;subsequently the cloned regions are expressed in specific vectors. e) technologies based on DNA and messenger RNA. On the other hand, monoclonal, chimeric, bispecific antibodies, antibody fragments can be obtained in vitro, with particular functional and pharmacological properties. By the end of 2021 there were approximately 100 types of antibodies approved for use in the clinic of viral infections, worldwide. Conclusions. The improvement and the emergence of new approaches to cellular and molecular cloning technologies, as well as the industrialization of processes under automated conditions, lead to the possibility of developing monoclonal antibodies with high efficiency and the considerable shortening of the time required for their control and evaluation for market registration. The use of neutralizing antibodies remains one of the most promising options in the fight against viral infections, being a strategic decision in the context of the emergence of new epidemics or bioterrorist threats. Funding source: works carried out within the project PSCD/2022 - VIROMAB H, funded by the Ministry of National Defense.

SARS-CoV-2 mRNA Dual Immunization Induces Innate Transcriptional Signatures, Establishes T-Cell Memory and Coordinates the Recall Response.

BACKGROUND: mRNA vaccines have played a crucial role in controlling the SARS-CoV-2 global pandemic. However, the immunological mechanisms involved in the induction, magnitude and longevity of mRNA-vaccine-induced protective immunity are still unclear. METHODS: In our study, we used whole-RNA sequencing along with detailed immunophenotyping of antigen-specific T cells and humoral RBD-specific response to dual immunization with the Pfizer-BioNTech mRNA vaccine (BNT162b2) and correlated them with response to an additional dose, administered 10 months later, in order to comprehensively profile the immune response of healthy volunteers to BNT162b2. RESULTS: Primary dual immunization induced upregulation of the Type I interferon pathway and generated spike protein (S)-specific IFN-γ+ and TNF-α+ CD4 T cells, S-specific memory CD4 T cells, and RBD-specific antibodies against SARS-CoV-2. S-specific CD4 T cells induced by the primary series correlated with the RBD-specific antibody titers to a third dose. CONCLUSIONS: This study demonstrates the induction of both innate and adaptive immunity in response to the BNT162b2 mRNA vaccine in a coordinated manner and identifies the central role of primarily induced CD4+ T cells as a predictive biomarker of the magnitude of anamnestic immune response.

Clinical effects of 2-DG drug restraining SARS-CoV-2 infection: A fractional order optimal control study.

Fractional calculus is very convenient tool in modeling of an emergent infectious disease system comprising previous disease states, memory of disease patterns, profile of genetic variation etc. Significant complex behaviors of a disease system could be calibrated in a proficient manner through fractional order derivatives making the disease system more realistic than integer order model. In this study, a fractional order differential equation model is developed in micro level to gain perceptions regarding the effects of host immunological memory in dynamics of SARS-CoV-2 infection. Additionally, the possible optimal control of the infection with the help of an antiviral drug, viz. 2-DG, has been exemplified here. The fractional order optimal control would enable to employ the proper administration of the drug minimizing its systematic cost which will assist the health policy makers in generating better therapeutic measures against SARS-CoV-2 infection. Numerical simulations have advantages to visualize the dynamical effects of the immunological memory and optimal control inputs in the epidemic system.

Durable CD8 T Cell Memory against SARS-CoV-2 by Prime/Boost and Multi-Dose Vaccination: Considerations on Inter-Dose Time Intervals.

Facing the COVID-19 pandemic, anti-SARS-CoV-2 vaccines were developed at unprecedented pace, productively exploiting contemporary fundamental research and prior art. Large-scale use of anti-SARS-CoV-2 vaccines has greatly limited severe morbidity and mortality. Protection has been correlated with high serum titres of neutralizing antibodies capable of blocking the interaction between the viral surface protein spike and the host SARS-CoV-2 receptor, ACE-2. Yet, vaccine-induced protection subsides over time, and breakthrough infections are commonly observed, mostly reflecting the decay of neutralizing antibodies and the emergence of variant viruses with mutant spike proteins. Memory CD8 T cells are a potent weapon against viruses, as they are against tumour cells. Anti-SARS-CoV-2 memory CD8 T cells are induced by either natural infection or vaccination and can be potentially exploited against spike-mutated viruses. We offer here an overview of current research about the induction of anti-SARS-CoV-2 memory CD8 T cells by vaccination, in the context of prior knowledge on vaccines and on fundamental mechanisms of immunological memory. We focus particularly on how vaccination by two doses (prime/boost) or more (boosters) promotes differentiation of memory CD8 T cells, and on how the time-length of inter-dose intervals may influence the magnitude and persistence of CD8 T cell memory.