HUMORAL AND CELLULAR IMMUNOGENICITY INDUCED BY THIRD BOOSTER OF SARS-CoV-2 VACCINES IN PATIENTS WITH RHEUMATIC MUSCULOSKELETAL DISEASES

BackgroundAmid the coronavirus disease 2019 (COVID-19) crisis, two messenger RNA (mRNA) vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have benefited most people worldwide. While healthy people can acquire sufficient humoral immunity against COVID-19 even in the elderly by vaccination with three doses of vaccine., recent studies have shown that complex factors other than age, including the type of vaccines and immunosuppressive drugs, are associated with immunogenicity in patients with rheumatic musculoskeletal disease (RMD). Identifying factors that contribute to the vulnerability of those patients to acquire not only humoral but also cellular immunity to SARS-CoV-2 despite multiple vaccinations is crucial for establishing an appropriate booster vaccine strategy.ObjectivesTo assess humoral,and T cell immune responses after third doses of mRNA vaccines against SARS-CoV-2.MethodsThis prospective observational study included consecutive RMD patients treated with immunosuppressant who received three doses of mRNA vaccines including BNT162b2 and mRNA-1273. Blood samples were obtained 2-6 weeks after second and third dose of mRNA vaccines. We measured neutralizing antibody titres, which against the receptor-binding domain (RBD) of the spike protein of SARS-CoV-2 and seroconversion rates to evaluate the humoral responses. We also assessed T-cell immunity responses using interferon releasing assay against SARS-CoV-2.ResultsA total of 586 patients with RMD treated with mmunosuppressive treatments were enrolled. The mean age was 54 years, and 70% of the patients were female. Seroconversion rates and neutralizing antibody titres after third vaccination of SARS-CoV-2 were significantly higher compared to those after second vaccination (seroconversion rate, 94.5% vs 83.6%, p<0.001;titres of neutralizing antibody, 48.2 IU/mL vs 11.0 IU/mL, p<0.001, respectively). Interferon releasing assay after third vaccinations demonstrated that T cell reaction against SARS-CoV-2 was also increased from that of second vaccination (interferon for antigen 1, 1.11.9 vs 0.61.9, p=0.004,interferon for antigen 2, 1.72.6 vs 0.82.3, p=0.004). Humoral and cellular immunogenicity did not differ between the types of third vaccination including full dose of BNT162 and half dose of mRNA1273.(neutralizing antibody titers, 47.8±76.1 IU/mL vs 49.0±60.1 IU/mL, p<0.001;interferon for antigen 1, 1.12.0 vs 1.01.5, p=0.004, respectively). Attenuated humoral response to third vaccination was associated with BNT162b2 as second vaccination age (>60 years old), glucocorticoid (equivalent to prednisolone > 7.5 mg/day), and immunosuppressant use including mycophenolate, and rituximab. On another front, use of mycophenolate and abatacept or tacrolimus but not rituximab were identified as negative factors for T-cell reactions against SARS-CoV-2. Although 53 patients (9.0%) who had been immunised with third-vaccination contracted COVID-19 during Omicron pandemic phase, no one developed severe pulmonary disease that required corticosteroid therapy.ConclusionOur results demonstrated third mRNA vaccination booster of SARS-CoV-2 contributed to restore both humeral and cellular immunity in RMD patients with immunosuppressants. We also identified that certain immunosuppressive therapy with older RMD patients having BNT162b2 as a second vaccination may need additional booster vaccination.Reference[1]Furer V, Eviatar T, Freund T, et al. Ann Rheum Dis. 2022 Nov;81(11):1594-1602. doi: 10.1136/ard-2022-222550.Acknowledgements:NIL.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.

PRE-EXPOSURE PROPHYLAXIS WITH TIXAGEVIMAB/CILGAVIMAB: SINGLE CENTRE EXPERIENCE IN A COHORT OF RHEUMATIC PATIENTS

BackgroundVaccination against SARS-CoV2 had a critical role in the fight against COVID19 pandemic.A weaker humoral response to COVID19 vaccine has been found in rheumatic patients treated with Rituximab (RTX) or Mycophenolate Mofetil (MMF)[1]. Despite the evidence that anti-SARS-CoV-2 mRNA vaccines can elicit a T-cell response [2], some data show that even the cellular immunity could be impaired in rheumatic patients [3] but COVID19 serology is the only parameter that is feasible to measure in daily practice.Tixagevimab+cilgavimab are two human-derived monoclonal antibodies administered parenterally and authorized by regulatory agencies in February 2022 for pre-exposure prophylaxis (PrEP) against COVID19 from different virus variants in fragile patients.ObjectivesTo demonstrate safety and effectiveness of tixagevimab+cilgavimab.MethodsPatients with autoimmune rheumatic diseases undergoing immunosuppressive treatment with RTX or MMF during the vaccination campaign were enrolled between April and June 2022. All patients must have anti-spike antibody levels below the protective threshold (defined by anti-spike IgG titre <250 BAU/ml) after receiving at least 2 vaccine doses.Patients were monitored with a questionnaire every month about COVID19 symptoms (including respiratory and gastrointestinal symptoms, anosmia and ageusia, skin rash and potential contact with COVID19+ subjects) and were checked for anti-spike and anti-nucleocapside antibodies titres every 2 months for a total of a 6 month follow-up. MMF dose was reduced at 1 g/die at the time of vaccine administration.ResultsFifteen patients were enrolled: 9 participants had a connective tissue disease (CTD;1 dermatomyositis, 3 anti-syntethase syndrome, 4 systemic sclerosis, 1 systemic lupus erythematosus) and 6 had vasculitis (all granulomatosis with polyangiitis). 12 of them received RTX in the preceding 12 months and 3 were taking MMF.About safety, the therapy was very well tolerated and only 4 patients (26%) reported a non-severe adverse event in the 2 weeks following drug administration (2 myalgia, 1 headache, 1 fatigue), none of them requiring hospitalization nor pharmacologic treatment.Regarding effectiveness, 3/15 patients contracted SARS-Cov2 infection (20%) with mild symptoms and no need for hospitalization nor oxygen therapy. Only 1 of them received an antiviral drug (nirmatrelvir+ritonavir). All infected patients had a CTD diagnosis. No significant correlation was observed between the type of rheumatic disease and the risk of infection or response to tixagevimab+cilgavimab.ConclusionNone of our patients developed severe adverse events after tixagevimab+cilgavimab administration and, among the 3 SARS-CoV2 infected patients, none required hospitalization nor oxygen therapy.We conclude that in our experience tixagevimab+cilgavimab is a safe and useful complementary immunization strategy to vaccination for COVID19 prophylaxis.These data will be implemented in a larger study, comprehending various immunocompromised patients from several departments.References[1] Furer et al., Ann Rheum Dis, 2021[2] Mangalakumari et al., Nat Rev Immunol, 2020[3] Picchianti-Diamanti et al., Front Immunol, 2021Charateristic of the cohortIdentificativeAgeDiagnosisRTX/MMFSARS-CoV2 InfectionHospitalizationAntiviral drugs180SScMMF-//270ASSDRTX+nono370ASSDRTX+noyes452GPARTX-//551GPARTX-//649SSc+SSjRTX-//768SScMMF-//847LESRTX-//964ASSDRTX-//1068GPARTX-//1123GPARTX-//1258DMRTX+nono1361SScMMF-//1475GPARTX-//1569GPARTX-//Figure 1.Acknowledgements:NIL.Disclosure of InterestsNone Declared.

Sustained cell-mediated but not humoral responses in rituximab-treated rheumatic patients after vaccination against SARS-CoV-2.

OBJECTIVES: B cell depleting monoclonal antibodies are associated with increased COVID-19 severity and impaired immune response to vaccination. We aimed to assess the humoral and cell mediated (CMI) immune response after SARS-CoV-2 vaccination in rituximab (RTX)-treated rheumatic patients. METHODS: Serum and whole blood samples were collected from rituximab (RTX)-treated rheumatic patients 3-6 months after last vaccination against SARS-CoV-2. Serum was tested by ELISA for quantitative detection of anti-spike SARS-CoV-2 IgG. Cell-mediated variant-specific SARS-CoV-2 immunity (CMI) was assessed by interferon-γ release assay Covi-FERON FIA. Patients were interviewed for breakthrough COVID-19 infection (BTI) 3 months post sampling. RESULTS: Sixty patients were studied after a median (IQR) of 179 (117-221.5) days from last vaccine to sampling. Forty (66.7%) patients had positive Covi-FERON and 23 (38.3%) had detectable anti-spike IgG. Covi-FERON positive patients had lower median RTX cumulative dose [6 (4-10.75) vs 11 (6.75-14.75) grams, (p= 0.019). Patients with positive anti-spike IgG had received fewer RTX cycles [2 (2-4) vs 6 (4-8), p= 0.002) and cumulative dose [4 (3-7) vs 10 (6.25-13) grams, p= 0.002] and had shorter time from last vaccination to sampling [140 (76-199) vs 192 (128-230) days, p= 0.047). Thirty-seven percent were positive only for Covi-FERON and 7% only for anti-spike IgG. Twenty (33.3%) BTI occurred post sampling, exclusively during Omicron variant predominance. The proportion of patients with CMI response against Delta variant was lower in patients who experienced BTI (25% vs 55%, p= 0.03). CONCLUSIONS: Four out of ten RTX-treated vaccinated patients show lasting cell-mediated immune response despite undetectable anti-spike antibodies. Cumulative RTX dose affects both humoral and cell-mediated responses to SARS-CoV-2 vaccines. Cell-mediated immune responses call for attention as a vaccine efficacy marker against SARS-CoV-2.

T cell immunity following COVID-19 vaccination in adult patients with primary antibody deficiency - a 22-month follow-up.

Primary antibody deficiencies, such as common variable immunodeficiency (CVID), are heterogenous disease entities consisting of primary hypogammaglobulinemia and impaired antibody responses to vaccination and natural infection. CVID is the most common primary immunodeficiency in adults, presenting with recurrent bacterial infections, enteropathy, autoimmune disorders, interstitial lung diseases and increased risk of malignancies. Patients with CVID are recommended to be vaccinated against SARS-CoV-2, but there are relatively few studies investigating humoral and cellular responses to immunization. We studied the dynamics of humoral and cell-mediated immunity responses up to 22 months in 28 patients with primary immunodeficiency and three patients with secondary immunodeficiency receiving ChAdOx1, BNT162b2 and mRNA-1273 COVID-19 vaccines. Despite inadequate humoral response to immunization, we demonstrate a robust T cell activation likely protecting from severe COVID-19.

CELL-MEDIATED AND HUMORAL IMMUNITY DURING COVID-19 IN THE REPUBLIC OF CRIMEA

The COVID-19 (coronavirus disease 2019) pandemic has spurred the development ofhighly effective quantitative methods for assessing the adaptive immune response to the SARS-CoV-2 (severe acute respiratory syndrome-related coronavirus 2) virus. In order to assess the humoralcomponentofthe immune response, various methods for detecting immunoglobulins A, M, Gare widely used. ELISPOTseems to be the most accessible and effective method to assess the level of T cells that specifically respond to the SARS-CoV-2 virus antigens. The aim. To assess cell-mediated and humoral immunity in COVID-19 in residents of the Republic of Crimea. Methods. The study was performed on 24 volunteers: the presence of coronavirus antibodies was determinedby ELISAmethod, andthe presence ofcontact withcoronavirus proteins - by the ELISPOT "TigraTest® SARS-CoV-2” method (Generium, Russia). For retrospective study of humoral immunity in the population, we assessed 10 000 ELISA tests (ECOlab IgM and IgG, Russia) performed in our laboratory for the period from July 2020 to January 2022. Results. The results show the effectiveness of using the ELISPOT method to detect latent forms of coronavirus infection. It is important to note that there is statistically significant relationship between the timing of the disease and the number of spots in both antigen panels. After vaccination against SARS-CoV-2, cell-mediated immunity lasts up to 6 months or more. Conclusions. As a result of the study, it was found that during 2021, the level of immunization of the population of the Republic of Crimea against COVID-19 has significantly increased;the proportion of residents who have positive IgG test has increasedfrom 27%to 87%. The results ofELISPOTstudies using a setofreagents for in vitro detection ofbloodT-lymphocytes thatspecifically respondto SARS-COV-2 virus antigens ("TigraTest® SARS-CoV-2”) showed that this method is more sensitive than ELISA in detecting latent diseases. © 2023 Voprosy Literatury. All rights reserved.

Immune correlates of protection for SARS-CoV-2, Ebola and Nipah virus infection.

Correlates of protection (CoP) are biological parameters that predict a certain level of protection against an infectious disease. Well-established correlates of protection facilitate the development and licensing of vaccines by assessing protective efficacy without the need to expose clinical trial participants to the infectious agent against which the vaccine aims to protect. Despite the fact that viruses have many features in common, correlates of protection can vary considerably amongst the same virus family and even amongst a same virus depending on the infection phase that is under consideration. Moreover, the complex interplay between the various immune cell populations that interact during infection and the high degree of genetic variation of certain pathogens, renders the identification of immune correlates of protection difficult. Some emerging and re-emerging viruses of high consequence for public health such as SARS-CoV-2, Nipah virus (NiV) and Ebola virus (EBOV) are especially challenging with regards to the identification of CoP since these pathogens have been shown to dysregulate the immune response during infection. Whereas, virus neutralising antibodies and polyfunctional T-cell responses have been shown to correlate with certain levels of protection against SARS-CoV-2, EBOV and NiV, other effector mechanisms of immunity play important roles in shaping the immune response against these pathogens, which in turn might serve as alternative correlates of protection. This review describes the different components of the adaptive and innate immune system that are activated during SARS-CoV-2, EBOV and NiV infections and that may contribute to protection and virus clearance. Overall, we highlight the immune signatures that are associated with protection against these pathogens in humans and could be used as CoP.

Vaccinating children: the pros and cons. (Special Issue: The SARS-CoV-2 vaccines: retrospective and perspectives.)

Vaccinating children against Covid raised a debate, due to generally mild clinical presentation. The decision to vaccinate teenagers was motivated by the global public health need: to decrease transmission to other age groups. Among adolescents, the efficacy (better immunity than in young adults) and safety of vaccines was clearly demonstrated. Among 5-to-12-year-olds, due to lower contamination the collective benefit is less clear, and when the m-RNA vaccines were available for this age group, the Omicron variant was predominant and their effect on non-severe infections and transmission had yet to be determined. Individual benefit is based both on somatic criteria and on the child's schooling and mental health. Children under 5 years of age received a 3 micro g dose of vaccine, which is one tenth of the adult dose, resulting in immunogenicity similar to that of 16-to-25-year-olds.

An optimized flow cytometry protocol for simultaneous detection of T cell activation induced markers and intracellular cytokines: Application to SARS-CoV-2 immune individuals.

Antigen (ag)-specific T cell analysis is an important step for investigation of cellular immunity in many settings, such as infectious diseases, cancer and vaccines. Multiparameter flow cytometry has advantages in studying both the rarity and heterogeneity of these cells. In the cellular immunologist's toolbox, the expression of activation-induced markers (AIM) following antigen exposure has made possible the study and sorting of ag-specific T cells without using human leukocyte antigen (HLA)-multimers. In parallel, assessing the cytokine profile of responding T cells would support a more comprehensive description of the ongoing immune response by providing information related to cell function, such as polarization and effector activity. Here, a method and flow cytometry panel were optimized to combine the detection of activated CD4+ and CD8+ T cells in a TCR-dependent manner with the evaluation of cytokine production by intracellular staining, without affecting the positivity of activation markers. In particular, the expression of CD134 (OX40) and CD69 have been tested in conjunction with intracellular (ic) CD137 (4-1BB) to detect SARS-CoV-2 Spike protein-specific activated T cells. In our setting, CD134 provided minimal contribution to detect the pool of AIM+ T cells, whereas a key role was described for ic-CD69 which was co-expressed with ic-CD137 in both CD4+ and CD8+ lymphocytes. Moreover, the analysis of TCR-triggered cytokine-producing T cells (IFNγ, TNFα and IL-2 were assessed) further confirmed the capacity of ic-CD69 to identify functionally responsive antigen-specific T cells which were often largely negative or weakly positive for CD134 expression. In parallel, the use of CD45RA, CCR7 and CXCR5 allowed us to describe the T cell matuarion curve and detect T follicular helper (Tfh) CD4+ cells, including the antigen specific activated subsets. In conclusion, we optimized a method and flow cytometry panel combining assessment of activation induced markers and intracellular cytokines that will be useful for measuring TCR stimulation-dependent activation of CD4+ and CD8+ T cells.

HLA-I and HLA-II Peptidomes of SARS-CoV-2: A Review.

The adaptive (T-cell-mediated) immune response is a key player in determining the clinical outcome, in addition to neutralizing antibodies, after SARS-CoV-2 infection, as well as supporting the efficacy of vaccines. T cells recognize viral-derived peptides bound to major histocompatibility complexes (MHCs) so that they initiate cell-mediated immunity against SARS-CoV-2 infection or can support developing a high-affinity antibody response. SARS-CoV-2-derived peptides bound to MHCs are characterized via bioinformatics or mass spectrometry on the whole proteome scale, named immunopeptidomics. They can identify potential vaccine targets or therapeutic approaches for SARS-CoV-2 or else may reveal the heterogeneity of clinical outcomes. SARS-CoV-2 epitopes that are naturally processed and presented on the human leukocyte antigen class I (HLA-I) and class II (HLA-II) were identified for immunopeptidomics. Most of the identified SARS-CoV-2 epitopes were canonical and out-of-frame peptides derived from spike and nucleocapsid proteins, followed by membrane proteins, whereby many of which are not caught by existing vaccines and could elicit effective responses of T cells in vivo. This review addresses the detection of SARS-CoV-2 viral epitopes on HLA-I and HLA-II using bioinformatics prediction and mass spectrometry (HLA peptidomics). Profiling the HLA-I and HLA-II peptidomes of SARS-CoV-2 is also detailed.

SARS-CoV-2 Vaccine-Induced T-Cell Response after Three Doses in People Living with HIV on Antiretroviral Therapy Compared to Seronegative Controls (CTN 328 COVAXHIV Study).

People living with HIV (PLWH) may be at risk for poor immunogenicity to certain vaccines, including the ability to develop immunological memory. Here, we assessed T-cell immunogenicity following three SARS-CoV-2 vaccine doses in PLWH versus uninfected controls. Blood was collected from 38 PLWH on antiretroviral therapy and 24 age-matched HIV-negative controls, pre-vaccination and after 1st/2nd/3rd dose of SARS-CoV-2 vaccines, without prior SARS-CoV-2 infection. Flow cytometry was used to assess ex vivo T-cell immunophenotypes and intracellular Tumor necrosis factor (TNF)-α/interferon(IFN)-γ/interleukin(IL)-2 following SARS-CoV-2-Spike-peptide stimulation. Comparisons were made using Wilcoxon signed-rank test for paired variables and Mann-Whitney for unpaired. In PLWH, Spike-specific CD4 T-cell frequencies plateaued post-2nd dose, with no significant differences in polyfunctional SARS-CoV-2-specific T-cell proportions between PLWH and uninfected controls post-3rd dose. PLWH had higher frequencies of TNFα+CD4 T-cells and lower frequencies of IFNγ+CD8 T-cells than seronegative participants post-3rd dose. Regardless of HIV status, an increase in naive, regulatory, and PD1+ T-cell frequencies was observed post-3rd dose. In summary, two doses of SARS-CoV-2 vaccine induced a robust T-cell immune response in PLWH, which was maintained after the 3rd dose, with no significant differences in polyfunctional SARS-CoV-2-specific T-cell proportions between PLWH and uninfected controls post-3rd dose.

Robust humoral and cellular recall responses to AZD1222 attenuate breakthrough SARS-CoV-2 infection compared to unvaccinated.

Background: Breakthrough severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in coronavirus disease 2019 (COVID-19) vaccinees typically produces milder disease than infection in unvaccinated individuals. Methods: To explore disease attenuation, we examined COVID-19 symptom burden and immuno-virologic responses to symptomatic SARS-CoV-2 infection in participants (AZD1222: n=177/17,617; placebo: n=203/8,528) from a 2:1 randomized, placebo-controlled, phase 3 study of two-dose primary series AZD1222 (ChAdOx1 nCoV-19) vaccination (NCT04516746). Results: We observed that AZD1222 vaccinees had an overall lower incidence and shorter duration of COVID-19 symptoms compared with placebo recipients, as well as lower SARS-CoV-2 viral loads and a shorter median duration of viral shedding in saliva. Vaccinees demonstrated a robust antibody recall response versus placebo recipients with low-to-moderate inverse correlations with virologic endpoints. Vaccinees also demonstrated an enriched polyfunctional spike-specific Th-1-biased CD4+ and CD8+ T-cell response that was associated with strong inverse correlations with virologic endpoints. Conclusion: Robust immune responses following AZD1222 vaccination attenuate COVID-19 disease severity and restrict SARS-CoV-2 transmission potential by reducing viral loads and the duration of viral shedding in saliva. Collectively, these analyses underscore the essential role of vaccination in mitigating the COVID-19 pandemic.

Immunogenicity of an adjuvanted SARS-CoV-2 trimeric S-protein subunit vaccine (SCB-2019) in SARS-CoV-2-naïve and exposed individuals in a phase 2/3, double-blind, randomized study.

BACKGROUND: We evaluated immunogenicity of SCB-2019, a subunit vaccine candidate containing a pre-fusion trimeric form of the SARS-CoV-2 spike (S)-protein adjuvanted with CpG-1018/alum. METHODS: The phase 2/3, double-blind, randomized SPECTRA trial was conducted in five countries in participants aged ≥ 18 years, either SARS-CoV-2-naïve or previously exposed. Participants were randomly assigned to receive two doses of SCB-2019 or placebo administered intramuscularly 21 days apart. In the phase 2 part of the study, on days 1, 22, and 36, neutralizing antibodies were measured by pseudovirus and wild-type virus neutralization assays to SARS-CoV-2 prototype and variants, and ACE2-receptor-binding antibodies and SCB-2019-binding antibodies were measured by ELISA. Cell-mediated immunity was measured by intracellular cytokine staining via flow cytometry. RESULTS: 1601 individuals were enrolled between 24 March and 13 September 2021 and received at least one vaccine dose. Immunogenicity analysis was conducted in a phase 2 subset of 691 participants, including 428 SARS-CoV-2-naïve (381 vaccine and 47 placebo recipients) and 263 SARS-CoV-2-exposed (235 vaccine and 28 placebo recipients). In SARS-CoV-2-naïve participants, GMTs of neutralizing antibodies against prototype virus increased 2 weeks post-second dose (day 36) compared to baseline (224 vs 12.7 IU/mL). Seroconversion rate was 82.5 %. In SARS-CoV-2-exposed participants, one SCB-2019 dose increased GMT of neutralizing antibodies by 48.3-fold (1276.1 IU/mL on day 22) compared to baseline. Seroconversion rate was 92.4 %. Increase was marginal post-second dose. SCB-2019 also showed cross-neutralization capability against nine variants, including Omicron, in SARS-CoV-2-exposed participants at day 36. SCB-2019 stimulated Th1-biased cell-mediated immunity to the S-protein in both naïve and exposed participants. The vaccine was well tolerated, no safety concerns were raised from the study. CONCLUSIONS: A single dose of SCB-2019 was immunogenic in SARS-CoV-2-exposed individuals, whereas two doses were required to induce immune response in SARS-CoV-2-naïve individuals. SCB-2019 elicited a cross-neutralizing response against emergent SARS-CoV-2 variants at antibody levels associated with clinical protection, underlining its potential as a booster. CLINICALTRIALS: gov: NCT04672395; EudraCT: 2020-004272-17.

T-Cell Mediated Response after Primary and Booster SARS-CoV-2 Messenger RNA Vaccination in Nursing Home Residents.

OBJECTIVES: Nursing home (NH) residents have been significantly affected by the coronavirus disease 2019 (COVID-19) pandemic. Studies addressing the immune responses induced by COVID-19 vaccines in NH residents have documented a good postvaccination antibody response and the beneficial effect of a third booster vaccine dose. Less is known about vaccine-induced activation of cell-mediated immune response in frail older individuals in the long term. The aim of the present study is to monitor messenger RNA SARS-CoV-2 vaccine-induced T-cell responses in a sample of Italian NH residents who received primary vaccine series and a third booster dose and to assess the interaction between T-cell responses and humoral immunity. DESIGN: Longitudinal cohort study. SETTING AND PARTICIPANTS: Thirty-four residents vaccinated with BNT162b2 messenger RNA SARS-CoV-2 vaccine between February and April 2021 and who received a third BNT162b2 booster dose between October and November 2021 were assessed for vaccine-induced immunity 6 (prebooster) and 12 (postbooster) months after the first BNT162b2 vaccine dose. METHODS: Pre- and postbooster cell-mediated immunity was assessed by intracellular cytokine staining of peripheral blood mononuclear cells stimulated in vitro with peptides covering the immunodominant sequence of SARS-CoV-2 spike protein. The simultaneous production of interferon-γ, tumor necrosis factor-α, and interleukin-2 was measured. Humoral immunity was assessed in parallel by measuring serum concentration of antitrimeric spike IgG antibodies. RESULTS: Before the booster vaccination, 31 out of 34 NH residents had a positive cell-mediated immunity response to spike. Postbooster, 28 out of 34 had a positive response. Residents without a previous history of SARS-CoV-2 infection, who had a lower response prior the booster administration, showed a greater increase of T-cell responses after the vaccine booster dose. Humoral and cell-mediated immunity were, in part, correlated but only before booster vaccine administration. CONCLUSIONS AND IMPLICATIONS: The administration of the booster vaccine dose restored spike-specific T-cell responses in SARS-CoV-2 naïve residents who responded poorly to the first immunization, while a previous SARS-CoV-2 infection had an impact on the magnitude of vaccine-induced cell-mediated immunity at earlier time points. Our findings imply the need for a continuous monitoring of the immune status of frail NH residents to adapt future SARS-CoV-2 vaccination strategies.

LNP-CpG ODN-adjuvanted varicella-zoster virus glycoprotein E induced comparable levels of immunity with Shingrix™ in VZV-primed mice.

Latent varicella-zoster virus (VZV) may be reactivated to cause herpes zoster, which affects one in three people during their lifetime. The currently available subunit vaccine Shingrix™ is superior to the attenuated vaccine Zostavax® in terms of both safety and efficacy, but the supply of its key adjuvant component QS21 is limited. With ionizable lipid nanoparticles (LNPs) that were recently approved by the FDA for COVID-19 mRNA vaccines as carriers, and oligodeoxynucleotides containing CpG motifs (CpG ODNs) approved by the FDA for a subunit hepatitis B vaccine as immunostimulators, we developed a LNP vaccine encapsulating VZV-glycoprotein E (gE) and CpG ODN, and compared its immunogenicity with Shingrix™ in C57BL/6J mice. The results showed that the LNP vaccine induced comparable levels of gE-specific IgG antibodies to Shingrix™ as determined by enzyme-linked immunosorbent assay (ELISA). Most importantly, the LNP vaccine induced comparable levels of cell-mediated immunity (CMI) that plays decisive roles in the efficacy of zoster vaccines to Shingrix™ in a VZV-primed mouse model that was adopted for preclinical studies of Shingrix™. Number of IL-2 and IFN-γ secreting splenocytes and proportion of T helper 1 (Th1) cytokine-expressing CD4+ T cells in LNP-CpG-adjuvanted VZV-gE vaccinated mice were similar to that of Shingrix™ boosted mice. All of the components in this LNP vaccine can be artificially and economically synthesized in large quantities, indicating the potential of LNP-CpG-adjuvanted VZV-gE as a more cost-effective zoster vaccine.

Evaluation of humoral and cellular response to four vaccines against COVID-19 in different age groups: A longitudinal study.

To date there has been limited head-to-head evaluation of immune responses to different types of COVID-19 vaccines. A real-world population-based longitudinal study was designed with the aim to define the magnitude and duration of immunity induced by each of four different COVID-19 vaccines available in Italy at the time of this study. Overall, 2497 individuals were enrolled at time of their first vaccination (T0). Vaccine-specific antibody responses induced over time by Comirnaty, Spikevax, Vaxzevria, Janssen Ad26.COV2.S and heterologous vaccination were compared up to six months after immunization. On a subset of Comirnaty vaccinees, serology data were correlated with the ability to neutralize a reference SARS-CoV-2 B strain, as well as Delta AY.4 and Omicron BA.1. The frequency of SARS-CoV-2-specific CD4+ T cells, CD8+ T cells, and memory B cells induced by the four different vaccines was assessed six months after the immunization. We found that mRNA vaccines are stronger inducer of anti-Spike IgG and B-memory cell responses. Humoral immune responses are lower in frail elderly subjects. Neutralization of the Delta AY.4 and Omicron BA.1 variants is severely impaired, especially in older individuals. Most vaccinees display a vaccine-specific T-cell memory six months after the vaccination. By describing the immunological response during the first phase of COVID-19 vaccination campaign in different cohorts and considering several aspects of the immunological response, this study allowed to collect key information that could facilitate the implementation of effective prevention and control measures against SARS-CoV-2.

Messenger RNA Therapeutics: Start of a New Era in Medicine

Last decade has witnessed tremendous growth in the new promising treatment options based on mRNA, RNAi, antisense RNA, and RNA aptamers, the four classes of RNA-based therapeutics. Among these, mRNA-based therapy is centered on producing proteins within the cells to supplant deficient or abnormal proteins and in vaccination to a target pathogen. The potential of mRNA therapeutics is evident from the two major mRNA vaccines approved for COVID-19: developed by Moderna and by Pfizer. Nonetheless, mRNA therapeutic potential extends far beyond this, such as in treating genetic diseases, cancers, and other infectious diseases. Given the potential of mRNA therapeutics, this chapter is written to provide the reader an insight into the features of several synthetic mRNA platforms, production, purification;strategies to increase the stability and reduce the immunogenicity of therapeutic mRNA molecules;delivery methods of these mRNAs in vivo;and their applications, safety, and efficacy. Graphical : A detailed diagram of the chemically modified mRNA, with the in vitro delivery modes on the left, and the myriad of applications, namely the treatment of major genetic diseases on the right. The IVT mRNA is represented with more details above the diagram. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.

Variants of SARS coronavirus-2 and their potential impact on the future of the COVID-19 pandemic

The emergence of SARS-CoV-2 variants of concern (VOCs), especially the sweeping spread of the delta variant, and differing public health management strategies, have rendered global eradication of SARS-CoV-2 unlikely. The currently available COVID-19 vaccines, including the inactivated whole virus vaccines, mRNA vaccines, and adenovirus-vectored vaccines, are effective in protecting people from severe disease and death from COVID-19, but they may not confer good mucosal immunity to prevent the establishment of infection and subsequent viral shedding and transmission. Mucosal vaccines delivered via intranasal route may provide a promising direction, which, if given as a third dose after a two-dose series of intramuscular vaccination, likely promotes mucosal immunity in addition to boosting the systemic cell-mediated immunity and antibody response. However, immunity induced by vaccination, and natural infection as well, is likely to wane followed by re-infection as in the case of human coronaviruses OC43, 229E, NL63, and HKU1. It is a challenge to prevent and control COVID-19 worldwide with the increasing number of VOCs associated with increased transmissibility and changing antigenicity. Nevertheless, we may seek to end the current pandemic situation through mass vaccination and gradual relaxation of non-pharmaceutical measures, which would limit the incidence of severe COVID-19. Repeated doses of booster vaccine will likely be required, similar to influenza virus, especially for the elderly and the immunocompromised patients who are most vulnerable to infection.

Commercialized kits to assess T-cell responses against SARS-CoV-2 S peptides. A pilot study in health care workers.

Background: It is crucial to assess the levels of protection generated by natural infection or SARS-CoV-2 vaccines, mainly in individuals professionally exposed and in vulnerable groups. Measuring T-cell responses may complement antibody tests currently in use as correlates of protection. Our aim was to assess the feasibility of a validated assay of T-cell responses. Methods: Twenty health-care-workers (HCW) were included. Antibody test to SARS-CoV-2 N and S-proteins in parallel with a commercially available whole-blood-interferon-gamma-release-assay (IGRA) to S-peptides and two detection methods, CLIA and ELISA were determined. Results: IGRA test detected T-cell responses in naturally exposed and vaccinated HCW already after first vaccination dose. The correlation by the two detection methods was very high (R > 0.8) and sensitivity and specificity ranged between 100 and 86% and 100-73% respectively. Even though there was a very high concordance between specific antibody levels and the IGRA assay in the ability to detect immune response to SARS-CoV-2, there was a relatively low quantitative correlation. In the small group primed by natural infection, one vaccine dose was sufficient to reach immune response plateau. IGRA was positive in one, with Ig(S) antibody negative vaccinated immunosuppressed HCW illustrating another advantage of the IGRA-test. Conclusion: Whole-blood-IGRA-tests amenable to automation and constitutes a promising additional tool for measuring the state of the immune response to SARS-CoV-2; they are applicable to large number of samples and may become a valuable correlate of protection to COVID-19, particularly for vulnerable groups at risk of being re-exposed to infection, as are health-care-workers.

Introducción: Es fundamental evaluar los niveles de protección inmune en infectados o tras la vacunación frente a SARS-CoV-2. La cuantificación de la respuesta inmune celular T puede complementar la determinación de anticuerpos. Evaluamos la viabilidad de un ensayo comercial validado de respuesta celular T específica frente a SARS-CoV-2. Métodos: Se incluyeron veinte trabajadores sanitarios (TS). Medimos anticuerpos contra las proteínas N y S de SARS-CoV-2 y realizamos el ensayo de liberación de interferón-gamma (IFNγ) en sangre completa (IGRA) frente a péptidos de la proteína S. IFNγ se determinó mediante dos métodos de detección: CLIA y ELISA. Resultados: IGRA detectó respuesta celular T en TS tanto infectados como vacunados. La correlación de los dos métodos de detección de IFNγ fue muy alta (R >0,8) y la sensibilidad y la especificidad variaron entre 100 y 86% y 100-73% respectivamente. Hubo una concordancia muy alta entre los niveles de anticuerpos específicos y el ensayo IGRA aunque la correlación cuantitativa fue relativamente baja. En el grupo de infectados, una dosis de vacuna fue suficiente para alcanzar el «plateau¼ de respuesta inmune. IGRA fue claramente positivo en un profesional vacunado inmunosuprimido que presentaba anticuerpos contra la proteína S negativos. Conclusiones: IGRA frente a péptidos de la proteína-S es susceptible de automatización y constituye una herramienta prometedora para medir la respuesta inmune celular frente a SARS-CoV-2; es aplicable a un gran número de muestras y puede servir para valorar la protección, particularmente en los grupos vulnerables en riesgo de volver a exponerse a la infección, como los TS.

Progress of research on changes of cellular immunity after SARS-CoV-2 infection

The major causes of death of patients with COVID-19 include metabolic acidosis, septic shock, pulmonary edema, multiple organ failure and deep venous thrombosis. These systemic manifestations are associated with severe pathological damages of vital organs like lung and kidney that are caused by inflammatory storms. The occurrence, development and deterioration of disease is closely associated with the immune imbalance mechanisms such as disorder of lymphocyte subsets and emergence of cytokine storm. The cellular immunity plays a vital role. The expression levels of some blood inflammatory factors of the severe COVID-19 patients are remarkably elevated, IL-6 is a typical proinflammatory factor that causes the cytokine storm, which can be used for prediction of prognosis. IL-6 blockade may be an effective method to block the cytokine storm.