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The TG6002.03 trial is a dose-escalation phase 1 clinical trial of TG6002 infusion via the hepatic artery in patients with liver-dominant colorectal cancer metastases. TG6002 is an engineered Copenhagen strain oncolytic Vaccinia virus, deleted of thymidine kinase and ribonucleotide reductase to enhance tumor selective viral replication and expressing FCU1, an enzyme converting the non-cytotoxic prodrug 5-fluorocytosine (5-FC) into the chemotherapeutic compound 5-fluorouracil (5-FU). In this trial, patients with advanced unresectable liver-dominant metastatic colorectal cancer who had failed previous oxaliplatin and irinotecan-based chemotherapy were treated with up to 2 cycles of TG6002 infusion 6 weeks apart via the hepatic artery on day 1 combined with oral 5-FC on days 5 to 14 (where day 1 = TG6002 infusion). TG6002 infusion was performed over 30 minutes via selective catheterization of the hepatic artery proper. 5-FC oral dosing was 50mg/kg x4 daily. Blood was sampled for TG6002 pharmacokinetics and 5-FC and 5-FU measurements. Sampling of liver metastases was performed at screening and on day 4 or day 8 for virus detection and 5-FC and 5-FU quantification. In total, 15 patients (median age 61 years, range 37-78) were treated in 1 UK centre and 2 centres in France and received a dose of TG6002 of 1 x 106 (n=3), 1 x 107 (n=3), 1 x 108 (n=3), or 1 x 109 pfu (n=6). Fourteen of the 15 patients received a single cycle of treatment, including one patient who did not received 5-FC, and one patient received two cycles. TG6002 was transiently detected in plasma following administration, suggesting a strong tissue selectivity for viral replication. In the highest dose cohort, a virus rebound was observed on day 8, concordant with replication time of the virus. In serum samples, 5-FU was present on day 8 in all patients with a high variability ranging from 0.8 to 1072 ng/mL and was measurable over several days after initiation of therapy. Seven of the 9 patients evaluable showed the biodistribution of the virus in liver lesions by PCR testing on day 4 or day 8. Translational blood samples showed evidence for T-cell activation and immune checkpoint receptor-ligand expression. At 1 x 109 pfu, there was evidence for T-cell proliferation and activation against tumour-associated antigens by ELISpot and for immunogenic cell death. In terms of safety, a total of 34 TG6002-related adverse events were reported, of which 32 were grade 1-2 and 2 were grade 3. The maximum tolerated dose was not reached, and a single dose-limiting toxicity was observed consisting of a myocardial infarction in a context of recent Covid-19 infection in a 78-year-old patient. These results indicate that TG6002 infused via the hepatic artery in combination with oral 5-FC was well tolerated, effectively localized and replicated in the tumor tissues, expressed its therapeutic payload and showed anti-tumoral immunological activity.
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Objective. To assess the T-cell immune status against SARS-CoV-2 in HIV patients with or without antiretroviral therapy. Patients and methods. The study included 21 HIV patients who had laboratory-confirmed COVID-19 between September and December 2021 without previous immunization against SARS-CoV-2. The characteristics of HIV infection (CD4-lymphocytes count, HIV viral load in blood plasma, the presence of antiretroviral therapy) and COVID-19 (the severity degree and duration of the disease) were analyzed, the T-cell immune response to SARS-CoV-2 was assessed using the ELISPOT method 1 month after COVID-19. Statistical analysis was carried out by non-parametric methods (Mann-Whitney U test, Spearman's rank correlation coefficient) using the IBM SPSS Statistics 22 software package. Results. The study showed a more favorable course of COVID-19 in HIV-infected persons who achieved HIV suppression in the blood: a mild form of the disease was significantly more common, and the virus was eliminated faster. T-cell immune response to SARS-CoV-2 was recorded more frequently in these patients. Significant correlation of T-cell immune status with the CD4-lymphocytes count and HIV suppression in the blood was revealed. Conclusion. Thus, T-cell immune response to SARS-CoV-2 as assessed using the ELISPOT method was registered significantl.Copyright © 2023, Dynasty Publishing House. All rights reserved.
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Background & Aim: Immunological characteristics of COVID-19 show pathological hyperinflammation associated with lymphopenia and dysfunctional T cell responses. These features provide a rationale for restoring functional T cell immunity in COVID-19 patients by adoptive transfer of SARS-CoV-2 specific T cells. Methods, Results & Conclusion(s): To generate SARS-CoV-2 specific T cells, we isolated peripheral blood mononuclear cells from 7 COVID-19 recovered and 13 unexposed donors. Consequently, we stimulated cells with SARS-CoV-2 peptide mixtures covering spike, membrane and nucleocapsid proteins. Then, we culture expanded cells with IL-2 for 21 days. We assessed immunophenotypes, cytokine profiles, antigen specificity of the final cell products. Our results show that SARSCoV- 2 specific T cells could be expanded in both COVID-19 recovered and unexposed groups. Immunophenotypes were similar in both groups showing CD4+ T cell dominance, but CD8+ and CD3+CD56+ T cells were also present. Antigen specificity was determined by ELISPOT, intracellular cytokine assay, and cytotoxicity assays. One out of 14 individuals who were previously unexposed to SARS-CoV-2 failed to show antigen specificity. Moreover, ex-vivo expanded SARS-CoV-2 specific T cells mainly consisted of central and effector memory subsets with reduced alloreactivity against HLA-unmatched cells suggesting the possibility for the development of third-party partial HLA-matching products. In conclusion, our findings show that SARSCoV- 2 specific T cell can be readily expanded from both COVID-19 and unexposed individuals and can therefore be manufactured as a biopharmaceutical product to treat severe COVID-19 patients.Copyright © 2023 International Society for Cell & Gene Therapy
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Background: To understand T-cell responses to SARS-CoV-2, it is essential to define the contribution of infection versus immunization to virus-specific hybrid immunity. Here, we characterized the breadth and magnitude of T-cell responses to the entire SARS-CoV2 proteome over a 2-year follow-up period in infected and vaccinated (CoV2+Vac+) and vaccinated and infected (Vac+CoV2+) individuals. Method(s): We selected samples from 38 (19 CoV2+ and 19 CoV2-, time1, T1) ProHEpiC-19 cohort participants, a prospective, longitudinal study starting in March 2020 involving 7,776 healthcare workers in Spain. Longitudinal samples were available from 10 of them after a 3-dose mRNA vaccination, including 5 CoV2+Vac+ and 5 Vac+CoV2+, at 824.5 and 250.5 days from symptoms onset (DfSO, time 2, T2). We measured the breadth and magnitude of IFN-y T-cell responses by ELISpot assay in cryopreserved PBMCs, using a 15-mer overlapping peptide (OLP) library of 2,790 SARS-CoV-2 peptides in 100 pools. Result(s): We identified immunodominant T-cell responses in S1, S2, nsp3, Env, NC, and M proteins across the SARS-CoV2 proteome. We observed an increased breadth of T-cell responses (responding pools over the entire region) to S1 (44 - 30%) and S2 (31 - 40%) in CoV2+Vac+ and Vac+CoV2+, respectively. In addition, CoV2+Vac+ had an exclusive and sustained response to M. We found significantly stronger responses in CoV2+Vac+ (P=0.0313). Particularly the total magnitude was greater in CoV2+Vac+ vs. Vac+CoV2+ in S1 (4476.88 vs. 1498.53), Env (457.34 vs. 250.50), and M (455.13 vs. 0.00) but not in S2 and nsp3. The total number of peptides for deconvolution was higher in CoV2+Vac+ (32 peptides) than in Vac+CoV2+ (3 peptides) during the follow-up. Seventy-five percent of the responses targeted S, and 25% M, ORF1a, and Env. Conclusion(s): These results profile immunodominant T-cell responses in S1, S2, nsp3, Env, NC, and M proteins across the entire SARS-CoV2 proteome. The data delineate differences in the number of T-cell responses primed hybrid immunity by infection previous to vaccination (CoV2+Vac+), being broader and of higher magnitude and underlining an exclusive T-cell response to the M region. Overall, these findings identify differences in long-term T-cell hybrid immunity primed by infection or vaccination, which may have implications in protection from re-infection and vaccine design.
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Background: People with HIV (PWH) older than age 55 have an enhanced risk of complications from SARS-CoV-2 infection. It is unclear whether COVID-19 vaccines with a booster are as durable in terms of immunogenicity in this cohort or whether these vaccines can destabilize HIV reservoirs. Method(s): We prospectively studied 91 PWH on cART aged 55 or over (n=91) and 23 age-matched individuals without HIV (control group, CG) who received three doses of COVID-19 vaccines (D1-D3) over 48 weeks. Participants received combinations of BNT162b2, mRNA-1273, and ChAdOx1. Of PWH, 42 were immune responders (IR), 20 were non-responders (INR), and 3 had a low-level viremia (LLV). Total and neutralizing Abs to SARS-CoV-2 spike (S) and RBD in sera and saliva, frequency of anti-RBD/NTD memory B cells (spectral flow cytometry), S-specific T cell immunity (IFN-g, IL-2 ELISpot) and HIV reservoirs in peripheral CD4+ T cells (IPDA) were measured. Result(s): No significant differences in vaccine regimens or dosing intervals were observed between PWH and CG. Vaccines elicited equally strong anti-S IgG in PWH vs CG in serum and saliva, and RBD IgG in serum. Serum Abs peaked at 4w after D3. Week 48 serum IgG in PWH vs CG were 916 vs 919 BAU/ mL for S (p=0.624) and 706 vs 752 for RBD (p=0.198), respectively. Week 48 median saliva S IgG: 48.1% AUC of the positive control in PWH vs 95.9% for CG (p=0.384). S IgA: 3.83 vs 20.5 in PWH vs CG (p=0.039). Median neutralizing titers post-D2 were significantly lower in PWH than in CG (NT50 82.9 vs 535, p< 0.001). However, after D3, at 48w, PWH had similar titers as CG: 309 vs 269 (p=0.745), mirroring an increase in RBD/NTD-specific B cells in PWH. Anti-S T cell cytokine responses were stronger in IR PWH after D2 and D3 than in CG. Week 48 S IL-2 responses: median 135 SFC/106 PBMC vs 43.8 (p< 0.001), but only 12.5 in INR (p=0.001 vs IR). COVID-19 vaccines did not affect the size of HIV reservoir in PWH (change in median frequency of intact proviruses from baseline: 95.0 vs 90.9, p=0.952), except in three LLV PWH (mean increase 93.7% at 48w). Conclusion(s): PWH aged 55 and over show diminished neutralizing Ab responses to SARS-CoV-2 with two vaccine doses which are 'rescued' after a booster. PWH have lower S-specific IgA in saliva after vaccination which may affect protection. Enhanced S-specific T cell immunity in PWH suggests Th1 imprinting from preexistent HIV infection. COVID-19 vaccines did not destabilize the HIV reservoir in most PWH but may pose potential risk in unsuppressed viremia.
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Background: Individuals living with HIV are at increased risk of morbidity and mortality from COVID-19. Furthermore, SARS-CoV-2 infection in immunocompromised HIV infected individuals poses a risk to prolonged infection and viral shedding and the emergence of new variants of concern (VOCs). Using the SIV macaque model for AIDS, we are investigating the hypothesis that immune dysfunction during HIV infection will prolong SARSCoV- 2 viral infection, promote enhanced COVID-19 disease, and accelerate viral evolution. Here, we report the impact of SIV-CoV-2 co-infection on immune responses and pathogenesis. Method(s): Eight female rhesus macaques (aged 7-15 years, 5.5-9.9kg) were infected with SIVmac251 via low dose intravaginal challenge and then inoculated with 6.5x105 TCID50/mL SARS-CoV-2 (WA-1) at 17-34 weeks post-SIV infection via combined intranasal and intratracheal routes. Blood, bronchoalveolar lavage (BAL), stool, and nasal, oral, and rectal swabs were collected pre-infection through 14 days post-infection (DPI) to measure immune responses and viremia. ELISAs, ELISPOT, qRT-PCR, lung pathology, cytokine multiplex, and virus neutralization assays were performed to measure viral loads, pathogenesis, and immune responses. Result(s): Three days post-SARS-CoV-2 infection, we observed a transient decrease in CD4 counts, but there were no changes in clinical symptoms or plasma SIV viral loads. However, SARS-CoV-2 replication persisted in the upper respiratory tract, but not the lower respiratory tract. In addition, SARS-CoV-2 IgG seroconversion was delayed and antigen-specific T-cell responses were dampened. Notably, viral RNA levels in nasal swabs were significantly higher 7-14 DPI in SIV+ compared to previously published results using the same SARS-CoV-2 challenge virus in SIV- rhesus (PMCID: PMC8462335, PMC8829873). In addition, SIV/CoV-2 co-infected animals exhibited elevated levels of myeloperoxidase (MPO), a marker of neutrophil activation and increased lung inflammation. Conclusion(s): Here we provide evidence for the utility of the rhesus macaque in modeling human HIV-SARS-CoV-2 co-infection. Our results suggest that immunosuppression during SIV infection impairs de novo generation of anti-SARS-CoV-2 immunity, that may contribute to prolonged SARS-CoV-2 viral shedding, increased transmission windows, altered disease pathogenesis, and lower protection against subsequent SARS-CoV-2 exposures. Studies in progress will determine if SARS-CoV-2 viral evolution is accelerated in SIV-infected macaques.
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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).
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Background: T cells play a critical role in the adaptive immune response to SARS-CoV-2 in both infection and vaccination. Identifying T cell epitopes and understanding how T cells recognize these epitopes can help inform future vaccine design and provide insight into T cell recognition of newly emerging variants. Here, we identified SARS-CoV-2 specific T cell epitopes, analyzed epitope-specific T cell repertoires, and characterized the potency and cross-reactivity of T cell clones across different common human coronaviruses (HCoVs). Method(s): SARS-CoV-2-specific T cell epitopes were determined by IFNgamma ELISpot using PBMC from convalescent individuals with mild/moderate disease (n=25 for Spike (S), Nucleocapsid (N) and Membrane (M)), and in vaccinated individuals (n=27 for S). Epitope-specific T cells were isolated based on activation markers following a 6-hour peptide stimulation, and scRNAseq was performed for TCR repertoire analysis. T cell lines were generated by expressing recombinant TCRs in Jurkat cells and activation was measured by CD69 upregulation. Result(s): We identified multiple immunodominant T cell epitopes across S, N and M proteins in convalescent individuals. In vaccinated individuals, we detected many of the same dominant S-specific epitopes at similar frequencies as compared to convalescent individuals. T cell responses to peptide S205 (amino acids 817-831) were observed in 56% and 59% of individuals following infection and vaccination, respectively, while 20% and 19% of individuals responded to S302 (a.a. 1205-1219) following infection and vaccination, respectively. For S205, a CD4+ T cell response, we confirmed 8 unique TCRs and determined the minimal epitope to be a 9mer (IEDLLFNKV). While TCR genes TRAV8-6*01 and TRBV30*01 were commonly utilized across the TCRs, we did identify TCRs with unique immunogenetic properties with different potencies of cross-reactivity to other HCoVs. For S302, a CD8+ T cell response, we identified two unique TCRs with different immunogenetic properties that recognized the same 9mer (YIKWPWYIW) and cross-reacted with different HCoV peptides (Figure 1). Conclusion(s): These data identify immunodominant T cell epitopes following SARS-CoV-2 infection and vaccination and provide a detailed analysis of epitope-specific TCR repertoires. The prospect of developing a vaccine that broadly protects against multiple human coronaviruses is bolstered by the identification of conserved immunodominant SARS-CoV-2 T cell epitopes that cross react with multiple other HCoVs.
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Introduction. In the context of a pandemic of a new coronavirus infection (COVID-19), research on the peculiarities of the formation of an immune response to SARS-CoV-2 in patients who have been ill and vaccinated is of particular relevance. However, most studies are currently devoted to evaluating only the humoral link of immunity, and its cellular component remains insufficiently studied. The aim of the study was to evaluate the features of the formation and changes of the T-cell link of immunity in patients with a new coronavirus infection and vaccinated against this disease. Materials and methods. The study was performed on the basis of the clinical and diagnostic laboratory of the European Medical Center "UMMC-Health "LLC. Specific T-cell immunity was evaluated using ELISPOT technology. In the course of the study, 72 blood samples of employees of medical organizations were analyzed, including 26 from those who had a new coronavirus infection, 23 from persons who were intact according to COVID-19 before vaccination and 23 from the same employees after vaccination (<<Gam-Covid-Vac>>). In addition, each of the study participants was examined to determine specific class G antibodies (IgG) by solid-phase enzyme immunoassay using SARS-CoV-2-IgG-ELISA-BEST test systems (manufactured by VECTOR-BEST JSC). Results and discussion. In the group of patients (26 people), T-lymphocytes capable of specifically reacting to SARSCoV-2 antigens were detected in 100% of cases, even in individuals with IgG elimination. It should be noted that the response was more pronounced when meeting with M-and N-pepdids, compared with S-protein. 22 out of 23 COVID-19 intact individuals had no T-cell immunity to coronavirus infection before vaccination, but one employee had a response to 3 proteins-M, N, S, which indicates that he had previously encountered the SARS-CoV-2 virus. After vaccination with the drug "Gam-Covid-Vac", 22 (95.6%) employees revealed a T-cell response, while 21-only to S-protein, and an employee with a previously detected immune response-after vaccination, the response to M -, N-proteins remained almost at the same level, and the cellular response to S-peptide doubled. Conclusion. Thus, based on the results of the study, important materials were obtained on the peculiarities of the formation of a specific T-cell immune response to a new coronavirus infection. The obtained data provide a broader understanding of the immune response in new coronavirus infection in patients who have been ill and vaccinated and can be used in the future when planning preventive and anti-epidemic measures.Copyright © 2022 Interregional public organization Association of infectious disease specialists of Saint-Petersburg and Leningrad region (IPO AIDSSPbR). All rights reserved.
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Introduction. In the context of a pandemic of a new coronavirus infection (COVID-19), research on the peculiarities of the formation of an immune response to SARS-CoV-2 in patients who have been ill and vaccinated is of particular relevance. However, most studies are currently devoted to evaluating only the humoral link of immunity, and its cellular component remains insufficiently studied. The aim of the study was to evaluate the features of the formation and changes of the T-cell link of immunity in patients with a new coronavirus infection and vaccinated against this disease. Materials and methods. The study was performed on the basis of the clinical and diagnostic laboratory of the European Medical Center "UMMC-Health "LLC. Specific T-cell immunity was evaluated using ELISPOT technology. In the course of the study, 72 blood samples of employees of medical organizations were analyzed, including 26 from those who had a new coronavirus infection, 23 from persons who were intact according to COVID-19 before vaccination and 23 from the same employees after vaccination (<<Gam-Covid-Vac>>). In addition, each of the study participants was examined to determine specific class G antibodies (IgG) by solid-phase enzyme immunoassay using SARS-CoV-2-IgG-ELISA-BEST test systems (manufactured by VECTOR-BEST JSC). Results and discussion. In the group of patients (26 people), T-lymphocytes capable of specifically reacting to SARSCoV-2 antigens were detected in 100% of cases, even in individuals with IgG elimination. It should be noted that the response was more pronounced when meeting with M-and N-pepdids, compared with S-protein. 22 out of 23 COVID-19 intact individuals had no T-cell immunity to coronavirus infection before vaccination, but one employee had a response to 3 proteins-M, N, S, which indicates that he had previously encountered the SARS-CoV-2 virus. After vaccination with the drug "Gam-Covid-Vac", 22 (95.6%) employees revealed a T-cell response, while 21-only to S-protein, and an employee with a previously detected immune response-after vaccination, the response to M -, N-proteins remained almost at the same level, and the cellular response to S-peptide doubled. Conclusion. Thus, based on the results of the study, important materials were obtained on the peculiarities of the formation of a specific T-cell immune response to a new coronavirus infection. The obtained data provide a broader understanding of the immune response in new coronavirus infection in patients who have been ill and vaccinated and can be used in the future when planning preventive and anti-epidemic measures.Copyright © 2022 Interregional public organization Association of infectious disease specialists of Saint-Petersburg and Leningrad region (IPO AIDSSPbR). All rights reserved.
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The year 2020 was the most challenging period due to the havoc caused by the outbreak of novel coronavirus SARS-CoV-2. Scientists and researchers all around the world have endeav-ored every possible approach to find solutions in context to therapeutics and vaccines to control the spread of this life-threatening virus. The acceleration instigated by the outbreak of SARS-CoV-2 and its mutated strains has leveraged the use of numerous platform technologies for the development of vaccines against this unfathomable disease. Vaccines could play an important role in miti-gating the effects of COVID-19 and reducing the ongoing health crisis. Various innovative plat-forms like proteins, nucleic acids, viruses, and viral vectors have been exploited to fabricate vaccines depicting almost 90% of efficacy like BNT162b2, AZD1222, Ad5-nCoV, etc. Some of these vaccines are multipotent and have shown potent activity against newly emerged malicious strains of SARS-CoV-2 like B.1.351 and B.1.1.7. In this review article, we have gathered key findings from various sources of recently popularized vaccine candidates, which will provide an overview of potential vaccine candidates against this virus and will help the researchers to investi-gate possible ways to annihilate this menace and design new moieties.Copyright © 2022 Bentham Science Publishers.
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Background: The effects of immunosuppressive medications on immune responses to COVID-19 vaccination in patients with inflammatory bowel diseases (IBD) have been reported. However there is little data on immune responses in naturally infected SARS-CoV-2 patients compared with vaccination. We compared in a longitudinal study SARS-CoV-2 antibody and T cell responses in naturally-infected vs. vaccinated IBD patients Methods: 110 IBD patients enrolled at the Icahn School of Medicine at Mount Sinai were prospectively followed with serial blood collection between May 2020, and February 2022. Samples were screened by ELISA to determine seropositivity, and stratified by infection, vaccination status, and IBD medications. Subsequently, ELISA-based inhibition assay and pseudotyped SARS-CoV-2 microneutralization assays were used to determine the inhibition and neutralization capacity of the seropositive individuals for wild type (WT) delta variant (Dv) and Omicron. Cellular responses were measured by IFN-gamma ELIspot using nucleocapsid and spike peptide libraries Results: Overall, 64 patients had Crohn's Disease and 46 had Ulcerative Colitis (UC), 69 were naturally infected. Only Anti-TNF (N=52), Ustekinumab (N=16), and Vedolizumab (VDZ) (N=33) treatment groups were considered. Only US-available vaccinations were included. Double-vaccinated IBD patients showed greater neutralizing responses to SARS-CoV-2 WT and Dv than naturally-infected individuals (p=0.0003, p=0.0025). Moreover, double-vaccinated individuals had greater neutralizing reactions against WT than DV (p 0.017) and Omicron (p 0.001) variants. Following natural infection, there were no differences between treatment groups in neutralization response, however those double-vaccinated on anti-TNF had lower neutralization than VDZ (p=0.008). Neutralization responses were maintained for a period of 8 months following natural infection and double vaccination SARS-CoV-2 spike T cell responses were significantly higher in naturally infected (p=0.009) and double vaccinated individuals (p=0.005) with no significant differences between treatment groups (p<0.999) Conclusion(s): After a second vaccine dose, IBD patients showed stronger neutralizing antibody titers than naturally infected patients. Those on anti-TNF exhibited lower neutralizing responses than VDZ. T-cell responses were similar in infected and double-vaccinated subjects after vaccination or infection. These data imply COVID-19 immunization provides additional serological protection over natural infection.
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Pre-existing SARS-CoV-2-specific T cells, but not antibodies, have been detected in some unexposed individuals. This may account for some of the diversity in clinical outcomes ranging from asymptomatic infection to severe COVID-19. Although age is a risk factor for COVID-19, how age affects SARS-CoV-2-specific T cell responses remains unknown. We found that pre-existing T cell responses to specific SARS-CoV-2 proteins, Spike (S) and Nucleoprotein (N), were significantly lower in elderly donors (>70 years old) than in young donors. However, substantial pre-existing T cell responses to the viral membrane (M) protein were detected in both young and elderly donors. In contrast, young and elderly donors exhibited comparable T cell responses to S, N, and M proteins after infection with SARS-CoV-2. These data suggest that although SARS-CoV-2 infection can induce T cell responses specific to various viral antigens regardless of age, diversity of target antigen repertoire for long-lived memory T cells specific for SARS-CoV-2 may decline with age;however, memory T cell responses can be maintained by T cells reactive to specific viral proteins such as M. A better understanding of the role of pre-existing SARS-CoV-2-specific T cells that are less susceptible to age-related loss may contribute to development of more effective vaccines for elderly people.Copyright © 2021
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Background: Viral infections and reactivations (e.g. cytomegalovirus (CMV)) are a major cause of morbidity and mortality after hematopoietic stem cell transplantation (HSCT) and solid organ transplantation (SOT) and in patients with immunodeficiencies. Here, antiviral drugs are the mainstay of treatment, but they have side effects and cannot achieve complete viral clearance without prior reconstitution of functional virus-specific T cells (VSTs). Method(s): We performed serological testing and measured VST frequencies against 23 viral protein-derived peptide pools of 11 clinically relevant human viruses by Interferon-gamma (IFN-gamma) ELISpot assay in a cohort of healthy donors (n=151). Moreover, we performed in-depth immune profiling in patients actively infected with SARS-CoV-2 (n=92) and in unvaccinated, recovered COVID-19 patients (n=204) by ELISA, ELISpot, multicolor flow cytometry and multiplex analysis. Result(s): Based on serological testing, IFN-gamma ELISpot results, age and sex, we established normal ranges for VST frequencies in healthy donors for better interpretation of VST frequencies observed in immunocompromised patients. While in SARS-CoV-2 recovered patients, the antiviral immune response was characterized by a broad specificity, significantly lower T-cell responses were observed during active infection. Comparison with the previously established reference values for VST frequencies revealed an overall reduced T-cell functionality based on the lack of CMV-pp65-reactive T cells in CMV-seropositive COVID-19 patients, which was associated with an inflammatory milieu, expression of inhibitory molecules, and effector caspase activity in T cells. Conclusion(s): The established reference values are an invaluable tool for immune response assessment, therapeutic agent intensity and decision making in immunocompromised patients. Further, we provide evidence that the low T-cell response observed during SARS-CoV-2 infection is not exclusively due to lymphopenia, but rather due to checkpoint- and cell death-associated mechanisms, suggesting that these patients may benefit from SARS-CoV-2-specific T-cell therapy.
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Background. The SARS-CoV-2 pandemic continues, with new variants of concern fueling periodic increases in COVID-19 cases. Authorized vaccines have provided protection against severe disease but less so for incident cases. Boosts with these vaccines have demonstrated waning protection. New vaccines, including those which induce immunity against more conserved regions outside of Spike, may improve upon these and be key to long-term protection and may be a useful approach against novel coronaviruses. Methods. GO-009 (CORAL-Boost, NCT05148962) is an open-label study, conducted in the UK, of a self-amplifying mRNA vaccine encoding for Wuhan Spike (S) and highly conserved non-S T cell epitopes (GRT-R910;R910). R910 is given as 1 or 2 doses after vaccination with an authorized adenovirus or mRNA SARS-CoV-2 vaccine. The first two cohorts assessed 10mug and 30mug doses of R910 in older (>=60y) adults who had previously received ChAdOx1. Subsequent cohorts assess two boost doses in older and younger adults who have received an adenovirus or mRNAvaccine. Primary objectives are safety and reactogenicity and secondary objectives include cellular and humoral immunogenicity. Results. Ten and seven adults received 10 or 30mug (cohorts 1 and 2) of R910, respectively. Reactogenicity and unsolicited adverse events were mostly mild/moderate and transient. The majority of severe events (malaise, fatigue, myalgia, Inj. site pain/ tenderness/swelling) after dose 1 were experienced by 1 subject in cohort 2. Analysis of both IgG binding and neutralizing antibodies demonstrated a boost of anti-S antibodies after one dose of R910;geomean ID50 titers from 92 to 2370 and 99 to 1553 for 10 and 30mug, respectively. ELISpot analyses demonstrated that R910 boosted and broadened T cell responses to S and non-S T cell epitopes. Conclusion. R910 was well tolerated. One R910 boost vaccination increased existing humoral and cellular immunity against S while inducing a broad T cell response against non-S SARS-CoV-2 proteins. A 10mug R910 boost increased neutralizing antibody titers comparable to a 10-fold higher dose (100mug) with authorized mRNA vaccines in a similar population (Munro et al 2021). A 10mug dose was selected for further study. Data post mRNA primary series will also be presented.
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Background. Which components of the immune response to SARS-CoV-2 vaccination best protect against subsequent infection remains unclear. We explored SARS-CoV-2 specific antibody and B-cell responses post 3rd dose vaccine and their relationship to subsequent SARS-CoV-2 infection. Methods. In a multicentre prospective cohort, adult subjects provided samples before and 14 days (d14) post 3rd dose vaccine with Pfizer-BioNTech 162b2. At 18-22 weeks post vaccine, subjects self-reported SARS-CoV-2 infection (confirmed by PCR or antigen test). We used electrochemiluminescence assays to quantify antibodies to SARS-CoV-2 spike subunit 1 (S1), subunit 2 (S2) and receptor-binding domain (RBD) in plasma (reported inWHOIU/mL). In a subset of subjects, we assessed SARS-CoV-2 specific differentiated B-cell (plasma cell) and memory B-cell responses from peripheral blood mononuclear cells. Unstimulated plasma cells, and memory B cells stimulated with R848 and IL2, were seeded on plates coated with RBD or full Spike antigen and antigen-specific responses measured by ELISpot (Mabtech ELISpot, Sweden). We compared between group differences by Wilcoxon signed rank or Mann-Whitney tests. Data are median [IQR] unless specified. Results. Of 133 subjects (age 43 [32-50], 81.2% female (table 1), 77 subjects in the B-cell subgroup (table 2)), 47 (35.3%) reported SARS-CoV-2 infection post 3rd vaccine. Antibody titres, plasma cell and memory B-cell responses all increased significantly at d14 post 3rd vaccine (Table 1 & 2, all P< 0.001). Although d14 antibody titres did not differ in those with and without subsequent infection (table 1), those reporting subsequent infection had significantly lower d14 RBD-specific plasma cells and a lower proportion of RBD-specific memory B-cells (Figure 1a-b, both P< 0.05). Similar results were observed with full-spike-specific memory B-cell responses (Figure 1d). The differences persisted when the non-infected group was restricted only to those reporting a confirmed close contact (n=26). Conclusion. Infection following 3rd dose vaccine is associated with lower d14 circulating and memory B cell responses, but not antibody titres, suggesting B-cell responses better predict protection against subsequent SARS-CoV-2 infection.
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Background. To describe post-COVID-19 vaccination [fully vaccinated (FV) and first booster] immune response and occurrence of reinfection ( >90 days from prior infection) in nursing home residents (NHr) with/without evidence of prior SARS-CoV-2 infection. Methods. In a longitudinal prospective cohort of 36 NHr from 3 NHs, interviews, chart ions, and specimens [blood and anterior nasal swabs (ANs)] were collected at baseline and monthly visits. ANs underwent molecular and BinaxNOWTM antigen testing. Quantitative Meso Scale Discovery platform tested blood specimens for anti-spike (S) protein and anti-nucleocapsid (N) antibodies. In addition, in a subset (n=13), S-specific memory B cells (MBCs) were tested with ELISpot assays. Results. The cohort's median age was 72 years;46% male, 64% White Non-Hispanic, 80% had >=3 comorbidities, and 29 (81%) had prior SARS-CoV-2 infection. Of 36, 76% received Pfizer-BioNTech and 24% Moderna homologous vaccine. The median distribution of anti-S IgG concentrations among those with prior infection increased 15-30 days post-FV, remained stable for 90 days, and declined by 120 days. The anti-S IgG remained above the estimated vaccine effectiveness (VE) thresholds published [Pfizer-BioNTech (95% VE: 530 BAU/ml), Moderna (90% VE: 298 BAU/ml)]. Among those without previous infection, anti-S IgG declined after 60 days and stayed near the VE thresholds until a recent infection/booster. Age, sex, and comorbidities had no appreciable impact on anti-S IgG. From enrollment to November 2021, 1of 29 had reinfection. From December 2021 to January 2022, 2 of 7 had a new infection, and 4 of 29 had reinfection, as shown by anti-N IgG rise. Persistently low numbers of total and anti-S MBC were seen across the evaluation, even with post-booster anti-S MBC rise. There was an immediate rise in anti-S IgG concentrations in all participants post-booster, irrespective of recent infection. Conclusion. These findings from a NH convenience cohort suggest that prior SARS-CoV-2 infection has a pronounced immunomodulatory enhancing effect on the magnitude and duration of FV immune response. The decline of anti-S antibodies post-FV and rise after booster supported the booster recommendation in this cohort. The low MBC counts indicate immunosenescence in this high-risk population.
ABSTRACT
The cellular responses to the BNT162b2 vaccine and their correlation with antibody titer and gender determinants are critical to assess. We aimed to evaluate the cellular response kinetics, correlating it with gender and antibody titer.Peripheral Blood Mononuclear Cells (PBMC) were stimulated with SARS-CoV-2 Spike protein, and the IFN-gamma was evaluated by Elispot assay at 5 different timepoints, for up to 9 months after the BNT162b2 vaccine. 107 healthcare workers were divided into 4 age groups: <40 and >40 years for men, based on the gradual decline of testosterone with aging;<48 and >48 years for women based on the decrease of estrogen with menopause. Furthermore, seropositive individuals were analyzed at baseline to avoid confounding factors caused by the previous infection with SARS-CoV-2. We also analyzed pre-pandemic samples as controls to consider the cross-reactivity toward other coronaviruses. Among seronegative at baseline, the T-cell response against Sprotein changed from a median of 2 spot forming cells (SFC)/400.000 PBMC (Interquartile range, IQR, 0-17) before vaccination to a median of 42 (17.5-78.0) after the second dose. Then, it progressively decreased to 13 (0-34) at 6 months after vaccination and 11 (0-31) after 9 months. At all timepoints, the differences were statistically significant compared to baseline values. Moreover, the results obtained after the second dose were significantly higher than those observed at any other time point. Indeed, a significant correlation was observed between T-cell response and anti-S antibody titer (p<0.001), previously analyzed, even if it was weak in magnitude (r=0.314). Natural seropositive showed higher T cell response at baseline than seronegative ones (median: 2 vs. 29, p=0.003), even if there were no significant differences in response at later time points. Our data suggest that T-cell reactiveness is poorly impacted by sex and age, whereas age was significantly associated with anti-S antibody titer. T-cell response declines 9 months later administration, indicating a waning of immune response over time. So, the positive correlation with the antibody titer confirms a linkage between different arms of adaptive responses and potentially converts future vaccinations into a tailored process.
ABSTRACT
Introduction: Prevention of COVID by vaccination is important in allogeneic HSCT recipients but impaired humoral and cellular responses have been reported. To gain further insights into the immune defects leading to impaired immune, we performed a high-throughput T cell receptor (TCR) repertoire profiling of cells recovered from allogeneic HSCT recipients or healthy controls after SARS-CoV2 natural infection or mRNA-based vaccination. Method(s): Peripheral blood samples were obtained from allogeneic HSCT recipients after a median of 3 months after COVID- 19 infection (n = 11) or 44 days after vaccination with 3 doses of mRNA-based SARS-CoV-2 vaccines (n = 13). Healthy controls at 1 to 3 months after SARS-CoV-2 infection (n = 10) or vaccination served as controls (n = 10). SARS-CoV-2- specific T cell clonotypes were identified by genomic DNA T-cell receptor (TCR) sequencing (immunoSEQ T-MAPTM COVID, Adaptive). SARS-CoV-2-specific T cell responses were quantified based on IFN-gamma release against a range of peptides from the SARS-CoV-2 proteins using an ELISpot assay. Result(s): HSCT recipients displayed significantly reduced SARS-CoV-2-specific T cell clonotypes compared with HC (p = 0.0037;Figure 1 A-B)as well as a less diverse TCR repertoire as revealed by higher Simpson clonality (p = 0.0079). We also observed significantly lower numbers of IFN-gamma spot forming units after stimulation of PBMCs from HSCT recipients with peptides from both the S protein (p = 0.0068) and the M plus N proteins (p = 0.0067) compared with HC. Performing the same analysis after SARS-CoV-2 mRNA vaccination, we observed a significant reduction in S-protein-specific T cell clonotypes in allogeneic HSCT recipient compared to HC (p = 0.0003;Figure 1D-E). We detected a significantly negative correlation between the Simpson clonality and the number of different S-protein specific T cell clonotypes after vaccination (r2 = 0.55, p = 7.8e-05;Figure 1F). ELISpot analysis of PBMCs recovered after vaccination and stimulated with S-protein peptides revealed significantly lower numbers of IFN-gamma spot forming units in HSCT recipients compared with HC (p = 0.019), confirming the results obtained by TCR-seq. Conclusion(s): Allogeneic HSCT recipients display a quantitative and qualitative defect in cellular SARS-CoV-2-specific responses asscociated with a reduced TCR repertoire after COVID-19 infection and vaccination. (Figure Presented).