Detectable T-cell Responses Research Articles

Immunogenicity of third dose COVID-19 vaccine strategies in patients who are immunocompromised with suboptimal immunity following two doses (OCTAVE-DUO): an open-label, multicentre, randomised, controlled, phase 3 trial

The humoral and T-cell responses to booster COVID-19 vaccine types in multidisease immunocompromised individuals who do not generate adequate antibody responses to two COVID-19 vaccine doses, is not fully understood. The OCTAVE DUO trial aimed to determine the value of third vaccinations in a wide range of patients with primary and secondary immunodeficiencies. OCTAVE-DUO was a prospective, open-label, multicentre, randomised, controlled, phase 3 trial investigating humoral and T-cell responses in patients who are immunocompromised following a third vaccine dose with BNT162b2 or mRNA-1273, and of NVX-CoV2373 for those with lymphoid malignancies. We recruited patients who were immunocompromised from 11 UK hospitals, aged at least 18 years, with previous sub-optimal responses to two doses of SARS-CoV-2 vaccine. Participants were randomly assigned 1:1 (1:1:1 for those with lymphoid malignancies), stratified by disease, previous vaccination type, and anti-spike antibody response following two doses. Individuals with lived experience of immune susceptibility were involved in the study design and implementation. The primary outcome was vaccine-specific immunity defined by anti-SARS-CoV-2 spike antibodies (Roche Diagnostics UK and Ireland, Burgess Hill, UK) and T-cell responses (Oxford Immunotec, Abingdon, UK) before and 21 days after the third vaccine dose analysed by a modified intention-to-treat analysis. The trial is registered with the ISRCTN registry, ISRCTN 15354495, and the EU Clinical Trials Register, EudraCT 2021-003632-87, and is complete. Between Aug 4, 2021 and Mar 31, 2022, 804 participants across nine disease cohorts were randomly assigned to receive BNT162b2 (n=377), mRNA-1273 (n=374), or NVX-CoV2373 (n=53). 356 (45%) of 789 participants were women, 433 (55%) were men, and 659 (85%) of 775 were White. Anti-SARS-CoV-2 spike antibodies measured 21 days after the third vaccine dose were significantly higher than baseline pre-third dose titres in the modified intention-to-treat analysis (median 1384 arbitrary units [AU]/mL [IQR 4·3-7990·0] compared with median 11·5 AU/mL [0·4-63·1]; p<0·001). Of participants who were baseline low responders, 380 (90%) of 423 increased their antibody concentrations to more than 400 AU/mL. Conversely, 166 (54%) of 308 baseline non-responders had no response after the third dose. Detectable T-cell responses following the third vaccine dose were seen in 494 (80%) of 616 participants. There were 24 serious adverse events (BNT612b2 eight [33%] of 24, mRNA-1273 12 [50%], NVX-CoV2373 four [17%]), two (8%) of which were categorised as vaccine-related. There were seven deaths (1%) during the trial, none of which were vaccine-related. A third vaccine dose improved the serological and T-cell response in the majority of patients who are immunocompromised. Individuals with chronic renal disease, lymphoid malignancy, on B-cell targeted therapies, or with no serological response after two vaccine doses are at higher risk of poor response to a third vaccine dose. Medical Research Council, Blood Cancer UK.

Orthopoxvirus-Specific T-Cell Responses in Convalescent Mpox Patients.

Orthopoxvirus-specific T-cell responses were analyzed in 10 patients who had recovered from Mpox including 7 people with human immunodeficiency virus (PWH). Eight participants had detectable virus-specific T-cell responses, including a PWH who was not on antiretroviral therapy and a PWH on immunosuppressive therapy. These 2 participants had robust polyfunctional CD4+ T-cell responses to peptides from the 121L vaccinia virus (VACV) protein. T-cells from 4 of 5 HLA-A2-positive participants targeted at least 1 previously described HLA-A2-restricted VACV epitope, including an epitope targeted in 2 participants. These results advance our understanding of immunity in convalescent Mpox patients.

Features of cytomegalovirus DNAemia and virus-specific T-cell responses in allogeneic hematopoietic stem-cell transplant recipients during prophylaxis with letermovir.

There is scarce information on the natural kinetics of cytomegalovirus (CMV) DNAemia and dynamics of CMV-specific T-cell reconstitution in allogeneic hematopoietic transplant recipients (allo-HSCT) undergoing letermovir (LMV) prophylaxis. Twelve adult CMV-seropositive high-risk recipients (median age, 53 years; 9 males/3 females) undergoing LMV prophylaxis and 13 non-LMV allo-HSCT controls (median age, 58 years; 7 males/6 females) were included. CMV DNAemia in plasma was monitored by real-time polymerase chain reaction. Preemptive antiviral therapy (PET) was administered upon detection of ≥1500IU/ml. CMV-specific interferon-gamma (IFN-γ)-producing CD8+ and CD4+ T cells were enumerated by flow cytometry around days +30, +60, and +90 after allo-HSCT. Ex vivo experiments assessing of the potential effect of LMV on CMV-specific T-cell expansion in a single CMV-seropositive donor were also conducted. Five LMV patients (41.6%) developed CMV DNAemia that cleared spontaneously. Four patients (33.3%) developed CMV DNAemia after LMV cessation, of which two required PET. Nine non-LMV patients (69.2%) developed CMV DNAemia (five required PET). The percentage of LMV and non-LMV patients exhibiting detectable CMV-specific T-cell responses was comparable (7/10 vs. 10/13; p=.71). Nevertheless, median CMV-specific CD4+ and CD8+ T-cell counts were lower in LMV patients by days +60 (p=.006 and .02, respectively) and +90 (p=.08 and .02). Ex vivo, CMV-specific CD8+ T cells expanded to the same level either in the presence (19.8%) or in the absence of LMV (20.6%). In our series, episodes of CMV DNAemia in LMV patients cleared spontaneously. A diminished degree of CMV-specific T-cell reconstitution in LMV patients compared to non-LMV patients was observed.

Attenuated humoral responses in HIV after SARS-CoV-2 vaccination linked to B cell defects and altered immune profiles

We assessed a cohort of people living with human immunodeficiency virus (PLWH) (n= 110) and HIV negative controls (n= 64) after 1, 2 or 3 SARS-CoV-2 vaccine doses. At all timepoints, PLWH had significantly lower neutralizing antibody (nAb) titers than HIV-negative controls. We also observed a delayed development of neutralization in PLWH that was underpinned by a reduced frequency of spike-specific memory B cells (MBCs). Improved neutralization breadth was seen against the Omicron variant (BA.1) after the third vaccine dose in PLWH but lower nAb responses persisted and were associated with global MBC dysfunction. In contrast, SARS-CoV-2 vaccination induced robust Tcell responses that cross-recognized variants in PLWH. Strikingly, individuals with low or absent neutralization had detectable functional Tcell responses. These PLWH had reduced numbers of circulating T follicular helper cells and an enriched population of CXCR3+CD127+CD8+T cells after two doses of SARS-CoV-2 vaccination.

Immune responses following 3rd and 4th doses of heterologous and homologous COVID-19 vaccines in kidney transplant recipients.

BackgroundSolid organ transplant recipients have attenuated immune responses to SARS-CoV-2 vaccines. In this study, we report on immune responses to 3rd- (V3) and 4th- (V4) doses of heterologous and homologous vaccines in a kidney transplant population.MethodsWe undertook a single centre cohort study of 724 kidney transplant recipients prospectively screened for serological responses following 3 primary doses of a SARS-CoV2 vaccine. 322 patients were sampled post-V4 for anti-spike (anti-S), with 69 undergoing assessment of SARS-CoV-2 T-cell responses. All vaccine doses were received post-transplant, only mRNA vaccines were used for V3 and V4 dosing. All participants had serological testing performed post-V2 and at least once prior to their first dose of vaccine.Findings586/724 (80.9%) patients were infection-naïve post-V3; 141/2586 (24.1%) remained seronegative at 31 (21-51) days post-V3. Timing of vaccination in relation to transplantation, OR: 0.28 (0.15-0.54), p=0.0001; immunosuppression burden, OR: 0.22 (0.13-0.37), p<0.0001, and a diagnosis of diabetes, OR: 0.49 (0.32-0.75), p=0.001, remained independent risk factors for non-seroconversion. Seropositive patients post-V3 had greater anti-S if primed with BNT162b2 compared with ChAdOx1, p=0.001.Post-V4, 45/239 (18.8%) infection-naïve patients remained seronegative. De novo seroconversion post-V4 occurred in 15/60 (25.0%) patients. There was no difference in anti-S post-V4 by vaccine combination, p=0.50. T-cell responses were poor, with only 11/54 (20.4%) infection-naive patients having detectable T-cell responses post-V4, with no difference seen by vaccine type.InterpretationA significant proportion of transplant recipients remain seronegative following 3- and 4- doses of SARS-CoV-2 vaccines, with poor T-cell responses, and are likely to have inadequate protection against infection. As such alternative strategies are required to provide protection to this vulnerable group.FundingMW/PK received study support from Oxford Immunotec.

MO877: Dynamics of SARS-COV-2-Spike-Reactive Antibody and T-Cell Responses in Chronic Kidney Disease Patients Within 3 Months After Covid-19 Full Vaccination

BACKGROUND AND AIMSLittle is known regarding the dynamics of antibody and T-cell responses in chronic kidney disease (CKD) following COVID-19 vaccination.METHODProspective observational cohort study including 144 participants on haemodialysis (HD) (n = 52), peritoneal dialysis (PD) (n = 14), kidney transplantation (KT) (n = 30) or advanced chronic kidney disease not on dialysis (ACKD), and healthy controls (n = 18). Anti-Spike(S) antibody and T-cell responses were assessed at 15 days (15D) and 3 months (3M) after vaccination.RESULTSAnti-S antibodies at 15D and 3M were detectable in 95% (48/50)/98% (49/50) of HD patients, 93% (13/14)/100% of PD patients, 67% (17/26)/75% (21/28) of KT patients and 96% (25/26)/100% (24/24) of ACKD patients. Rates for healthy controls were 81% (13/16)/100% (17/17). Antibody levels decreased at 3M in HD (P = 0.04), PD (P = 0.008) and ACKD patients (P = 0.0009). In KT, patients levels increased (P = 0.04) between 15D and 3M, although they were low at both time points.Detectable T-cell responses notably increased at 3M in HD patients (P < 0.022). In PD, patients response increased by 15D (13/14; 93%) and 3M (9/9; 100%), while they were present in KT patients at 41% (12/27), 84% (22/26) and 96% (25/26) at baseline. Detectable T-cell responses in ACKD patients reached 80% (20/25) and 89% (17/19) at 15D and 3M, respectively. whereas in healthy controls it was 67% and 89% at 15D and 3M.CONCLUSION Most HD, PD and ACKD patients develop SARS-CoV-2-S antibody responses comparable to that of healthy controls, in contrast to KT recipients. Antibody waning at 3M was faster in HD, PD, ACKD patients. No differences in SARS-CoV-2 T-cell immunity responses were noticed across study groups.

Cellular and humoral responses to SARS-CoV-2 vaccination in immunosuppressed patients

ObjectiveSARS-CoV-2 vaccinations have demonstrated vaccine-immunogenicity in healthy volunteers, however, efficacy in immunosuppressed patients is less well characterised. There is an urgent need to address the impact of immunosuppression on vaccine immunogenicity. MethodsSerological, T-cell ELISpot, cytokines and immunophenotyping were used to assess vaccine responses (either BNT162b2 mRNA or ChAdOx1 nCoV-19) in double-vaccinated patients receiving immunosuppression for renal transplants or haematological malignancies (n = 13). Immunological responses in immunosuppressed patients (VACC-IS) were compared to immunocompetent vaccinated (VACC-IC, n = 12), unvaccinated (UNVACC, n = 11) and infection-naïve unvaccinated (HC, n = 3) cohorts. ResultsNo significant different differences in T-cell responses were observed between VACC-IS and VACC-IC (92%) to spike-peptide (S) stimulation. UNVACC had the highest T-cell non-responders (n = 3), whereas VACC-IC and VACC-IS both had one T-cell non-responder. No significant differences in humoral responses were observed between VACC-IC and VACC-IS, with 92% (12/13) of VACC-IS patients demonstrating seropositivity. One VACC-IS failed to seroconvert, however had detectable T-cell responses. All VACC-IC participants were seropositive for anti-spike antibodies. VACC-IS and VACC-IC participants elicited strong Th1 cytokine response with immunodominance towards S-peptide. Differences in T-cell immunophenotyping were seen between VACC-IS and VACC-IC, with lower CD8+ activation and T-effector memory phenotype observed in VACC-IS. ConclusionSARS-CoV-2 vaccines are immunogenic in patients receiving immunosuppressive therapy, with responses comparable to vaccinated immunocompetent participants. Lower humoral responses were seen in patients treated with B-cell depleting therapeutics, but with preserved T-cell responses. We suggest further work to correlate both protective immunity and longevity of these responses in both healthy and immunosuppressed patients.

Comparison of T-cell immune responses to SARS-CoV-2 spike (S) and nucleocapsid (N) protein using an in-house flow-cytometric assay in laboratory employees with and without previously confirmed COVID-19 in South Africa: nationwide cross-sectional study

AimsTo compare specific T-cell responses between laboratory employees in South Africa with and without previously diagnosed SARS-CoV-2 infection.MethodsEmployees at a private pathology laboratory in South Africa were invited to participate...

Humoral and cellular immunogenicity to a second dose of COVID-19 vaccine BNT162b2 in people receiving methotrexate or targeted immunosuppression: a longitudinal cohort study.

SummaryBackgroundCOVID-19 vaccines have robust immunogenicity in the general population. However, data for individuals with immune-mediated inflammatory diseases who are taking immunosuppressants remains scarce. Our previously published cohort study showed that methotrexate, but not targeted biologics, impaired functional humoral immunity to a single dose of COVID-19 vaccine BNT162b2 (Pfizer-BioNTech), whereas cellular responses were similar. Here, we aimed to assess immune responses following the second dose.MethodsIn this longitudinal cohort study, we recruited individuals with psoriasis who were receiving methotrexate or targeted biological monotherapy (ie, tumour necrosis factor [TNF] inhibitors, interleukin [IL]-17 inhibitors, or IL-23 inhibitors) from a specialist psoriasis centre serving London and South-East England. The healthy control cohort were volunteers without psoriasis, not receiving immunosuppression. Immunogenicity was evaluated immediately before, on day 28 after the first BNT162b2 vaccination and on day 14 after the second dose (administered according to an extended interval regimen). Here, we report immune responses following the second dose. The primary outcomes were humoral immunity to the SARS-CoV-2 spike glycoprotein, defined as titres of total spike-specific IgG and of neutralising antibody to wild-type, alpha (B.1.1.7), and delta (B.1.617.2) SARS-CoV-2 variants, and cellular immunity defined as spike-specific T-cell responses (including numbers of cells producing interferon-γ, IL-2, IL-21).FindingsBetween Jan 14 and April 4, 2021, 121 individuals were recruited, and data were available for 82 participants after the second vaccination. The study population included patients with psoriasis receiving methotrexate (n=14), TNF inhibitors (n=19), IL-17 inhibitors (n=14), IL-23 inhibitors (n=20), and 15 healthy controls, who had received both vaccine doses. The median age of the study population was 44 years (IQR 33–52), with 43 (52%) males and 71 (87%) participants of White ethnicity. All participants had detectable spike-specific antibodies following the second dose, and all groups (methotrexate, targeted biologics, and healthy controls) demonstrated similar neutralising antibody titres against wild-type, alpha, and delta variants. By contrast, a lower proportion of participants on methotrexate (eight [62%] of 13, 95% CI 32–86) and targeted biologics (37 [74%] of 50, 60–85; p=0·38) had detectable T-cell responses following the second vaccine dose, compared with controls (14 [100%] of 14, 77–100; p=0·022). There was no difference in the magnitude of T-cell responses between patients receiving methotrexate (median cytokine-secreting cells per 106 cells 160 [IQR 10–625]), targeted biologics (169 [25–503], p=0·56), and controls (185 [133–328], p=0·41).InterpretationFunctional humoral immunity (ie, neutralising antibody responses) at 14 days following a second dose of BNT162b2 was not impaired by methotrexate or targeted biologics. A proportion of patients on immunosuppression did not have detectable T-cell responses following the second dose. The longevity of vaccine-elicited antibody responses is unknown in this population.FundingNIHR Biomedical Research Centre at Guy's and St Thomas' NHS Foundation Trust and King's College London; The Psoriasis Association.

Depletion of Human Papilloma Virus E6- and E7-Oncoprotein-Specific T-Cell Responses in Women Living With HIV.

BackgroundCervical cancer - caused by persistent High Risk Human Papilloma Virus (HR HPV) infections - is the second most common cancer affecting women globally. HIV infection increases the risk for HPV persistence, associated disease progression and malignant cell transformation. We therefore hypothesized that this risk increase is directly linked to HIV infection associated dysfunction or depletion of HPV-oncoprotein-specific T-cell responses.MethodsThe 2H study specifically included HIV+ and HIV- women with and without cervical lesions and cancer to analyze HPV oncogene-specific T cell responses in relation to HPV infection, cervical lesion status and HIV status. Oncoprotein E6 and E7 specific T-cell responses were quantified for the most relevant types HPV16, 18 and 45 and control antigens (CMV-pp65) and M.tb-PPD in 373 women, using fresh peripheral blood mononuclear cells in an IFN-γ release ELISpot assay.ResultsOverall, systemic E6- and E7-oncoprotein-specific T-cell responses were infrequent and of low magnitude, when compared to CMV-pp65 and M.tb-PPD (p < 0.001 for all HR HPV types). Within HIV negative women infected with either HPV16, 18 or 45, HPV16 infected women had lowest frequency of autologous-type-E6/E7-specific T-cell responses (33%, 16/49), as compared to HPV18 (46% (6/13), p = 0.516) and HPV45 (69% (9/13), p = 0.026) infected women. Prevalent HPV18 and 45, but not HPV16 infections were linked to detectable oncoprotein-specific T-cell responses, and for these infections, HIV infection significantly diminished T-cell responses targeting the autologous infecting genotype. Within women living with HIV, low CD4 T-cell counts, detectable HIV viremia as well as cancerous and precancerous lesions were significantly associated with depletion of HPV oncoprotein-specific T-cell responses.DiscussionDepletion of HPV-oncoprotein-specific T-cell responses likely contributes to the increased risk for HR HPV persistence and associated cancerogenesis in women living with HIV. The low inherent immunogenicity of HPV16 oncoproteins may contribute to the exceptional potential for cancerogenesis associated with HPV16 infections.

Anti–SARS-CoV-2 Antibody Responses in Patients With IBD Treated With Biologics: Are We Finding CLARITY?

Anti–SARS-CoV-2 Antibody Responses in Patients With IBD Treated With Biologics: Are We Finding CLARITY?

Humoral and T-cell responses to SARS-CoV-2 vaccination in patients receiving immunosuppression

ObjectiveThere is an urgent need to assess the impact of immunosuppressive therapies on the immunogenicity and efficacy of SARS-CoV-2 vaccination.MethodsSerological and T-cell ELISpot assays were used to assess the response...

Abstract LB049: Preliminary analysis of immunogenicity of HB-201 and HB-202, an arenavirus-based cancer immunotherapy, in patients with advanced HPV16-positive cancers

Abstract Background: Human Papillomavirus 16 (HPV16) is linked to most HPV-associated cancers such as cervical, head and neck, vaginal and anal cancers. Treatment options are limited for patients with HPV16+ recurrent or metastatic cancers. The generation and maintenance of the HPV16+ malignant state requires the stable expression of HPV16-specific E7 and E6 oncogenes, which therefore constitute attractive targets for immunotherapy. HB-201 and HB-202 are both replicating live-attenuated vectors based on arenaviruses LCMV and PICV, respectively, expressing the same non-oncogenic HPV16 E7E6 fusion protein for induction of tumor specific T-cell responses. In preclinical models, administration of HB-201 alone and sequential administration of HB-202 followed by HB-201 was safe and demonstrated potent immunogenicity by induction of E7 and E6 -specific CD8+ T cell responses and efficient tumor control of HPV+ TC-1 tumors. Methods: A first-in-human, Phase I/II open-labelled clinical trial of HB-201 single vector therapy and HB-201 &amp; HB-202 two-vector therapy in patients with treatment-refractory HPV16+ cancers is currently ongoing (NCT04180215). Here, we present first immunogenicity results from the dose escalation phase I of this study. The phase I of the trial is designed to evaluate different dose levels and dosing schedules of HB-201 as a single-vector therapy or as an alternating two-vector therapy together with HB-202. Peripheral blood mononuclear cells (PBMCs) were collected before and after treatment from all patients. PBMCs from a subset of patients were examined for HPV16-specific T cell responses measured by IFN-γ enzyme-linked immunospot. Paired tissue biopsy and serum samples were also collected and being currently evaluated for histology and pharmacokinetics. Results: We demonstrated induction of a directly ex vivo (i.e. no expansion) detectable HPV16-specific T-cell response in PBMCs from patients receiving a single dose of HB-201 or HB-202. Additional exploratory analysis will be available at the time of the meeting. Conclusion: These preliminary data demonstrate for the first time with arenavirus vectors, the induction of HPV16-specific T cells in cancer patients following a single injection of HB-201 or HB-202. Arenavirus vectors expressing E7E6 may constitute a new potential therapy for patients with treatment refractory HPV16+ cancers. Clinical data will be presented in an upcoming scientific meeting. Additional schedules, alternating two-vector therapy with HB-201/HB-202, and combination with anti-PD-1 mAbs are being explored in additional cohorts. Citation Format: Kia Katchar, Michael Schwendinger, Diane DaSilva, Henning Lauterbach, Klaus Orlinger, Xiaoping Qing, Daniel Pinschewer, Igor Matushansky. Preliminary analysis of immunogenicity of HB-201 and HB-202, an arenavirus-based cancer immunotherapy, in patients with advanced HPV16-positive cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB049.

Acute FPIES reactions are associated with an IL-17 inflammatory signature

Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated food allergy characterized by profuse vomiting within hours of ingestion of the causative food. We have previously reported that FPIES is associated with systemic innate immune activation in the absence of a detectable antigen-specific antibody or T-cell response. The mechanism of specific food recognition by the immune system remains unclear. Our aim was to identify immune mechanisms underlying FPIES reactions by proteomic and flow cytometric analysis of peripheral blood. Children with a history of FPIES underwent supervised oral food challenge. Blood samples were taken at baseline, at symptom onset, and 4 hours after symptom onset. We analyzed samples from 23 children (11 reactors and 12 outgrown). Atotal of 184 protein markers were analyzed by proximity ligation assay and verified by multiplex immunoassay. Analysis of cell subset activation was performed by mass cytometry and spectral cytometry. Symptomatic FPIES challenge results were associated with significant elevation of levels of cytokines and chemokines, including IL-17 family markers (IL-17A, IL-22, IL-17C, and CCL20) and T-cell activation (IL-2), and innate inflammatory markers (IL-8, oncostatin M, leukemia inhibitory factor, TNF-α, IL-10, and IL-6). The level of the mucosal damage marker regenerating family member 1 alpha (REG1A) was also significantly increased. These biomarkers were not increased in asymptomatic challenges or IgE-mediated allergy. The level of phospho-STAT3 was significantly elevated in myeloid and T cells after challenge in individuals with symptoms. Mass cytometry indicated preferential activation of nonconventional T-cell populations, including γδ T cells and CD3+CD4-CD8-CD161+ cells; however, the potential sources of IL-17 in PBMCs were primarily CD4+ TH17 cells. These results demonstrate a unique IL-17 signature and activation of innate lymphocytes in FPIES.

Comprehensive Screening of Mouse T-Cell Epitopes in Human Herpesvirus 6B Glycoprotein H/L/Q1/Q2 Tetramer Complex.

Human herpesvirus 6 (HHV-6) infects over 90% of people. The HHV-6 subtype, HHV-6B in particular, is often associated with exanthem subitum in early childhood. Exanthem subitum is usually self-limiting and good prognosis disease; however, some infants primarily infected with HHV-6B develop encephalitis/encephalopathy, and half of the patients developed encephalopathy reported to have neurological sequelae. Furthermore, after primary infection, HHV-6B remains in a latent state and sometimes reactivated in immunosuppressed patients, causing life-threatening severe encephalopathy. However, effective immunotherapies or vaccines for controlling HHV-6B infection and reactivation have not yet been established. Recently, we have found that the HHV-6B tetrameric glycoprotein (g) complex, gH/gL/gQ1/gQ2 is a promising vaccine candidate, and currently under preclinical development. To confirm our vaccine candidate protein complex induce detectable T-cell responses, in this study, we comprehensively screened CD4+ and CD8+ T-cell epitopes in the gH/gL/gQ1/gQ2 tetrameric complex protein in mice immunisation model. Both BALB/c and C57BL/6 mice were immunised with the tetrameric complex protein or plasmid DNA encoding gH, gL, gQ1, and gQ2, and then restimulated with 162 20-mer peptides covering the whole gH/gL/gQ1/gQ2 sequences; multiple CD4+ and CD8+ T-cell-stimulating peptides were identified in both BALB/c and C57BL/6 mice. Our study demonstrates that gH/gL/gQ1/gQ2 tetramer-targeted vaccination has potential to induce T-cell responses in two different strains of mice and supports the future development and application of T-cell-inducing vaccine and immunotherapies against HHV-6B.

Characterisation of clinical and immune reactivity to barley and rye ingestion in children with coeliac disease

ObjectiveBarley and rye are major components of the Western diet, and historic feeding studies indicate that they cause clinical effects in patients with coeliac disease (CD). This toxicity has been...

Efficacy of PD-1 blockade in cervical cancer is related to a CD8+FoxP3+CD25+ T-cell subset with operational effector functions despite high immune checkpoint levels

BackgroundCervical cancer (CxCa) is mainly a locally invading disease that metastasizes to loco-regional lymph node basins before involving distant organs in more advanced stages. Local immune potentiation of tumor-draining lymph nodes (TDLN) may thus protect against tumor progression.MethodsTo identify therapeutic targets for local immune modulation, multi-parameter flow cytometric T-cell profiling of primary cervical tumors (PT) and TDLN (n = 37) was performed. The in-vitro effect of PD-1 blockade on T-cell reactivity to HPV16 E6 oncoproteins was determined in cultures of TDLN and PT single cell suspensions (n = 19). Also, intracellular cytokine staining (ICS) upon anti-CD3 stimulation was performed in metastatic TDLN (LN+) and PT (n = 7), as well as multiplexed immunofluorescence histochemistry staining (n = 8).ResultsOur data revealed elevated rates of activated regulatory T cells (aTregs) and of central or effector memory CD8+ T cells in metastatic TDLN (LN+) as compared to tumor-free TDLN (LN-), and equally high or even higher rates of these subsets in PT. Both memory subsets co-expressed multiple immune checkpoints. PD-1 blockade significantly enhanced detectable E6-specific T-cell responses in 4/5 HPV16+ LN+ and in 1/5 HPV16+ PT. Whereas aTreg rates were higher in anti-PD-1 non-responders, in responders elevated levels of CD8+FoxP3+CD25+ T cells were observed, which correlated with the efficacy of PD-1 blockade (P = 0.018). This subset was characterized by an early effector memory phenotype with particularly high levels of co-expressed PD-1, CTLA-4, TIM-3 and LAG-3 checkpoints, but, rather than exhausted, was shown upon polyclonal activation to produce higher levels of Granzyme-B and effector cytokines as compared to its CD8+FoxP3− counterparts.ConclusionThese observations support local PD-(L)1 blockade to interrupt loco-regional immune suppression in CxCa and control metastatic spread to TDLN. Furthermore, our data identify CD8+FoxP3+CD25+ T cells as therapeutic targets, which may also serve as predictive biomarker for PD-(L)1 checkpoint blockade.

Application of replication-defective West Nile virus vector to non-flavivirus vaccine targets

ABSTRACTThe RepliVax vaccine platform(RV) is based on flavivirus genomes that are rationally attenuated by deletion. The self-limiting infection provided by RV has been demonstrated to be safe, highly immunogenic and efficacious for several vaccine candidates against flaviviruses. Here respiratory syncytial virus (RSV) F, influenza virus HA, and simian immunodeficiency virus (SIV) Env proteins were expressed in place of either prM-E or C-prM-E gene deletions of the West Nile (WN) virus genome. The resulting RV-RSV, -influenza and -SIV vaccine prototypes replicated efficiently in complementing helper cells expressing the WN structural proteins in trans. Expressed antigens exhibited correct post-translational processing and the RV recombinants were shown to be highly attenuated and immunogenic in mice, eliciting strong antigen-specific antibodies as well as detectable T-cell responses. These data support the utility of RV vectors for development of vaccines against non-flavivirus targets including rabies and HIV.

Lipoprotein immunoproteomics question the potential of Staphylococcus aureus TLR2 agonists as vaccine antigens.

Toll-like receptor 2 (TLR2) is regarded as the major innate immunity sensor in infections caused by the Gram-positive bacterial pathogen Staphylococcus aureus. However, previous studies on the roles of TLR2 in S. aureus infections have been elusive and in part contradictory. It has remained particularly unclear if bacterial lipoproteins, the major TLR2 ligands, could serve as antigens with intrinsic adjuvant property for the development of protective vaccines. The study by Vu etal. published in this issue of Proteomics analyzed the antibody and T-cell responses in human sera against major S. aureus lipoproteins. Notably, even lipoproteins released to culture filtrates at similar levels as established immunodominant antigens elicited only very weak or no detectable antibody and T-cell responses, indicating that the potent TLR2-stimulating capacity of S. aureus lipoproteins does not promote and may rather impair robust immune responses so lipoprpteins. Among several potential explanations it is tempting to speculate that the role of TLR2 in S. aureus infections may be more complex and more ambiguous than previously thought. The study of Vu etal. may thus provoke more detailed investigations on the roles of lipoproteins and TLR2 in innate and adaptive immunity against bacterial pathogens.

Safety, immune and clinical responses in metastatic melanoma patients vaccinated with a long peptide derived from indoleamine 2,3-dioxygenase in combination with ipilimumab

Background aimIndoleamine 2,3-dioxygenase (IDO) is an emerging new target in cancer therapy that can be targeted with active immunotherapy (e.g. through peptide vaccination). Furthermore, IDO has been identified as a key mechanism underlying resistance to treatment with the checkpoint blocking antibody ipilimumab (ipi). MethodsTen patients with metastatic melanoma participated in a phase I first-in-human clinical study assessing safety of combining ipi with a 21-mer synthetic peptide vaccine from IDO denoted IDOlong. Secondary and tertiary end points included vaccine and clinical response. ResultsTreatment was generally safe and well tolerated. Vaccine related adverse reactions included grade I and II erythema, oedema and pruritus at the vaccination site, which were manageable with mild topical corticosteroids. One patient developed presumed ipi-induced colitis. It initially responded to high-dose parenteral corticosteroids but later relapsed while the patient was admitted to a local hospital, where he died after receiving suboptimal therapy. Vaccine-specific T-cell responses were detectable ex vivo in three patients. At first evaluation, five of the 10 treated patients were in stable disease, one of whom had an unconfirmed partial response. ConclusionsTreatment with IDOlong synthetic peptide vaccine in combination with ipi was generally safe and without augmented toxicity. The vaccine induced readily detectable T-cell responses in a subset of patients. Treatment showed signs of clinical activity, although not exceeding efficacy of ipi alone. Results should be confirmed in a larger study.