Cell-mediated Immunogenicity Research Articles

Effect of RTS,S/AS01E vaccine booster dose on cellular immune responses in African infants and children

RTS,S/AS01E, the first approved malaria vaccine, demonstrated moderate efficacy during the phase 3 pediatric trial. We previously investigated cell-mediated immune (CMI) responses following the primary 3-dose immunization and now report responses to the booster dose given 18 months later. Thirty CMI markers were measured by Luminex in supernatants of peripheral blood mononuclear cells from 709 children and infants after RTS,S/AS01E antigen stimulation, and their associations with malaria risk and antibodies one month post-booster and one year later were assessed. IL-2, IFN-γ, IL-17, IL-5, and IL-13 were associated with RTS,S/AS01E booster vaccination, and IL-2 responses to the circumsporozoite protein (CSP) remained higher after one year. IL-2 was associated with reduced malaria risk in one site, and IL-10 was associated with increased risk in infants. Anti-CSP IgG and IL-2 were moderately correlated one year after booster. This study highlights the moderate cell-mediated immunogenicity of the RTS,S/AS01E booster dose that aligns with partial recovery of RTS,S/AS01E vaccine efficacy.

Safety and Immunogenicity of a Carbohydrate Fatty Acid Monosulphate Ester Adjuvant Combined with a Low-Dose Quadrivalent Split-Virion Inactivated Influenza Vaccine: A Randomised, Observer-Blind, Active-Controlled, First-in-Human, Phase 1 Study.

Seasonal influenza vaccine effectiveness is low. Carbohydrate fatty acid monosulphate ester (CMS), a new oil-in-water adjuvant, has proven potency in animal models with suggested capacity for dose-sparing. The objective was to evaluate safety and immunogenicity of CMS when added to a low-dose influenza vaccine (QIV) in humans. In a randomised, double-blind, active-controlled, first-in-human study, sixty participants (18-50 years) received either 0.5 mg CMS or 2 mg CMS with 1/5th dose QIV, or a full dose QIV without CMS. Adverse events (AE) were monitored until 7 days post-vaccination. Haemagglutinin inhibition (HI) titres in serum and CD4+ T cells in PBMCs were determined at day 0, 7, 28, and 180. Mean age was 37.6 (±10.1) years and 42/60 (70.0%) were female. Pain at injection site (42/60, 86.7%) and headache (34/60, 56.7%) were reported most and more frequently in the 2 mg CMS group. HI titres and the frequency of influenza specific CD4+ T cells were equal across strains for the three cohorts on all visits, increased until day 28 and decreased at day 180 to values higher than baseline. CMS was safe in humans. Humoral and cell-mediated immunogenicity was similar across vaccines, even with 1/5th antigen dose. CMS can have beneficial implications in low-resource settings or in a pandemic context.

Abstract 4103: Novel mRNA-encoded HPV vaccine with APC maturation signal and endolysosomal trafficking domain demonstrates superior T cell-mediated immunogenicity and efficacious tumor clearance in vivo

Abstract Human Papillomavirus (HPV), particularly HPV16, is a known causative agent of cancers in various anatomical sites, notably the anogenital and oropharyngeal regions. Despite the availability of prophylactic HPV vaccines for almost two decades, vaccination rates among young females, who are at a heightened risk for cervical intraepithelial neoplasia (CIN) and subsequent invasive cancer, remain suboptimal. The current standard of care for cervical cancer, involving invasive surgery and chemotherapy-based treatments, underscores the pressing need for safer and more effective therapeutics to enhance patient survival and quality of life. In this context, while several HPV16-E6/E7 targeted therapeutic vaccines are in development and clinical trials, their clinical efficacy has been limited due to inadequate antigen presentation and suboptimal immunogenicity. Addressing this, our team has developed a novel, highly immunogenic mRNA therapeutic cancer vaccine, engineered to activate a robust T cell-mediated adaptive immune response and exhibit strong anti-tumor potential. Our innovative approach includes the design of an HPV16-E6/E7 mRNA vaccine (ABO2101) that incorporates a unique antigen-expressing cassette. This cassette features endolysosomal trafficking domains and antigen presenting cell (APC) activation stimulators, enhancing both Class I and Class II antigen presentation and APC maturation, thereby amplifying antigen-specific T cell responses. In both murine and human-derived experimental models, ABO2101 has demonstrated a significantly more potent adaptive T cell response against HPV16 antigens compared to other HPV16 mRNA therapeutic vaccines. In antitumor efficacy evaluations using TC-1 tumor-bearing mice, ABO2101 single-dose administration successfully eradicated both early-stage (50 mm³) and advanced (500 mm³) tumors. This was accompanied by a marked increase in HPV16-specific CD8+ cytotoxic T lymphocytes within the tumor microenvironment. Moreover, in prophylactic and adjuvant therapy models, ABO2101 prevented tumor growth across various dosages, indicating its robust preventative capabilities. Further, the combination of ABO2101 with immune checkpoint inhibitors, including PD-1 and CTLA-4 antibodies, displayed a synergistic effect in both immune-oncology sensitive and resistant animal models, suggesting a potential for combinational clinical therapy. In conclusion, our development of ABO2101, a mRNA-based HPV16-E6/E7 therapeutic cancer vaccine inclusive of APC maturation signals, represents a groundbreaking advancement in HPV-associated cancer treatment, as supported by our compelling preclinical data. Citation Format: Liang Du, Hongya Han, Jingshu Ma, Zhenxing Yang, Jinjuan Mao, Jijun Yuan, Bo Ying. Novel mRNA-encoded HPV vaccine with APC maturation signal and endolysosomal trafficking domain demonstrates superior T cell-mediated immunogenicity and efficacious tumor clearance in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4103.

Immunogenicity and Safety Following 1 Dose of AS01E-Adjuvanted Respiratory Syncytial Virus Prefusion F Protein Vaccine in Older Adults: A Phase 3 Trial.

The recently approved AS01E-adjuvanted respiratory syncytial virus (RSV) prefusion F protein-based vaccine for older adults (RSVPreF3 OA) demonstrated high efficacy against RSV-related disease in ≥60-year-olds. This ongoing phase 3 study in ≥60-year-olds evaluates immune persistence until 3 years after RSVPreF3 OA vaccination. Here, we describe interim results on humoral and cell-mediated immunogenicity, reactogenicity, and safety until 1 year post-dose 1. In total, 1653 participants were vaccinated. One month post-dose 1, neutralization titers increased 10.5-fold (RSV-A) and 7.8-fold (RSV-B) vs pre-dose 1. Titers then declined to levels 4.4-fold (RSV-A) and 3.5-fold (RSV-B) above pre-dose 1 at month 6 and remained 3.1-fold (RSV-A) and 2.3-fold (RSV-B) above pre-dose 1 levels after 1 year. RSVPreF3-binding immunoglobulin G levels and CD4+ T-cell frequencies showed similar kinetics. Solicited administration-site and systemic adverse events (mostly mild to moderate and transient) were reported by 62.2% and 49.5% of participants. Serious adverse events were reported by 3.9% of participants within 6 months post-dose 1; 1 case was considered vaccine related. One RSVPreF3 OA dose elicited cell-mediated and RSV-A- and RSV-B-specific humoral immune responses that declined over time but remained above pre-dose 1 levels for at least 1 year. The vaccine was well tolerated with an acceptable safety profile. Clinical Trials Registration. NCT04732871 (ClinicalTrials.gov).

Analysis of T Cell Immunity Generated by Takeda’s Tetravalent Dengue Vaccine

Abstract Dengue is a viral disease transmitted to humans through the bite of infected mosquitoes and is caused by dengue virus (DENV), which has four distinct serotypes, DENV1 to DENV4. Severe dengue is a leading cause of serious illness and death in some Asian and Latin American countries. The Walter Reed Army Institute of Research (WRAIR) has been working to investigate the cell mediated immunogenicity of Takeda’s live attenuated virus tetravalent dengue vaccine (TAK-003). Previously, we have used ELISPOT and Flow-ICS assays to show that TAK-003 induces a robust IFN-γ producing DENV-specific T cell response that is durable to at least 6 months post-vaccination. In addition, this response is mediated by both CD8+ and CD4+ T cells that produce IFN-γ and/or TNFα and IL-2. Using samples from a phase II study, DEN-313 (NCT02948829) conducted in healthy children aged 4 to 16 years in dengue endemic locations, herewith we extend the findings on TAK-003 induced DENV-specific T cell responses to: (1) present data on durability of the CMI response through 3 years post-vaccination; (2) verify the serotype coverage of the T cell response; (3) assess multifunctional capacity of the durable memory T cells, and (4) describe the phenotypic changes that occur among these cells based upon central memory (CD45RA−/CCR7+), effector memory (CD45RA−/CCR7−) and effector memory RA phenotyping (CD45RA+/CCR7−). Our data describe the frequency, functionality, and memory phenotype of T cells induced by TAK-003 up to 3 years post vaccination. Finding received through corporative research and development agreement with Takeda vaccine company.

Preserved SARS-CoV-2 Vaccine Cell-Mediated Immunogenicity in Patients With Inflammatory Bowel Disease on Immune-Modulating Therapies.

Immune-modulating medications for inflammatory bowel diseases (IBDs) have been associated with suboptimal vaccine responses. There are conflicting data with SARS-CoV-2 vaccination. We therefore assessed SARS-CoV-2 vaccine immunogenicity at 2 weeks after second mRNA vaccination in 29 patients with IBD compared with 12 normal healthy donors. We observed reduced humoral immunity in patients with IBD on infliximab. However, we observed no difference in humoral and cell-mediated immunity in patients with IBD on infliximab with a thiopurine or vedolizumab compared with normal healthy donors. This is the first study to demonstrate comparable cell-mediated immunity with SARS-CoV-2 vaccination in patients with IBD treated with different immune-modulating medications.

TGF-β2 Reduces the Cell-Mediated Immunogenicity of Equine MHC-Mismatched Bone Marrow-Derived Mesenchymal Stem Cells Without Altering Immunomodulatory Properties.

Allogeneic mesenchymal stem cells (MSCs) are a promising cell therapy for treating numerous diseases, but major histocompatibility complex (MHC)-mismatched MSCs can be rejected by the recipient’s immune system. Pre-treating MSCs with transforming growth factor-β2 (TGF-β2) to downregulate surface expression of MHC molecules may enhance the ability of allogeneic MSCs to evade immune responses. We used lymphocyte proliferation assays and ELISAs to analyze the immunomodulatory potential of TGF-β2-treated equine bone marrow-derived MSCs. T cell activation and cytotoxicity assays were then used to measure the in vitro cell-mediated immunogenicity. Similar to untreated MSCs, TGF-β2-treated MSCs inhibited T cell proliferation and did not stimulate MHC-mismatched T cells to proliferate. Additionally, similar quantities of prostaglandin E2 and TGF-β1 were detected in assays with untreated and TGF-β2-treated MSCs supporting that TGF-β2-treated MSCs retain their strong immunomodulatory properties in vitro. Compared to untreated MSCs, TGF-β2-treated MSCs induced less T cell activation and had reduced cell-mediated cytotoxicity in vitro. These results indicate that treating MSCs with TGF-β2 is a promising strategy to reduce the cell-mediated immunogenicity of MHC-mismatched MSCs and facilitate allogeneic MSC therapy.

4. Immunogenicity of the Adjuvanted Recombinant Zoster Vaccine in Immunocompromised Adults

BackgroundImmunocompromised (IC) populations are at increased risk of developing herpes zoster (HZ) due to disease- and/or therapy-induced immunosuppression. The adjuvanted recombinant zoster vaccine (RZV) has demonstrated 68.2% efficacy in preventing HZ in autologous hematopoietic stem cell transplant (HSCT) recipients and 87.2% efficacy in a post-hoc analysis in hematologic malignancy (HM) patients ≥ 18 years of age (YOA). Here we present the immunogenicity of RZV in representative IC populations.MethodsOur analysis includes five phase I/II/III clinical trials conducted worldwide between 2010–2017 (Table 1) in IC populations (autologous HSCT, human immunodeficiency virus [HIV]-infected, HM, solid tumor [ST] on chemotherapy and renal transplant [RT] patients) ≥ 18 YOA. Anti-glycoprotein E (gE) antibody geometric mean concentrations (GMCs) and gE-specific CD4 T cell frequencies were descriptively evaluated by age group (18–49 YOA and ≥ 50 YOA) and overall at 1 month (M) and 12M post-last RZV dose.Table 1. Clinical studies with immunocompromised populations included in our analysis ResultsThe according-to-protocol cohorts for immunogenicity from the included trials are presented in Table 1. At 1M post-last RZV dose, anti-gE GMCs and median CD4 T-cell frequencies increased in all IC populations compared to pre-vaccination and persisted above baseline up to 12M post-last RZV dose (Figures 1 and 2). No meaningful differences were seen between age groups in terms of humoral (except a slight trend for stronger responses in the 18–49 YOA RT and HM patients compared to their corresponding ≥ 50 YOA group) and gE-specific CD4 T-cell responses in any of the IC populations.Figure 1. Humoral immune responses to RZV in immunocompromised populations (adapted ATP cohort for humoral immunogenicity) Figure 2. Cell-mediated immune responses to RZV in immunocompromised populations (adapted ATP cohort for cell-mediated immunogenicity) ConclusionRZV induced robust and persistent humoral and cell-mediated immune (CMI) responses that lasted up to at least 12M post-last vaccination in all evaluated IC populations. Humoral responses in the IC populations were robust although not as strong as in the non-IC adults ≥ 50 YOA. CMI responses were mostly similar across IC populations and adults ≥ 50 YOA, with a potent response occurring even in ST patients undergoing chemotherapy. This data shows that RZV is immunogenic even in severely IC adults. Funding: GlaxoSmithKline Biologicals SA Acknowledgment: M Maior/S Hulsmans (Modis c/o GSK) provided writing/editorial supportDisclosuresAlemnew F. Dagnew, MD, MSc, GSK group of companies (Employee, Shareholder) Peter Vink, MD, GSK group of companies (Employee, Shareholder) Mamadou Drame, MSc, GSK group of companies (Employee) David Willer, PhD, GSK group of companies (Employee, Shareholder) Bruno Salaun, PhD, GSK group of companies (Employee) Anne Schuind, MD, GSK (Employee, Other Financial or Material Support, own GSK stock options or restricted shares as part of renumeration)

Immunogenicity of a Recombinant Herpes Zoster Vaccine in Patients with Chronic Lymphocytic Leukemia

Immunogenicity of a Recombinant Herpes Zoster Vaccine in Patients with Chronic Lymphocytic Leukemia

A phase 1, randomized, placebo-controlled study to evaluate the safety and immunogenicity of an mRNA-based RSV prefusion F protein vaccine in healthy younger and older adults

ABSTRACT Respiratory Syncytial Virus (RSV) causes lower respiratory tract infections that can be severe and sometimes fatal. The risk for severe RSV infection is highest in infants and older adults. A safe and effective RSV vaccine for older adults represents a serious unmet medical need due to higher morbidity and mortality in this age group. In this randomized, partially double-blind, placebo-controlled, phase 1 dose-escalation study, we evaluated the safety, tolerability and immunogenicity of an investigational messenger ribonucleic acid (mRNA) vaccine encoding the RSV fusion protein (F) stabilized in the prefusion conformation. The study was conducted in healthy younger adults (ages ≥18 and ≤49 years) and healthy older adults (ages ≥60 and ≤79 years). Participants received mRNA-1777 (V171) or placebo as a single intramuscular dose. For each dose level, three sentinel participants were administered open-label mRNA-1777 (V171). Seventy-two younger adults were randomized and administered 25, 100, or 200 µg mRNA-1777 (V171) or placebo, and 107 older adults were randomized and administered 25, 100, 200 or 300 µg mRNA-1777 (V171) or placebo. Primary objectives were safety and tolerability and secondary objectives included humoral and cell-mediated immunogenicity. All dose levels of mRNA-1777 (V171) were generally well tolerated and no serious adverse events related to the vaccine were reported. Immunization with mRNA-1777 (V171) elicited a humoral immune response as measured by increases in RSV neutralizing antibody titers, serum antibody titers to RSV prefusion F protein, D25 competing antibody titers to RSV prefusion F protein, and cell-mediated immune responses to RSV-F peptides.

Cell-Mediated Immunogenicity of Influenza Vaccination in Patients With Cancer Receiving Immune Checkpoint Inhibitors.

We assessed cell-mediated immune (CMI) responses of influenza vaccination in patients with cancer receiving immune checkpoint inhibitors (ICIs), which remain elusive. Vaccine-elicited CMI responses in patients receiving ICIs or cytotoxic agents were investigated by flow cytometry. Polyfunctional cells were defined as T cells that express 2 or more of interleukin 2 (IL-2), interleukin 4 (IL-4), interferon gamma (IFN-γ), and CD107a. An adequate CMI response was defined as an increase of polyfunctional T cells against both H1N1 and H3N2 strains. When comparing ICI (n = 11) and cytotoxic chemotherapy (n = 29) groups, H1N1-specific IL-4 or IFN-γ-expressing CD4+ T cells, IL-2, IL-4, IFN-γ, or CD107a-expressing CD8+ T cells, H3N2-specific IFN-γ-expressing CD4+ T cells, and CD107a-expressing CD8+ T cells were more frequent in the ICI group. Fold changes in polyfunctional H3N2-specific CD4+ (median, 156.0 vs 95.7; P = .005) and CD8+ (155.0 vs 103.4; P = .044) T cells were greater in the ICI group. ICI administration was strongly associated with an adequate CMI response for both CD4+ and CD8+ T cells (P = .003). CMI responses following influenza vaccination were stronger in the ICI group than in the cytotoxic chemotherapy group. Influenza vaccination should be strongly recommended in patients with cancer receiving ICIs.

Current In Vitro Assays for Prediction of T Cell Mediated Immunogenicity of Biotherapeutics and Manufacturing Impurities

Biotherapeutics are a large and rapidly growing class of drugs being produced by pharmaceutical companies to treat a diverse range of clinical indications. The overall efficacy and safety of these products can be greatly impacted by their capacity to induce undesired immune responses. This review discusses in vitro cell-based methods used to assess the T cell mediated immunogenicity risk of proteinaceous therapeutic modalities and manufacturing impurities. Here, we outline the potential sources and factors that influence immunogenicity. We present patient and product considerations that should be made in designing appropriate in vitro experiments that evaluate T cell epitopes capable of triggering treatment and outcome impacting anti-drug antibody responses and other adverse events. We present the current in vitro assays used to assess T cell activation towards biotherapeutics and the product impurities. Lastly, we outline the caveats, concerns, and challenges that remain with these cell-based assays. Data generated from these in vitro antigenicity/immunogenicity assays may be used to derive immunogenicity risk assessments for programs and production processes and provides an opportunity for early selection of candidates or manufacturing impurities with lower likelihood of generating or exacerbating clinical immunogenicity.

First-in-Human Randomized Study to Assess the Safety and Immunogenicity of an Investigational Respiratory Syncytial Virus (RSV) Vaccine Based on Chimpanzee-Adenovirus-155 Viral Vector-Expressing RSV Fusion, Nucleocapsid, and Antitermination Viral Proteins in Healthy Adults.

BackgroundRespiratory syncytial virus (RSV) disease is a major cause of infant morbidity and mortality. This Phase I, randomized, observer-blind, placebo- and active-controlled study evaluated an investigational vaccine against RSV (ChAd155-RSV) using the viral vector chimpanzee-adenovirus-155, encoding RSV fusion (F), nucleocapsid, and transcription antitermination proteins.MethodsHealthy 18–45-year-old adults received ChAd155-RSV, a placebo, or an active control (Bexsero) at Days (D) 0 and 30. An escalation from a low dose (5 × 109 viral particles) to a high dose (5 × 1010 viral particles) occurred after the first 16 participants. Endpoints were solicited/unsolicited and serious adverse events (SAEs), biochemical/hematological parameters, cell-mediated immunogenicity by enzyme-linked immunospot, functional neutralizing antibodies, anti RSV-F immunoglobin (Ig) G, and ChAd155 neutralizing antibodies.ResultsThere were 7 participants who received the ChAd155-RSV low dose, 31 who received the ChAd155-RSV high dose, 19 who received the placebo, and 15 who received the active control. No dose-related toxicity or attributable SAEs at the 1-year follow-up were observed. The RSV-A neutralizing antibodies geometric mean titer ratios (post/pre-immunization) following a high dose were 2.6 (D30) and 2.3 (D60). The ratio of the fold-rise (D0 to D30) in anti-F IgG over the fold-rise in RSV-A–neutralizing antibodies was 1.01. At D7 after the high dose of the study vaccine, the median frequencies of circulating B-cells secreting anti-F antibodies were 133.3/106 (IgG) and 16.7/106 (IgA) in peripheral blood mononuclear cells (PBMCs). The median frequency of RSV-F–specific interferon γ–secreting T-cells after a ChAd155-RSV high dose was 108.3/106 PBMCs at D30, with no increase after the second dose.ConclusionsIn adults previously naturally exposed to RSV, ChAd155-RSV generated increases in specific humoral and cellular immune responses without raising significant safety concerns.Clinical Trials RegistrationNCT02491463.

Immunogenicity and Safety of an Adjuvanted Herpes Zoster Subunit Candidate Vaccine in Adults with Hematologic Malignancies: A Phase III, Randomized Clinical Trial

BackgroundHematologic malignancy (HM) patients receiving immunosuppressive cancer therapy (ICT) are at increased risk of herpes zoster (HZ). Currently, no HZ vaccine is indicated for immunocompromised patients. The HZ subunit vaccine candidate (HZ/su), containing recombinant varicella zoster virus glycoprotein E and AS01B Adjuvant System, showed >90% efficacy and an acceptable safety profile in immunocompetent adults in all age groups ≥50 years. Here we report HZ/su immunogenicity and safety in HM adults ≥18 years of age who completed or are undergoing ICT.MethodsIn this phase III, observer-blind, multicenter study (NCT01767467), participants were randomized 1:1 to receive HZ/su or placebo (2 doses, 1–2 months apart) ≥10 days pre- or post-ICT. Humoral and cell-mediated immunogenicity (CMI) were assessed. The co-primary immunogenicity objectives were to evaluate HZ/su vaccine response rate and compare the immune response to HZ/su and placebo in participants excluding those with non-Hodgkin B-cell lymphoma (NHBCL) or chronic lymphocytic leukemia (CLL) at 1 month post-dose 2 (M2). Solicited and unsolicited adverse events (AEs) were recorded for 7 and 30 days after each dose, respectively. Serious AEs (SAEs), disease-related events and potential immune-mediated diseases (pIMDs) were recorded throughout the study. Partial safety results up to 6 months post-dose 2 are shown (partially blinded, ongoing study).ResultsOf 562 participants (283 HZ/su 283; placebo 279), (mean age 57.3 [HZ/su 56.8; placebo 57.8] years), 415 were included in the according-to-protocol (ATP) cohort for humoral immunogenicity and 132 in the ATP sub-cohort for CMI. M2 immune responses were higher in the HZ/su group (Table 1). Both co-primary immunogenicity objectives were met (Figure 1). The most frequent local and general solicited AEs were pain and fatigue, reported by 48.2% and 47.8% of all participants (per-group data remain blinded). The frequency of unsolicited AEs, SAEs and pIMDs in the 2 groups was similar (Table 2).ConclusionHZ/su induced robust humoral and cellular immune responses at M2 in HM adults excluding NHBCL and CLL, who completed or are undergoing ICT. No safety concerns were observed up to 6 months post-dose 2.FundingGlaxoSmithKline Biologicals SADisclosures L. Oostvogels, GSK group of companies: Employee and Shareholder, Salary and Shares

Coxsackievirus B1 reveals strain specific differences in plasmacytoid dendritic cell mediated immunogenicity

Enterovirus infections are usually mild but can also cause severe illnesses and play a role in chronic diseases, such as cardiomyopathies and type 1 diabetes. Host response to the invading virus can markedly modulate the course of the infection, and this response varies between individuals due to the polymorphism of immune response genes. However, it is currently not known if virus strains also differ in their ability to stimulate the host immune system. Coxsackievirus B1 (CBV1) causes severe epidemics in young infants and it has recently been connected with type 1 diabetes in seroepidemiological studies. This study evaluated the ability of different field isolates of CBV1 to induce innate immune responses in PBMCs. CBV1 strains differed markedly in their capacity to induce innate immune responses. Out of the 18 tested CBV1 strains two induced exceptionally strong alpha interferon (IFN-α) response in PBMC cultures. The responding cell type was found to be the plasmacytoid dendritic cell. Such a strong innate immune response was accompanied by an up-regulation of several other immune response genes and secretion of cytokines, which modulate inflammation, and adaptive immune responses. These results suggest that enterovirus-induced immune activation depends on the virus strain. It is possible that the immunotype of the virus modulates the course of the infection and plays a role in the pathogenesis of chronic immune-mediated enterovirus diseases.

Immunogenic biologics: validation of screening, deimmunization and tolerization approaches (P3251)

Abstract Immune responses directed against protein therapeutics can directly impact drug pharmacology, safety and efficacy. While many factors contribute to protein immunogenicity, T cell-dependent responses play a critical role. Tools to predict and reduce T cell responses to protein therapeutics present benefits at every stage of drug development. We provide evidence for two different approaches to mitigate therapeutic protein immunogenicity: epitope modification and antigen-specific tolerance induction. Following a systematic process of in silico epitope mapping applied to either Factor VIII or botulinum toxin, rational epitope modification resulted in reduced immunogenicity. In vitro and in vivo validation of computational predictions and iterative in silico modification of immunogenic epitopes were experimentally validated for selected modified sequences. Tolerance induction is achieved by co-delivery or by chemical or recombinant linkage of regulatory T cell epitopes (Tregitopes) to therapeutic proteins. We have demonstrated that Tregitope incorporation leads to lower immune responses against target epitopes identified in insulin, Factor VIII and botulinum toxin. Analysis, prediction, and modification of T cell-mediated immunogenicity of therapeutic proteins expands the available strategies for mitigating therapeutic protein immunogenicity, enables quality by design for drugs in development and improvement of licensed biologics to create biobetters.

Cutaneous delayed-type hypersensitivity (DTH) in a multi-formulation comparator trial of the anti-falciparum malaria vaccine candidate RTS,S in rhesus macaques

Background Studies are underway to identify more immunogenic formulations of the existing anti-falciparum malaria vaccine RTS,S/AS02A. To supplement in vitro immunogenicity assays, cutaneous delayed-type hypersensitivity (DTH) may be a useful indicator of functional, cell-mediated immunogenicity. Methods Adult rhesus monkeys were immunized with saline or one of four RTS,S/adjuvant formulations: RTS,S/AS01B, RTS,S/AS02A-standard (current formulation), RTS,S/AS05 or RTS,S/AS06 at 0, 4, and 12 weeks. An additional cohort received RTS,S/AS02A-accelerated, at 0, 1, and 4 weeks. Six months after completing immunizations, five vaccine-relevant antigens (high and low doses) and two controls were administered intradermally. DTH reactivity (induration) was measured at 48 and 72 h, and selected sites were biopsied for histological confirmation. Results In comparison with RTS,S/AS02A-standard, RTS,S/AS01B and RTS,S/AS05 each had larger mean reactions (induration) at 5 of 10 ( p < 0.01, at each site) and 1 of 10 ( p < 0.05, at the single site) vaccine relevant test sites, respectively. Histologically, perivascular mononuclear cell infiltrates, a cardinal feature of DTH, were largest in the RTS,S/AS01B monkeys. Interpretation In DTH testing, with histological confirmation, RTS,S/AS01B was immunogenically superior to RTS,S/AS02A-standard and two other novel RTS,S formulations. The DTH outcomes paralleled conventional in vitro cellular immunogenicity assessments in distinguishing among similar RTS,S formulations, even at 6 months after final vaccination.

Assessment of cell mediated immunogenicity of Mycobacterium leprae-derived antigens

The antigenicity of Mycobacterium leprae ( M. leprae)-derived cell membrane fraction was examined using human dendritic cells (DCs). Immature DCs internalized and processed the cell membrane components, and expressed M. leprae-derived antigens (Ags) on their surface. The expression of MHC class II, CD86, and CD83 Ags on DCs and CD40 ligand (L)-associated IL-12 p70 production from DCs were up-regulated by the membrane Ags. Moreover these stimulated DCs induced significantly higher level of interferon-γ (IFN-γ) production by autologous CD4 + and CD8 + T cells than those pulsed with equivalent doses of live M. leprae or its cytosol fraction. Both subsets of T cells from tuberculoid leprosy patients also produced several fold more IFN-γ than those from normal individuals. Furthermore, the intracellular perforin production in CD8 + T cells was up-regulated in an Ag-dose dependent manner. These results suggest that M. leprae membrane Ags might be useful as the vaccinating agents against leprosy.