Glycoprotein Antigen Research Articles

Performance of an envelope glycoprotein-based multiplex immunoassay for Ebola virus antibody detection in a cohort of Ebola virus disease survivors

Serological surveillance in animal and human hosts can be a cost-effective strategy for orthoebolavirus detection, but is challenged by accurate estimates of seroprevalence, potential pauci-symptomatic disease presentation, and antigenic cross-reactivity. Here, we describe the use of an envelope glycoprotein (GP)-based multiplex microsphere immunoassay, consisting of nine filovirus GP antigens, for the detection of anti-Ebola virus (EBOV) antibodies in a well-characterized cohort of Guinean Ebola virus disease (EVD) survivors and contacts from the 2013 – 2016 West African EVD outbreak. We examined sensitivity and specificity for the detection of anti-EBOV antibodies by GP expressed as recombinant trimeric ectodomains, yielding an assay performance of 95.96% sensitivity and 98.61% specificity. Additionally, agreement between the multiplex test and a whole virus ELISA and virus neutralization test showed strong correlations. The results demonstrate this filovirus multiplex test is a sensitive tool for high-throughput serosurveillance

Efficacy of argon-helium cryoablation combined with chemotherapy in the treatment of advanced NSCLC.

To explore the efficacy of argon-helium cryoablation (AHC) combined with chemotherapy in the treatment of advanced non-small cell lung cancer (NSCLC). A retrospective study was carried out between February 2020 to June 2022 of 85 patients with advanced NSCLC admitted to Tianjin Cancer Hospital Airport Hospital. Patients were categorized into two groups based on whether they had received AHC: patients received chemotherapy treatment alone (chemotherapy group, n=41); patients received chemotherapy combined with AHC (combined group, n=44). Tumor control rate, serum tumor marker levels, quality of life, and median survival time between the two groups were compared. Tumor control rate in the combined group (86.36%) was significantly higher than that in the chemotherapy group (68.29%) (P<0.05). After treatment, the levels of serum cytokeratin 19 fragment (CYFRA21-1), carcinoembryonic antigen (CEA) and glycoprotein antigen 125 (CA125) in the two groups were significantly lower than those before the treatment, and significantly lower in the combined group compared to the chemotherapy group (P<0.05). After the treatment, the quality of life of patients in both groups was significantly higher than before the treatment. Quality of life in the combined group was significantly higher than in the chemotherapy group (P<0.05). One year after treatment, the median survival time of the combined group (10.5 months; 95% CI: 9.775-11.225) was significantly higher than that of the chemotherapy group (9.4 months; 95% CI: 8.55-10.323) (P=0.045). Compared with chemotherapy alone, conventional chemotherapy combined with AHC in the treatment of advanced NSCLC can significantly reduce the levels of serum tumor markers and improve overall treatment efficacy, quality of life and 1-year overall survival rate.

Immunogenicity and protective efficacy of a recombinant lactococcus lactis vaccine against HSV-1 infection

BackgroundHerpes simplex virus type 1 (HSV-1) is a major cause of viral encephalitis, genital mucosal infections, and neonatal infections. Lactococcus lactis (L. lactis) has been proven to be an effective vehicle for delivering protein antigens and stimulating both mucosal and systemic immune responses. In this study, we constructed a recombinant L. lactis system expressing the protective antigen glycoprotein D (gD) of HSV-1.ResultsTo improve the stability and persistence of antigen stimulation of the local mucosa, we inserted the immunologic adjuvant interleukin (IL)-2 and the Fc fragment of IgG into the expression system, and a recombinant L. lactis named NZ3900-gD-IL-2-Fc was constructed. By utilizing this recombinant L. lactis strain to elicit an immune response and evaluate the protective effect in mice, the recombinant L. lactis vaccine induced a significant increase in specific neutralizing antibodies, IgG, IgA, interferon-γ, and IL-4 levels in the serum of mice. Furthermore, in comparison to the mice in the control group, the vaccine also enhanced the proliferation levels of lymphocytes in response to gD. Moreover, recombinant L. lactis expressing gD significantly boosted nonspecific immune reactions in mice through the activation of immune-related genes. Furthermore, following the HSV-1 challenge of the murine lung mucosa, mice inoculated with the experimental vaccine exhibited less lung damage than control mice.ConclusionOur study presents a novel method for constructing a recombinant vaccine using the food-grade, non-pathogenic, and non-commercial bacterium L. lactis. The findings indicate that this recombinant vaccine shows promise in preventing HSV-1 infection in mice.

Immunogenicity and Neutralization of Recombinant Vaccine Candidates Expressing F and G Glycoproteins against Nipah Virus.

Nipah virus (NiV), of the Paramyxoviridae family, causes highly fatal infections in humans and is associated with severe neurological and respiratory diseases. Currently, no commercial vaccine is available for human use. Here, eight structure-based mammalian-expressed recombinant proteins harboring the NiV surface proteins, fusion glycoprotein (F), and the major attachment glycoprotein (G) were produced. Specifically, prefusion NiV-F and/or NiV-G glycoproteins expressed in monomeric, multimeric (trimeric F and tetra G), or chimeric forms were evaluated for their properties as sub-unit vaccine candidates. The antigenicity of the recombinant NiV glycoproteins was evaluated in intramuscularly immunized mice, and the antibodies in serum were assessed. Predictably, all homologous immunizations exhibited immunogenicity, and neutralizing antibodies to VSV-luciferase-based pseudovirus expressing NiV-GF glycoproteins were found in all groups. Comparatively, neutralizing antibodies were highest in vaccines designed in their multimeric structures and administered as bivalent (GMYtet + GBDtet) and trivalent (Ftri + GMYtet + GBDtet). Additionally, while all adjuvants were able to elicit an immunogenic response in vaccinated groups, bivalent (GMYtet + GBDtet) and trivalent (Ftri + GMYtet + GBDtet) induced more potent neutralizing antibodies when administered with oil-in-water nano-emulsion adjuvant, AddaS03. For all experiments, the bivalent GMYtet + GBDtet was the most immunogenic vaccine candidate. Results from this study highlight the potential use of these mammalian-expressed recombinant NiV as vaccine candidates, deserving further exploration.

An efficient plasmid-based system for the recovery of recombinant vesicular stomatitis virus encoding foreign glycoproteins

Viral glycoproteins mediate entry into host cells, thereby dictating host range and pathogenesis. In addition, they constitute the principal target of neutralizing antibody responses, making them important antigens in vaccine development. Recombinant vesicular stomatitis virus (VSV) encoding foreign glycoproteins can provide a convenient and safe surrogate system to interrogate the function, evolution, and antigenicity of viral glycoproteins from viruses that are difficult to manipulate or those requiring high biosafety level containment. However, the production of recombinant VSV can be technically challenging. In this work, we present an efficient and robust plasmid-based system for the production of recombinant VSV encoding foreign glycoproteins. We validate the system using glycoproteins from different viral families, including arenaviruses, coronaviruses, and hantaviruses, as well as highlight their utility for studying the effects of mutations on viral fitness. Overall, the methods described herein can facilitate the study of both native and recombinant VSV encoding foreign glycoproteins and can serve as the basis for the production of VSV-based vaccines.

Ebola virus circulation in a non‐epidemic Guinean rural area: A mixed‐method approach to assessing endemicity

ObjectivesThis study aimed to investigate the prevalence of orthoebolavirus antibodies in Madina Oula, a non-epidemic rural area in Guinea, in 2022. MethodsA cross-sectional study was conducted from March 14 to April 3, 2022 involving recording household and socio-demographic characteristics, lifestyle data, and collecting dried blood spots from 878 individuals in 235 households. Dried blood spots were tested using multiplex serology to detect antibodies to different orthoebolaviruses: Ebola virus, Bundibugyo virus, Sudan virus, Reston virus, and Bombali virus. Seroprevalence was estimated with a 95% confidence interval and a Z-test was performed to compare the seropositivity between children aged under 15 years and those over 15 years. Household and participant characteristics were analyzed using descriptive statistic, and socio-historical conditions were discussed. ResultsThe serological analysis conducted in 2022 on 878 participants revealed varying reactivity to orthoebolavirus antigens, notably, with glycoprotein antigens, particularly, glycoprotein Sudan virus (16%). A total of 21 samples exhibited reactivity with at least two antigens, with a median age of 27 years (interquartile range 10.00-35.00), ranging from 2 to 80 years. There is no significant difference between seropositivity in children aged under 15 (2.86%) years and those over 15 (2.14%) years. The antibody presence varied per village, with the highest prevalence observed in Ouassou and Dar-es-Salam. ConclusionsSerological data in a region unaffected by recent Ebola outbreaks indicate possible orthoebolavirus endemicity, emphasizing the need for preparedness against known or novel orthoebolaviruses with potential cross-reactivity.

Hyperosmotic cold shock mouse melanoma cells encapsulated with doxorubicin for targeted treatment of melanoma.

The primary treatment strategies for melanoma include surgical excision, chemotherapy, and radiotherapy. However, the efficacy of these treatments is often limited by drug resistance, recurrence, and severe side effects. Therefore, we aimed to develop a targeted drug delivery system capable of selectively locating tumor sites to minimize systemic toxicity and enhance therapeutic efficacy. This cell drug delivery system can also deliver chemotherapeutic drugs to the tumor microenvironment. We treated B16F10 cells with hyperosmotic cold shock (HCS) to obtain and characterize HCS cells. We then investigated the anti-tumor effects and immune activation capabilities of these cells and explored their potential as a targeted drug delivery system. HCS cells not only maintained an intact cellular structure and tumor antigens but also exhibited high expression of the homologous melanoma-associated antigen glycoprotein 100. These cells demonstrated an exceptional capacity for loading and releasing doxorubicin, which has chemotherapeutic anti-tumor effects. HCS cells can precisely target the tumor microenvironment to minimize systemic toxicity, inducing an immune response by activating CD3+ and CD4+ T cells. HCS cells are non-carcinogenic, with both cellular and tumor antigens intact; thus, they are suitable drug delivery carriers. Our findings highlight the potential of HCS cells for carrying doxorubicin because of their high drug-loading efficiency, effective tumor-targeting and anti-tumor effects. Therefore, our results will facilitate the development of melanoma treatments that have higher efficacy than those in the literature.

Unveiling Cryptosporidium parvum sporozoite-derived extracellular vesicles: profiling, origin, and protein composition.

Cryptosporidium parvum is a common cause of a zoonotic disease and a main cause of diarrhea in newborns. Effective drugs or vaccines are still lacking. Oocyst is the infective form of the parasite; after its ingestion, the oocyst excysts and releases four sporozoites into the host intestine that rapidly attack the enterocytes. The membrane protein CpRom1 is a large rhomboid protease that is expressed by sporozoites and recognized as antigen by the host immune system. In this study, we observed the release of CpRom1 with extracellular vesicles (EVs) that was not previously described. To investigate this phenomenon, we isolated and resolved EVs from the excystation medium by differential ultracentrifugation. Fluorescence flow cytometry and transmission electron microscopy (TEM) experiments identified two types of sporozoite-derived vesicles: large extracellular vesicles (LEVs) and small extracellular vesicles (SEVs). Nanoparticle tracking analysis (NTA) revealed mode diameter of 181 nm for LEVs and 105 nm for SEVs, respectively. Immunodetection experiments proved the presence of CpRom1 and the Golgi protein CpGRASP in LEVs, while immune-electron microscopy trials demonstrated the localization of CpRom1 on the LEVs surface. TEM and scanning electron microscopy (SEM) showed that LEVs were generated by means of the budding of the outer membrane of sporozoites; conversely, the origin of SEVs remained uncertain. Distinct protein compositions were observed between LEVs and SEVs as evidenced by their corresponding electrophoretic profiles. Indeed, a dedicated proteomic analysis identified 5 and 16 proteins unique for LEVs and SEVs, respectively. Overall, 60 proteins were identified in the proteome of both types of vesicles and most of these proteins (48 in number) were already identified in the molecular cargo of extracellular vesicles from other organisms. Noteworthy, we identified 12 proteins unique to Cryptosporidium spp. and this last group included the immunodominant parasite antigen glycoprotein GP60, which is one of the most abundant proteins in both LEVs and SEVs.

Structure and design of Langya virus glycoprotein antigens

Langya virus (LayV) is a recently discovered henipavirus (HNV), isolated from febrile patients in China. HNV entry into host cells is mediated by the attachment (G) and fusion (F) glycoproteins which are the main targets of neutralizing antibodies. We show here that the LayV F and G glycoproteins promote membrane fusion with human, mouse, and hamster target cells using a different, yet unknown, receptor than Nipah virus (NiV) and Hendra virus (HeV) and that NiV- and HeV-elicited monoclonal and polyclonal antibodies do not cross-react with LayV F and G. We determined cryoelectron microscopy structures of LayV F, in the prefusion and postfusion states, and of LayV G, revealing their conformational landscape and distinct antigenicity relative to NiV and HeV. We computationally designed stabilized LayV G constructs and demonstrate the generalizability of an HNV F prefusion-stabilization strategy. Our data will support the development of vaccines and therapeutics against LayV and closely related HNVs.

Abstract 6740: Next-generation LNPs induce effective anti-tumor T cell responses

Abstract mRNA immunotherapies have gained interest for the treatment of tumors from various origins, however, their ability to provide long -term durable tumor control has been underwhelming. Here we report that novel mRNA lipid nanoparticle (LNP) vaccinations induce robust expansion of antigen-specific T cells, although this does not always correlate with their ability to infiltrate and kill solid tumors. Using a portfolio of novel ionizable lipids and a robust in vivo model that reliably identifies LNPs with prominent anti-tissue T cell activity we have identified a putative LNP candidate that provides long term tumor control in a murine syngeneic tumor model. We utilized the model antigen glycoprotein (Gp), from the lymphocytic choriomeningitis virus (LCMV), and produced mRNA encoding the immunodominant epitopes gp3333-41, gp6161-80 and gp276276-286 (3GP-mRNA). This mRNA was encapsulated in various novel LNP formulations and administered i.m. into naïve C57Bl/6 mice to track the induction of a robust CD8+ T cell response identified using tetramers to gp33 and gp276. Successful candidate LNPs were then tested in the RIPgp model of autoimmune diabetes. RIPgp transgenic mice express LCMV-Gp in the pancreatic β cells and offer a robust assay for the ability to induce antigen-specific T cells capable of breaking self-tolerance and infiltrating and killing target tissue. Utilizing the RIPgp model to screen LNP candidates we identified a lead candidate, C2-5A, that both induced a robust expansion of antigen-specific T cells and tissue destruction. When utilized in a colon adenocarcinoma model expressing the LCMV-Gp antigen (MC38-Gp), therapeutic dosing of LNP C2-5A as a monotherapy lead to long term tumor clearance in 40% of the treated animals. We believe this screening platform allows the selection of LNP candidates capable of breaking self-tolerance, and one such candidate C2-5A provides a potent vehicle and adjuvant for mRNA based cancer vaccines. Citation Format: Douglas G. Millar, Matthew J. Gold, Kirsten Olsen, Yu Wu, Yury Karpov, Robert Nechanitzky, Haritha Menon, Rajesh Krishnan, Robert Georgantas, Pamela Ohashi, Natalia Martin-Orozco. Next-generation LNPs induce effective anti-tumor T cell responses [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 6740.

The Role of SARS-CoV-2 Nucleocapsidic Antigen and Krebs von den Lungen 6 Serum Levels in Predicting COVID-19 Pneumonia Outcome.

The COVID-19 pandemic caused by SARS-CoV-2 continues to pose a significant threat worldwide, with severe cases leading to hospitalization and death. This study aims to evaluate the potential use of serum nucleocapsid antigen (NAg) and Krebs von den Lungen-6 glycoprotein (KL-6) as biomarkers of severe COVID-19 and to investigate their correlation with clinical, radiological, and biochemical parameters. This retrospective study included 128 patients with confirmed SARS-CoV-2 infection admitted to a Neapolitan hospital in Italy between October 2020 and July 2021. Demographic, clinical, and laboratory data were collected, including serum levels of NAg and KL-6. The Chung et al. Computed Tomography Severity Score (TSS) was used to assess the severity of pneumonia, and outcomes were classified as home discharge, rehabilitation, and death. Statistical analyses were performed to compare Group I (home discharge and rehabilitation) and Group II (death, sub-intensive care, and ICU stay) based on demographic data, laboratory parameters, and TSS. Group II patients showed worse outcomes with higher levels of NAg, KL-6, and inflammatory markers, including interleukin-6 (IL-6), interleukin-2 receptor (IL-2R), and adrenomedullin. TSS was also significantly higher in Group II, with a positive correlation between TSS and NAg and KL-6 levels. Group I patients had higher values of hemoglobin (Hb) and platelets (PLT), while Group II patients had higher values of C-reactive protein (CRP), procalcitonin (PCT), D-Dimer, and glycemia. No significant difference was observed in gender distribution. Serum NAg and KL-6 levels are potential biomarkers of severe COVID-19 pneumonia, with higher levels indicating greater inflammation and organ damage. NAg may help identify infected patients at an increased risk of severe COVID-19 and ensure their admission to the most appropriate level of care. KL-6 may help predict interstitial lung damage and the severity of clinical features. Further studies are needed to establish a decision-making cut-off for these biomarkers in COVID-19.

Investigation of the Electrokinetic Properties of HIV-Based Virus-Like Particles.

The antigen density on the surface of HIV-based virus-like particles (VLPs) plays a crucial role in the improvement of HIV vaccine potency. HIV VLPs consist of a dense protein core, which is surrounded by a lipid bilayer and whose surface is usually decorated with antigenic glycoproteins. The successful downstream processing of these particles is challenging, and the high-resolution and cost-efficient purification of HIV-based VLPs has not yet been achieved. Chromatography, one of the major unit operations involved in HIV VLP purification strategies, is usually carried out by means of ion exchangers or ion-exchange membranes. Understanding the electrokinetic behavior of HIV-based VLPs may help to improve the adjustment and efficiency of the corresponding chromatographic processes. In this study, we investigated the electrokinetics and aggregation of both undecorated and decorated VLPs and interpreted the data from the perspective of the soft particle model developed by Ohshima (OSPM), which fails to fully predict the behavior of the studied VLPs. Post-Ohshima literature, and particularly the soft multilayer particle model developed by Langlet et al., provides an alternative theoretical framework to overcome the limits of the OSPM. We finally hypothesized that the electrophoretic mobility of HIV-based VLPs is controlled by an electrohydrodynamic interplay between envelope glycoproteins, lipid bilayer, and Gag envelope.

P338 The dependence of the level of Glycoprotein type 2 on the level of Zonulin in Crohn's disease

Abstract Background Introduction. Type 2 glycoprotein (GP2) is a quantitatively predominant membrane protein of excretory granules of pancreatic acinar cells. In a number of studies, it has been demonstrated that this protein is the main antigen for pancreatic antibodies associated with Crohn's disease Zonulin – a protein that can reversibly increase the permeability of the intestinal wall by changing the structure of tight junctions of the lateral surfaces of intestinal epithelial cells. The determination of fecal zonulin is used for noninvasive assessment of increased intestinal permeability. Normal values of zonulin in stool (≤ 110 ng/ml) indicate the absence of damage to the villous surface of the intestinal mucosa and normal density of intercellular contacts The aim of the study was to establish the dependence of the level of type 2 glycoprotein on the level of fecal zonulin (FZ) in the feces of CD patients with exacerbation of the disease. Methods 122 patients with CD in the form of ilekolitis with exacerbation of the disease (Me age — 32 years) were examined. FZ was evaluated by ELISA (IDK ® Zonulin ELISA Kit, Immunodiagnostik AG, Germany) in ng/ml. Reference values: &amp;lt; 83.15 ng/ml is a variant of the norm, 83.15-110 ng/ml is an elevated level, 110 ng/ml is a high level. The level of IgG and IgA to GP2 (antibodies to glycoprotein) antigen of pancreatic centroacinar cells (Anti-GP2, IgG, IgA) was determined by ELISA. Reference values: IgG GP-2 less than 10 units/ml, Ig and GP-2 less than 5 units/ml – positive values. Results In the stool samples of CD patients during the period of exacerbation in 92 patients, an increase in FZ was detected, the average value was 333.4 ±16.9 ng/ml. In the blood samples of 87 patients with CD during the period of exacerbation, an increase in Ig A GP-2 was detected, the average value was 43.4±6.9 units/ml. In the blood samples of 107 CD patients during the period of exacerbation, an increase in Ig G GP-2 was detected, the average value was 17.1 ± 1.3 units/ml. There is a high correlation force between the concentration of FZ and the concentration of Ig A GP-2 (r-0.760) (p=0.010). There is a moderate correlation force (r-0.490) (p=0.023) between the concentration of FZ and the concentration of Ig G GP-2. Conclusion An increase in the concentration of FZ in the feces of CD patients during exacerbation significantly correlates with an increase in the concentration of Ig A GP-2 and Ig G GP-2.

T-B Collaboration in Autoimmunity, Infection, and Transplantation.

We have attempted here to provide an up-to-date review of the collaboration between helper T cells and B cells in response to protein and glycoprotein antigens. This collaboration is essential as it not only protects from many pathogens but also contributes to a litany of autoimmune and immune-mediated diseases.

Recombinantly Expressed Tagged SUrface Protein (RETSUP) assay: a new diagnostic system for the detection of antibodies to platelets

BackgroundCurrent assays for the detection of (allo)antibodies to platelet antigens are often laborious and widely based on the presence of well-characterized donor platelets. ObjectivesTo develop an easy-to-perform, sensitive, and specific test for the detection of antibodies against platelet antigens, in particular, glycoprotein (GP) antigens, called “Recombinantly Expressed Tagged SUrface Protein” (RETSUP) assay, which does not require donor platelets. MethodsTwin-Strep-tagged GP complexes were recombinantly expressed in human embryonic kidney 293 cells after stable transfection. These cell lines were used as antigen sources in the RETSUP assay, combining cell-based and enzyme-linked immunosorbent assay–based assay procedures. The assay performance was tested with recombinant antibodies, anti–human platelet antigen (HPA) reference plasmas, and anti-HPA patient sera. ResultsHuman embryonic kidney 293 cell lines stably expressing either Twin-Strep-labeled GPIa/IIa, GPIIb/IIIa, GPIb/IX, or GPIb/IX/V complexes or GPV as well as the distinct HPA-1, HPA-3, and HPA-5 epitopes were successfully generated. Applying the generated GP-expressing cell lines, the developed RETSUP assay proved very sensitive and specific with recombinant antibodies targeting different GPs and human plasma/serum samples. The results of the test were not affected by the GP carrying the Twin-Strep-tag or by using freshly harvested or cryopreserved cells. ConclusionThe RETSUP assay is an easy-to-perform, sensitive, and specific assay for the detection of plasma/serum antibodies to platelet GP, with performance comparable to or better than those of current state-of-the-art assays in antiplatelet antibody diagnostics. Owing to the recombinant nature of the target antigens, it can be easily adapted to detect antibodies in other antibody-mediated diseases.

Effect of anti-Ebola virus monoclonal antibodies on endogenous antibody production in survivors of Ebola virus disease in the Democratic Republic of the Congo: an observational cohort study

The use of specific anti-Ebola virus therapy, especially monoclonal antibodies, has improved survival in patients with Ebola virus disease. We aimed to assess the effect of monoclonal antibodies on anti-Ebola virus antibody responses in survivors of the 2018-20 Ebola outbreak in the Democratic Republic of the Congo. In this observational prospective cohort study, participants were enrolled at three Ebola survivor clinics in Beni, Mangina, and Butembo (Democratic Republic of the Congo). Eligible children and adults notified as survivors of Ebola virus disease (ie, who had confirmed Ebola virus disease [RT-PCR positive in blood sample] and were subsequently declared recovered from the virus [RT-PCR negative in blood sample] with a certificate of recovery from Ebola virus disease issued by an Ebola treatment centre) during the 2018-20 Ebola virus disease outbreak were invited to participate in the study. Participants were recruited on discharge from Ebola treatment centres and followed up for 12-18 months depending on recruitment date. Routine follow-up assessments were done at 1, 3, 6, and 12-18 months after inclusion. We collected sociodemographic (age, sex, visit site), clinical (anti-Ebola virus drugs), and laboratory data (RT-PCR and Ct values). The primary outcome was the antibody concentrations against Ebola virus glycoprotein, nucleoprotein, and 40-kDa viral protein antigens over time assessed in all participants. Antibody concentrations were measured by the multiplex immunoassay, and the association between anti-Ebola virus antibody levels and the relevant exposures, such as anti-Ebola virus disease drugs (ansuvimab, REGN-EB3, ZMapp, or remdesivir), was assessed using both linear and logistic mixed regression models. This study is registered at ClinicalTrials.gov, NCT04409405. Between April 16, 2020, and Oct 18, 2021, 1168 survivors were invited to participate in the Les Vainqueurs d'Ebola cohort study. 787 survivors were included in the study, of whom 358 had data available for antibody responses. 85 (24%) of 358 were seronegative for at least two Ebola virus antigens on discharge from the Ebola treatment centre. The antibody response over time fluctuated but a continuous decrease in an overall linear evolution was observed. Quantitative modelling showed a decrease in nucleoprotein, glycoprotein, and VP-40 antibody concentrations over time (p<0·0001) with the fastest decrease observed for glycoprotein. The probability of being seropositive for at least two antigens after 36 months was 53·6% (95% CI 51·6-55·6) for participants who received ansuvimab, 73·5% (71·5-75·5) for participants who received REGN-EB3, 76·8% (74·8-78·8) for participants who received remdesivir, and 78·5% (76·5-80·5) for participants who received ZMapp. Almost a quarter of survivors were seronegative on discharge from the Ebola treatment centre and antibody concentrations decreased rapidly over time. These results indicate that monoclonal antibodies might negatively affect the production of anti-Ebola virus antibodies in survivors of Ebola virus disease which could increase the risk of reinfection or reactivation. The French National Agency for AIDS Research-Emergent Infectious Diseases-The French National Institute of Health and Medical Research, the French National Research Institute for Development, and the European and Developing Countries Clinical Trials Partnership. For the French translation of the abstract see Supplementary Materials section.

IMMU-52. LOW-INTENSITY PULSED ULTRASOUND CONDUCTS ANTIGEN-INDEPENDENT T CELL HOMING INTO THE BRAIN PARENCHYMA WITH THE INTACT BLOOD-BRAIN BARRIER

Abstract The blood-brain barrier (BBB) protects the brain parenchyma from excessive inflammation but also leads to poor immune cell homing, hampering the success of immunotherapies, such as ones for low-grade glioma, where the BBB is intact. Low-intensity pulsed ultrasound (LIPU) combined with the application of microbubbles allows the non-invasive, transient opening of the BBB and recent studies have observed immune cell infiltration into malignant gliomas following LIPU. While these data warrant mechanistic investigations on the effects of LIPU in preclinical settings, most mouse models of malignant glioma already display BBB disruption. Therefore, to study whether LIPU affects antigen-specific immune cell trafficking through the BBB, we created a novel immunocompetent mouse model of non-tumor bearing mice that display an intact BBB and express a minigene cassette encoding for four immunogenic peptides in glia cells under the glial fibrillary acidic protein (GFAP) promotor. These peptides are either presented by major histocompatibility complex (MHC) class I: human melanoma antigen glycoprotein (gp) 100 and lymphocytic choriomeningitis virus (LCMV)gp31) or class II: LCMV gp66 and tyrosinase-related protein 1. Minigene expression in astrocytes induced antigen-specific T cell proliferation and Interferon-γ release in vitro. Intravenous adoptive T cell transfer of naïve or respectively CD3/CD28-coactivated antigen-specific CD 8 T cells targeting gp100 peptide followed by immediate LIPU treatment induced T cell homing into the CNS parenchyma, and astrocyte-T cell interaction was confirmed by ex-vivo two-photon imaging. Furthermore, some animals that underwent immediate LIPU treatment after transfer of preactivated antigen-specific T cells developed neurological deficits such as ataxia, while no deficits were observed in those animals that underwent LIPU but did not receive T cells or received activated T cells but did not undergo LIFU treatment. In conclusion, LIPU might be a novel effective tool to support antigen-independent immune cell homing with the intact BBB.

Effect of Nanoknife Ablation Therapy in Patients with Pancreatic Cancer

This study was established to explore the therapeutic effect of nanoknife ablation in the treatment of pancreatic cancer with comprehensive perioperative nursing. The clinical data of 92 patients with pancreatic cancer who underwent nanoknife ablation surgery in The First Affiliated Hospital, Sun Yat-sen University and Sun Yat-sen University Cancer Center from January 2015 to December 2018 were retrospectively studied. These 92 patients were randomly and equally divided into a group with comprehensive perioperative nursing care and a group with routine nursing care. After the intervention period, the satisfaction with the nursing, serum albumin, total protein, and hemoglobin levels, length of hospital stay, and incidence of postoperative complications were compared between the two groups. Meanwhile, blood biochemical indicators and related immune indicators of 30 patients in the comprehensive nursing group were analyzed and compared between before and after the operation. Results: The hospitalization time of patients in the routine care group was significantly longer than that in the comprehensive care group (P &lt; 0.05). Meanwhile, the levels of albumin, total protein, and hemoglobin in the serum of patients in the comprehensive care group were significantly higher than those in the routine care group (P &lt; 0.05). All patients exhibited a certain increase in serum amylase level on the day after the operation, which then gradually decreased. There was no statistically significant difference in myocardial enzyme indexes at different time points before and after the operation. The glycoprotein antigen tumor markers carbohydrate antigen (CA)-19-9 and CA-242 increased on the 1st day after surgery, and gradually decreased thereafter. This study indicated that the safety of nanoknife ablation in patients with pancreatic cancer is relatively high. In addition, there is a clear clinical effect of comprehensive nursing care in the perioperative period, which can effectively improve the levels of albumin, total protein, and hemoglobin, shorten the hospitalization time, and reduce the incidence of postoperative complications. Such nursing care also relieved the tumor-related immunosuppression after surgery and significantly decreased the levels of tumor markers.

O-linked sialic acid residues on platelet membrane glycoprotein IIb mask the human HPA-9b alloepitope

AbstractSialic acids occupy the terminal position of glycan chains and have the potential to influence the antigenicity of glycoproteins (GP). The polymorphisms of human platelet alloantigens (HPA)-3 and HPA-9, located near the C-terminus of the extracellular domain of platelet membrane GPIIb, are adjacent to sialyl-core 1 O-glycans emanating from serines 845 and 847. Whether the nearby O-glycans affect the antigenicity of HPA-9b or influence the binding of anti-HPA-9b alloantibodies in clinically significant cases of neonatal alloimmune thrombocytopenia is unknown. To address this issue, we generated a series of O-glycan mutant HPA-9 allele-specific induced pluripotent stem cell lines, differentiated them to megakaryocytes (MKs), and examined their ability to bind HPA-9b-specific alloantibodies. We found that both wild-type MKs treated with neuraminidase and those genetically modified to lack the sialidases ST3GAL1 and ST3GAL2 dramatically increased anti-HPA-9b alloantibody binding, indicating that the HPA-9b epitope is partially masked by terminal sialic acids on nearby O-glycans of GPIIb. Interestingly, mutating the serine residues that carry these glycan chains to alanine actually reduced the binding of anti-HPA-9b alloantibodies, indicating that these 2 O-glycan chains contribute to the presentation of the HPA-9b epitope—perhaps by stabilizing the conformation of the GP in this region. Collectively, our data suggest that detection of anti-HPA-9b alloantibodies may be enhanced through the use of HPA-9b-specific MKs that have been genetically altered to lack nearby terminal sialic acid residues but retain the glycan chains to which they are attached.

Vaccination with prefusion-stabilized respiratory syncytial virus fusion protein elicits antibodies targeting a membrane-proximal epitope.

Respiratory syncytial virus (RSV) is the leading cause of bronchiolitis and pneumonia in infants, infecting all children by age 5. RSV also causes substantial morbidity and mortality in older adults, and a vaccine for older adults based on a prefusion-stabilized form of the viral F glycoprotein was recently approved by the FDA. Here, we investigate a set of antibodies that belong to the same public clonotype and were isolated from individuals vaccinated with a prefusion-stabilized RSV F protein. Our results reveal that these antibodies are highly potent and recognize a previously uncharacterized antigenic site on the prefusion F protein. Vaccination with prefusion RSV F proteins appears to boost the elicitation of these neutralizing antibodies, which are not commonly elicited by natural infection.