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Convalescent plasma therapy has been described as an attractive approach to treat critically ill patients with COVID-19 (Coronavirus disease 2019). The selection of convalescent plasma donors (CPD) is commonly based on neutralizing antibody titer. A better understanding of the quality of immune responses following COVID-19 will enable the optimization of convalescent donors' selection in convalescent plasma programs. The involvement of SARS-CoV-2 specific T cells in the induction and persistence of high affinity anti-SARS-CoV-2 neutralizing antibody is still poorly investigated. In this study, 115 CPD who presented SARS-CoV-2 and who were eligible for plasma donation were included. Comprehensive analysis of T cells together with humoral responses were performed in regards of sex, age and blood group type. High frequency of T cell responses against SARS-CoV-2 related protein such as spike glycoprotein (80.0%), nucleocapsid (NCAP) (70.4%) and membrane protein (VME1) (74.8%) were detected in CPD by ex vivo IFN-γ and TNF-α ELISpot assays. Among CPD responders, most exhibited poly-specific T cell responses (75%) defined by the ability to mount responses against at least two SARS-CoV-2 antigens. We found a positive correlation between the magnitude and the poly-specificity of anti-SARS-CoV-2 T cell responses in CPD. Notably, both the magnitude and poly-specificity of SARS-CoV-2 T cell responses were highly correlated with neutralizing antibody titer in CPD. The present study highlights that the poly-specificity and strength of SARS-CoV-2 specific T cell responses predicts neutralizing antibody titer following COVID-19. These observations show the interest to combine T cell assays and antibody titer for the selection of CPD and to a latter extend to assess COVID-19 vaccine efficacy in at-risk patients.

We compared the performance of SARS-CoV-2 neutralising antibody testing between 12 European laboratories involved in convalescent plasma trials. Raw titres differed almost 100-fold differences between laboratories when blind-testing 15 plasma samples. Calibration of titres in relation to the reference reagent and standard curve obtained by testing a dilution series reduced the inter-laboratory variability ca 10-fold. The harmonisation of neutralising antibody quantification is a vital step towards determining the protective and therapeutic levels of neutralising antibodies. ispartof: EUROSURVEILLANCE vol:26 issue:27 ispartof: location:Sweden status: published

Human cytomegalovirus (HCMV) causes serious complications to immune compromised hosts. Dendritic cells (iDCgB) expressing granulocyte-macrophage colony-stimulating factor, interferon-alpha and HCMV-gB were developed to promote de novo antiviral adaptive responses. Mice reconstituted with a human immune system (HIS) were immunized with iDCgB and challenged with HCMV, resulting into 93% protection. Immunization stimulated the expansion of functional effector memory CD8+ and CD4+ T cells recognizing gB. Machine learning analyses confirmed bone marrow T/CD4+, liver B/IgA+ and spleen B/IgG+ cells as predictive biomarkers of immunization (≈87% accuracy). CD8+ and CD4+ T cell responses against gB were validated. Splenic gB-binding IgM-/IgG+ B cells were sorted and analyzed at a single cell level. iDCgB immunizations elicited human-like IgG responses with a broad usage of various IgG heavy chain V gene segments harboring variable levels of somatic hypermutation. From this search, two gB-binding human monoclonal IgGs were generated that neutralized HCMV infection in vitro. Passive immunization with these antibodies provided proof-of-concept evidence of protection against HCMV infection. This HIS/HCMV in vivo model system supported the validation of novel active and passive immune therapies for future clinical translation., Author summary Human cytomegalovirus (HCMV) is a ubiquitous pathogen. As long as the immune system is functional, T and B cells can control HCMV. Yet, for patients who have debilitated immune functions, HCMV infections and reactivations cause major complications. Vaccines or antibodies to prevent or treat HCMV are not yet approved. Novel animal models for testing new immunization approaches are emerging and are important tools to identify biomedical products with a reasonable chance to work in patients. Here, we used a model based on mice transplanted with human immune cells and infected with a traceable HCMV. We tested a cell vaccine (iDCgB) carrying gB, a potent HCMV antigen. The model showed that iDCgB halted the HCMV infection in more than 90% of the mice. We found that antibodies were key players mediating protection. Using state-of-the-art methods, we were able to use the sequences of the human antibodies generated in the mice to construct and produce monoclonal antibodies in the laboratory. Proof-of-concept experiments indicated that administration of these monoclonal antibodies into mice protected them against HCMV infection. In summary, this humanized mouse model was useful to test a vaccine and to generate and test novel antibodies that can be further developed for human use.

Temporary passive immunity such as serotherapy against venoms requires the full knowledge of all venom's components. Here, four venoms from Moroccan common yellow scorpions belonging to Buthus occitanus, subspecies tunetanus , paris, malhommei, and mardochei , all collected in four different restricted areas, were analysed in deep. They were fractionated by reversed-phase high-performance liquid chromatography (RP-HPLC) and their molecular masse profile determined by off-line MALDI-TOF mass spectrometry. Characterisation of their main components was achieved by enzyme-linked immunosorbent assay (ELISA) using specific antisera against the major lethal scorpion toxins identified so far, i.e. voltage-gated sodium channels (Na v ) modulators α- and β-toxins, as well as diverse potassium channel pore blocker toxins. For fractions with identical RP-HPLC retention times, we observe that their relative quantities show large differences. Moreover, identical masses present simultaneously in the four venoms are infrequent. ELISAs show that the majority of the RP-HPLC compounds cross-react with the antiserum against the “α-like” toxin Bot I, which has been previously identified in the Algerian Buthus occitanus tunetanus venom. Moreover, minor fractions were recognised by the antiserum against the highly lethal “classical” α-toxin of reference AaH II from the Androctonus australis venom. As such, our results bring new sights for further improving scorpion venom serotherapy in Morocco.

Comment in [Infection and pregnancy: a threat for mother and child]. [Presse Med. 2014]; International audience; The incidence of varicella is low in pregnant women, and estimated around 1/1000 pregnancies. Vaccination is the cornerstone of prevention, but is contraindicated during pregnancy. Varicella is more severe in pregnant women. The risk of viral pneumonia is not increased, but VZV-associated pneumonia is usually more severe in pregnant women. Infection between 0-20 WG is associated with a 2 % risk of congenital varicella syndrome. Infection between D-5 and D+2 of delivery is associated with high risk of severe neonatal infection. Non-immune pregnant women with significant exposure to VZV require post-exposure prophylaxis with specific anti-VZV immunoglobulins that should be administered ideally within 4 days post-exposure and maximum within 10 days of exposure. Anti-VZV immunoglobulins are available in France in the context of an approved expanded access to an investigational new drug. Pregnant women with varicella should receive within 24 hours antiviral treatment based either on valaciclovir or, in case of severe infection, intravenous aciclovir. Both drugs were shown safe during pregnancy, even during the first trimester. Neonates born from mothers who developed varicella between D-5 and D+2 of delivery should also receive as soon as possible specific anti-VZV immunoglobulins.; L’incidence de la varicelle chez la femme enceinte est faible : moins de 1 grossesse/1000.La prévention de l’infection passe par la vaccination. Le vaccin vivant atténué est contre-indiqué chez la femme enceinte. La vaccination est donc recommandée pour les femmes en âge de procréer n’ayant pas d’antécédent clinique de varicelle, après un test négatif de grossesse et sous couvert d’une contraception efficace de trois mois après chaque dose de vaccin.Les femmes enceintes n’ont pas de risque accru de pneumopathie au cours de la varicelle par rapport à la population adulte, en revanche ces pneumopathies sont volontiers plus sévères.L’infection maternelle entre 0 et 20 SA expose l’enfant à un risque faible d’embryo-fœtopathie (1 à 2 %).L’infection maternelle entre j-5 et j + 2 par rapport à la date de l’accouchement expose l’enfant à un risque majeur de varicelle néonatale grave.Les femmes enceintes non immunes exposées au VZV (contact familial, contact face à face > 5 minutes ou dans une même pièce > 1 heure) doivent recevoir des immunoglobulines spécifiques anti-VZV, idéalement dans les 4 jours suivant le contage, et au maximum dans les 10 jours suivant le contage. Ces immunoglobulines sont disponibles en autorisation temporaire d’utilisation.Les femmes enceintes développant une varicelle doivent recevoir dans les 24 heures un traitement par valaciclovir (aciclovir IV en cas de forme grave) : ces antiviraux sont autorisés et considérés comme non tératogènes à tout terme de la grossesse.Les nouveau-nés dont la mère développe une éruption varicelleuse entre j-5 et j + 2 par rapport à la date de l’accouchement doivent également recevoir des immunoglobulines spécifiques anti-VZV le plus précocement possible.

International audience; Rabies is responsible for 50,000 deaths per year worldwide. Mainland France has been officially freed from rabies in non-flying animals since 2001.; We wanted to provide an update on the French situation, using published data, and describe possible options since official guidelines are lacking.; Post-exposure prophylaxis (PEP) (early and careful cleaning and dressing of the wound, vaccination, and in case of high-risk exposure, injection of specific anti-rabies immunoglobulins) is known to be efficient except in rare cases. It is recommended after grade II contact (+specific immunoglobulins in immunodepressed patients), or grade III contact (vaccination+immunoglobulins).; Mainland France being rabies-free, 3 options may be considered in case of bite by a dog or a cat that cannot be monitored in France: (a) consider the risk of rabies as null, so no PEP should be administrated, whatever the severity of bites; (b) consider there is a weak but lethal risk, so the international recommendations should be applied, using immunoglobulins in some cases; (c) consider that the risk is extremely low but cannot be excluded, and that the patient should be vaccinated to be protected, but without adding immunoglobulins (whether in case of grade II or III bites).; There are no national guidelines for rabies in France, and so the physician managing the patient is the one who will decide to treat or not.

International audience; BACKGROUND: The purpose of this study was to report long-term results of rituximab induction monotherapy in patients with low-tumor-burden follicular lymphoma (LTBFL). PATIENTS AND METHODS: Of 49 first-line LTBFL patients who received weekly doses of rituximab (375 mg/m(2)), 46 have been followed with a long-term analysis of clinical and molecular responses. RESULTS: Best clinical response (at any staging within a year following treatment) was 80%, 24 (52%) patients had complete or unconfirmed complete response, 13 (28%) had partial response and 9 (20%) had stable or progressive disease. Of 31 patients having a positive bcl2-JH rearrangement, 15 (48%) became negative following treatment. After 83.9 months of follow-up (95% confidence interval 6.4-92.8 months), the median progression-free survival is 23.5 months and overall survival (OS) is 91.7%. Five patients died (one progression, one myelodysplasia, one diffuse large B-cell lymphoma and two solid tumors). Seven patients (15%) are progression-free including five who are bcl2 informative. No unexpected long-term adverse event has been observed. CONCLUSION: A significant proportion of patients remain progression-free 7 years after a single 4-dose rituximab treatment in first-line LTBFL. The 7-year overall survivalOS is very high in this selected population of patients.

Antibody-dependent cell cytotoxicity (ADCC) plays a critical role in monoclonal antibody (mAb)-mediated cancer therapy. ADCC, however, has not been directly shown in vivo but inferred from the requirement for IgG Fc receptors (FcγR) in tumor rejection in mice. Here, we investigated the mechanism of action of a Tn antigen-specific chimeric mAb (Chi-Tn), which binds selectively to a wide variety of carcinomas, but not to normal tissues, in both humans and mice. Chi-Tn mAb showed no direct toxicity against carcinomas cell lines in vitro but induced the rejection of a murine breast tumor in 80% to 100% of immunocompetent mice, when associated with cyclophosphamide. Tumor rejection was abolished in Fc receptors–associated γ chain (FcR-γ)–deficient mice, suggesting a role for ADCC. Indeed, tumor cells formed stable conjugates in vivo with FcR-γ chain-expressing macrophages and neutrophils in Chi-Tn mAb-treated but not in control mAb-treated mice. The contact zone between tumor cells and ADCC effectors accumulated actin, FcγR and phospho-tyrosines. The in vivo formed ADCC synapses were organized in multifocal supra-molecular activation clusters. These results show that in vivo ADCC mediated by macrophages and neutrophils during tumor rejection by Chi-Tn mAb involves a novel type of multifocal immune synapse between effectors of innate immunity and tumor cells. Cancer Res; 71(15); 5134–43. ©2011 AACR.

International audience; Rabies is a fatal disease transmitted by infected animals by bite, scratch, licking on broken skin or contamination of mucosis by saliva. The regimen of post-exposure prophylaxis for people not previously vaccinated, that is currently recommended by WHO, consists of a combination of wound cleaning, active immunization and passive immunization when the exposure is of category 3. Most of the products available on the market, in particular human rabies immunoglobulins, highly purified equine rabies immunoglobulins and the derived F(ab')(2) fragments, are now characterized by high potency and safety. Although the interest of passive anti-rabies immunization was first demonstrated in the first half of the 20th century, there is still an inadequate supply of these products to the target populations mostly in developing countries. Therefore, it is urgent to set-up training and information actions for healthcare personnel on the need to use passive immunotherapy and the lack of adverse effects of the related products. For the future, we hope that a scale up of production and a lower price will improve the accessibility to these products. The development of new products based on monoclonal antibodies and molecular biology, and which may be cheaper, is promising.

International audience; The protective capacity of a parenterally administered beta-glucan-conjugate vaccine formulated with the human-compatible MF59 adjuvant was assessed in a murine model of vaginal candidiasis. To monitor infection, an in vivo imaging technique exploiting genetically engineered, luminescent Candida albicans was adopted, and compared with measurements of colony forming units. The vaccine conferred significant protection, and this was associated with production of serum and vaginal anti-beta-glucan IgG antibodies. Vaginal IgG molecules were the likely mediators of protection as inferred by the efficacy of passive transfer of immune vaginal fluid and passive protection by an anti-beta-1,3-glucan mAb. Overall, the in vivo imaging technique was more reliable than vaginal CFU counts in assessing the extent and duration of the vaginal infection, and the consequent protection level.

International audience; Rabies is a fatal disease transmitted by infected animals by bite, scratch, licking on broken skin or contamination of mucosis by saliva. The regimen of post-exposure prophylaxis for people not previously vaccinated, that is currently recommended by WHO, consists of a combination of wound cleaning, active immunization and passive immunization when the exposure is of category 3. Most of the products available on the market, in particular human rabies immunoglobulins, highly purified equine rabies immunoglobulins and the derived F(ab')(2) fragments, are now characterized by high potency and safety. Although the interest of passive anti-rabies immunization was first demonstrated in the first half of the 20th century, there is still an inadequate supply of these products to the target populations mostly in developing countries. Therefore, it is urgent to set-up training and information actions for healthcare personnel on the need to use passive immunotherapy and the lack of adverse effects of the related products. For the future, we hope that a scale up of production and a lower price will improve the accessibility to these products. The development of new products based on monoclonal antibodies and molecular biology, and which may be cheaper, is promising.

Background Imported cases threaten rabies reemergence in rabies-free areas. During 2000–2005, five dog and one human rabies cases were imported into France, a rabies-free country since 2001. The Summer 2004 event led to unprecedented media warnings by the French Public Health Director. We investigated medical practice evolution following the official elimination of rabies in 2001; impact of subsequent episodic rabies importations and national newspaper coverage on demand for and delivery of antirabies prophylaxis; regular transmission of epidemiological developments within the French Antirabies Medical Center (ARMC) network; and ARMC discussions on indications of rabies post-exposure prophylaxis (RPEP). Methodology/Principal Findings Annual data collected by the National Reference Center for Rabies NRCR (1989–2006) and the exhaustive database (2000–2005) of 56 ARMC were analyzed. Weekly numbers of patients consulting at ARMC and their RPEP- and antirabies-immunoglobulin (ARIG) prescription rates were determined. Autoregressive integrated moving-average modeling and regression with autocorrelated errors were applied to examine how 2000–2005 episodic rabies events and their related national newspaper coverage affected demand for and delivery of RPEP. A slight, continuous decline of rabies-dedicated public health facility attendance was observed from 2000 to 2004. Then, during the Summer 2004 event, patient consultations and RPEP and ARIG prescriptions increased by 84%, 19.7% and 43.4%, respectively. Moreover, elevated medical resource use persisted in 2005, despite communication efforts, without any secondary human or animal case. Conclusions Our findings demonstrated appropriate responsiveness to reemerging rabies cases and effective newspaper reporting, as no secondary case occurred. However, the ensuing demand on medical resources had immediate and long-lasting effects on rabies-related public health resources and expenses. Henceforth, when facing such an event, decision-makers must anticipate the broad impact of their media communications to counter the emerging risk on maintaining an optimal public health organization and implement a post-crisis communication strategy., Author Summary Rabies has been eliminated from a large part of the European Union and, thus, any newly imported cases threaten its reemergence. The 2000–2005 data derived from the exhaustive surveillance system implemented in France was analyzed to evaluate the impact on demand for and delivery of antirabies prophylaxis following introduction of five rabies-infected dogs and one infected human into this rabies-free area. Using these events, we were able to illustrate the difficulties encountered in reducing the demand for and prescription of post-exposure rabies prophylaxis in this context of episodic importation. Moreover, we highlighted the need for public health decision-makers to anticipate the broad spectrum of consequences of their media communications and to prepare appropriate responses (in terms of health resources) to maintain an optimally effective public health organization after importation of an exotic infectious agent or its emergence. These responses are particularly relevant in the context of limited availability of rabies post-exposure prophylaxis, especially antirabies immunoglobulin.

The absence of specific immune response is a hallmark of prion diseases. However, in vitro and in vivo experiments have provided evidence that an anti-PrP humoral response could have beneficial effects. Prophylactic passive immunization performed at the time of infection delayed or prevented disease. Nonetheless, the potential therapeutic effect of PrP antibodies administered shortly before the clinical signs has never been tested in vivo. Moreover, a recent study showed the potential toxicity of PrP antibodies administered intracerebrally. We aimed at evaluating the effect of a prolonged intracerebral anti-PrP antibody administration at the time of neuroinvasion in BSE infected Tg20 mice. Unexpectedly, despite a good penetration of the antibodies in the brain parenchyma, the treatment was not protective against the development of BSE. Instead, it led to an extensive neuronal loss, strong astrogliosis and microglial activation. Since this effect was observed after injection of anti-PrP antibodies as whole IgGs, F(ab')(2) or Fab fragments, the toxicity was directly related to the ability of the antibodies to recognize native PrP and to the intracerebral concentration achieved, and not to the Fc portion or the divalence of the antibodies. This experiment shows that a prolonged treatment with anti-PrP antibodies by the intracerebral route can induce severe side-effects and calls for caution with regard to the use of similar approaches for late therapeutic interventions in humans.

Amino acid substitutions and deletions in Spike protein of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants can reduce the effectiveness of monoclonal antibodies (mAbs). In contrast, heterologous polyclonal antibodies raised against S protein, through the recognition of multiple target epitopes, have the potential to maintain neutralization capacities. XAV-19 is a swine glyco-humanized polyclonal neutralizing antibody raised against the receptor binding domain (RBD) of the Wuhan-Hu-1 Spike protein of SARS-CoV-2. XAV-19 target epitopes were found distributed all over the RBD and particularly cover the receptor binding motives (RBM), in direct contact sites with the Angiotensin Converting Enzyme-2 (ACE-2). Therefore, in Spike/ACE2 interaction assays, XAV-19 showed potent neutralization capacities of the original Wuhan Spike and of the United Kingdom (Alpha/B.1.1.7) and South African (Beta/B.1.351) variants. These results were confirmed by cytopathogenic assays using Vero E6 and live virus variants including the Brazil (Gamma/P.1) and the Indian (Delta/B.1.617.2) variants. In a selective pressure study with the Beta strain on Vero E6 cells conducted over 1 month, no mutation was associated with addition of increasing doses XAV-19. The potential to reduce viral load in lungs was confirmed in a human ACE2 transduced mouse model. XAV-19 is currently evaluated in patients hospitalized for COVID-19-induced moderate pneumonia in a phase 2a-2b (NCT04453384) where safety was already demonstrated and in an ongoing 2/3 trial (NCT04928430) to evaluate the efficacy and safety of XAV-19 in patients with moderate-to-severe COVID-19. Owing to its polyclonal nature and its glyco-humanization, XAV-19 may provide a novel safe and effective therapeutic tool to mitigate the severity of coronavirus disease 2019 (Covid-19) including the different variants of concern identified so far.