Resistance of Omicron subvariants BA.2.75.2, BA.4.6 and BQ.1.1 to neutralizing antibodies

Convergent evolution of SARS-CoV-2 Omicron BA.2, BA.4 and BA.5 lineages has led to the emergence of several new subvariants, including BA.2.75.2, BA.4.6. and BQ.1.1. The subvariants BA.2.75.2 and BQ.1.1 are expected to become predominant in many countries in November 2022. They carry an additional and often redundant set of mutations in the spike, likely responsible for increased transmissibility and immune evasion. Here, we established a viral amplification procedure to easily isolate Omicron strains. We examined their sensitivity to 6 therapeutic monoclonal antibodies (mAbs) and to 72 sera from Pfizer BNT162b2-vaccinated individuals, with or without BA.1/BA.2 or BA.5 breakthrough infection. Ronapreve (Casirivimab and Imdevimab) and Evusheld (Cilgavimab and Tixagevimab) lost any antiviral efficacy against BA.2.75.2 and BQ.1.1, whereas Xevudy (Sotrovimab) remained weakly active. BQ.1.1 was also resistant to Bebtelovimab. Neutralizing titers in triply vaccinated individuals were low to undetectable against BQ.1.1 and BA.2.75.2, 4 months after boosting. A BA.1/BA.2 breakthrough infection increased these titers, which remained about 18-fold lower against BA.2.75.2 and BQ.1.1, than against BA.1. Reciprocally, a BA.5 breakthrough infection increased more efficiently neutralization against BA.5 and BQ.1.1 than against BA.2.75.2. Thus, the evolution trajectory of novel Omicron subvariants facilitated their spread in immunized populations and raises concerns about the efficacy of most currently available mAbs.N

Human CD8+ T cell cross-reactivity across influenza A, B and C viruses

Influenza A, B and C viruses (IAV, IBV and ICV, respectively) circulate globally and infect humans, with IAV and IBV causing the most severe disease. CD8+ T cells confer cross-protection against IAV strains, however the responses of CD8+ T cells to IBV and ICV are understudied. We investigated the breadth of CD8+ T cell cross-recognition and provide evidence of CD8+ T cell cross-reactivity across IAV, IBV and ICV. We identified immunodominant CD8+ T cell epitopes from IBVs that were protective in mice and found memory CD8+ T cells directed against universal and influenza-virus-type-specific epitopes in the blood and lungs of healthy humans. Lung-derived CD8+ T cells displayed tissue-resident memory phenotypes. Notably, CD38+Ki67+CD8+ effector T cells directed against novel epitopes were readily detected in IAV- or IBV-infected pediatric and adult subjects. Our study introduces a new paradigm whereby CD8+ T cells confer unprecedented cross-reactivity across all influenza viruses, a key finding for the design of universal vaccines

Immune cellular networks underlying recovery from influenza virus infection in acute hospitalized patients

How innate and adaptive immune responses work in concert to resolve influenza disease is yet to be fully investigated in one single study. Here, we utilize longitudinal samples from patients hospitalized with acute influenza to understand these immune responses. We report the dynamics of 18 important immune parameters, related to clinical, genetic and virological factors, in influenza patients across different severity levels. Influenza disease correlates with increases in IL-6/IL-8/MIP-1α/β cytokines and lower antibody responses. Robust activation of circulating T follicular helper cells correlates with peak antibody-secreting cells and influenza heamaglutinin-specific memory B-cell numbers, which phenotypically differs from vaccination-induced B-cell responses. Numbers of influenza-specific CD8+ or CD4+ T cells increase early in disease and retain an activated phenotype during patient recovery. We report the characterisation of immune cellular networks underlying recovery from influenza infection which are highly relevant to other infectious diseases

Étude du mode d'action des anticorps dans deux contextes différents : infection par le virus SARS-CoV-2 et traitement par anticorps anti-CD20

Antibodies are produced upon infection or vaccination. They fight pathogens through several mechanisms including neutralization and Fc-dependent effector functions. The constant fragment (Fc) of antibodies recruits effector cells such as Natural Killer (NK) cells, complement and macrophages/monocytes. Fc-mediated antiviral mechanisms include antibody-dependent cell cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC) and antibody-dependent cell phagocytosis (ADCP). These mechanisms are not induced to the same extent by all antibodies. In this thesis, we explored two different aspects of the activity of antibodies. We studied antibodies produced during SARS-CoV-2 infection virus and also examined the regulation of efficacy of therapeutic anti-CD20 monoclonal antibodies. We first developed a sensitive and specific assay based on flow cytometry to detect anti-SARS-CoV-2 antibodies. It enabled us to identify individuals that were convalescent for COVID-19 before systematic testing was established. It also allowed us to study the duration of the humoral response. We showed that antibody levels were decreasing more rapidly in males. We studied the function of antibodies elicited after symptomatic of asymptomatic SARS-CoV-2 infection. The antibodies not only neutralized the virus but also induced ADCC and CDC, to a similar extent in asymptomatic and symptomatic individuals. We examined the impact of antibodies on the infectivity of virus present in nasopharyngeal swabs of patients infected with Alpha or former variants. The antibodies in the swabs inhibited viral infectivity. Antigenic test results were predictive of infectious viral particles release. The Alpha variant was associated with increased cytokine release, when compared to previous variants. Antibodies are produced by the immune system upon pathogen exposure but can also be engineered in laboratory to be used as therapeutics. Anti-CD20 antibodies such as Rituximab, Ofatumumab and Obinutuzumab are widely used to treat B-cell-associated diseases. Anti-CD20 antibodies deplete B cells by triggering apoptosis and effector functions. Some patients experience resistance to the treatment or disease relapses. We studied the mechanisms regulating the efficacy of therapeutic anti-CD20 with a genome-wide screening approach. We showed that expression of the transcription factor IRF8 (Interferon Regulatory Factor 8) was associated with CD20 expression in normal B cells, and in tumoral B cells, especially from diffuse-large-B-cell-lymphoma patients. A decrease in IRF8 expression is thus responsible for a decreased efficacy of anti-CD20 antibodies in cell culture. In conclusion, we have described the polyfunctional activity of anti-SARS-CoV-2. We have also unveiled a new mechanism of regulation of the levels of CD20 by IRF8, impacting the efficacy of therapeutic anti-CD20 antibodies.Les anticorps sont une des composantes essentielles du système immunitaire des vertébrés, et sont produits après infection ou vaccination. Ils possèdent plusieurs activités : une activité de neutralisation (liaison au pathogène qui bloque l'infection) et des fonctions médiées par leur fragment constant Fc. Les anticorps recrutent et activent d'autres effecteurs de l'immunité tels que les cellules Natural Killer (NK), le complément ou les macrophages/monocytes. Ils peuvent induire différents phénomènes antiviraux, tels que la cytotoxicité cellulaire dépendante des anticorps (ADCC), la cytotoxicité dépendante du complément (CDC) et la phagocytose dépendante des anticorps (ADCP). Ces différentes fonctions varient avec chaque anticorps. Nous nous sommes intéressés au mécanisme d'action de deux catégories d'anticorps. Nous avons étudié les anticorps produits après infection par le virus SARS-CoV-2. Nous nous sommes aussi penchés sur les mécanismes de régulation de l'efficacité des anticorps monoclonaux thérapeutiques anti-CD20. Nous avons tout d'abord mis en place un test de détection sensible et spécifique des anticorps anti-SARS-CoV-2 basé sur la cytométrie de flux, qui nous a permis d'identifier des personnes convalescentes de la COVID-19. Nous avons étudié la durée de la réponse humorale et démontré que les niveaux d'anticorps diminuaient au cours du temps et ce d'autant plus rapidement chez les individus masculins. Nous avons comparé les fonctions des anticorps provenant de personnes ayant fait une infection asymptomatique ou symptomatique. Nous avons confirmé que les anticorps produits après infection neutralisaient le virus, et induisaient ADCC et CDC, de façon similaire chez les individus symptomatiques et asymptomatiques. Nous avons aussi étudié l'impact des anticorps présents dans les prélèvements nasopharyngés de patients infectés par le variant Alpha ou des variants précédents. Nous avons démontré que ces anticorps inhibaient le virus dans la plupart des cas, que les résultats des tests antigéniques étaient cohérents avec la présence de virus infectieux et que le variant Alpha était associé à une libération accrue de cytokines. Les anticorps sont produits par le système immunitaire face à un pathogène mais peuvent également être produits en laboratoire pour être utilisés en tant que thérapie. Les anticorps anti-CD20, tels que Rituximab, Ofatumumab et Obinutuzumab, sont largement utilisés pour traiter des pathologies liées aux lymphocytes B, car le CD20 est présent sur ces cellules jusqu'au stade plasmocytaire. L'injection des anti-CD20 provoque une déplétion des lymphocytes B par apoptose et autres fonctions effectrices. Certains patients sont cependant résistants au traitement ou subissent des rechutes. Nous avons étudié les mécanismes régulant l'efficacité de ces anticorps utilisés en clinique. Nous avons réalisé un test de criblage afin d'identifier les protéines cellulaires impliquées dans l'échappement aux anti-CD20. Nous avons démontré que le facteur de transcription IRF8 (Interferon Regulatory Factor 8) est impliqué dans l'expression de CD20 dans les lymphocytes B normaux ou tumoraux, en particulier dans les lymphomes diffus à grandes cellules B. Une diminution des niveaux d'IRF8 est responsable d'une moins bonne efficacité de trois anti-CD20 en culture cellulaire. En conclusion, nous avons démontré que les anticorps anti-SARS-CoV-2 étaient polyfonctionnels. Nous avons également décrit un nouveau mécanisme de régulation des niveaux de CD20 par IRF8 qui impacte l'efficacité des anticorps thérapeutiques anti-CD20

Étude du mode d'action des anticorps dans deux contextes différents : infection par le virus SARS-CoV-2 et traitement par anticorps anti-CD20

Antibodies are produced upon infection or vaccination. They fight pathogens through several mechanisms including neutralization and Fc-dependent effector functions. The constant fragment (Fc) of antibodies recruits effector cells such as Natural Killer (NK) cells, complement and macrophages/monocytes. Fc-mediated antiviral mechanisms include antibody-dependent cell cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC) and antibody-dependent cell phagocytosis (ADCP). These mechanisms are not induced to the same extent by all antibodies. In this thesis, we explored two different aspects of the activity of antibodies. We studied antibodies produced during SARS-CoV-2 infection virus and also examined the regulation of efficacy of therapeutic anti-CD20 monoclonal antibodies. We first developed a sensitive and specific assay based on flow cytometry to detect anti-SARS-CoV-2 antibodies. It enabled us to identify individuals that were convalescent for COVID-19 before systematic testing was established. It also allowed us to study the duration of the humoral response. We showed that antibody levels were decreasing more rapidly in males. We studied the function of antibodies elicited after symptomatic of asymptomatic SARS-CoV-2 infection. The antibodies not only neutralized the virus but also induced ADCC and CDC, to a similar extent in asymptomatic and symptomatic individuals. We examined the impact of antibodies on the infectivity of virus present in nasopharyngeal swabs of patients infected with Alpha or former variants. The antibodies in the swabs inhibited viral infectivity. Antigenic test results were predictive of infectious viral particles release. The Alpha variant was associated with increased cytokine release, when compared to previous variants. Antibodies are produced by the immune system upon pathogen exposure but can also be engineered in laboratory to be used as therapeutics. Anti-CD20 antibodies such as Rituximab, Ofatumumab and Obinutuzumab are widely used to treat B-cell-associated diseases. Anti-CD20 antibodies deplete B cells by triggering apoptosis and effector functions. Some patients experience resistance to the treatment or disease relapses. We studied the mechanisms regulating the efficacy of therapeutic anti-CD20 with a genome-wide screening approach. We showed that expression of the transcription factor IRF8 (Interferon Regulatory Factor 8) was associated with CD20 expression in normal B cells, and in tumoral B cells, especially from diffuse-large-B-cell-lymphoma patients. A decrease in IRF8 expression is thus responsible for a decreased efficacy of anti-CD20 antibodies in cell culture. In conclusion, we have described the polyfunctional activity of anti-SARS-CoV-2. We have also unveiled a new mechanism of regulation of the levels of CD20 by IRF8, impacting the efficacy of therapeutic anti-CD20 antibodies.Les anticorps sont une des composantes essentielles du système immunitaire des vertébrés, et sont produits après infection ou vaccination. Ils possèdent plusieurs activités : une activité de neutralisation (liaison au pathogène qui bloque l'infection) et des fonctions médiées par leur fragment constant Fc. Les anticorps recrutent et activent d'autres effecteurs de l'immunité tels que les cellules Natural Killer (NK), le complément ou les macrophages/monocytes. Ils peuvent induire différents phénomènes antiviraux, tels que la cytotoxicité cellulaire dépendante des anticorps (ADCC), la cytotoxicité dépendante du complément (CDC) et la phagocytose dépendante des anticorps (ADCP). Ces différentes fonctions varient avec chaque anticorps. Nous nous sommes intéressés au mécanisme d'action de deux catégories d'anticorps. Nous avons étudié les anticorps produits après infection par le virus SARS-CoV-2. Nous nous sommes aussi penchés sur les mécanismes de régulation de l'efficacité des anticorps monoclonaux thérapeutiques anti-CD20. Nous avons tout d'abord mis en place un test de détection sensible et spécifique des anticorps anti-SARS-CoV-2 basé sur la cytométrie de flux, qui nous a permis d'identifier des personnes convalescentes de la COVID-19. Nous avons étudié la durée de la réponse humorale et démontré que les niveaux d'anticorps diminuaient au cours du temps et ce d'autant plus rapidement chez les individus masculins. Nous avons comparé les fonctions des anticorps provenant de personnes ayant fait une infection asymptomatique ou symptomatique. Nous avons confirmé que les anticorps produits après infection neutralisaient le virus, et induisaient ADCC et CDC, de façon similaire chez les individus symptomatiques et asymptomatiques. Nous avons aussi étudié l'impact des anticorps présents dans les prélèvements nasopharyngés de patients infectés par le variant Alpha ou des variants précédents. Nous avons démontré que ces anticorps inhibaient le virus dans la plupart des cas, que les résultats des tests antigéniques étaient cohérents avec la présence de virus infectieux et que le variant Alpha était associé à une libération accrue de cytokines. Les anticorps sont produits par le système immunitaire face à un pathogène mais peuvent également être produits en laboratoire pour être utilisés en tant que thérapie. Les anticorps anti-CD20, tels que Rituximab, Ofatumumab et Obinutuzumab, sont largement utilisés pour traiter des pathologies liées aux lymphocytes B, car le CD20 est présent sur ces cellules jusqu'au stade plasmocytaire. L'injection des anti-CD20 provoque une déplétion des lymphocytes B par apoptose et autres fonctions effectrices. Certains patients sont cependant résistants au traitement ou subissent des rechutes. Nous avons étudié les mécanismes régulant l'efficacité de ces anticorps utilisés en clinique. Nous avons réalisé un test de criblage afin d'identifier les protéines cellulaires impliquées dans l'échappement aux anti-CD20. Nous avons démontré que le facteur de transcription IRF8 (Interferon Regulatory Factor 8) est impliqué dans l'expression de CD20 dans les lymphocytes B normaux ou tumoraux, en particulier dans les lymphomes diffus à grandes cellules B. Une diminution des niveaux d'IRF8 est responsable d'une moins bonne efficacité de trois anti-CD20 en culture cellulaire. En conclusion, nous avons démontré que les anticorps anti-SARS-CoV-2 étaient polyfonctionnels. Nous avons également décrit un nouveau mécanisme de régulation des niveaux de CD20 par IRF8 qui impacte l'efficacité des anticorps thérapeutiques anti-CD20

Mechanisms of action of antibodies in two distinct settings : infection by SARS-CoV-2 and treatment by anti-CD20 antibodies

Les anticorps sont une des composantes essentielles du système immunitaire des vertébrés, et sont produits après infection ou vaccination. Ils possèdent plusieurs activités : une activité de neutralisation (liaison au pathogène qui bloque l'infection) et des fonctions médiées par leur fragment constant Fc. Les anticorps recrutent et activent d'autres effecteurs de l'immunité tels que les cellules Natural Killer (NK), le complément ou les macrophages/monocytes. Ils peuvent induire différents phénomènes antiviraux, tels que la cytotoxicité cellulaire dépendante des anticorps (ADCC), la cytotoxicité dépendante du complément (CDC) et la phagocytose dépendante des anticorps (ADCP). Ces différentes fonctions varient avec chaque anticorps. Nous nous sommes intéressés au mécanisme d'action de deux catégories d'anticorps. Nous avons étudié les anticorps produits après infection par le virus SARS-CoV-2. Nous nous sommes aussi penchés sur les mécanismes de régulation de l'efficacité des anticorps monoclonaux thérapeutiques anti-CD20. Nous avons tout d'abord mis en place un test de détection sensible et spécifique des anticorps anti-SARS-CoV-2 basé sur la cytométrie de flux, qui nous a permis d'identifier des personnes convalescentes de la COVID-19. Nous avons étudié la durée de la réponse humorale et démontré que les niveaux d'anticorps diminuaient au cours du temps et ce d'autant plus rapidement chez les individus masculins. Nous avons comparé les fonctions des anticorps provenant de personnes ayant fait une infection asymptomatique ou symptomatique. Nous avons confirmé que les anticorps produits après infection neutralisaient le virus, et induisaient ADCC et CDC, de façon similaire chez les individus symptomatiques et asymptomatiques. Nous avons aussi étudié l'impact des anticorps présents dans les prélèvements nasopharyngés de patients infectés par le variant Alpha ou des variants précédents. Nous avons démontré que ces anticorps inhibaient le virus dans la plupart des cas, que les résultats des tests antigéniques étaient cohérents avec la présence de virus infectieux et que le variant Alpha était associé à une libération accrue de cytokines. Les anticorps sont produits par le système immunitaire face à un pathogène mais peuvent également être produits en laboratoire pour être utilisés en tant que thérapie. Les anticorps anti-CD20, tels que Rituximab, Ofatumumab et Obinutuzumab, sont largement utilisés pour traiter des pathologies liées aux lymphocytes B, car le CD20 est présent sur ces cellules jusqu'au stade plasmocytaire. L'injection des anti-CD20 provoque une déplétion des lymphocytes B par apoptose et autres fonctions effectrices. Certains patients sont cependant résistants au traitement ou subissent des rechutes. Nous avons étudié les mécanismes régulant l'efficacité de ces anticorps utilisés en clinique. Nous avons réalisé un test de criblage afin d'identifier les protéines cellulaires impliquées dans l'échappement aux anti-CD20. Nous avons démontré que le facteur de transcription IRF8 (Interferon Regulatory Factor 8) est impliqué dans l'expression de CD20 dans les lymphocytes B normaux ou tumoraux, en particulier dans les lymphomes diffus à grandes cellules B. Une diminution des niveaux d'IRF8 est responsable d'une moins bonne efficacité de trois anti-CD20 en culture cellulaire. En conclusion, nous avons démontré que les anticorps anti-SARS-CoV-2 étaient polyfonctionnels. Nous avons également décrit un nouveau mécanisme de régulation des niveaux de CD20 par IRF8 qui impacte l'efficacité des anticorps thérapeutiques anti-CD20.Antibodies are produced upon infection or vaccination. They fight pathogens through several mechanisms including neutralization and Fc-dependent effector functions. The constant fragment (Fc) of antibodies recruits effector cells such as Natural Killer (NK) cells, complement and macrophages/monocytes. Fc-mediated antiviral mechanisms include antibody-dependent cell cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC) and antibody-dependent cell phagocytosis (ADCP). These mechanisms are not induced to the same extent by all antibodies. In this thesis, we explored two different aspects of the activity of antibodies. We studied antibodies produced during SARS-CoV-2 infection virus and also examined the regulation of efficacy of therapeutic anti-CD20 monoclonal antibodies. We first developed a sensitive and specific assay based on flow cytometry to detect anti-SARS-CoV-2 antibodies. It enabled us to identify individuals that were convalescent for COVID-19 before systematic testing was established. It also allowed us to study the duration of the humoral response. We showed that antibody levels were decreasing more rapidly in males. We studied the function of antibodies elicited after symptomatic of asymptomatic SARS-CoV-2 infection. The antibodies not only neutralized the virus but also induced ADCC and CDC, to a similar extent in asymptomatic and symptomatic individuals. We examined the impact of antibodies on the infectivity of virus present in nasopharyngeal swabs of patients infected with Alpha or former variants. The antibodies in the swabs inhibited viral infectivity. Antigenic test results were predictive of infectious viral particles release. The Alpha variant was associated with increased cytokine release, when compared to previous variants. Antibodies are produced by the immune system upon pathogen exposure but can also be engineered in laboratory to be used as therapeutics. Anti-CD20 antibodies such as Rituximab, Ofatumumab and Obinutuzumab are widely used to treat B-cell-associated diseases. Anti-CD20 antibodies deplete B cells by triggering apoptosis and effector functions. Some patients experience resistance to the treatment or disease relapses. We studied the mechanisms regulating the efficacy of therapeutic anti-CD20 with a genome-wide screening approach. We showed that expression of the transcription factor IRF8 (Interferon Regulatory Factor 8) was associated with CD20 expression in normal B cells, and in tumoral B cells, especially from diffuse-large-B-cell-lymphoma patients. A decrease in IRF8 expression is thus responsible for a decreased efficacy of anti-CD20 antibodies in cell culture. In conclusion, we have described the polyfunctional activity of anti-SARS-CoV-2. We have also unveiled a new mechanism of regulation of the levels of CD20 by IRF8, impacting the efficacy of therapeutic anti-CD20 antibodies

Single-cell approach to influenza-specific CD8⁺ T cell receptor repertoires across different age groups, tissues, and following influenza virus infection

CD8+ T cells recognizing antigenic peptides derived from conserved internal viral proteins confer broad protection against distinct influenza viruses. As memory CD8+ T cells change throughout the human lifetime and across tissue compartments, we investigated how T cell receptor (TCR) composition and diversity relate to memory CD8+ T cells across anatomical sites and immunological phases of human life. We used ex vivo peptide-HLA tetramer magnetic enrichment, single-cell multiplex RT-PCR for both the TCR-alpha (TCRα) and TCR-beta (TCRβ) chains, and new TCRdist and grouping of lymphocyte interactions by paratope hotspots (GLIPH) algorithms to compare TCRs directed against the most prominent human influenza epitope, HLA-A*02:01-M158–66 (A2+M158). We dissected memory TCR repertoires directed toward A2+M158 CD8+ T cells within human tissues and compared them to human peripheral blood of young and elderly adults. Furthermore, we compared these memory CD8+ T cell repertoires to A2+M158 CD8+ TCRs during acute influenza disease in patients hospitalized with avian A/H7N9 virus. Our study provides the first ex vivo comparative analysis of paired antigen-specific TCR-α/β clonotypes across different tissues and peripheral blood across different age groups. We show that human A2+M158 CD8+ T cells can be readily detected in human lungs, spleens, and lymph nodes, and that tissue A2+M158 TCRαβ repertoires reflect A2+M158 TCRαβ clonotypes derived from peripheral blood in healthy adults and influenza-infected patients. A2+M158 TCRαβ repertoires displayed distinct features only in elderly adults, with large private TCRαβ clonotypes replacing the prominent and public TRBV19/TRAV27 TCRs. Our study provides novel findings on influenza-specific TCRαβ repertoires within human tissues, raises the question of how we can prevent the loss of optimal TCRαβ signatures with aging, and provides important insights into the rational design of T cell-mediated vaccines and immunotherapies

Anti‐ HIV ‐1 antibodies trigger non‐lytic complement deposition on infected cells

International audienceThe effect of anti-HIV-1 antibodies on complement activation at the surface of infected cells remains partly understood. Here, we show that a subset of anti-Envelope (Env) broadly neutralizing antibodies (bNAbs), targeting the CD4 binding site and the V3 loop, triggers C3 deposition and complement-dependent cytotoxicity (CDC) on Raji cells engineered to express high surface levels of HIV-1 Env. Primary CD4 T cells infected with laboratory-adapted or primary HIV-1 strains and treated with bNAbs are susceptible to C3 deposition but not to rapid CDC. The cellular protein CD59 and viral proteins Vpu and Nef protect infected cells from CDC mediated by bNAbs or by polyclonal IgGs from HIV-positive individuals. However, complement deposition accelerates the disappearance of infected cells within a few days of culture. Altogether, our results uncover the contribution of complement to the antiviral activity of anti-HIV-1 bNAbs

IRF8 regulates efficacy of therapeutic anti‐CD20 monoclonal antibodies

International audienceAnti-CD20 monoclonal antibodies such as Rituximab, Ofatumumab, and Obinutuzumab are widely used to treat lymphomas and autoimmune diseases. They act by depleting B cells, mainly through Fc-dependent effectors functions. Some patients develop resistance to treatment but the underlying mechanisms are poorly understood. Here, we performed a genome-wide CRISPR/Cas9 screen to identify genes regulating the efficacy of anti-CD20 antibodies. We used as a model the killing of RAJI B cells by Rituximab through complement-dependent-cytotoxicity (CDC). As expected, the screen identified MS4A1, encoding CD20, the target of Rituximab. Among other identified genes, the role of Interferon Regulatory Factor 8 (IRF8) was validated in two B-cell lines. IRF8 KO also decreased the efficacy of antibody-dependent cellular cytotoxicity and phagocytosis (ADCC and ADCP) induced by anti-CD20 antibodies. We further show that IRF8 is necessary for efficient CD20 transcription. Levels of IRF8 and CD20 RNA or proteins correlated in normal B cells and in hundreds of malignant B cells. Therefore, IRF8 regulates CD20 expression and controls the depleting capacity of anti-CD20 antibodies. Our results bring novel insights into the pathways underlying resistance to CD20-targeting immunotherapies

Characteristics Associated with Olfactory and Taste Disorders in COVID-19

International audienceIntroduction: Olfactory and taste disorders (OTDs) have been reported in COVID-19 caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the mechanisms of which remain unclear. We conducted a detailed analysis of OTDs as part of 2 seroepidemiological investigations of COVID-19 outbreaks. Methods: Two retrospective cohort studies were conducted in a high school and primary schools of Northern France following a COVID-19 epidemic in February-March 2020. Students, their relatives, and school staff were included. Anti-SARS-CoV-2 antibodies were identified using a flow-cytometry-based assay detecting anti-S IgG. Results: Among 2,004 participants (median [IQR] age: 31 [11–43] years), 303 (15.2%) tested positive for SARS-CoV-2 antibodies. OTDs were present in 91 (30.0%) and 92 (30.3%) of them, respectively, and had 85.1 and 78.0% positive predictive values for SARS-CoV-2 infection, respectively. In seropositive participants, OTDs were independently associated with an age above 18 years, female gender, fatigue, and headache. Conclusion: This study confirms the higher frequency of OTDs in females than males and adults than children. Their high predictive value for the diagnosis of COVID-19 suggests that they should be systematically searched for in patients with respiratory symptoms, fever, or headache. The association of OTDs with headache, not previously reported, suggests that they share a common mechanism, which deserves further investigation