Dengue virus NS1 protein conveys pro-inflammatory signals by docking onto high-density lipoproteins.

The dengue virus nonstructural protein 1 (NS1) is a secreted virulence factor that modulates complement, activates immune cells and alters endothelial barriers. The molecular basis of these events remains incompletely understood. Here we describe a functional high affinity complex formed between NS1 and human high-density lipoproteins (HDL). Collapse of the soluble NS1 hexamer upon binding to the lipoprotein particle leads to the anchoring of amphipathic NS1 dimeric subunits into the HDL outer layer. The stable complex can be visualized by electron microscopy as a spherical HDL with rod-shaped NS1 dimers protruding from the surface. We further show that the assembly of NS1-HDL complexes triggers the production of pro-inflammatory cytokines in human primary macrophages while NS1 or HDL alone do not. Finally, we detect NS1 in complex with HDL and low-density lipoprotein (LDL) particles in the plasma of hospitalized dengue patients and observe NS1-apolipoprotein E-positive complexes accumulating overtime. The functional reprogramming of endogenous lipoprotein particles by NS1 as a means to exacerbate systemic inflammation during viral infection provides a new paradigm in dengue pathogenesis.

Rifampin-moxifloxacin-metronidazole combination therapy for severe Hurley stage 1 hidradenitis suppurativa: prospective short-term trial and 1-year follow-up in 28 consecutive patients.

BACKGROUND: Severe Hurley stage 1 hidradenitis suppurativa (HS1) is a difficult-to-treat form of the disease. OBJECTIVE: To assess the efficacy and tolerance of the oral combination of rifampin (10 mg/kg once daily)/moxifloxacin (400 mg once daily)/metronidazole (250-500 mg 3 times daily) (RMoM) treatment strategy in patients with severe HS1. METHODS: Prospective, open-label, noncomparative cohort study in 28 consecutive patients. Nineteen patients were treated for 6 weeks by RMoM, followed by 4 weeks of rifampin/moxifloxacin alone, then by cotrimoxazole after remission. Moxifloxacin was replaced by pristinamycin (1 g 3 times daily) in 9 patients because of contraindications or intolerance. The primary endpoint was a Sartorius score of 0 (clinical remission) at week 12. RESULTS: The median Sartorius score dropped from 14 to 0 (P = 6 × 10-6) at week 12, with 75% of patients reaching clinical remission. A low initial Sartorius score was a prognosis factor for clinical remission (P = .049). The main adverse effects were mild gastrointestinal discomfort, mucosal candidiasis, and asthenia. At 1 year of follow-up, the median number of flares dropped from 21/year to 1 (P = 1 × 10-5). LIMITATIONS: Small, monocentric, noncontrolled study. CONCLUSIONS: Complete and prolonged remission can be obtained in severe HS1 by using targeted antimicrobial treatments.

Estimated protection against COVID-19 based on predicted neutralisation titres from multiple antibody measurements in a longitudinal cohort, France, April 2020 to November 2021.

BackgroundThe risk of SARS-CoV-2 (re-)infection remains present given waning of vaccine-induced and infection-acquired immunity, and ongoing circulation of new variants.AimTo develop a method that predicts virus neutralisation and disease protection based on variant-specific antibody measurements to SARS-CoV-2 antigens.MethodsTo correlate antibody and neutralisation titres, we collected 304 serum samples from individuals with either vaccine-induced or infection-acquired SARS-CoV-2 immunity. Using the association between antibody and neutralisation titres, we developed a prediction model for SARS-CoV-2-specific neutralisation titres. From predicted neutralising titres, we inferred protection estimates to symptomatic and severe COVID-19 using previously described relationships between neutralisation titres and protection estimates. We estimated population immunity in a French longitudinal cohort of 905 individuals followed from April 2020 to November 2021.ResultsWe demonstrated a strong correlation between anti-SARS-CoV-2 antibodies measured using a low cost high-throughput assay and antibody response capacity to neutralise live virus. Participants with a single vaccination or immunity caused by infection were especially vulnerable to symptomatic or severe COVID-19. While the median reduced risk of COVID-19 from Delta variant infection in participants with three vaccinations was 96% (IQR: 94-98), median reduced risk among participants with infection-acquired immunity was only 42% (IQR: 22-66).ConclusionOur results are consistent with data from vaccine effectiveness studies, indicating the robustness of our approach. Our multiplex serological assay can be readily adapted to study new variants and provides a framework for development of an assay that would include protection estimates.

Characteristics Associated with Olfactory and Taste Disorders in COVID-19.

INTRODUCTION: 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.

SARS-CoV-2 infection in schools in a northern French city: a retrospective serological cohort study in an area of high transmission, France, January to April 2020.

BackgroundChildren's role in SARS-CoV-2 epidemiology remains unclear. We investigated an initially unnoticed SARS-CoV-2 outbreak linked to schools in northern France, beginning as early as mid-January 2020.AimsThis retrospective observational study documents the extent of SARS-CoV-2 transmission, linked to an affected high school (n = 664 participants) and primary schools (n = 1,340 study participants), in the context of unsuspected SARS-CoV-2 circulation and limited control measures.MethodsBetween 30 March and 30 April 2020, all school staff, as well as pupils and their parents and relatives were invited for SARS-CoV-2 antibody testing and to complete a questionnaire covering symptom history since 13 January 2020.ResultsIn the high school, infection attack rates were 38.1% (91/239), 43.4% (23/53), and 59.3% (16/27), in pupils, teachers, and non-teaching staff respectively vs 10.1% (23/228) and 12.0% (14/117) in the pupils' parents and relatives (p < 0.001). Among the six primary schools, three children attending separate schools at the outbreak start, while symptomatic, might have introduced SARS-CoV-2 there, but symptomatic secondary cases related to them could not be definitely identified. In the primary schools overall, antibody prevalence in pupils sharing classes with symptomatic cases was higher than in pupils from other classes: 15/65 (23.1%) vs 30/445 (6.7%) (p < 0.001). Among 46 SARS-CoV-2 seropositive pupils < 12 years old, 20 were asymptomatic. Whether past HKU1 and OC43 seasonal coronavirus infection protected against SARS-CoV-2 infection in 6-11 year olds could not be inferred.ConclusionsViral circulation can occur in high and primary schools so keeping them open requires consideration of appropriate control measures and enhanced surveillance.

Anoxia and glucose supplementation preserve neutrophil viability and function.

Functional studies of human neutrophils and their transfusion for clinical purposes have been hampered by their short life span after isolation. Here, we demonstrate that neutrophil viability is maintained for 20 hours in culture media at 37°C under anoxic conditions with 3 mM glucose and 32 µg/mL dimethyloxalylglycine supplementation, as evidenced by stabilization of Mcl-1, proliferating cell nuclear antigen (PCNA), and pro-caspase-3. Notably, neutrophil morphology (nucleus shape and cell-surface markers) and functions (phagocytosis, degranulation, calcium release, chemotaxis, and reactive oxygen species production) were comparable to blood circulating neutrophils. The observed extension in neutrophil viability was reversed upon exposure to oxygen. Extending neutrophil life span allowed efficient transfection of plasmids (40% transfection efficiency) and short interfering RNA (interleukin-8, PCNA, and Bax), as a validation of effective and functional genetic manipulation of neutrophils both in vitro and in vivo. In vivo, transfusion of conditioned neutrophils in a neutropenic guinea pig model increased bacterial clearance of Shigella flexneri upon colonic infection, strongly suggesting that these conditioned neutrophils might be suitable for transfusion purposes. In summary, such conditioning of neutrophils in vitro should facilitate their study and offer new opportunities for genetic manipulation and therapeutic use.

The Microbiological Landscape of Anaerobic Infections in Hidradenitis Suppurativa: A Prospective Metagenomic Study.

BACKGROUND: Hidradenitis suppurativa (HS) is a frequent and severe disease of the skin, characterized by recurrent or chronic skinfold suppurative lesions with a high impact on quality of life. Although considered inflammatory, antimicrobial treatments can improve or lead to clinical remission of HS, suggesting triggering microbial factors. Indeed, mixed anaerobic microbiota are associated with a majority of HS lesions. Our aim in this study was to characterize the landscape of anaerobic infections in HS using high-throughput sequencing. METHODS: We sampled and cultured 149 lesions and 175 unaffected control skinfold areas from 65 adult HS patients. The microbiome of 80 anaerobic lesions was compared to that of 88 control samples by 454 high-throughput sequencing after construction of 16S ribosomal RNA gene libraries. RESULTS: Bacterial cultures detected anaerobes in 83% of lesions vs 53% of control samples, combined with milleri group streptococci and actinomycetes in 33% and 26% of cases, respectively. High-throughput sequencing identified 43 taxa associated with HS lesions. Two gram-negative anaerobic rod taxa, Prevotella and Porphyromonas, predominated, contrasting with a reduced abundance of aerobic commensals. These rare taxa of normal skinfold microbiota were associated with lesions independently of gender, duration and familial history of HS, body mass index, and location. Two main additional taxa, Fusobacterium and Parvimonas, correlated with the clinical severity of HS. CONCLUSIONS: In this study we reveal the high prevalence and particular landscape of mixed anaerobic infection in HS, paving the way for rationale targeted antimicrobial treatments.

Standardized whole blood stimulation improves immunomonitoring of induced immune responses in multi-center study.

Functional immune responses are increasingly important for clinical studies, providing in depth biomarker information to assess immunotherapy or vaccination. Incorporating functional immune assays into routine clinical practice has remained limited due to challenges in standardizing sample preparation. We recently described the use of a whole blood syringe-based system, TruCulture®, which permits point-of-care standardized immune stimulation. Here, we report on a multi-center clinical study in seven FOCIS Centers of Excellence to directly compare TruCulture to conventional PBMC methods. Whole blood and PBMCs from healthy donors were exposed to LPS, anti-CD3 anti-CD28 antibodies, or media alone. 55 protein analytes were analyzed centrally by Luminex multi-analyte profiling in a CLIA-certified laboratory. TruCulture responses showed greater reproducibility and improved the statistical power for monitoring differential immune response activation. The use of TruCulture addresses a major unmet need through a robust and flexible method for immunomonitoring that can be reproducibly applied in multi-center clinical studies. ONE SENTENCE SUMMARY: A multi-center study revealed greater reproducibility from whole blood stimulation systems as compared to PBMC stimulation for studying induced immune responses.

Opiorphin levels in fluids of burning mouth syndrome patients: a case-control study.

OBJECTIVES: Idiopathic Burning mouth syndrome (iBMS) is a poorly understood affection characterized by persistent pain in the oral cavity without any clinical or biological abnormality. Opiorphin is a natural inhibitor of enkephalin-inactivating ectopeptidases, mainly produced by salivary glands, that has demonstrated analgesic properties. The objective of the present case-control study was to test the hypothesis of a decrease in opiorphin levels in iBMS patients. MATERIALS AND METHODS: Twenty-one iBMS patients and 21 matched controls subjects were included between 2011 and 2013. Submandibular and sublingual salivary, blood, and urinary opiorphin levels of iBMS patients were compared to controls. RESULTS: Results are expressed as mean values ± SD and compared using the Wilcoxon Signed Rank test. Correlations were analyzed with Spearman coefficient. The level of significance was fixed at p < 0.05. Opiorphin levels in iBMS and controls were respectively (in ng/ml) in basal saliva: 37.8 ± 42.5 and 67.6 ± 188.9 (p = NS); stimulated saliva: 28.8 ± 25.3 and 31.1 ± 29.1 (p = NS); blood: 4.6 ± 5.4 and 1.9 ± 1.4 (p < 0.05); and urines: 68.5 ± 259.8 and 8.9 ± 6.2 (p = NS). CLINICAL RELEVANCE: In conclusion, the lack of significative difference in salivary opiorphin levels between iBMS and controls does not favor a direct local role for opiorphin in the etiopathogeny of iBMS. However, higher blood opiorphin levels may reflect a systemic dysregulation in iBMS. Trial registration NCT02686359 https://clinicaltrials.gov/ct2/show/NCT02686359.

Are International Units of Anti-HBs Antibodies Always Indicative of Hepatitis B Virus Neutralizing Activity?

OBJECTIVE: Anti-HBs antibodies are elicited upon hepatitis B vaccination, and concentrations above 10 mIU/mL are considered protective. Our aim was to assess the relationship between IU/mL of anti-HBs and neutralization activity. METHODS: Immunoglobulins G (IgGs) were purified from individuals who received a serum-derived vaccine (Group 1), a recombinant vaccine, Genevac-B or Engerix-B (Group 2), or who recovered from acute infection (Group 3). IgGs were tested for anti-HBs, anti-preS1, and anti-preS2 antibodies and for their neutralizing activity in an in vitro infection assay. RESULTS: Anti-HBs IUs/mL value did not strictly correlate with neutralization activity. The Group 1 antibodies demonstrated a greater neutralizing activity than those of Group 2. Anti-preS1 antibodies were detected in Groups 1 and 3, and anti-preS2 in Group 1 and Group 2/Genhevac-B, but the contribution of anti-preS antibodies to neutralization could not be demonstrated. Virions bearing immune escape HBsAg variants were less susceptible to neutralization than wild-type virions. CONCLUSION: The level of anti-HBs antibodies in IUs is not sufficient to assess neutralizing activity. Consequently, (i) an in vitro neutralization assay should be included in the quality control procedures of antibody preparations intended for HB prophylaxis or immunotherapy, and (ii) a greater emphasis should be placed on ensuring that vaccine genotype/subtype matches with that of the circulating HBV.

Immunogenicity of a Plasmodium vivax vaccine based on the duffy binding protein formulated using adjuvants compatible for use in humans.

The invasion of reticulocytes by Plasmodium vivax merozoites is dependent on the interaction of the Plasmodium vivax Duffy Binding Protein (PvDBP) with the Duffy antigen receptor for chemokines (DARC). The N-terminal cysteine-rich region II of PvDBP (PvDBPII), which binds DARC, is a leading P. vivax malaria vaccine candidate. Here, we have evaluated the immunogenicity of recombinant PvDBPII formulated with the adjuvants Matrix-M and GLA-SE in mice. Analysis of the antibody responses revealed comparable ELISA recognition titres as well as similar recognition of native PvDBP in P. vivax schizonts by immunofluorescence assay. Moreover, antibodies elicited by the two adjuvant formulations had similar functional properties such as avidity, isotype profile and inhibition of PvDBPII-DARC binding. Furthermore, the anti-PvDBPII antibodies were able to block the interaction of DARC with the homologous PvDBPII SalI allele as well as the heterologous PvDBPII PvW1 allele from a Thai clinical isolate that is used for controlled human malaria infections (CHMI). The cross-reactivity of these antibodies with PvW1 suggest that immunization with the PvDBPII SalI strain should neutralize reticulocyte invasion by the challenge P. vivax strain PvW1.

Seroepidemiology of the Seasonal Human Coronaviruses NL63, 229E, OC43 and HKU1 in France.

Background: The seasonal human coronaviruses (HCoV) NL63, 229E, OC43, and HKU1 are globally endemic, yet the majority of HCoV infections remain undiagnosed. Methods: In a cross-sectional study, 2389 serum samples were collected from children and adults in France in 2020. In a longitudinal cohort study, 2520 samples were collected from 898 French individuals followed up between 2020 and 2021. Antibodies to HCoVs were measured using a bead-based multiplex assay. Results: The rate of waning of anti-HCoV spike immunoglobulin G antibodies was estimated as 0.22-0.47 year-1 for children, and 0.13-0.27 year-1 for adults. Seroreversion was estimated as 0.31-1.37 year-1 in children and 0.19-0.72 year-1 in adults. The estimated seroconversion rate in children was consistent with 20%-39% of children being infected every year with each HCoV. Conclusions: The high force of infection in children indicates that HCoVs may be responsible for a substantial proportion of fever episodes experienced by children.

T cell migration and effector function differences in familial adenomatous polyposis patients with APC gene mutations.

Familial adenomatous polyposis (FAP) is an inherited disease characterized by the development of large number of colorectal adenomas with high risk of evolving into colorectal tumors. Mutations of the Adenomatous polyposis coli (APC) gene is often at the origin of this disease, as well as of a high percentage of spontaneous colorectal tumors. APC is therefore considered a tumor suppressor gene. While the role of APC in intestinal epithelium homeostasis is well characterized, its importance in immune responses remains ill defined. Our recent work indicates that the APC protein is involved in various phases of both CD4 and CD8 T cells responses. This prompted us to investigate an array of immune cell features in FAP subjects carrying APC mutations. A group of 12 FAP subjects and age and sex-matched healthy controls were studied. We characterized the immune cell repertoire in peripheral blood and the capacity of immune cells to respond ex vivo to different stimuli either in whole blood or in purified T cells. A variety of experimental approaches were used, including, pultiparamater flow cytometry, NanosString gene expression profiling, Multiplex and regular ELISA, confocal microscopy and computer-based image analyis methods. We found that the percentage of several T and natural killer (NK) cell populations, the expression of several genes induced upon innate or adaptive immune stimulation and the production of several cytokines and chemokines was different. Moreover, the capacity of T cells to migrate in response to chemokine was consistently altered. Finally, immunological synapses between FAP cytotoxic T cells and tumor target cells were more poorly structured. Our findings of this pilot study suggest that mild but multiple immune cell dysfunctions, together with intestinal epithelial dysplasia in FAP subjects, may facilitate the long-term polyposis and colorectal tumor development. Although at an initial discovery phase due to the limited sample size of this rare disease cohort, our findings open new perspectives to consider immune cell abnormalities into polyposis pathology.

Complement-dependent mpox-virus-neutralizing antibodies in infected and vaccinated individuals.

Mpox virus (MPXV) caused a multi-country outbreak in non-endemic areas in 2022. Following historic success of smallpox vaccination with vaccinia virus (VACV)-based vaccines, the third generation modified vaccinia Ankara (MVA)-based vaccine was used as prophylaxis for MPXV, but its effectiveness remains poorly characterized. Here, we applied two assays to quantify neutralizing antibodies (NAbs) in sera from control, MPXV-infected, or MVA-vaccinated individuals. Various levels of MVA NAbs were detected after infection, historic smallpox, or recent MVA vaccination. MPXV was minimally sensitive to neutralization. However, addition of complement enhanced detection of responsive individuals and NAb levels. Anti-MVA and -MPXV NAbs were observed in 94% and 82% of infected individuals, respectively, and 92% and 56% of MVA vaccinees, respectively. NAb titers were higher in individuals born before 1980, highlighting the impact of historic smallpox vaccination on humoral immunity. Altogether, our results indicate that MPXV neutralization is complement dependent and uncover mechanisms underlying vaccine effectiveness.

SHERLOCK4HAT: A CRISPR-based tool kit for diagnosis of Human African Trypanosomiasis.

BACKGROUND: To achieve elimination of Human African Trypanosomiasis (HAT) caused by Trypanosoma brucei gambiense (gHAT), the development of highly sensitive diagnostics is needed. We have developed a CRISPR based diagnostic for HAT using SHERLOCK (Specific High-sensitivity Enzymatic Reporter unLOCKing) that is readily adaptable to a field-based setting. METHODS: We adapted SHERLOCK for the detection of T. brucei species. We targeted 7SLRNA, TgSGP and SRA genes and tested SHERLOCK against RNA from blood, buffy coat, dried blood spots (DBS), and clinical samples. FINDINGS: The pan-Trypanozoon 7SLRNA and T. b. gambiense-specific TgSGP SHERLOCK assays had a sensitivity of 0.1 parasite/µL and a limit of detection 100 molecules/µL. T. b. rhodesiense-specific SRA had a sensitivity of 0.1 parasite/µL and a limit of detection of 10 molecules/µL. TgSGP SHERLOCK and SRA SHERLOCK detected 100% of the field isolated strains. Using clinical specimens from the WHO HAT cryobank, the 7SLRNA SHERLOCK detected trypanosomes in gHAT samples with 56.1%, 95% CI [46.25-65.53] sensitivity and 98.4%, 95% CI [91.41-99.92] specificity, and rHAT samples with 100%, 95% CI [83.18-100] sensitivity and 94.1%, 95% CI [80.91-98.95] specificity. The species-specific TgSGP and SRA SHERLOCK discriminated between the gambiense/rhodesiense HAT infections with 100% accuracy. INTERPRETATION: The 7SLRNA, TgSGP and SRA SHERLOCK discriminate between gHAT and rHAT infections, and could be used for epidemiological surveillance and diagnosis of HAT in the field after further technical development. FUNDING: Institut Pasteur (PTR-175 SHERLOCK4HAT), French Government's Investissement d'Avenir program Laboratoire d'Excellence Integrative Biology of Emerging Infectious Diseases (LabEx IBEID), and Agence Nationale pour la Recherche (ANR-PRC 2021 SherPa).

Age-associated gut microbiota impair hippocampus-dependent memory in a vagus-dependent manner.

Aging is known to be associated with hippocampus-dependent memory decline, but the underlying causes of this age-related memory impairment remain highly debated. Here, we show that fecal microbiota transplantation (FMT) from aged, but not young, animal donors into young mice is sufficient to trigger profound hippocampal alterations, including astrogliosis, decreased adult neurogenesis, decreased novelty-induced neuronal activation, and impairment in hippocampus-dependent memory. Furthermore, similar alterations were reported when mice were subjected to an FMT from aged human donors. To decipher the mechanisms involved in mediating these microbiota-induced effects on brain function, we mapped the vagus nerve-related (VN-related) neuronal activity patterns and report that aged FMT animals showed a reduction in neuronal activity in the ascending-VN output brain structure, whether under basal condition or after VN stimulation. Targeted pharmacogenetic manipulation of VN-ascending neurons demonstrated that the decrease in vagal activity is detrimental to hippocampal functions. In contrast, increasing vagal ascending activity alleviated the adverse effects of aged mouse FMT on hippocampal functions and had a promnesic effect in aged mice. Thus, pharmacogenetic VN stimulation is a potential therapeutic strategy to lessen microbiota-dependent age-associated impairments in hippocampal functions.

The tumor suppressor adenomatous polyposis coli regulates T lymphocyte migration.

Adenomatous polyposis coli (APC) is a tumor suppressor whose mutations underlie familial adenomatous polyposis (FAP) and colorectal cancer. Although its role in intestinal epithelial cells is well characterized, APC importance in T cell biology is ill defined. APC regulates cytoskeleton organization, cell polarity, and migration in various cell types. Here, we address whether APC plays a role in T lymphocyte migration. Using a series of cell biology tools, we unveiled that T cells from FAP patients carrying APC mutations display impaired adhesion and motility in constrained environments. We further dissected the cellular mechanisms underpinning these defects in APC-depleted CEM T cell line that recapitulate the phenotype observed in FAP T cells. We found that APC affects T cell motility by modulating integrin-dependent adhesion and cytoskeleton reorganization. Hence, APC mutations in FAP patients not only drive intestinal neoplasms but also impair T cell migration, potentially contributing to inefficient antitumor immunity.

Neutralising antibody responses to SARS-CoV-2 omicron among elderly nursing home residents following a booster dose of BNT162b2 vaccine: A community-based, prospective, longitudinal cohort study.

Background: The protective immunity against omicron following a BNT162b2 Pfizer booster dose among elderly individuals (ie, those aged >65 years) is not well characterised. Methods: In a community-based, prospective, longitudinal cohort study taking place in France in which 75 residents from three nursing homes were enrolled, we selected 38 residents who had received a two-dose regimen of mRNA vaccine and a booster dose of Pfizer BNT162b2 vaccine. We excluded individuals that did not receive three vaccine doses or did not have available sera samples. We measured anti-S IgG antibodies and neutralisation capacity in sera taken 56 (28-68) and 55 (48-64) days (median (range)) after the 2nd and 3rd vaccine doses, respectively. Antibodies targeting the SARS-CoV-2 Spike protein were measured with the S-Flow assay as binding antibody units per milliliter (BAU/mL). Neutralising activities in sera were measured as effective dilution 50% (ED50) with the S-Fuse assay using authentic isolates of delta and omicron BA.1. Findings: Among the 38 elderly individuals recruited to the cohort study between November 23rd, 2020 and April 29th, 2021, with median age of 88 (range 72-101) years, 30 (78.95%) had been previously infected with SARS-CoV-2. After three vaccine doses, serum neutralising activity was lower against omicron BA.1 (median ED50 of 774.5, range 15.0-34660.0) than the delta variant (median ED50 of 4972.0, range 213.7-66340.0), and higher among previously infected (ie, convalescent; median ED50 against omicron: 1088.0, range 32.6-34660.0) compared with infection-naive residents (median ED50 against omicron: 188.4, range 15.0-8918.0). During the French omicron wave in December 2021-January 2022, 75% (6/8) of naive residents were infected, compared to 25% (7/30) of convalescent residents (P=0.0114). Anti-Spike antibody levels and neutralising activity against omicron BA.1 after a third BNT162b2 booster dose were lower in those with breakthrough BA.1 infection (n=13) compared with those without (n=25), with a median of 1429.9 (range 670.9-3818.3) BAU/mL vs 2528.3 (range 695.4-8832.0) BAU/mL (P=0.029) and a median ED50 of 281.1 (range 15.0-2136.0) vs 1376.0 (range 32.6-34660.0) (P=0.0013), respectively. Interpretation: This study shows that elderly individuals who received three vaccine doses elicit neutralising antibodies against the omicron BA.1 variant of SARS-CoV-2. Elderly individuals who had also been previously infected showed higher neutralising activity compared with naive individuals. Yet, breakthrough infections with omicron occurred. Individuals with breakthrough infections had significantly lower neutralising titers compared to individuals without breakthrough infection. Thus, a fourth dose of vaccine may be useful in the elderly population to increase the level of neutralising antibodies and compensate for waning immunity. Funding: Institut Pasteur, Fondation pour la Recherche Médicale (FRM), European Health Emergency Preparedness and Response Authority (HERA), Agence nationale de recherches sur le sida et les hépatites virales - Maladies Infectieuses Emergentes (ANRS-MIE), Agence nationale de la recherche (ANR), Assistance Publique des Hôpitaux de Paris (AP-HP) and Fondation de France.

Potent human broadly SARS-CoV-2-neutralizing IgA and IgG antibodies effective against Omicron BA.1 and BA.2.

Memory B-cell and antibody responses to the SARS-CoV-2 spike protein contribute to long-term immune protection against severe COVID-19, which can also be prevented by antibody-based interventions. Here, wide SARS-CoV-2 immunoprofiling in Wuhan COVID-19 convalescents combining serological, cellular, and monoclonal antibody explorations revealed humoral immunity coordination. Detailed characterization of a hundred SARS-CoV-2 spike memory B-cell monoclonal antibodies uncovered diversity in their repertoire and antiviral functions. The latter were influenced by the targeted spike region with strong Fc-dependent effectors to the S2 subunit and potent neutralizers to the receptor-binding domain. Amongst those, Cv2.1169 and Cv2.3194 antibodies cross-neutralized SARS-CoV-2 variants of concern, including Omicron BA.1 and BA.2. Cv2.1169, isolated from a mucosa-derived IgA memory B cell demonstrated potency boost as IgA dimers and therapeutic efficacy as IgG antibodies in animal models. Structural data provided mechanistic clues to Cv2.1169 potency and breadth. Thus, potent broadly neutralizing IgA antibodies elicited in mucosal tissues can stem SARS-CoV-2 infection, and Cv2.1169 and Cv2.3194 are prime candidates for COVID-19 prevention and treatment.

Nasopharyngeal and serological anti SARS-CoV-2 IgG/IgA responses in COVID-19 patients.

Background: The systemic antibody responses to SARS-CoV-2 in COVID-19 patients has been extensively studied. However, less is known about the mucosal responses in the upper airways, the site of initial SARS-CoV-2 replication. Methods: The IgG and IgA antibody responses were analysed in plasma and nasopharyngeal swabs from the first four confirmed COVID-19 patients in France. Two were pauci-symptomatic while two developed severe disease. We characterized their antibody profiles by using an in-house ELISA to detect antibodies directed against SARS-CoV-2 Nucleoprotein and Spike. Results: Anti-N IgG and IgA antibodies were detected in the NPS of severe patients only. The levels of antibodies in the plasma markedly differed amongst the patients. The most distinctive features are a strong anti-N IgG response in the severe patient who recovered, and a high anti-N IgA response specifically detected in the fatal case of COVID-19. Conclusions: Anti-N IgG and IgA antibodies are detected in NPS only for severe patients, with levels related to serological antibodies. The severe patients showed different antibody profiles in the plasma, notably regarding the IgA and IgG response to the N antigen, that may reflect different disease outcome. By contrast, pauci-symptomatic patients did not exhibit any mucosal antibodies in NSP, which is associated with a low or absent serological response against both N and S.