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Infection with severe acute respiratory syndrome coronavirus 2 associates with diverse symptoms, which can persist for months. While antiviral antibodies are protective, those targeting interferons and other immune factors are associated with adverse coronavirus disease 2019 (COVID-19) outcomes. Here we discovered that antibodies against specific chemokines were omnipresent post-COVID-19, were associated with favorable disease outcome and negatively correlated with the development of long COVID at 1 yr post-infection. Chemokine antibodies were also present in HIV-1 infection and autoimmune disorders, but they targeted different chemokines compared with COVID-19. Monoclonal antibodies derived from COVID-19 convalescents that bound to the chemokine N-loop impaired cell migration. Given the role of chemokines in orchestrating immune cell trafficking, naturally arising chemokine antibodies may modulate the inflammatory response and thus bear therapeutic potential.
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COVID-19 , Humanos , SARS-CoV-2 , Autoanticuerpos , Síndrome Post Agudo de COVID-19 , QuimiocinasRESUMEN
Neutralizing antibodies that target the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein are among the most promising approaches against COVID-191,2. A bispecific IgG1-like molecule (CoV-X2) has been developed on the basis of C121 and C135, two antibodies derived from donors who had recovered from COVID-193. Here we show that CoV-X2 simultaneously binds two independent sites on the RBD and, unlike its parental antibodies, prevents detectable spike binding to the cellular receptor of the virus, angiotensin-converting enzyme 2 (ACE2). Furthermore, CoV-X2 neutralizes wild-type SARS-CoV-2 and its variants of concern, as well as escape mutants generated by the parental monoclonal antibodies. We also found that in a mouse model of SARS-CoV-2 infection with lung inflammation, CoV-X2 protects mice from disease and suppresses viral escape. Thus, the simultaneous targeting of non-overlapping RBD epitopes by IgG-like bispecific antibodies is feasible and effective, and combines the advantages of antibody cocktails with those of single-molecule approaches.
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Anticuerpos Biespecíficos/inmunología , Anticuerpos Neutralizantes/inmunología , COVID-19/inmunología , COVID-19/virología , Inmunoglobulina G/inmunología , SARS-CoV-2/inmunología , Enzima Convertidora de Angiotensina 2/antagonistas & inhibidores , Enzima Convertidora de Angiotensina 2/genética , Enzima Convertidora de Angiotensina 2/metabolismo , Animales , Anticuerpos Biespecíficos/uso terapéutico , Anticuerpos Monoclonales/inmunología , Anticuerpos Neutralizantes/uso terapéutico , Peso Corporal , COVID-19/prevención & control , Dependovirus/genética , Modelos Animales de Enfermedad , Epítopos de Linfocito B/química , Epítopos de Linfocito B/inmunología , Femenino , Humanos , Evasión Inmune/genética , Ratones , Ratones Endogámicos C57BL , SARS-CoV-2/genética , Glicoproteína de la Espiga del Coronavirus/antagonistas & inhibidores , Glicoproteína de la Espiga del Coronavirus/química , Glicoproteína de la Espiga del Coronavirus/inmunología , Tratamiento Farmacológico de COVID-19RESUMEN
During the coronavirus disease-2019 (COVID-19) pandemic, severe acute respiratory syndrome-related coronavirus-2 (SARS-CoV-2) has led to the infection of millions of people and has claimed hundreds of thousands of lives. The entry of the virus into cells depends on the receptor-binding domain (RBD) of the spike (S) protein of SARS-CoV-2. Although there is currently no vaccine, it is likely that antibodies will be essential for protection. However, little is known about the human antibody response to SARS-CoV-21-5. Here we report on 149 COVID-19-convalescent individuals. Plasma samples collected an average of 39 days after the onset of symptoms had variable half-maximal pseudovirus neutralizing titres; titres were less than 50 in 33% of samples, below 1,000 in 79% of samples and only 1% of samples had titres above 5,000. Antibody sequencing revealed the expansion of clones of RBD-specific memory B cells that expressed closely related antibodies in different individuals. Despite low plasma titres, antibodies to three distinct epitopes on the RBD neutralized the virus with half-maximal inhibitory concentrations (IC50 values) as low as 2 ng ml-1. In conclusion, most convalescent plasma samples obtained from individuals who recover from COVID-19 do not contain high levels of neutralizing activity. Nevertheless, rare but recurring RBD-specific antibodies with potent antiviral activity were found in all individuals tested, suggesting that a vaccine designed to elicit such antibodies could be broadly effective.
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Anticuerpos Neutralizantes/inmunología , Anticuerpos Antivirales/inmunología , Betacoronavirus/inmunología , Infecciones por Coronavirus/inmunología , Neumonía Viral/inmunología , Adolescente , Adulto , Anciano , Anticuerpos Monoclonales/análisis , Anticuerpos Monoclonales/inmunología , Anticuerpos Neutralizantes/análisis , Anticuerpos Antivirales/análisis , Especificidad de Anticuerpos , COVID-19 , Vacunas contra la COVID-19 , Infecciones por Coronavirus/prevención & control , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Masculino , Persona de Mediana Edad , Pruebas de Neutralización , Pandemias , SARS-CoV-2 , Glicoproteína de la Espiga del Coronavirus/química , Glicoproteína de la Espiga del Coronavirus/inmunología , Vacunas Virales/inmunología , Adulto JovenRESUMEN
Analytical ultracentrifugation (AUC) analysis shows that the SARS-CoV-2 trimeric Spike (S) protein adopts different quaternary conformations in solution. The relative abundance of the "open" and "close" conformations is temperature-dependent, and samples with different storage temperature history have different open/close distributions. Neutralizing antibodies (NAbs) targeting the S receptor binding domain (RBD) do not alter the conformer populations; by contrast, a NAb targeting a cryptic conformational epitope skews the Spike trimer toward an open conformation. The results highlight AUC, which is typically applied for molecular mass determination of biomolecules as a powerful tool for detecting functionally relevant quaternary protein conformations.
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SARS-CoV-2 , Glicoproteína de la Espiga del Coronavirus , Humanos , Anticuerpos Neutralizantes/inmunología , Anticuerpos Antivirales/inmunología , Epítopos/química , Epítopos/inmunología , SARS-CoV-2/química , SARS-CoV-2/inmunología , Glicoproteína de la Espiga del Coronavirus/química , Glicoproteína de la Espiga del Coronavirus/inmunología , Ultracentrifugación , Dominios ProteicosRESUMEN
The pandemic emergency caused by the spread of COVID-19 has stressed the importance of promptly identifying new epidemic clusters and patterns, to ensure the implementation of local risk containment measures and provide the needed healthcare to the population. In this framework, artificial intelligence, GIS, geospatial analysis and space assets can play a crucial role. Social media analytics can be used to trigger Earth Observation (EO) satellite acquisitions over potential new areas of human aggregation. Similarly, EO satellites can be used jointly with social media analytics to systematically monitor well-known areas of aggregation (green urban areas, public markets, etc.). The information that can be obtained from the Earth Cognitive System 4 COVID-19 (ECO4CO) are both predictive, aiming to identify possible new clusters of outbreaks, and at the same time supervisorial, by monitoring infrastructures (i.e. traffic jams, parking lots) or specific categories (i.e. teenagers, doctors, teachers, etc.). In this perspective, the technologies described in this paper will allow us to detect critical areas where individuals can be involved in risky aggregation clusters. The ECO4CO data lake will be integrated with ad hoc data obtained by health care structures to understand trends and dynamics, to assess criticalities with respect to medical response and supplies, and to test possibilities useful to tackle potential future emergencies. The System will also provide geographical information on the spread of the infection which will allow an appropriate context-specific public health response to the epidemic. This project has been co-funded by the European Space Agency under its Business Applications programme.
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BACKGROUND: Endogenous ovarian hormones as well as exogenous oestradiol and progesterone play an important role in cognitive processing. Specifically, these hormones play a role in different aspects of memory, both in terms of storage capacity and temporal duration of the mnemonic track. These hormones also have various effects on different types of memory (i.e., verbal, visuo-spatial, prospective). This study investigated the effects of hormones on topographic memory, a type of memory specifically needed to recall a pathway and to acquire spatial information about locations, distances, and directions. METHODS: We compared 25 naturally cycling women (NCW) in two different cycling phases, the early follicular phase (4th - 5th days) and the mid-luteal phase (20th-21st days), with 26 women taking oral contraceptives (OC) tested in the active pill phase (20th to 21st day of OC cycle) and the inactive pill phase (2nd to 4th day of OC cycle). Both groups performed the Walking Corsi Test to assess topographic memory in their respective cycling phases. Women were instructed to learn an eight-step sequence path and recall the path five minutes later. RESULTS: We found that the two groups differed in terms of learning the 8-step sequence path; OC users were always better (4-5 days vs. 20-21 days) than NCW. No differences emerged in the delayed recall of the same path. CONCLUSIONS: As already observed in other memory domains (i.e., verbal memory, emotional memory), OC users showed an advantage in terms of topographic learning. Our results might be explained by hormonal mechanisms and may suggest the future application of OC in women with topographic disorders or visuo-spatial difficulties.
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Cognición/fisiología , Anticonceptivos/farmacología , Estradiol/fisiología , Memoria/efectos de los fármacos , Memoria/fisiología , Ciclo Menstrual/fisiología , Progesterona/fisiología , Adulto , Cognición/efectos de los fármacos , Femenino , Humanos , Estudios Prospectivos , Adulto JovenRESUMEN
Developmental topographical disorientation (DTD) causes impaired spatial orientation and navigation from early childhood with no evidence of cerebral damage. Using fMRI and a landmark sequencing task, we investigated the hypothesis that Dr Wai's abnormal cerebral activation pattern was related to his peculiar behavioral profile. Although Dr Wai was able to correctly perform landmark sequencing, he showed a lack of activity in regions activated in all control subjects and activity in areas that were not activated in any control subject. These results are discussed in light of cognitive and functional model of navigation, with relevant implications for DTD physiology.
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Corteza Cerebral/fisiopatología , Orientación/fisiología , Navegación Espacial/fisiología , Procesamiento Espacial/fisiología , Adulto , Mapeo Encefálico , Humanos , Imagen por Resonancia Magnética , Masculino , Pruebas Neuropsicológicas , Adulto JovenRESUMEN
Flaviviruses such as dengue virus (DENV), Zika virus (ZIKV), and yellow fever virus (YFV) are spread by mosquitoes and cause human disease and mortality in tropical areas. In contrast, Powassan virus (POWV), which causes severe neurologic illness, is a flavivirus transmitted by ticks in temperate regions of the Northern hemisphere. We find serologic neutralizing activity against POWV in individuals living in Mexico and Brazil. Monoclonal antibodies P002 and P003, which were derived from a resident of Mexico (where POWV is not reported), neutralize POWV lineage I by recognizing an epitope on the virus envelope domain III (EDIII) that is shared with a broad range of tick- and mosquito-borne flaviviruses. Our findings raise the possibility that POWV, or a flavivirus closely related to it, infects humans in the tropics.
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Anticuerpos Neutralizantes , Humanos , Brasil , Anticuerpos Neutralizantes/inmunología , México , Anticuerpos Antivirales/inmunología , Animales , Virus de la Encefalitis Transmitidos por Garrapatas/inmunología , Flavivirus/inmunología , Epítopos/inmunología , Anticuerpos Monoclonales/inmunología , Garrapatas/virología , Garrapatas/inmunología , Femenino , MasculinoRESUMEN
INTRODUCTION: Discordant findings have been reported about the change in pregnant women's cognitive test performance. Visuo-spatial abilities, which are crucial in terrestrial/flight navigation, could be influenced by hormonal variations. CASE REPORT: A 32-yr-old Italian Air Force pilot underwent a 2-D Mental Rotation Task (MRT) and hormonal assessment in the second trimester of pregnancy and 1 yr after delivery. Her performance was compared with that of two nonpregnant groups of women: one with flying experience and the other without. Estradiol and progesterone were significantly higher in pregnancy compared with postpartum, while testosterone was almost unchanged. During pregnancy, we observed a significant difference in the subject's response time compared with pilots (she was slower) and nonpilots (she was faster). One year after delivery, her performance was still better than the nonpilot group and was almost the same as the pilot group. DISCUSSION: Our data are consistent with an effect of pregnancy on visuo-spatial ability that can last for some time after delivery, even with the early recovery of the hormonal levels. MRT smoothly changed in our subject, supporting previous findings that women who are experts in flight navigation are less sensitive to hormonal fluctuations. CONCLUSION: In this case, visuospatial ability requiring effortful processing underwent variations during pregnancy and postpartum. Further studies are needed in order to confirm our observations in a wider population.
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Cognición/fisiología , Embarazo/fisiología , Percepción Espacial , Adulto , Estradiol/sangre , Femenino , Humanos , Pruebas Neuropsicológicas , Periodo Posparto , Embarazo/sangre , Progesterona/sangre , Análisis y Desempeño de Tareas , Testosterona/sangreRESUMEN
INTRODUCTION: Mental rotation ability has an important role in human navigation and, together with other cognitive abilities such as processing speed, working memory, and attention, is crucial for aircraft navigation. In the human performance literature, mental rotation tasks have consistently yielded reports of gender differences favoring men. The aim of this study was to compare the gender difference measured in a specialized population of aviators vs. a matched population of nonpilots. METHODS: : Studied were 41 pilots (20 men and 21 women) and 38 nonpilots (20 men and 18 women) matched for age and education. Pilots were stratified for flying hours. Participants performed a mental rotation task (MRT) in which accuracy and response time were recorded, and also completed sense-of-direction (SOD) and spatial cognitive styles self-evaluation scales. RESULTS: Men had significantly smaller response time in the MRT (men 279.6 +/- 147.0 s, women 401.6 +/- 361.3) and greater SOD (men's score 49.1 +/- 8.6, women's score 46.6 +/- 7.8), but these differences were absent among pilots. A positive relationship was also identified between pilots' response times and their flight hours. CONCLUSION: These data suggest that the effect of gender on the speed of cognitive spatial processing is absent in a population with aviation experience. Gender effects may be associated with a low spatial cognitive style, whereas in groups such as aviators, who are expected to have high spatial cognitive style, other factors such as experience may come into play.
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Imaginación/fisiología , Rotación , Factores Sexuales , Percepción Espacial/fisiología , Adulto , Medicina Aeroespacial , Cognición/fisiología , Femenino , Humanos , Masculino , Desempeño Psicomotor/fisiología , Tiempo de Reacción , Análisis de Regresión , Adulto JovenRESUMEN
Objective: Coronavirus disease 2019 demonstrated the inconsistencies in adequately responding to biological threats on a global scale due to a lack of powerful tools for assessing various factors in the formation of the epidemic situation and its forecasting. Decision support systems have a role in overcoming the challenges in health monitoring systems in light of current or future epidemic outbreaks. This paper focuses on some applied examples of logistic planning, a key service of the Earth Cognitive System for Coronavirus Disease 2019 project, here presented, evidencing the added value of artificial intelligence algorithms towards predictive hypotheses in tackling health emergencies. Methods: Earth Cognitive System for Coronavirus Disease 2019 is a decision support system designed to support healthcare institutions in monitoring, management and forecasting activities through artificial intelligence, social media analytics, geospatial analysis and satellite imaging. The monitoring, management and prediction of medical equipment logistic needs rely on machine learning to predict the regional risk classification colour codes, the emergency rooms attendances, and the forecast of regional medical supplies, synergically enhancing geospatial and temporal dimensions. Results: The overall performance of the regional risk colour code classifier yielded a high value of the macro-average F1-score (0.82) and an accuracy of 85%. The prediction of the emergency rooms attendances for the Lazio region yielded a very low root mean square error (<11 patients) and a high positive correlation with the actual values for the major hospitals of the Lazio region which admit about 90% of the region's patients. The prediction of the medicinal purchases for the regions of Lazio and Piemonte has yielded a low root mean squared percentage error of 16%. Conclusions: Accurate forecasting of the evolution of new cases and drug utilisation enables the resulting excess demand throughout the supply chain to be managed more effectively. Forecasting during a pandemic becomes essential for effective government decision-making, managing supply chain resources, and for informing tough policy decisions.
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Emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants diminishes the efficacy of vaccines and antiviral monoclonal antibodies. Continued development of immunotherapies and vaccine immunogens resilient to viral evolution is therefore necessary. Using coldspot-guided antibody discovery, a screening approach that focuses on portions of the virus spike glycoprotein that are both functionally relevant and averse to change, we identified human neutralizing antibodies to highly conserved viral epitopes. Antibody fp.006 binds the fusion peptide and cross-reacts against coronaviruses of the four genera, including the nine human coronaviruses, through recognition of a conserved motif that includes the S2' site of proteolytic cleavage. Antibody hr2.016 targets the stem helix and neutralizes SARS-CoV-2 variants. Antibody sd1.040 binds to subdomain 1, synergizes with antibody rbd.042 for neutralization, and, similar to fp.006 and hr2.016, protects mice expressing human angiotensin-converting enzyme 2 against infection when present as a bispecific antibody. Thus, coldspot-guided antibody discovery reveals donor-derived neutralizing antibodies that are cross-reactive with Orthocoronavirinae, including SARS-CoV-2 variants.
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Anticuerpos Neutralizantes , COVID-19 , Humanos , Animales , Ratones , SARS-CoV-2 , Epítopos , Glicoproteína de la Espiga del Coronavirus , Anticuerpos Antivirales , Pruebas de NeutralizaciónRESUMEN
The long-term effects of cannabis on human cognition are still unclear, but, considering that cannabis is a widely used substance and, overall, its potential use in therapeutic interventions, it is important to evaluate them. We hypothesize that the discrepancies among studies could be attributed to the specific cognitive function investigated and that skills subserved by the hippocampus, such as the spatial orientation abilities and, specifically, the ability to form and use cognitive maps, should be more compromised than others. Indeed it has been showed that cannabis users have a reduced hippocampus and that the hippocampus is the brain region in which cannabis has the greatest effect since it contains the highest concentration of cannabinoid receptors. To test this hypothesis we asked 15 heavy cannabis users and 19 nonusers to perform a virtual navigational test, the CMT, that assesses the ability to form and use cognitive maps. We found that using cannabis has no effect on these hippocampus-dependent orientation skills. We discuss the implications of our findings and how they relate to evidence reported in the literature that the intervention of functional reorganization mechanisms in cannabis user allows them to cope with the cognitive demands of navigational tasks.
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Abuso de Marihuana/psicología , Orientación , Adulto , Estudios de Casos y Controles , Humanos , Masculino , Abuso de Marihuana/fisiopatología , Pruebas Neuropsicológicas , Desempeño Psicomotor , Percepción EspacialRESUMEN
Emergence of SARS-CoV-2 variants diminishes the efficacy of vaccines and antiviral monoclonal antibodies. Continued development of immunotherapies and vaccine immunogens resilient to viral evolution is therefore necessary. Using coldspot-guided antibody discovery, a screening approach that focuses on portions of the virus spike that are both functionally relevant and averse to change, we identified human neutralizing antibodies to highly conserved viral epitopes. Antibody fp.006 binds the fusion peptide and cross-reacts against coronaviruses of the four genera , including the nine human coronaviruses, through recognition of a conserved motif that includes the S2' site of proteolytic cleavage. Antibody hr2.016 targets the stem helix and neutralizes SARS-CoV-2 variants. Antibody sd1.040 binds to subdomain 1, synergizes with antibody rbd.042 for neutralization and, like fp.006 and hr2.016, protects mice when present as bispecific antibody. Thus, coldspot-guided antibody discovery reveals donor-derived neutralizing antibodies that are cross-reactive with Orthocoronavirinae , including SARS-CoV-2 variants. One sentence summary: Broadly cross-reactive antibodies that protect from SARS-CoV-2 variants are revealed by virus coldspot-driven discovery.
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Infection by SARS-CoV-2 leads to diverse symptoms, which can persist for months. While antiviral antibodies are protective, those targeting interferons and other immune factors are associated with adverse COVID-19 outcomes. Instead, we discovered that antibodies against specific chemokines are omnipresent after COVID-19, associated with favorable disease, and predictive of lack of long COVID symptoms at one year post infection. Anti-chemokine antibodies are present also in HIV-1 infection and autoimmune disorders, but they target different chemokines than those in COVID-19. Monoclonal antibodies derived from COVID- 19 convalescents that bind to the chemokine N-loop impair cell migration. Given the role of chemokines in orchestrating immune cell trafficking, naturally arising anti-chemokine antibodies associated with favorable COVID-19 may be beneficial by modulating the inflammatory response and thus bear therapeutic potential. One-Sentence Summary: Naturally arising anti-chemokine antibodies associate with favorable COVID-19 and predict lack of long COVID.
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Ungulates in alpine ecosystems are constrained by winter harshness through resource limitation and direct mortality from weather extremes. However, little empirical evidence has definitively established how current climate change and other anthropogenic modifications of resource availability affect ungulate winter distribution, especially at their range limits. Here, we used a combination of historical (1997-2002) and contemporary (2012-2015) Eurasian roe deer (Capreolus capreolus) relocation datasets that span changes in snowpack characteristics and two levels of supplemental feeding to compare and forecast probability of space use at the species' altitudinal range limit. Scarcer snow cover in the contemporary period interacted with the augmented feeding site distribution to increase the elevation of winter range limits, and we predict this trend will continue under climate change. Moreover, roe deer have shifted from historically using feeding sites primarily under deep snow conditions to contemporarily using them under a wider range of snow conditions as their availability has increased. Combined with scarcer snow cover during December, January, and April, this trend has reduced inter-annual variability in space use patterns in these months. These spatial responses to climate- and artificial resource-provisioning shifts evidence the importance of these changing factors in shaping large herbivore spatial distribution and, consequently, ecosystem dynamics.
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Ciervos/psicología , Conducta Alimentaria/fisiología , Migración Animal/fisiología , Animales , Cambio Climático , Ciervos/fisiología , Demografía/tendencias , Ecosistema , Conducta Alimentaria/psicología , Alimentos , Herbivoria/fisiología , Estaciones del Año , Nieve , Tundra , Tiempo (Meteorología)RESUMEN
Tick-borne encephalitis virus (TBEV) is an emerging human pathogen that causes potentially fatal disease with no specific treatment. Mouse monoclonal antibodies are protective against TBEV, but little is known about the human antibody response to infection. Here, we report on the human neutralizing antibody response to TBEV in a cohort of infected and vaccinated individuals. Expanded clones of memory B cells expressed closely related anti-envelope domain III (EDIII) antibodies in both groups of volunteers. However, the most potent neutralizing antibodies, with IC50s below 1 ng/ml, were found only in individuals who recovered from natural infection. These antibodies also neutralized other tick-borne flaviviruses, including Langat, louping ill, Omsk hemorrhagic fever, Kyasanur forest disease, and Powassan viruses. Structural analysis revealed a conserved epitope near the lateral ridge of EDIII adjoining the EDI-EDIII hinge region. Prophylactic or early therapeutic antibody administration was effective at low doses in mice that were lethally infected with TBEV.
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Anticuerpos Monoclonales/inmunología , Anticuerpos Neutralizantes/inmunología , Anticuerpos Antivirales/inmunología , Virus de la Encefalitis Transmitidos por Garrapatas/inmunología , Encefalitis Transmitida por Garrapatas/inmunología , Inmunoglobulina G/inmunología , Secuencia de Aminoácidos , Animales , Anticuerpos Monoclonales/administración & dosificación , Anticuerpos Monoclonales/genética , Anticuerpos Neutralizantes/administración & dosificación , Anticuerpos Neutralizantes/genética , Anticuerpos Antivirales/administración & dosificación , Anticuerpos Antivirales/genética , Células Cultivadas , Estudios de Cohortes , Reacciones Cruzadas/inmunología , Virus de la Encefalitis Transmitidos por Garrapatas/efectos de los fármacos , Virus de la Encefalitis Transmitidos por Garrapatas/fisiología , Encefalitis Transmitida por Garrapatas/prevención & control , Encefalitis Transmitida por Garrapatas/virología , Epítopos/inmunología , Femenino , Humanos , Inmunoglobulina G/administración & dosificación , Ratones Endogámicos BALB C , Homología de Secuencia de Aminoácido , Análisis de Supervivencia , Proteínas del Envoltorio Viral/genética , Proteínas del Envoltorio Viral/inmunologíaRESUMEN
Neutralizing antibodies targeting the receptor binding domain (RBD) of the SARS-CoV-2 Spike (S) are among the most promising approaches against coronavirus disease 2019 (COVID-19) 1,2 . We developed a bispecific, IgG1-like molecule (CoV-X2) based on two antibodies derived from COVID-19 convalescent donors, C121 and C135 3 . CoV-X2 simultaneously binds two independent sites on the RBD and, unlike its parental antibodies, prevents detectable S binding to Angiotensin-Converting Enzyme 2 (ACE2), the virus cellular receptor. Furthermore, CoV-X2 neutralizes SARS-CoV-2 and its variants of concern, as well as the escape mutants generated by the parental monoclonals. In a novel animal model of SARS-CoV-2 infection with lung inflammation, CoV-X2 protects mice from disease and suppresses viral escape. Thus, simultaneous targeting of non-overlapping RBD epitopes by IgG-like bispecific antibodies is feasible and effective, combining into a single molecule the advantages of antibody cocktails.
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During the COVID-19 pandemic, SARS-CoV-2 infected millions of people and claimed hundreds of thousands of lives. Virus entry into cells depends on the receptor binding domain (RBD) of the SARS-CoV-2 spike protein (S). Although there is no vaccine, it is likely that antibodies will be essential for protection. However, little is known about the human antibody response to SARS-CoV-21-5. Here we report on 149 COVID-19 convalescent individuals. Plasmas collected an average of 39 days after the onset of symptoms had variable half-maximal neutralizing titers ranging from undetectable in 33% to below 1:1000 in 79%, while only 1% showed titers >1:5000. Antibody cloning revealed expanded clones of RBD-specific memory B cells expressing closely related antibodies in different individuals. Despite low plasma titers, antibodies to three distinct epitopes on RBD neutralized at half-maximal inhibitory concentrations (IC50s) as low as single digit ng/mL. Thus, most convalescent plasmas obtained from individuals who recover from COVID-19 do not contain high levels of neutralizing activity. Nevertheless, rare but recurring RBD-specific antibodies with potent antiviral activity were found in all individuals tested, suggesting that a vaccine designed to elicit such antibodies could be broadly effective.