• Discordant neutralizing antibody and T cell responses in asymptomatic and mild #SARS-CoV-2 infection | Science Immunology
    https://immunology.sciencemag.org/content/5/54/eabf3698.full

    ... the majority of individuals with mild or asymptomatic SARS-CoV-2 infection carry nAb complemented by multispecific T cell responses at 16-18 weeks after mild or asymptomatic SARS-CoV-2 infection.

    #immunité #anticorps

  • Defining the features and duration of antibody responses to #SARS-CoV-2 infection associated with disease severity and outcome | Science Immunology
    https://immunology.sciencemag.org/content/5/54/eabe0240.full

    COVID-19 severity affected by proportion of antibodies targeting crucial viral protein, study finds | News Center | Stanford Medicine
    http://med.stanford.edu/news/all-news/2020/12/study-identifies-difference-between-severe-and-mild-covid-19.html

    “Although previous studies have assessed the overall antibody response to infection, we compared the viral proteins targeted by these antibodies,” Boyd said. “We found that the severity of the illness correlates with the ratio of antibodies recognizing domains of the spike protein compared with other nonprotective viral targets. Those people with mild illness tended to have a higher proportion of anti-spike antibodies, and those who died from their disease had more antibodies that recognized other parts of the virus.”

    The researchers caution, however, that although the study identified trends among a group of patients, there is still substantial variability in the immune response mounted by individual patients, particularly those with severe disease. 

    “Antibody responses are not likely to be the sole determinant of someone’s outcome,” Boyd said. “Among people with severe disease, some die and some recover. Some of these patients mount a vigorous immune response, and others have a more moderate response. So, there are a lot of other things going on. There are also other branches of the immune system involved. It’s important to note that our results identify correlations but don’t prove causation.”

    #immunité #anticorps #covid-19

  • Rapid generation of durable B cell memory to #SARS-CoV-2 spike and nucleocapsid proteins in COVID-19 and convalescence | Science Immunology
    https://immunology.sciencemag.org/content/5/54/eabf8891.full

    [...] antibodies are detectable from approximately 6 days after PCR confirmation of infection, and those directed against spike receptor binding domain (RBD) show neutralizing capacity and hence, can prevent infection. However, the rapid decline of anti-SARS-CoV-2 serum IgG levels beyond 20 days post-diagnosis and the transient presence of circulating plasmablasts have led to questions about the longevity of immunity. In contrast, antigen-specific memory T cells and memory B (#Bmem) cells can be detected in convalescence. As these memory cells are programmed to respond rapidly upon subsequent antigen encounter, it is reasonable to hypothesize that these long-lived memory cells provide durable long-term immunity (4, 25). However, detailed insight into the nature and longevity of the Bmem cell compartment specific to SARS-CoV-2 is currently still unresolved.

    We extensively characterized the SARS-CoV-2-specific Bmem cell compartment using unique sets of fluorescently-labeled recombinant tetramers of the SARS-CoV-2 RBD and NCP antigens in combination with an extensive flow cytometry panel. The SARS-CoV-2-specific Bmem cells were quantified and characterized in 36 samples from 25 patients with COVID-19 or in convalescence. Circulating RBD- and NCP-specific Bmem cell subsets were detected early after infection and persisted over 242 days post-symptom onset. Early after infection, antigen-specific Bmem cells predominantly expressed IgM, followed over time by a predominance of IgG1. RBD-specific Bmem cell numbers were found to positively correlate with circulating TFH cell numbers suggesting prolonged germinal center (GC) activity. These analyses highlight that a decline in serum antibodies in convalescence may not reflect waning of immunity, but rather a contraction of the immune response with the development and persistence of B cell memory.

    #Covid-19 : une réponse immunitaire qui persiste au moins huit mois après les premiers symptômes
    https://www.lemonde.fr/sciences/article/2020/12/24/covid-19-une-reponse-immunitaire-qui-persiste-au-moins-huit-mois-apres-les-p

    Une étude australienne, publiée mardi 22 décembre dans la revue Science Immunology, offre un nouvel éclairage. Elle montre, chez 25 patients atteints du Covid-19 à des degrés variables puis convalescents, la présence d’une #immunité durable – au moins huit mois – qui mobilise des cellules B « mémoires », c’est-à-dire spécialisées contre ce virus.

    Ce résultat s’ajoute à ceux de quatre autres publications, qui toutes parviennent à une conclusion analogue. « Après une infection naturelle, ce virus peut déclencher la production de #cellules_mémoires spécifiques qui persistent un certain temps dans l’organisme. Cela laisse espérer que la #vaccination saura mobiliser ces mêmes cellules d’une manière au moins aussi efficace », estime Simon Fillatreau, professeur d’immunologie à l’Institut Necker - Enfants malades (AP-HP, Inserm, CNRS, Université de Paris).

  • Persistence and decay of human antibody responses to the receptor binding domain of SARS-CoV-2 spike protein in COVID-19 patients | Science Immunology
    https://immunology.sciencemag.org/content/5/52/eabe0367.full

    IgG responses persist over the first few months after infection and are highly correlated with neutralizing antibodies.

    The majority of SARS-CoV-2 positive cases were severe (93% hospitalized, 53% requiring ICU level care, 13% died), male (62%), and older (median age: 59)

    Persistence of serum and saliva antibody responses to SARS-CoV-2 spike antigens in COVID-19 patients | Science Immunology
    https://immunology.sciencemag.org/content/5/52/eabe5511.full

    Conclusions similaires avec en plus la constatation d’une présence d’anticorps dans la salive.

    Combien de temps les anticorps anti-Covid-19 restent-ils dans l’organisme ? | Pour la Science
    https://www.pourlascience.fr/sr/covid-19/combien-de-temps-les-anticorps-anti-covid-19-restent-ils-dans-lorganis

    Des anticorps quatre mois après l’infection | JDQ
    https://www.journaldequebec.com/2020/10/11/des-anticorps-quatre-mois-apres-linfection