TY - JOUR T1 - No substantial pre-existing B cell immunity against SARS-CoV-2 in healthy adults JF - bioRxiv DO - 10.1101/2021.09.08.459398 SP - 2021.09.08.459398 AU - Meryem Seda Ercanoglu AU - Lutz Gieselmann AU - Sabrina Dähling AU - Nareshkumar Poopalasingam AU - Susanne Detmer AU - Manuel Koch AU - Michael Korenkov AU - Sandro Halwe AU - Michael Klüver AU - Veronica Di Cristanziano AU - Hanna Janicki AU - Maike Schlotz AU - Johanna Worczinski AU - Birgit Gathof AU - Henning Gruell AU - Matthias Zehner AU - Stephan Becker AU - Kanika Vanshylla AU - Christoph Kreer AU - Florian Klein Y1 - 2021/01/01 UR - http://biorxiv.org/content/early/2021/09/08/2021.09.08.459398.abstract N2 - Pre-existing immunity against SARS-CoV-2 may have critical implications for our understanding of COVID-19 susceptibility and severity. Various studies recently provided evidence of pre-existing T cell immunity against SARS-CoV-2 in unexposed individuals. In contrast, the presence and clinical relevance of a pre-existing B cell immunity remains to be fully elucidated. Here, we provide a detailed analysis of the B cell response to SARS-CoV-2 in unexposed individuals. To this end, we extensively investigated the memory B cell response to SARS-CoV-2 in 150 adults sampled pre-pandemically. Comprehensive screening of donor plasma and purified IgG samples for binding and neutralization in various functional assays revealed no substantial activity against SARS-CoV-2 but broad reactivity to endemic betacoronaviruses. Moreover, we analyzed antibody sequences of 8,174 putatively SARS-CoV-2-reactive B cells on a single cell level and generated and tested 158 monoclonal antibodies. None of the isolated antibodies displayed relevant binding or neutralizing activity against SARS-CoV-2. Taken together, our results show no evidence of relevant pre-existing antibody and B cell immunity against SARS-CoV-2 in unexposed adults.Competing Interest StatementThe authors have declared no competing interest. ER -