Cross-reactivity of antibodies from non-hospitalized COVID-19 positive individuals against the native and B.1.351 SARS-CoV-2 spike proteins

Abstract SARS-CoV-2 variants of concern (VOCs) have emerged worldwide, with implications on the spread of the pandemic. Characterizing the cross-reactivity of antibodies against these VOCs is necessary to understand the humoral response of non-hospitalized individuals previously infected with SARS-CoV-2, a population that remains understudied. Thirty-two SARS-CoV-2-positive (PCR-confirmed) and non-hospitalized Canadian adults were enrolled 14-21 days post-diagnosis in 2020, before the emergence of the B.1.351 VOC (also known as Beta). Sera were collected 4 and 16 weeks post-diagnosis. Antibody levels and pseudo-neutralization of the ectodomain of SARS-CoV-2 spike protein/human ACE-2 receptor interaction were analyzed with native and B.1.351 variant spike proteins. Despite a lower response observed for the variant spike protein, we report evidence of a sustained humoral response against native and B.1.351 variant spike protein among non-hospitalized Canadian adults. Furthermore, this response inhibited the interaction between the spike protein variant of concern and ACE-2 receptor for ≥16 weeks post-diagnosis.