Convergent Antibody Responses to SARS-CoV-2 Infection in Convalescent Individuals
Authors: Robbiani et al.
Link to paper: https://doi.org/10.1101/2020.05.13.092619
Journal/ Pre-Print: bioXriv
Key Words: Immunology
1. Plasmas from convalescent individuals recovering from COVID-19 disease contain low levels of neutralizing antibodies
2. Rare, but recurring receptor binding domain (RBD)-specific antibodies with potent antiviral activity were found in all individuals tested
Plasma samples of 149 COVID-19 convalescent individuals were tested for binding to the SARS-CoV-2 receptor binding domain (RBD) and trimeric spike (S) proteins by ELISA. The majority of plasma samples contained anti-RBD and S protein specific IgG, whereas only a minority contained antigen-specific IgM. Males had higher IgG titres than females. Overall levels of neutralizing activity in the plasma were generally low and correlated with levels of RBD and S-reactivity. Isolation and analysis of Ag-specific B cells from 6 subjects showed that the anti-RBD IgG response is enriched in recurrent clonally expanded antibody sequences and that those shared antibody clones were among the best neutralizers, suggesting that even individuals with modest plasma neutralizing activity harbour rare memory IgG B cells that produce potent neutralizing antibodies
Impact for SARS-CoV2/COVID19 research efforts
Understand the immune response to SARS-CoV2/COVID19
Develop a vaccine for SARS-CoV2/COVID19
· In vitro study
· Clinical Cohort study (serum from 68 convalescent individuals)
Strengths and limitations of the paper
Novelty: Shows that individuals undergoing a milder disease progression are still uniformly developing rare anti-RBD antibodies with potent antiviral activity. In addition, most plasma tested in this cohort had very limited neutralizing capacity suggesting that transfer of plasma from convalescent patients with mild symptoms might have limited therapeutic benefit.
Standing in the field: This study corroborates and validates observations previously published.
Viral model used: Plasma from Sars-CoV-2 infected individuals (confirmed by RT-PCR and contact cases)
Translatability: The result suggests that anti-RBD antibody inducing vaccines may be especially effective. It also suggests that convalescent plasma from individuals that underwent a mild form of the disease on its own may not be the best treatment option, given the rarity of the B cells producing the potent neutralizing activity.
Main limitations: None obvious