This is a summary, written by members of the CITF Secretariat, of:

Anand SP, Prévost J, Richard J, Perreault J, Tremblay T, Drouin M, Fournier MJ, Lewin A, Bazin R, Finzi A. High-throughput detection of antibodies targeting the SARS-CoV-2 Spike in longitudinal convalescent plasma samples. Transfusion. 2021 Feb 18. doi: 10.1111/trf.16318.

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

Dr. Andrés Finzi from the Université de Montréal, Dr. Renée Bazin from Héma-Québec, and their teams, recently described a novel high-throughput method to track levels of antibodies made against SARS-CoV-2 spike protein in the plasma of donors that recovered from COVID-19. This publication is part of their research funded in part by Government of Canada through the COVID-19 Immunity Task Force (CITF) in collaboration with the Canadian Institutes of Health Research (CIHR).

The spike protein of SARS-CoV-2 mediate the virus’ entry into human cells. The region of the spike that binds to the cellular receptor enabling viral entry is known as Receptor Binding Domain (or RBD for short). It is widely recognized that the antibodies are key to controlling SARS-CoV-2 infections. Importantly, neutralizing antibodies can bind to the spike protein preventing it from binding to the human receptor and blocking new infections. Transfusion of plasma from donors that recovered from COVID-19 was suggested as a promising treatment to reduce the severity of the disease in susceptible patients. The neutralization activity of the plasma would therefore be the most significant factor when considering their use for plasma transfusion.

Dr. Finzi, Dr. Bazin, and their respective teams at CRCHUM and Héma-Québec, already reported that most individuals developed neutralizing antibodies within 2 weeks of infection, but the level of neutralizing activity significantly decreased over time. They also reported that antibodies targeting the RBD follow a similar kinetics. To extend these observations beyond the RBD, they performed a longitudinal analysis of the persistence of antibodies targeting the full‐length SARS‐CoV‐2 Spike in the plasma from 15 convalescent donors. For this purpose, they developed a novel high‐throughput assay. They found that the level of antibodies targeting the full‐length SARS‐CoV‐2 Spike also declines gradually over time. This decline coincides with the decline of RBD‐specific antibodies and depends on the number of days post‐symptom onset of each sample. Their results provide important information on when to collect plasma after recovery from active infection for convalescent plasma transfusion.