ABSTRACT This study attempted to understand the levels of neutralizing titers and the breadth of antibody protection against wild-type and variant severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Canadian blood donors during the first 3 months of 2021. During this period, it is unlikely that many of the blood donors had received a second dose, since vaccine rollout had not yet ramped up, and less than 2% of the Canadian population had received a second dose of vaccine. A repeated cross-sectional design was used. A random cross-sectional sampling of all available Canadian Blood Services retention samples ( n = 1,500/month) was drawn monthly for January, February, and March 2021. A tiered testing approach analyzed 4,500 Canadian blood donor specimens for potential evidence of a signal for anti-spike (anti-S), anti-receptor-binding domain (anti-RBD), and anti-nucleocapsid protein (anti-N). Specimens were stratified based on donor-declared vaccination history and then stratified on the presence or absence of anti-N as follows: (i) “vaccinated plus anti-N” ( n = 5), (ii) “vaccinated and no anti-N” ( n = 20), (iii) “unvaccinated plus anti-N” ( n = 20), and (iv) “unvaccinated and no anti-N” ( n = 20). Randomized specimens were then characterized for neutralizing capacity against wild-type as well as SARS-CoV-2 variants of concern (VOCs) (Alpha [B.1.1.7], Beta [B.1.351], Gamma [P.1], and Delta [B.1.617.2]) using S-pseudotyped virus-like particle (VLP) neutralization assays. There was no neutralizing capacity against wild-type and VOC VLPs within the “no vaccine and no anti-N” group. Neutralization of Beta VLPs was less than wild-type VLPs within “vaccinated plus anti-N,” “vaccinated and no anti-N”, and “unvaccinated plus anti-N” groups. IMPORTANCE In the first 3 months of 2021 as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination was in the initial stages of a mass rollout, Canadian blood donors had various levels of humoral protection against wild-type and variant of concern (VOC) SARS-CoV-2. Very few Canadians would have received a second dose of a SARS-CoV-2 vaccine. In this study, we identified elevated levels of neutralizing capacity, albeit with reduced neutralization capacity against one or more SARS-CoV-2 strains (wild type and VOCs) in vaccinated blood donors. This broad neutralizing response we present regardless of evidence of natural SARS-CoV-2 infection. Neutralizing capacity against wild type and VOCs varied significantly within the unvaccinated group, with one subset of unvaccinated plasma specimens (unvaccinated and no anti-N) having no measurable wild type- nor variant-neutralizing capacity. The study is important because it indicates that vaccination can be associated with a broad neutralizing antibody capacity of donor plasma against SARS-CoV-2 VOCs.
【저자키워드】 Neutralizing antibodies, spike, variants of concern, Receptor-binding domain, SARS-CoV-2 antibody, nucleocapsid, virus-like particles, 【초록키워드】 neutralizing antibody, SARS-CoV-2, Vaccine, coronavirus, vaccination, antibody, VoC, B.1.351, neutralization, cross-sectional, SARS-COV-2 infection, variant, SARS-CoV-2 variant, Delta, B.1.617.2, severe acute respiratory syndrome Coronavirus, SARS-CoV-2 vaccine, Protein, Blood donors, Pseudotyped virus, B.1.1.7, VOCs, Gamma, Alpha, plasma, Beta, Neutralizing, neutralizing capacity, respiratory, wild type, Blood, Anti-spike, VLP, Donor, breadth, Neutralizing titer, Evidence, neutralization capacity, anti-RBD, humoral, blood donor, evidence of, initial stages, presence or absence, cross-sectional design, acute respiratory syndrome, acute respiratory syndrome coronavirus, acute respiratory syndrome coronavirus 2, second dose, second dose of vaccine, signal, specimen, Stage, anti-receptor-binding domain, wild-type, neutralizing titers, random, anti-S, neutralization assays, service, SARS-CoV-2 strain, VLPs, repeated, approach, initial, analyzed, was used, significantly, elevated, unlikely, reduced, characterized, indicate, less, absence, groups, subset, stratified, Canadian, 【제목키워드】 SARS-CoV-2, Particle, Capacity, history, profile,