Análise molecular do repertório de anticorpos de cavalo após imunização com a proteína spike de SARS-COV-2

Abstract

Antibodies derived from horses have played a crucial role in the treatment of various diseases for over a century. In Brazil, the Vital Brazil Institute and the Butantan Institute have played a significant role in the production of therapeutic antibodies. Among these, studies have used horse plasma as a strategy to fight COVID-19. It has been shown that plasma from these animals can be 150 times more neutralizing than plasma from convalescent patients. However, our understanding of the equine immune system, including equine antibodies, is still very limited. Given the high neutralization of equine plasma, isolating antibodies from it could lead to a therapeutic alternative to combat COVID-19. Therefore, this work aims to deepen the understanding of transcribed and circulating antibodies against the SARS- CoV-2 spike protein in horses with the aim of developing new immunotherapeutics. In this study, we adopted an integrated approach, employing the sequencing of B-cell receptor transcripts (Rep-seq) to create a bank of sequences. These sequences were then used to map the peptides of the specific anti-spike antibodies present in plasma (Ig-Seq), allowing the identification of complete sequences of circulating antibodies. NGS sequencing of transcripts from 4 horses resulted in an average of 57,000 clones for the heavy chain (IGH), 71,000 for the lambda light chain (IGL) and 8,000 for the kappa light chain (IGK). Through serology, we identified 106 specific sequences for IGH, 49 for IGL and 19 for IGK. In addition, we were able to determine that the characteristics of the spike-specific antibodies are very similar to those of the total transcript repertoire. The heavy (19) and light (2) chains of the horse that showed the highest neutralizing title were analyzed and selected for antibody production. As a prospect, these antibodies will be produced and tested. This study is the first to reveal the unique composition of circulating equine anti- spike antibodies, highlighting distinct characteristics compared to previously characterized antibodies against SARS-CoV-2. This discovery opens up promising prospects for the creation of therapeutic equine antibodies to combat COVID-19.