Sequencing of the canine immunoglobulin repertoire

Profiling the adaptive immune repertoire using next generation sequencing (NGS) has become common in human medicine, showing promise in characterizing clonal expansion of B cell receptors (BCRs) in patients with lymphoid malignancies. In contrast, most work evaluating BCR repertoires in dogs has employed traditional PCR-based approaches analyzing the IGH locus only. The objectives of this study were to: (1) describe a novel NGS protocol to evaluate canine BCRs; (2) develop a bioinformatics pipeline for processing canine BCR sequencing data; and (3) apply these methods to derive insights into BCR repertoires of healthy dogs and dogs undergoing treatment for B-cell lymphoma. We isolated RNA from PBMCs of healthy dogs and dogs newly diagnosed with intermediate-to-large B-cell lymphoma with intent to pursue chemotherapy. Rapid amplification of cDNA ends and NGS were employed to generate cDNA libraries and evaluate BCR repertoires. We developed an analysis pipeline to process, identify, and quantify these repertoires. This work represents the first use of NGS to profile the complete BCR repertoire in healthy dogs and dogs undergoing treatment for intermediate-to-large B-cell lymphoma, a common canine hematopoietic neoplasm that we used as a model for B-cell clonality. Future studies employing these tools may improve disease tracking, provide earlier recognition of relapses, and ultimately offer better-informed and targeted therapeutics.