Templated insertions at VD and DJ junctions create unique B-cell receptors in the healthy B-cell repertoire

Abstract

RAG complexes recognise (cryptic) RSS sites both in and outside immunoglobulin sites. Excision circles may be reinserted into V(D)J rearrangements as long templated insertions to diversify the adaptive immune repertoire. We show that such VDJ with templated insertions are incidentally found in the repertoire of healthy donors.

Figure 1

Structure of the 6 VDJ transcripts sequences carrying large insertions. From 12 healthy donors, unbiased full‐length VDJ transcripts were obtained from 2 × 10⁶ B cells by ARTISAN PCR [10] and sequenced on the RSII platform (Pacific Biosciences, Menlo Park, CA, USA). VDJ sequences within the highest percentile for either CDR3 length, N nucleotides, or overall length were screened for insertions by NCBI BLAST. Six VDJ with templated insertions were identified. Numbers indicate nucleotide length of gene segments. Italicized numbers indicate the RSSsite score of RSS sites. Arrows mark sites of somatic hypermutation.