D‐D Recombination Diversifies the CDR 3 Region of Chicken Immunoglobulin Heavy Chains

Publisher Website
Google Scholar
Abstract
The occurrence of D‐D recombination during the embryonic differentiation of chicken B cells was studied, Ig heavy (H) chains were amplified by polymerase chain reaction from day‐12 bursal cDNA, and 30 random V‐D‐J regions were analysed by DNA sequencing. No gene conversion events were observed in any of the V regions, indicating that diversification of the H chains by gene conversion is not yet activated at this stage of embryonic B‐cell development. In contrast, the V‐D‐J joint regions were extremely heterogeneous. Most of the sequenced V‐D‐J joints were formed by direct joining of the single‐germline Vμ1 gene, one of the multiple‐germline D elements, and the single J gene. However, three V‐D‐J regions were clearly longer in size, and their D‐region structure indicated recombination between two or three different germline D elements. Thus, the present data suggest that D‐D recombination may have a role in diversification of the Ig H‐chain repertoire.