Polymorphism of the functional immunoglobulin variable region genes in the chicken by exchange of sequence with donor pseudogenes

✍ Scribed by Tania Benatar; Michael J. H. Ratcliffe

• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 726 KB
• Volume: 23
• Category: Article
• ISSN: 0014-2980
• DOI: 10.1002/eji.1830231011

✦ Synopsis

We have isolated a number of new allelic variants of the unique functional genes encoding chicken immunoglobulin heavy and light chain variable regions (VJ and V'I, respectively).The distribution and nature of nucleotide variation among these and previously identified VHI and V' l alleles demonstrates that random point mutations are likely not the predominant cause of allelic variation at these loci. Comparison of the variant nucleotides with sequences from the pseudo-VH and pseudo-VL gene families, which lie 5' to V H ~ and VLI, respectively, suggests that the great majority of allelic variants can be accounted for by segmental transfer of sequence from donor pseudogenes into the germ-line V, l and V,l genes. These results demonstrate that the chicken VHI and VLI genes are susceptible to sequence replacement at the germ-line level as well as somatically during antibody diversification. The limited repertoire of B cell specificities produced by gene rearrangement in the chicken has led to speculation that these specificities may play a critical role in the progression of chicken Bcell development. The results presented here d o not support this hypothesis since many of the allelic variant nucleotides described here encode non-conservative amino acid substitutions within the antigen-binding sites of the Ig molecule.