The sheep Ig variable region repertoire consists of a single VH family
Dufour, V.; Malinge, S.; Nau, F.
Journal of Immunology 156(6): 2163-2170
1996
ISSN/ISBN: 0022-1767 PMID: 8690905 Document Number: 467026
Nine germ-line Ig heavy chain variable (V-H) segments (including three pseudogenes) were isolated from sheep DNA. Three of them were isolated from a genomic DNA library, and the other six were obtained by PCR, using 5' and 3' primers deduced from the first three. They appear to belong to a homogeneous V-H gene family, with gt 80% sequence identity. This sheep V-H gene family is related to the human V-H4 family and to the murine V-H1 subgroup (clan II). Southern blot analysis shows a maximum of 10 positive restriction fragments; therefore, the nine V-H genes isolated probably constitute the major part of the repertoire. Thirty-one expressed mu variable regions (and one gamma-1 variable region) were obtained from adult spleen by either cDNA cloning or anchored reverse transcriptase-PCR; they are gt 80% similar to each other (in their leader to framework 3 regions) and to the germ-line sequences as well. The sheep V-H repertoire thus seems to derive from a small ( apprx 10 members) germ-line gene family, and its diversification must rely chiefly on junctional (D and/or N regions) diversity and somatic hypermutations.