Diversification of sheep immunoglobulins

The sheep antibody repertoire was assessed by sequence analysis of V lambda , V kappa and V-H cDNA clones. In fetuses, all immunoglobulin chains were e ssentially in germline configuration, although limited diversity occurred a t the junctional regions of V kappa chains. Fetal B cells expressed 12 dist inct V lambda and six V kappa gene segments. V-H gene segments were also in germline configuration in fetuses but became extensively mutated with adva ncing post natal age. Two distinct types of mutations, point mutations and block mutations, were detected in V-H transcripts and these localised diffe rently along the gene. This raises a question as to whether a novel mutatio nal mechanism may be involved in V-H diversification in sheep. (C) 1999 Els evier Science B.V. All rights reserved.