Large scale transcriptional analysis of MHC class I haplotype diversity in sheep

Abstract

Domestic sheep (Ovis aries) have been an important component of livestock agricultural production for thousands of years. Preserving genetic diversity within livestock populations maintains a capacity to respond to changing environments and rapidly evolving pathogens. MHC genetic diversity can influence immune functionality at individual and population levels. Here, we focus on defining functional MHC class I haplotype diversity in a large cohort of Scottish Blackface sheep pre‐selected for high levels of MHC class II DRB1 diversity. Using high‐throughput amplicon sequencing with three independent sets of barcoded primers we identified 134 MHC class I transcripts within 38 haplotypes. Haplotypes were identified with between two and six MHC class I genes, plus variable numbers of conserved sequences with very low read frequencies. One or two highly transcribed transcripts dominate each haplotype indicative of two highly polymorphic, classical MHC class I genes. Additional clusters of medium, low, and very low expressed transcripts are described, indicative of lower transcribed classical, non‐classical and genes whose function remains to be determined.