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Polymorphism at the ovine major histocompatibility complex class II loci
A P Escayg1, J G Hickford, G W Montgomery
1Department of Animal and Veterinary Sciences, Lincoln University, Canterbury, New Zealand.
Animal Genetics
|October 1, 1996
Summary
Extensive polymorphism was found in the ovine major histocompatibility complex (MHC) class II region, with a common null allele at the DQA1 locus raising questions about its function.
Area of Science:
- Immunogenetics
- Molecular genetics
- Animal breeding
Background:
- The ovine major histocompatibility complex (MHC) class II region is crucial for immune responses.
- Understanding genetic diversity within this region is vital for sheep breeding and disease resistance.
Purpose of the Study:
- To analyze the genetic polymorphism within the ovine MHC class II region.
- To identify allele frequencies and investigate linkage disequilibrium between specific loci.
Main Methods:
- Southern hybridization analysis using sheep-specific probes for DQA1, DQA2, DQB, and DRA loci.
- Allele frequency determination and linkage analysis.
Main Results:
- Extensive polymorphism observed across DQA1, DQA2, DQB, and DRA loci, with numerous alleles identified.
- A highly prevalent null allele (DQA1-N) was detected at the DQA1 locus (27-45% frequency).
- No recombination was observed between the analyzed DQA1, DQA2, DQB, and DRA loci.
Conclusions:
- The ovine MHC class II region exhibits significant genetic diversity.
- The high frequency of the DQA1 null allele suggests potential functional implications or selective pressures.
- The lack of recombination indicates tight linkage among these MHC class II genes in sheep.