Establishment of a sequence-based typing system for BoLA-DRB3 exon 2

Area of Science:

• Immunogenetics
• Molecular Biology
• Veterinary Genetics

Background:

• The bovine leukocyte antigen (BoLA) complex plays a crucial role in immune responses.
• Accurate typing of BoLA-DRB3 exon 2 is essential for understanding cattle disease resistance.
• Existing typing methods like PCR-RFLP have limitations in resolution and speed.

Purpose of the Study:

• To develop a rapid, high-resolution sequence-based typing (SBT) system for BoLA-DRB3 exon 2.
• To establish a reliable method for identifying heterozygous alleles.
• To create software for automated allele assignment.

Main Methods:

• Developed a fully nested PCR with locus-specific primers for complete exon amplification.
• Performed direct sequencing of PCR products and automated analysis of heterozygous data.
• Assembled forward and reverse sequence data for precise heterozygous position identification.
• Utilized Haplofinder software for automated allele assignment.
• Validated the SBT method by comparing results with DRB3 polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) typing.

Main Results:

• The SBT method successfully amplified and sequenced BoLA-DRB3 exon 2, accurately identifying heterozygous alleles.
• SBT identified 19 known alleles in 71 animals, compared to 15 types identified by PCR-RFLP.
• The developed SBT strategy and Haplofinder software demonstrated high resolution and efficiency.

Conclusions:

• The novel SBT system provides a rapid and high-resolution approach for BoLA-DRB3 exon 2 typing.
• This method enhances the accuracy of allele identification, particularly for heterozygous individuals.
• The SBT strategy and Haplofinder software are adaptable for analyzing other polymorphic genetic loci.