Comparative sequence analysis of equine and human MHC class II DQB genes.

Area of Science:

• Immunogenetics
• Comparative genomics
• Equine genetics

Background:

• The Major Histocompatibility Complex (MHC) plays a crucial role in immune responses.
• Equine MHC class II genes, particularly DQB, are important for understanding horse immune diversity.
• Previous characterization of equine MHC genes has provided a foundation for further investigation.

Purpose of the Study:

• To isolate and characterize the horse Major Histocompatibility Complex (MHC) class II DQB gene.
• To identify any mutations affecting protein structure or splicing.
• To investigate potential novel gene fragments within the equine DQB locus.

Main Methods:

• Isolation and nucleotide sequencing of the equine MHC class II DQB gene.
• Sequence analysis to detect mutations, including frame shifts and splicing alterations.
• Comparative sequence analysis between human and horse DQB genes to identify novel fragments.

Main Results:

• The equine MHC class II DQB gene was successfully isolated and characterized.
• No significant mutations affecting protein structure or splicing machinery were detected.
• A novel gene fragment, showing high identity to exon 3 of the DQB gene but truncated at the 5' end, was identified in the 3' intergenic region proximal to the ELA-DQB gene.
• This fragment was also found in a similar location in the human HLA-DQB gene.

Conclusions:

• The characterized equine DQB gene sequence is consistent with the W23 haplotype.
• The identification of a novel, truncated DQB-like gene fragment suggests potential evolutionary or functional significance.
• This finding contributes to the understanding of MHC gene organization and evolution in horses and provides a basis for further functional studies.