A second locus and new alleles in the major histocompatibility complex class II (ELA-DQB) region in the horse.

This study presents the discovery of a second locus and new alleles in the major histocompatibility complex class II region in horses. Using genetic sequencing and PCR techniques, the researchers were able to demonstrate the existence of these entities and visualize their molecular characteristics and behavior.

Understanding Genomic Structure

• Researchers were able to identify that there are at least two ELA-DQB loci in horses at the genomic level. This was achieved through examining more than two nucleotide sequences of the second exon of the ELA-DQB region from a single horse. They also observed two different sequences from horses that were homozygous in the MHC region, further evidencing the existence of at least two loci.
• The identification of these two loci was key to unveiling the underlying complexity of the MHC region in horses. This region is heavily involved in the immune response and has a broad array of functions, which the discovery of additional loci helps to explain.

New Allele Detection and Analysis

• The team identified new alleles in the ELA-DQB region using polymerase chain reaction single strand conformation polymorphism (SSCP) and nucleotide sequencing of the second exon of the DQB gene(s).
• The nucleotide sequences of these new alleles showed that they belonged to at least two distinct groups. This categorization was dependent on the level of nucleotide sharing among the alleles.
• Despite these findings, it wasn’t possible to assign these new alleles to a specific locus based on the data collected in this research. This indicates the need for further research for locus assignment of these newly identified alleles.

Transcription and Mutation Evaluation

• Researchers confirmed that at least one of these new alleles was transcribed, an important aspect in determining their functional role in the genetic machinery of the horse.
• No frame-shift mutations were identified among these newly discovered alleles. A frame-shift mutation often results in a dysfunctional protein, so its absence may suggest that these new alleles are functional in their current state.
• They did identify a pseudoallele containing a stop codon at the genomic DNA level. This could indicate that whilst this particular allele is present, it may not necessarily be functional or involved in typical genetic operations.