Molecular cloning and sequencing of equine cDNA encoding serum amyloid A (SAA).

The research involves the successful cloning and sequencing of the DNA sequence that codes for the Serum Amyloid A (SAA) protein in horses. This protein is known to play a key role in the acute phase response in all animals, thus, understanding its genetic basis may provide clues on how to manage diseases in animals, particularly horses.

Methods and Findings

• The researchers extracted the Serum Amyloid A (SAA) gene from the liver of a healthy horse and cloned it using a laboratory technique called Polymerase Chain Reaction (PCR).
• The cloned sequence (cDNA) was found to be 480 bases long and contained an open reading frame (ORF) of 387 nucleotides. This implies the protein which this sequence encodes is 128 amino acids long.
• Compared to prior research findings, a notable difference in the horse’s SAA protein sequence was observed at residue 81 where valine had been substituted.
• The team observed similarities between the horse SAA protein and those from dogs, minks, humans, and ducks. These similarities ranged from 71.9% (with ducks) up to 80.6% (with dogs).
• Unique from human SAA, there was an insertion of eight additional amino acids in the horse SAA between residues 85 and 92.

Implications of Research

• This cloned gene sequence provides a useful medical tool to further understand the SAA protein and its function in horses.
• As the SAA protein is a primary reactive for acute phase response in animals, this generated sequence can assist in the investigation of associated diseases in horses.
• The high sequence similarity between species highlights the universality of the SAA protein’s structure and function across different animals, showcasing potential relevance beyond equine health.
• The relative differences observed in the horse SAA protein, such as the substitution at residue 81 and the insertion between residues 85 and 92, suggest possible specificities in how acute phase response occurs in horses.