The complete cDNA and deduced amino acid sequence of equine IgE.

The research is about discovering and sequencing the complete genetic code (cDNA) for equine IgE, an immunoglobulin found in horses. The study reveals the sequence’s similarities to those of other species, including humans.

Background and Methodology

• The researchers studied the equine immunoglobulin IgE, which is an important part of a horse’s immune system.
• They started by extracting a section from the gene that produces this immunoglobulin, the epsilon gene, from the horse’s complementary DNA (cDNA).
• They amplified this particular fragment using Polymerase Chain Reaction (PCR), which is a common method in molecular biology that allows for the reproduction of specific sections of DNA.

Analysis and Sequencing

• This amplified segment was then used to probe a horse cDNA library that was prepared from peripheral blood lymphocytes, a type of white blood cells.
• Eventually, a recombinant clone containing the cDNA coding for the entire horse epsilon chain was isolated and sequenced.

Comparison with Other Species

• The researchers then compared the sequenced amino acids of the equine IgE to the C epsilon heavy chains of other species.
• They found that the equine IgE has 54% similarity to the human C epsilon, followed by sheep C epsilon with 52% similarity, which denotes a fairly significant evolutionary closeness in immunoglobulin genes among these species.
• They found the greatest sequence similarity in the C epsilon 3 and C epsilon 4 domains when compared across the species.

Associated V-Region Comparisons

• The associated V-region, another part of the immunoglobulin gene, also had similarities with those from other species.
• The highest similarity was found in the FR1 segment, where similarity with sheep and cow sequences was greater than 80%.
• However, the similarity fell below 60% when compared with the VH sequences of other species in the FR3 segment.

Conclusion

• Overall, the study provides insights into the genetic basis of the equine immune system and its similarities with other species, showcasing the potential for cross-species learning about immunoglobulins.