Proline-glutamic acid-proline-lysine peptide set as a specific antigen for the serological diagnosis of strangles.

The research article is about a study on the effectiveness of a synthesized peptide set, named proline-glutamic acid-proline-lysine (PEPK), for diagnosing Strangles disease in horses using ELISA test. The study reveals PEPK’s high reactivity with the sera of horses infected with Streptococcus equi and those recovering from Strangles, and low reactivity with horses infected with Streptococcus zooepidemicus and the control group.

Objective of The Study

The study aimed to test the reactivity of synthesized peptide sets associated with Strangles-causing M-like proteins, specifically SeM and SzPSe, with sera collected from horses. The target groups consisted of horses experimentally infected with Streptococcus equi or Streptococcus zooepidemicus, those recovering from Strangles, and a control group. The researchers used an ELISA test to ascertain the peptides’ efficiency, focusing primarily on the proline-glutamic acid-proline-lysine (PEPK) synthesized peptide set.

Methodology

• The researchers initially infected seventeen horses with either Streptococcus equi or Streptococcus zooepidemicus for the experiment.
• They collected convalescent sera (the serum from recovering horses) from 25 horses and control sera from 1,945 horses.
• The researchers then subjected these sera to ELISA tests. The tests were meant to investigate how the different sera samples would react to the synthesized peptide sets for proteins SeM and SzPSe.

Results and Findings

• The results turned out highly variable, as different horses showed distinct antibody responses to the peptide sets.
• Some peptide sets for SeM displayed strong reactions with sera from horses infected with Streptococcus equi. They also reacted with some sera from horses experimentally infected with Streptococcus zooepidemicus.
• However, the PEPK peptide set (synthesized from SzPSe’s PEPK repeats areas) reacted most strongly with sera from horses infected with Streptococcus equi and those recovering from Strangles.
• Interestingly, PEPK showed only minimal reactivity with sera from horses infected with Streptococcus zooepidemicus and the control group horses.

Conclusion

Based on the research findings, the PEPK peptide set exhibits specificity for the serological diagnosis of Strangles. Due to its strong reactivity to the sera of horses infected with Streptococcus equi or those recovering from Strangles, PEPK could serve as a promising antigen set in diagnosing the disease. However, more research may be needed to confirm this conclusion and assess PEPK’s efficiency in different and larger populations of horses.