The equine immune response to Streptococcus equi subspecies zooepidemicus during uterine infection.

This research article focuses on examining the specific immune responses in horses to Streptococcus equi subspecies zooepidemicus (S. zooepidemicus), a type of bacteria, during uterine infection.

Study Design

• The study started by characterizing five isolates of S. zooepidemicus into four antigenically different strains. This was accomplished through bactericidal testing in horses’ blood and genetic differentiation through a procedure known as pulsed-field gel electrophoresis.
• Thereafter, eight healthy mares were divided into two groups. Each group was inoculated intrauterinely (directly into the uterus) with one strain across three successive oestrous cycles. This was followed by an inoculation of a second strain for three more such cycles. The order of the strains was reversed for each group.

Evaluation of Immune Responses

• Immune responses to the strains were determined and evaluated through bactericidal testing and immunoblotting across eight cycles.
• The study revealed that immune responses to each strain appeared at varied timings. Immunoblotting also showed stronger binding to the first-inoculated strain than the second one.

Conclusion

• The results confirmed that immune responses to S. zooepidemicus during uterine infection are partly strain-specific, implying that the type of bacterial strain affects the immune response elicited in horses.
• This piece of information could prove influential in approaches towards treating and managing bacterial infections in horses, by forming a basis for the development of strain-specific prevention or treatment strategies.