Identification and opsonic activity of immunoglobulins recognizing Streptococcus zooepidemicus antigens in uterine fluids of mares.

The research article delineates the investigation into how immunoglobulins G, Gt, A, and M recognize and react to a strain of bacteria called Streptococcus zooepidemicus. The study was conducted on mares and assessed the immune response during ovulation cycles, comparing those resistant and susceptible to endometritis, a uterine infection.

Research Methodology

• The researchers employed a direct ELISA (enzyme-linked immunosorbent assay) to evaluate the presence and concentration of different immunoglobulin isotypes (G, Gt, A, and M) in the uterine lavage fluids obtained from mares during their ovulation cycles.
• The mares were divided into two groups: one resistant and the other susceptible to endometritis. The resistant group comprised younger, nulliparous (mares that have not given birth) mares with no history of reproductive issues. The susceptible group included older, pluriparous (mares that have given birth multiple times) mares with a history of endometritis and fertility issues.
• Both groups were exposed to a strain of Streptococcus zooepidemicus, a bacteria known to cause infections. This antigen was introduced into the uterus of the mares during three distinct stages of ovulation.

Testing and Results

• At specific points during the ovulation cycles, uterine samples were collected for bacterial culture testing. Additionally, a saline solution containing 125I-labelled human serum albumin (HSA) was used to wash (irrigate) the uterus, to determine the concentration of each immunoglobulin isotype in the uterine effluents.
• The total concentration of immunoglobulin G (IgG) in uterine effluents was measured using radial immunodiffusion.
• To evaluate the immune response, the uterine fluids were introduced to the S. zooepidemicus (the same strain used as antigen) in an assay of luminol-enhanced neutrophil chemiluminescence. This allowed for the measurement of the immune response (chemiluminescence) generated by the uterine fluids compared to a control serum.
• The study found that Streptococcus zooepidemicus was isolated from 67% of uterine samples collected from mares susceptible to endometritis, implying a significant immune response towards the bacteria in these mares.

The study provides valuable insights into how immunoglobulins in the uterine fluid react to Streptococcus zooepidemicus, contributing to broader understanding of mare’s reproductive immunology and providing potential strategies for mitigating uterine infections in horses.