Oxidative stress and DNA damage in horses naturally infected with Theileria equi.

The research study focuses on examining the levels of oxidative stress and DNA damage in horses naturally infected with a parasite known as Theileria equi.

Research Procedure

• The study began by selecting a sample of 30 horses infected with T. equi, along with 30 uninfected (control) horses from an initial pool of 110 horses. The selection was facilitated with the help of duplex PCR (a type of Polymerase Chain Reaction – a method used to amplify selected sections of DNA).
• Further tests were carried out to determine measures of oxidative stress which included parameters such as:
  • Extent of haemolysis (EH) – A process which destroys red blood cells and releases hemoglobin.
  • Plasma Free Haemoglobin (PHb) – Hemoglobin that is not contained within red blood cells.
  • Catalase (CAT) – An enzyme that helps protect the body from harmful effects of hydrogen peroxide.
  • Cu, Zn Superoxide dismutase (SOD1) – A type of enzyme that protects against oxidative stress.
  • Nitrite (NO), Total Nitrate and Nitrite (NOx), Malondialdehyde (MDA), and Free Thiol Groups (-SH).
• Additionally, the research also assessed the relative distribution of lactate dehydrogenase (LDH-LDH) activity and the DNA-damaging effects of the T. equi infection.

Key Findings

• Significantly higher activities of SOD1 and PHb, along with concentrations of NO, NOx, and MDA were found in horses infected with T. equi when compared to the control group.
• On the other hand, activities of EH, CAT, Paraoxonase (PON1), as well as concentrations of thiol groups were found to be significantly lower in infected horses.
• They applied the comet assay, a method to detect DNA damage, and found increased DNA damage in T. equi infected cells compared to non-infected cells.
• The infected horses also had significantly increased LDH isoenzyme activities indicating damage to the liver cells.
• T. equi infection resulted in higher production of Reactive Oxygen Species (ROS)/ Reactive Nitrogen Species (RNS) in horses, leading to changes in osmotic fragility, damage to lipids, proteins and DNA, haemolysis and hepatocellular damage.

Conclusion

• The research concluded that oxidative stress in horses naturally infected with T. equi could contribute to the progression of the infection. This implies that the parasite causes a significant imbalance between oxidants and antioxidants in the host’s system, thereby resulting in oxidative stress, which ultimately contributes to the pathogenesis of the infection.