Oxidative stress and DNA damage in horses naturally infected with Theileria equi.
Authors: Radakovic M, Davitkov D, Borozan S, Stojanovic S, Stevanovic J, Krstic V, Stanimirovic Z
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary: Oxidative Stress and DNA Damage in Theileria equi Infection Theileria equi, a blood parasite of significant concern in equine practice, triggers substantial oxidative and nitrosative stress in infected horses—a finding that may explain the variable clinical severity observed in the field. Serbian researchers compared 30 naturally infected horses with 30 uninfected controls, measuring multiple oxidative stress markers (antioxidant enzymes, lipid peroxides, protein thiols, reactive oxygen/nitrogen species) and DNA integrity via comet assay. Infected horses demonstrated a compromised antioxidative defence system characterised by reduced catalase and paraoxonase activity alongside elevated superoxide dismutase, coupled with significantly increased markers of cellular damage including malondialdehyde (lipid peroxidation), nitrite/nitrate accumulation, and free haemoglobin indicative of intravascular haemolysis. DNA damage was substantially elevated in infected animals, with altered lactate dehydrogenase isoenzyme distribution suggesting hepatocellular involvement. The clinical relevance lies in understanding that T. equi pathogenicity extends beyond direct parasitaemia to include systemic oxidative stress, which may inform supportive management strategies (antioxidant supplementation, management of secondary complications) alongside antimicrobial protocols and could explain why some infected horses develop severe clinical disease whilst others remain relatively asymptomatic.
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Practical Takeaways
- •Theileria equi infection triggers a cascade of oxidative stress markers that compromise cellular function; veterinarians should monitor for this parasite in horses showing signs of haemolysis or general malaise
- •The marked increase in free haemoglobin and oxidative damage suggests T. equi-infected horses may benefit from supportive antioxidant therapy and close monitoring of liver function
- •DNA damage detected in infected cells indicates potential for long-term health consequences; prevention through tick control and early detection via PCR screening is preferable to managing chronic infection
Key Findings
- •T. equi infected horses showed significantly elevated SOD1 activity, plasma free haemoglobin, nitrite, nitrate and malondialdehyde concentrations compared to controls
- •Catalase and paraoxonase activities were significantly reduced in infected horses, along with decreased thiol group concentrations
- •Comet assay demonstrated significantly increased DNA damage in T. equi infected cells compared to non-infected cells (P<0.001)
- •Higher ROS/RNS production in infected horses resulted in osmotic fragility changes, lipid and protein damage, and hepatocellular damage