Quantification by real-time PCR of the magnitude and duration of leucocyte-associated viraemia in horses infected with neuropathogenic vs. non-neuropathogenic strains of EHV-1.
Authors: Allen G P, Breathnach C C
Journal: Equine veterinary journal
Summary
# Editorial Summary: EHV-1 Strain Virulence and Leucocyte-Associated Viraemia Allen and Breathnach employed real-time PCR to quantify viral DNA in circulating leucocytes from horses experimentally infected with either neuropathogenic (paralytic) or non-neuropathogenic (abortigenic) strains of EHV-1, addressing a critical gap in our understanding of why certain strains trigger devastating neurological disease whilst others cause reproductive losses. The neuropathogenic strains demonstrated significantly higher levels of cell-associated viraemia that persisted for longer periods compared to the abortigenic isolates, suggesting this robust and sustained leucocytaemia may be a key pathogenic mechanism underpinning the neurological form of the disease. This distinction is particularly important for practitioners managing EHV-1 outbreaks, as the viral kinetics in circulation could influence transmission dynamics, clinical presentation timing, and potentially inform quarantine and treatment protocols. Understanding that paralytic strains maintain higher viraemic burdens in immune cells provides biological rationale for the unpredictable and severe neurological complications seen in field cases, and highlights that not all EHV-1 infections pose equivalent risk for catastrophic neurological sequelae. The quantitative approach used here establishes a more reliable foundation for future research into therapeutic interventions targeting leucocyte-associated viraemia as a potential strategy to limit neuropathogenic complications.
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Practical Takeaways
- •Horses infected with paralytic EHV-1 strains develop a higher burden of virus in circulating white blood cells, which may explain the increased neurological pathogenesis of certain isolates
- •Real-time PCR quantification of leucocyte-associated viraemia could help differentiate between EHV-1 strains and predict risk of neurological complications in clinical cases
- •Understanding strain-specific viraemia patterns is critical for managing EHV-1 outbreaks and may inform prevention strategies for neuropathogenic disease
Key Findings
- •Paralytic strains of EHV-1 produce more robust cell-associated viraemia in leucocytes compared to abortigenic strains
- •Quantification by real-time PCR enables precise measurement of EHV-1 DNA levels in viraemic leucocytes to differentiate pathogenic strain characteristics
- •Cell-associated viraemia magnitude and duration differs significantly between neuropathogenic and non-neuropathogenic EHV-1 isolates