Long-lasting airway inflammation associated with equid herpesvirus-2 in experimentally challenged horses.

This study examines the potential role of equid herpesvirus 2 (EHV-2), a type of equine herpes virus, in long-term airway inflammation in adult horses. The researchers induced the virus in some horses and gauged its effect on respiratory health and performance.

Research Methodology

• For the trial, six adult horses were selected. To suppress their immune system and make them more susceptible to infections, the horses were given corticosteroid treatments.
• These horses were then subjected either to a mock infection (n=2) or actual inoculation with EHV-2 strain LK4 (n=4).
• The four horses exposed to EHV-2 were additionally exposed to immunosuppression 84 days post inoculation.
• The presence and progression of EHV-2 were monitored by taking respiratory samples at regular intervals and testing them using quantitative PCR. Additional testing methods, including nested PCR, cloning, and sequencing, were used to detect five other ‘field’ strains of the virus throughout the trial.

Findings

• EHV-2 was detectable up to 21 days and 14 days in the respiratory samples of the subjects, confirming the persistent presence of the virus and its potential to cause ongoing inflammation.
• There was a transient increase in the neutrophils (a type of white blood cell responsible for fighting infections) proportion in respiratory fluids, signifying an immune response. This increased neutrophilia was significantly associated with the detection of EHV-2.
• The lab findings in this trial were found to be consistent with symptoms of subclinical lower airway inflammation.

Implications

• The findings of this study suggest a connection between EHV-2 infection and lower airway inflammation in horses. As such, EHV-2 infection should be suspected and tested for when assessing horses that are performing poorly or showing signs of respiratory distress.
• Further research might be needed to better understand the mechanisms by which EHV-2 causes airway inflammation, as well as to develop effective treatments and preventive measures.