Herpesviruses in respiratory liquids of horses: putative implication in airway inflammation and association with cytological features.

This research paper investigates the prevalence of equine herpesviruses (EHVs) in the bronchoalveolar lavage (BAL) and tracheal wash (TW) of horses, and their possible connection to respiratory diseases and inflammation. The study finds that EHV infections were more common in the TW of the group of horses with pathologies, with the highest prevalence being for EHV-2.

Research Objective

• The study aims to estimate the prevalence of equine herpesviruses in different techniques used to obtain respiratory samples from horses (bronchoalveolar lavage and tracheal wash).
• It also aims to explore the potential link between EHV detection and different forms of respiratory diseases in horses, such as tracheal inflammation, inflammatory airway disease, and recurrent airway obstruction.

Methodology

• The study subjects included a control group and a pathological group, the latter comprised of horses either suffering from respiratory diseases or under respiratory investigation due to exercise intolerance or poor performance.
• Both types of respiratory samples were subjected to a standardized cytological analysis. This process involved noting abnormalities and markers of potential viral infection in the exfoliated epithelial cells and ciliocytophthoria found in the samples.
• The samples were then tested using PCR assays specifically designed to detect the presence of two types of herpesviruses – alphaherpesviruses (EHV-1 and EHV-4) and gammaherpesviruses (EHV-2 and EHV-5).

Findings

• The study found that herpesvirus infections were more prevalent in the tracheal washes of the pathological group. Among all the herpesviruses, EHV-2 had the highest prevalence.
• The detection rate of herpesviruses in bronchoalveolar lavages was not significantly different between the control and the pathological group.
• The presence of herpesviruses in tracheal washes was found to be correlated with the count of polymorphonuclear neutrophils – a type of white blood cells – within the respiratory fluid. However, no such correlation was found with markers indicating potential viral infection.
• It was also found that certain morphological features of cells found in the bronchoalveolar lavage were associated with the detection of EHVs, specifically EHV-2 and EHV-5.

Implications

• The detection of herpesviruses in the tracheal washes of horses from the pathological group, along with increased counts of polymorphonuclear neutrophils, could suggest a possible link between these viruses and equine tracheal inflammation.
• This could lead to future research investigating the potential role of herpesviruses in equine respiratory diseases and inflammation. This could eventually help develop better diagnostic tools and treatment options for these conditions in horses.