Pathogenesis and clinical signs of equine herpesvirus-1 in experimentally infected ponies in vivo.

This research study investigates the effects and pathogenesis of Equine herpesvirus-1 (EHV-1) in ponies. EHV-1 is known to cause respiratory disease, neonatal death, abortion, and neurological issues in equine species. The study aims to identify the presence of EHV-1 in the respiratory tracts of ponies by using immunoperoxidase staining in the collected samples.

Experimental Setup

• Six seronegative (previously uninfected) pony foals were selected and isolated for the study.
• EHV-1 virus was introduced to these ponies using a nebulizer with a face mask.
• The health conditions of these infected ponies were monitored and discussed. Symptoms such as fever, nasal discharge, enlarged submandibular lymph nodes, and occasional coughing were noted as signs of infection.

Sample Collection and Analysis

• Nasopharyngeal swabs were obtained from the ponies, with EHV-1 being isolated from four out of the six ponies.
• Cytology brushes were used to collect respiratory tract samples at different sections with bronchoalveolar lavage used to get lung cells.
• The samples were then put through an immunocytochemistry technique to locate the presence of EHV-1 antigen.
• The staining of these samples with monoclonal antibodies specific for EHV-1 revealed the presence of this antigen associated with cellular debris.

Observations and Results

• All six of the pony foals showed seroconversion, meaning their body started producing antibodies against EHV-1.
• Hyperemia, or excessive blood flow, was observed in the large airways of the ponies.
• The occurrence of Actinobacillus suis, a type of bacteria, from the nasopharyngeal swabs was initially high but decreased with the increase in the recovery of Streptococcus zooepidemicus isolates at 3 weeks post EHV-1 infection.
• The viral antigen was primarily found in the nasopharyngeal samples collected between 3 to 9 days after the infection.