Characteristics of respiratory tract disease in horses inoculated with equine rhinitis A virus.

This research studied how the equine rhinitis A virus (ERAV) affects horses and if it causes respiratory disease. The authors also sought to understand if horses can be immune to reinfection, with the aim of developing prevention measures for ERAV.

Overview of the Research Methodology

• Eight ponies within the age bracket of 8 to 12 months were selected for this study. These ponies had no existing antibodies against the ERAV, meaning they had not been previously exposed to the virus.
• The research utilized a method known as nebulization to expose the ponies to the ERAV strain ERAV/ON/05.
• Four ponies were exposed to the ERAV while the other four ponies (controls) were exposed to cell culture mediums not containing the virus.
• Furthermore, four ponies previously exposed to the ERAV were exposed to the virus again after one year.
• Over a span of 21 days, the ponies underwent physical examinations and pulmonary function tests.
• Samples were collected from the ponies for virus isolation, blood tests were done for serologic testing, and clinical scores were determined for various factors.

Preliminary Outcomes of the Infection

• Upon exposure to ERAV, the ponies presented symptoms of respiratory disease such as fever, nasal discharge, abnormal lung sounds, and swelling of the mandibular lymph nodes.
• The virus was detected in the ponies’ upper and lower respiratory tract samples up to seven days post exposure, evidencing its successful inoculation.
• The ponies also exhibited purulent mucus in their lower airways for up to 21 days post inoculation, a symptom gauged via endoscopy.

Further Results and Future Implication

• Increased serum titers of neutralizing antibodies against ERAV were detected, coinciding with the time frame of virus isolation from respiratory tract samples.
• None of the ponies that were reinoculated after a year showed signs of disease, suggesting immunity to the virus post initial infection.
• These results show that the ERAV can induce respiratory disease in ponies, but also that an initial infection may protect against future instances of the disease.
• Indicatively, this study points towards the potential of immunizing horses against ERAV as a prevention strategy for respiratory disease attributed to this virus.