Epizotiology and phylogeny of equine arteritis virus in hucul horses.

This study investigates the prevalence of equine arteritis virus (EAV) infections in hucul horses in Poland. It found that EAV infections were present in over half of the horses tested, with a higher percentage in older mares and stallions, suggesting age and gender as possible factors.

Research Methods and Population

• The researchers examined a total of 176 hucul horses, with the majority being mares. The horses were from the largest hucul horse stud in Poland.
• Both mares and stallions were included in the study to examine potential differences between genders.
• Different age groups of mares were also tested to explore the relationship between age and EAV infection.

Findings on EAV Infection

• Nearly 55.1% of the sample were found to be infected with EAV. This percentage increased dramatically with age. Horses between 6-10 years and older than 10 years had an infection rate of 89.5% and 95%, respectively.
• Among the stallions, 68.2% had EAV. Five of the seropositive stallions were likely to carry the virus in their semen.
• The data suggests that EAV infections increase with age, and that female horses are more prone to infection than males. Additionally, it indicates that stallions with EAV may act as virus reservoirs, potentially transmitting the virus via their semen.

Genetic Study on EAV

• A deeper genetic examination was conducted on the ORF5 gene, which is involved in EAV infections.
• The genetic study revealed a high similarity between the viruses detected in different stallions, suggesting lateral transmission or sharing of the same virus strain among those residing in the same stable.
• The researchers also discovered a persistently infected young stallion, indicating that infection through respiratory exposure is another possible transmission route for EAV.

Phylogenetic Analysis of EAV

• A phylogenetic analysis was also carried out to understand the evolutionary history of the virus strains in the horse population.
• The analysis established that all the hucul EAV strains were descendants of a common ancestor, which belonged to the EU-1 subtype of EAV that is widespread in European horses.