Clinical and virological outcome of an infection with the Belgian equine arteritis virus strain 08P178.

This research investigates the effects of a Belgian strain of equine arteritis virus (EAV), 08P178, on horses, revealing that this strain can indeed cause mild symptoms despite prior assumptions that most European EAV infections run a subclinical course.

Methodology

• The study’s subjects were eight horses that had no previous exposure to EAV. These horses were intentionally infected with the EAV virus strain 08P178, which belongs to the EU-1 clade, and is native to Belgium.
• Throughout the study, the horses were regularly monitored for symptoms of equine viral arteritis (EVA), a disease caused by EAV. The symptoms of EVA typically include fever and swollen lymph nodes.
• Various samples, including nasopharyngeal and ocular swabs, bronchoalveolar cells (cells from the bronchioles and alveoli in the lungs), and blood samples were collected for testing both virological and serological aspects.
• At different stages of the infection (3, 7, 14, and 28 days post-infection), two horses were euthanized and their internal organs were collected for virus titration and immunofluorescence techniques, which helped to detect and quantify the virus.

Results

• The horses began to show symptoms of EVA such as fever and lymphadenomegaly (enlarged lymph nodes) between 3 to 10 days post-infection.
• The viral presence was confirmed in nasal secretions from Day 2 to Day 9 post-infection, and in bronchoalveolar cells from Day 3 to Day 7 post-infection. Moreover, a cell-associated viremia (presence of virus in blood) was observable from Day 3 to Day 10 post-infection.
• The researchers found high virus titers in the internal organ samples collected on Day 7 post-infection, suggesting that the virus had managed to infect a variety of organs beyond the respiratory tract and lymph nodes.
• By the 14th day post-infection, the virus titers had drastically decreased. By Day 28, only the tonsils were found to still carry the virus.
• Through immunofluorescence techniques, the team observed that both individual and clustered cells had been infected by the EAV. Moreover, antibodies against the virus were detected starting from Day 7 post-infection.

Conclusion

• Based on these findings, the researchers concluded that the Belgian strain 08P178 is a mildly virulent subtype of EAV. Though it was previously thought that most EAV infections in Europe didn’t cause observable illness, this study proves otherwise.