Experimental infection with African Horse Sickness Virus in horses induces only mild temporal hematologic changes and acute phase reactant response.

This research article investigates the hematologic changes and acute phase response in horses during infection with African Horse Sickness Virus (AHSV). The findings indicate severe thrombocytopenia and changes in signals of acute phase response, although these changes are mild and may not serve as useful clinical indicators.

Overview of the Study

In this research, an experiment was performed to understand the pathogenesis of African Horse Sickness (AHS), a vector-borne disease primarily found in sub-Saharan Africa that can lead to high morbidity and mortality in infected horses. The study intended to identify hematologic changes and the acute phase response that occurs during AHS infection.

The study was a prospective, longitudinal one carried out between November 23 and December 2, 2020. Four horses that had no AHSV group-specific antibodies were selected for the experiment. They were infected with AHSV, and blood samples were taken before infection and every 12 hours after until euthanasia.

Results of the Study

• All horses had to be euthanized due to severe symptoms of AHS.
• Significant hematologic changes were recorded over time. These include an increase in median hematocrit (the proportion of blood volume that is occupied by red blood cells), median white blood cell count, monocyte count, eosinophil count, and myeloperoxidase index (an enzyme in white blood cells).
• Horses developed severe thrombocytopenia, a condition characterized by a decrease in the number of platelets in the blood. The study recorded a median platelet concentration of 48 X 103 cells/µL.
• Markers of platelet activation also showed significant changes, suggesting a heightened reactive state of blood platelets during AHSV infection.
• Signs of acute phase response, marked by an increase in the level of serum amyloid A (SAA) and a decrease in the concentration of serum iron, were observed. However, these changes were not drastic.

Conclusion of the Study

The research concluded that severe thrombocytopenia with platelet activation happens during AHSV infection. Although they were statistically significant, the changes in acute phase reactants like SAA and iron were mild. This finding implies that these biomarkers might not be clinically useful in diagnosing or monitoring the progress of the disease. The study helps inform further research on the pathogenesis of AHS and may help in the development of new diagnostic methods or treatments.