Molecular detection, histopathological analysis, and immunohistochemical characterization of equine infectious anemia virus in naturally infected equids.

The researchers studied a virus responsible for causing equine infectious anemia (EIA) in horses. They developed an immunohistochemistry assay to detect the presence of the virus in tissue samples from infected horses. The study reveals the virus infecting not just the expected organ cells, but also those in the lungs and kidneys, bringing new insights into possible means of viral excretion.

Research Methods

• The researchers initially focused their study on EIA, a disease that has no known treatment or vaccine and hampers the horse industry.
• In order to understand the possible presence and spread of EIA virus (EIAV) in equids, the team developed an immunohistochemistry assay. This granted them the ability to detect viral antigens (a foreign substance that induces an immune response) in tissue samples from infected horses.
• The organ sections from the six equids (a family that includes horses, donkeys, and zebras) examined were obtained from Apodi-RN in Brazil. All these equids had previously tested positive for EIA via serological tests, namely ELISA and AGID.
• The selected sections from the organs were fixed in a 10% formalin solution before being embedded in paraffin, in order to prepare them for the immunohistochemistry analysis. This analysis was carried out using an anti-EIAV antibody.

Results and Findings

• The presence of EIAV antigens was observed not just in the spleen and liver (as expected due to the virus’s known propensity for macrophages, which these organs are rich in) but unexpectedly in the epithelial cells of kidney tubules and bronchiolar/alveolar cells in the lungs.
• These findings suggest that EIAV infects more than just macrophages, expanding it to lung and kidney epithelial cells as well, which would prove critical in understanding the spread and excretion of the virus.

Conclusion

• The immunohistochemical assay turned out to be successful in detecting EIAV antigens in liver, spleen, lung, and kidney cells of the naturally infected equids.
• The study confirmed EIAV’s tropism for mononuclear phagocytes as observed in the spleen, but its presence in lung and kidney cells indicates potential new routes for viral excretion, possibly through urine and/or oronasal secretions.