Maedi-visna virus detection in ovine third eyelids

Area of Science:

• Veterinary Virology
• Sheep Pathology
• Ophthalmology

Background:

• Maedi-visna virus (MVV) causes a systemic lentiviral disease in sheep.
• Primary targets include lungs and the central nervous system, with potential involvement of mammary glands and joints.
• The role of the third eyelid in MVV infection was previously uncharacterized.

Purpose of the Study:

• To investigate the involvement of the third eyelid in natural Maedi-visna virus infections in sheep.
• To determine if the third eyelid serves as a target tissue for MVV.
• To assess the potential role of the third eyelid in MVV transmission.

Main Methods:

• Collection of third eyelid and lung samples from naturally MVV-infected sheep.
• Nested polymerase chain reaction (PCR) for MVV proviral DNA detection in paraffin-embedded tissues.
• In-situ PCR and immunohistochemistry (IHC) for precise localization and assessment of viral activity.

Main Results:

• Histopathological examination revealed moderate to severe chronic lymphoproliferative inflammation in the third eyelids of all infected sheep.
• MVV proviral DNA was successfully amplified from both lung and third eyelid tissues using PCR.
• In-situ PCR and IHC confirmed MVV presence within macrophages, glandular, ductal, and surface epithelia of the nictitating membrane, indicating productive infection.

Conclusions:

• The third eyelid is a target organ for natural Maedi-visna virus infection in sheep.
• The presence of productive MVV infection in the third eyelid suggests its potential role in the pathogenesis and transmission of the disease.
• Further research into the third eyelid's role could inform disease control strategies.