MVV

MVV Full Name

Maedi Visna Virus

MVV Introduction

Maedi-Visna Virus (MVV) is a small ruminant lentivirus belonging to the Retroviridae family. It is closely related to Caprine Arthritis-Encephalitis Virus (CAEV), and together they form the Small Ruminant Lentiviruses group. As a lentivirus, MVV is characterized by a long incubation period, persistent infection, and the ability to integrate its RNA genome into the host's DNA via reverse transcription. The virus primarily targets cells of the monocyte/macrophage lineage in sheep. Its genome encodes standard retroviral structural proteins (Gag, Pol, Env) as well as regulatory and accessory proteins that are key to its replication and pathogenesis.

Figure 1. Structural basis for recruitment of host CypA and E3 ubiquitin ligase by maedi-visna virus Vif.

Pathogenesis and Transmission
MVV establishes a life-long, progressive infection. Following infection, the virus replicates slowly within macrophages in target tissues, particularly the lungs, central nervous system, joints, and mammary glands. The pathogenesis is largely driven by a cell-mediated immune response and subsequent chronic inflammation, rather than direct viral cytopathic effect. This results in lymphocytic infiltration and tissue damage over years. Transmission occurs primarily through the ingestion of infected colostrum and milk from ewes to lambs. Horizontal transmission via respiratory aerosols is also significant, especially in intensively housed flocks.

Clinical Disease and Manifestations
The disease caused by MVV presents in two main classical forms, which often overlap: Maedi (meaning "shortness of breath") and Visna (meaning "wasting"). Maedi is a progressive, interstitial pneumonia leading to weight loss and fatal respiratory distress. Visna is a neurological form characterized by chronic, non-supportative meningoencephalomyelitis, resulting in ataxia, paralysis, and wasting. Other common manifestations include indurative mastitis (hard udder) and arthritis. Clinical signs typically appear in adult animals (2-4 years of age or older) after a prolonged incubation period.

Alternate Names for MVV

MVV; Maedi Visna Virus

• 1.Hu Y, Gudnadóttir R B, Knecht K M, et al. Structural basis for recruitment of host CypA and E3 ubiquitin ligase by maedi-visna virus Vif. Science Advances, 2023, 9(2): eadd3422.