Alternanthera mosaic virus (AltMV) is a plant pathogenic virus. AltMV belongs to the virus genus Potexvirus and the virus family Alphaflexiviridae. AltMV was first identified in 1999 in Queensland, Australia. The virus was found in Alternanthera pugens (Amaranthaceae), a weed found in both the southern USA and Australia. Since then, AltMV has been identified in various ornamental plants in Italy, the United States (Maryland and Pennsylvania, Florida, and New York), and Brazil.