Citrus leprosis virus: properties, diagnosis, agro-ecology and phytosanitary importance

Citrus leprosis disease, caused by citrus leprosis virus (CiLV), had severe effects on sweet oranges in Florida (US) until the 1920s, after which it became rare. In South America, it appeared in the 1930s, first in Argentina and then in Brazil, where it is now widespread and very dangerous. It has also been reported in Paraguay, Peru, Uruguay and Venezuela. CiLV is transmitted by three species of Brevipalpus, mainly Brevipalpus phoenicis. The virus mainly attacks sweet orange, but also citrange, citron, Cleopatra mandarin, grapefruit, lemon, mandarin, sour orange and tangor. CiLV is a non‐enveloped rhabdovirus characterized by bacilliform particles measuring 120–130 × 50–55 nm, present in mesophyll and vascular parenchyma within cisternae of the endoplasm reticulum. Viroplasm structures are present in the infected cells. CiLV has been partially purified and its dsRNA as been investigated. It is mechanical transmissible to 13 test plant species belonging to the genera Atriplex, Beta and Chenopodium (Chenopodiaceae), Gomphrena (Amaranthaceae), and Tetragonia (Tetragoniaceae). Using some of these herbaceous test plants, grown at a suitable temperature, it is possible to diagnose CiLV in 3–4 days. CiLV is covered by lists and requirements in phytosanitary regulations, but the information given is often misleading. For phytosanitary purposes, it is important to consider the following main points: (a) both CiLV and its vectors need to be considered; (b) sweet orange fruits can be infected even more than propagation material; and (c) CiLV does not infect susceptible citrus systemically, or any of its known hosts.