Lettuce ring necrosis agent  (LRNA)

- classification : unassigned, Ophiovirus
- other name: Agent for orange spots


The agent ring necrosis lettuce ( Lettuce ring necrosis agent , LRNA) belongs to the family of Ophiovirus .

In France, “ orange spot disease ” owes its name to the primary symptoms it causes in batavia-type lettuce, on which it was observed for the first time. It has been referred to as " necrotic ring disease " in other countries.

Current research indicates that the causative agent is of the viral type. To date, the responsible virus has not been characterized; it is referred to in the literature as Lettuce ring necrosis agent . The mode of transmission of this virus by Olpidium virulentus (ex Olpidium brassicae ) and its frequent association in the field with the Big-vein suggested a common causative agent, despite an extremely different symptomatology. In fact, MLBVV (ophiovirus) and LBVV (varicosavirus) are frequently isolated as a mixture in lettuce affected by the orange spot disease. Recently, a varicosavirus isolate has been shown to be able, after mechanical transmission, to partially reproduce the disease syndrome, but Koch's postulate could not be established.