Shallot latent virus,a new carlavirus

A new carlavirus, apparently omnipresent in shallot (Allium ascalonicum) without causing symptoms, is described as shallot latent virus. It has also been detected in naturally infected onion (A. cepa) and leek (A. porrum). The virus was easily transmissible in sap and could be transferred withMyzus ascalonicus. Infection after inoculation was symptomless in onion, leek,A. fistulosum andA. jailae. Chenopodium album, C. amaranticolor andC. quinoa reacted with local lesions.A. neapolitanum andA. schoenoprasum and 20 other plant species were immune. Dilution end-point was 10⁴–10⁵, thermal inactivation at ca. 80°C and ageing in vitro 8–11 days. Purification by molecular sieving on Sephadex G-200 followed by equilibrium density-gradient centrifuging in CsCl was successful. Sedimentation coefficient was 147.5 S, bouyant density 1.313 g/cm³ and molecular mass of protein subunits 23 200 dalton. With the antiserum (titre 1024) distant serological relationships to some carlaviruses were determined. No inclusion bodies were observed with the light microscope. With the electron microscope a high concentration of straight or slightly curved particles with a normal length of 650 to 652 nm could easily be detected in crude sap and in purified preparations.