Daphne virus X: A potexvirus from daphne

Abstract

Daphne virus X (DVX) was found in all specimens of D. cneorum L. indexed for virus but was not associated with macroscopic symptoms. Experimental hosts of DVX included 18 spp. from 6 dicotyledonous families. Infectivity was retained in expressed sap of Nicotiana clevelandii Gray for 5 wk at approximately 20.degree. C, in sap diluted to 10-5, after heating for 10 min at 80.degree. C. Attempts to transmit DVX with Myzus persicae (Sulz) failed. DVX was purified from N. clevelandii leaves using chloroform:n-butanol clarification, 1 cycle of differential, then density-gradient centrifugation. Preparations had a 260:280 ratio of 1.22, a sedimentation coefficient of 110 S, and a buoyant density in CsCl of 1.28 g/ml. An antiserum to DVX had a titer of 1:2048. DVX was not serologically related to clover yellow mosaic virus, narcissus mosaic virus, potato virus X, and white clover mosaic virus. The flexuous filamentous particles of DVX had a normal length of 499 nm in negatively stained preparations from D. cneorum flowers. Ultra-thin sections of pea leaflets systematically infected with DVX contained aggregates of DVX-like particles and unaggregated particles scattered in the cytoplasm. It is proposed that DVX is a distinct potexvirus. The present cryptogram for DVX is */*:*/(6):E/E:S/*.