Purification and properties of two Swedish isolates of barley yellow dwarf virus and their serological relationships with American isolates

Two Swedish isolates of barley yellow dwarf virus (BYDV), one (39/78) transmitted much more efficiently by Rhopalosiphum padi than by Sitobion avenae and the other (27/77) transmitted specifically by Sitobion avenae, were purified with yields of 200–300 μg/100 g infected oat leaves. Three light scattering zones were obtained when isolate 39/78 was sedimented in 10–40% (w/w) sucrose density gradients but only one zone with the other isolate. The sedimentation coefficients of 39/78 particles were 94,106 and 150 S, respectively, whereas the 27/77 particles sedimented at 110 S. Four protein bands of mol. wts 31 900, 29 700, 28 000 and 15 000 were detected when disrupted 150 5 particles of the 39/78 isolate were electrophoresed in SDS-polyacrylamide gels. Only one major band of mol. wt 24 500 was detected when 94 or 106 S particles were electrophoresed under the same conditions. The 27/77 isolate yielded one major band of mol. wt 23 500. A weak serological relationship was found between isolates 39/78 and 27/77. In enzyme-linked immunosorbent assay, isolate 39/78 was serologically closely related to New York isolate PAY, whereas 27/77 was closely related to MAY.