Filamentous flexous particles and serologically related proteins of variable size associated with citrus psorosis and ringspot diseases

Filamentous flexous partic les of unusual morphology, previously associated with several ringspot isolates, were detected also in psorosis A and psorosis B isolates by serologically specific electron microscopy using an antiserum to citrus ringspot. Upon partial purification of six ringspot, six psorosis A, and three psorosis B isolates, a specific protein of 47 kDa was detected in most cases, but two isolates (one psorosis A and one ringspot) had a 46 and a 48 kDa-protein, respectively. These differences in molecular masses were observed when purification was done from different host species or from plants co-inoculated with two isolates differing by their protein size. The three types of protein were serologically related in Western blots. Our results indicate that a common virus with different strains may be involved in psorosis A, psorosis B, and ringspot diseases.