Studies on ''corky rugose wood'' of grapevine and on the diagnosis of grapevine virus B

Vines affected by corky rugose wood (CRW), a field syndrome characterized by pronounced cork production by the scion of several grapevine varieties just above the graft union, contain a number of filamentous and isometric phloem-limited viruses, such as grapevine leafroll-associated virus 1, 2, and 3 (GLRaV-1, GLRaV-2, GLRaV-3), grapevine virus A and B (GVA and GVB), and grapevine fleck virus (GFkV). However, the same viruses, with the exception of GVB, are widely represented also in vines with rugose wood without excessive corkyness. Although GVB was found in all vines indexing positive in LN 33 for corky bark disease, iis occurrence in CRW-affected vines was not consistent enough to suggest that it may have a determining role in the induction of this syndrome. Monoclonal antibodies to GVB raised previously were characterized and their possible use for reliable detection of GVB in field-grown vines investigated in detail. A triple antibody sandwich ELISA protocol that under our experimental conditions afforded consistent and repeatable results, was based on the use of crude cortical scraping extracts from mature canes collected in autumn, antibodies from a polyclonal antiserum for plate coating (trapping) and a monoclonal antibody for antigen detection