VITIVIRUS, A NEW GENUS OF PLANT-VIRUSES

Vitivirus is a novel genus of plant viruses with filamentous flexuous particles showing distinct cross banding, which comprises five virus s pecies formerly included in the Trichovirus genus. The morphological a nd physicochemical properties of vitiviruses and trichoviruses are sim ilar. However, there are differences in biological behaviour, tissue t ropism, epidemiology, genome structure and composition that justify th e separation of the two genera. As compared with apple chlorotic leafs pot (ACLSV) and potato T (PVT) trichoviruses, the genome of grapevine viruses A (GVA) and B (GVB), the two vitiviruses sequenced to date, co ntains two extra cistrons encoding polypeptides that are not represent ed among the expression products of ACLSV and PVT genome. Moreover, GV A and GVB constitute a phylogenetically more coherent cluster than ACL SV and PVT.