The present work describes the characterization of the coat protein gene of two isolates of Grapevine virus B (GVB), which can be differentiated by their biological behavior on some grape cultivars. The total RNA was extracted from leaves and petioles of infected grapevines (Vitis spp.) of the cultivars Rubi (GVB-C SP) and Italy (GVB-I SP) and used to amplify, by RT/PCR, a fragment between positions 6425 and 7118 (694 nucleotides, nt) of the genomic RNA (GenBank, access X75448). The fragment comprises the coat protein gene (594 nt) coding for 197 amino acids with a predicted Mr of 21,600 Da. The sequence of GVB-C SP showed a greater similarity of nucleotides and deduced amino acids with the Italian isolate (access X74448), while the GVB-I SP was similar to a Brazilian isolate described in the State of Rio Grande do Sul , Brazil (GVB BR1, access AF438410). The isolates GVB-C SP and GVB-I SP can be differentiated by digestion with the enzyme EcoRI, since this restriction site is present on the GVB-C SP but absent on GVB-I SP.
