The complete nucleotide sequence and genome organization of S(small) and M(medium) RNA segments of Groundnut bud necrosis virus from Vigna radiata (GBNV-MB) was determined. The organization of both these segments was similar to that of GBNV type isolate in terms of the ORFs and their location. The size of the 5\’ and 3\’ NCRs, intergenic regions (IGR), NSs and N ORFs of the SRNA were exactly the same for GBNV-MB and GBNV (type isolate). The size of 5\’ and 3\’ NCRs, NSm and Gn/Gc ORFs of MRNA were exactly the same for GBNV-MB and GBNV (type isolate). However, major differences were observed in the length of intergenic regions of M RNA segments. The M IGR of GBNV-MB (422nt) was 15-nucleotide longer than that of the GBNV (type isolate) (408nt). The size of M IGR of another GBNV isolate from tomato was also different (347nt), 75 nucleotides smaller than that of GBNV-MB isolate. The secondary structure of IGRs was also different in the three isolates. Comparison of size, sequence identity and secondary structure of M IGRs revealed that GBNV-MB and GBNV (type isolate) originating from leguminous hosts were more similar as compared to GBNV (tomato isolate) originating from solanaceous host, suggesting that the IGRs might have some role in host specificity of various isolates. Some differences were also observed in the topology of glycoprotein precursor of GBNV –MB and GBNV (type isolate). The two isolates differed in the N - and O - glycosylation sites and these differences might play important role in virus transmission by thrips, as insect transmission and specificity are mainly determined by tospoviral envelope glycoproteins.
