Analysis of genetic relations between Broad bean wilt virus 1 and Broad bean wilt virus 2

摘要

We determined the complete nucleotide sequence of RNA-1 and the 5'-terminal region of RNA-2 from Broad bean wilt virus 1 (BBWV-1) isolate PV132. This report is the first analysis of the genome organization of BBWV-1. We also determined the completenucleotide sequence of RNA-1 from Broad bean wilt virus 2 (BBWV-2) isolate IP and analyzed the genetic relations between BBWV-1 and BBWV-2. Similar to the BBWV-2 isolates, both RNAs of PV132 encoded a single large polyprotein, which was predicted to contain some functional proteins in a manner similar to those of comovirus. With respect to the deduced amino acid sequences of the mature proteins, PV132 and IP had only 20 percent-40 percent homology to comovirus. On the other hand, IP was 73 percent-98 percent homologous to BBWV-2 isolates, but PV132 was 39 percent-67 percent homologous to the isolates. Although the extent of the homologies differed, the homologies were limited between BBWV-1 and BBWV-2 not only for the coat protein but also for the other proteins. These results clearly support the placement of BBWV-1 and BBWV-2 in the genus Fabavirus as distinct species, proposed on the basis of double immunodiffusion tests.