Partial molecular characterization of a mild isolate of Grapevine fanleaf virus from South Moravia, Czech Republic

An atypical mild isolate HV5 of Grapevine fanleaf virus (GFLV) was found in a South Moravian viticulture region in Czech Republic. Partial sequence of its RNA2 was determined and compared with available sequences of typical GFLV isolates. Two genomic regions, namely a 814 nt-long one spanning the movement protein (MP) gene and a 5'-part of the coat protein (CP) gene. and a 1426 nt-long one covering a part of the CP gene and the adjacent 3'-non-coding region (3'-NCR) were analyzed. Although no HV5-specific molecular features could be found in the two regions, marked differences were observed in the 3'-NCR. There was a 54 nt-long portion in which the sequence identity of some compared isolates was only 54.7%. Moreover, an unique one-nucleotide deletion occurred in the HV5 3'-NCR. These changes were also reflected in the predicted RNA secondary structure of this region. Particular biological behavior of GFLV HV5 isolate, namely a symptomless infection, could be related to the observed molecular differences.