Quasispecies nature of the genome of Grapevine fanleaf virus.

Genetic diversity was characterized in 14 isolates of Grapevine fanleaf virus (GFLV) recovered from grapevine (Vitis vinifera). Virions were collected by immunocapture, and a 1557 bp fragment containing part of the viral coat protein gene and part of the untranslated region to its 3' side was amplified by RT-PCR. Sequence variation among isolates was characterized by restriction fragment length polymorphism (RFLP) analysis and by sequencing. The AvaII-generated RFLP patterns from the various isolates were highly variable. The isolates were passaged in Chenopodium quinoa. The RFLP patterns altered with passage through the alternate host, but the variation stabilized after a number of passages. Individual genomes were recovered by cloning. The subcloned sequences were found to vary from each other by as much as 13%, and the encoded amino acid sequences by as much as 9%. The data suggest that the GFLV genome consists of quasispecies populations.