A new grapevine leafroll-associated virus isolate (GLRaV-Pr) from Greek grapevines was recently reported. This virus, along with the genetically related GLRaV-4, -5, -6 and -9, form a separate diverse lineage within the genus Ampelovirus. In this paper, the complete nucleotide sequence of GLRaV-Pr was determined, making it the first fully sequenced virus of this lineage. Its genome is 13,696 nt long and contains seven open reading frames, which potentially encode a 253-kDa polyprotein containing papain-like protease, methyltransferase, AlkB and helicase domains, a 58.2-kDa RNA-dependent RNA polymerase, a 5.2-kDa hydrophobic protein, a 58.5-kDa heat shock 70 protein homologue, a 60-kDa protein, a 30-kDa coat protein (CP) and a 23-kDa protein. A virus-specific antibody was raised against the recombinant CP of GLRaV-Pr and was applied in western blot analysis. The genomic, serological and phylogenetic data reported here confirm that GLRaV-Pr is a member of a distinct Ampelovirus species. Comparisons of GLRaV-Pr with the only available genetically related, fully sequenced virus, PMWaV-1, PBNSPaV and the partially sequenced GLRaV-9 revealed that this lineage, including GLRaV-4, -5, -6, -9 and -De, exhibits a high uniformity of genome organization and includes the smallest and simplest viruses within the family Closteroviridae.