RESUMO
Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most important animal pathogens in swine industry worldwide. In this study, we isolated the large-plaque forming variant virus designated PL97-1/LP1 from the parental strain PL97-1, the first Korean strain of PRRSV, isolated from the serum of an infected pig in 1997. We found that the 15411-nucleotide genome of PL97-1/LP1 consisted of a 189-nucleotide 5' untranslated region (UTR), a 15071-nucleotide protein-coding region, and a 151-nucleotide 3'UTR, followed by a poly (A) tail of about 50~60 nucleotides in size. The 5'-end of PL97-1/LP1 began with ATGACGTAT. Comparison of the PL97-1/LP1 genome with the 11 fully sequenced PRRSV genomes currently available revealed sequence similarity from 99.6~99.7% (the North American VR-2332 and two VR-2332-derived vaccine strains MLV RespPRRS/Repro and RespPRRS MLV) to 62.0% (the Dutch Lelystad strain). Phylogenetc analysis revealed that PL97-1/LP1 is most closely related to the North American genotype VR-2332, two VR-2332-derived vaccine strains, and Chinese BJ-4. It is distantly related to the European genotype Lelystad. The entire nucleotide sequence of PL97-1/LP1 was identical to that of the parental virus PL97-1 except for three silent nucleotide substitutions, one in ORF1a (U4230C), one in ORF1b (C10977U), and one in ORF5 (U13976A). This nucleotide sequence has been submitted to the GenBank database under the accession number AY612613.