| PRRSV belongs to the family Arteriviridae in the genus Arterivirus, order Nidovirales. This group also includes lactate dehydrogenase-elevating virus (LDV) of mice, equine arteritis virus (EAV) and simian hemorrhagic fever virus (SHFV). PRRSV is a small, enveloped virus of 45-70 nm in diameter. Its genome consists of a polyadenylated, single-stranded, non-segmented, positivesense RNA polycystronic molecule of 15.1-15.5 kb. It contains, in the 5 to 3 direction, a 5 leader sequence, at least 10 open reading frames (ORF1a, ORF1b and ORFs 2a, 2b, 3, 4, 5, 5a, 6 and 7) and a 3 non-translated region. ORF1a and ORF1b are located directly downstream of the 5 leader and encode a large replicase polyprotein, which is thought to be autoproteolytically cleaved into at least 13 smaller non-structural proteins including a viral RNA-dependent RNA polymerase. |
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