GENETIC-VARIATION AND PHYLOGENETIC-RELATIONSHIPS OF 22 PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME VIRUS (PRRSV) FIELD STRAINS BASED ON SEQUENCE-ANALYSIS OF OPEN READING FRAME-5

Porcine reproductive and respiratory syndrome virus (PRRSV) strains fr om 13 states in the United States, Guatemala and Canada were used to c ompare the envelope glycoprotein gene (ORF 5) nucleotide and deduced a mino acid sequences. The gene was the same size, 603 nt, for all the 2 2 field strains. These strains had 89-94% amino acid identity compared to reference strain VR 2332. A putative signal sequence and cleavage site between residues 31 and 32 was identified and three potential gly cosylation sites were present on all but two strains. Hydrophobicity/h ydrophilicity and surface probability analyses reveal a primary struct ure for the envelope glycoprotein (E protein) with six potential surfa ce regions that could be antigenic sites. Similar E protein structural features are conserved for the prototype European PRRSV - Lelystad vi rus.