Seven new ovine progressive pneumonia virus (OPPV) field isolates from Dubois Idaho sheep comprise part of OPPV clade II based on surface envelope glycoprotein (SU) sequences

Seven new ovine progressive pneumonia virus (OPPV) field isolates were derived from colostrum and milk of 10 naturally OPPV-infected sheep from the US Sheep Experiment Station in Dubois, Idaho, USA. Sixteen sequences of the surface envelope glycoprotein (SU) from these seven Dubois OPPV field isolates and SU sequence from OPPV WLC1 were obtained, aligned with published SRLV SU sequences, and analyzed using phylogenetic analysis using parsimony (PAUP). Percent nucleotide identity in SU was greater than 95.8% among clones from individual Dubois OPPVs and ranged from 85.5 to 93.8% between different Dubois OPPV clones. SU sequences from Dubois OPPVs and WLC1 OPPV had significantly higher percent nucleotide identity to SU sequences from the North American OPPVs (85/34 and S93) than caprine-arthritis encephalitis virus (CAEVs) or MVVs. PAUP analysis also showed that SU sequences from the Dubois OPPVs and OPPV WLC1 grouped with other North American OPPVs (85/34 and S93) with a bootstrap value of 100 and formed one OPPV clade II group. In addition, Dubois and WLC1 SU amino acid sequences had significantly higher identity to SU sequences from North American OPPVs than CAEV or MVV. These data indicate that the seven new Dubois OPPV field isolates along with WLC1 OPPV are part of the OPPV clade II and are distinct from CAEVs and MVVs.