Porcine Reproductive and Respiratory Syndrome Virus: Origin Hypothesis
Figure 2. Phylogenetic tree of 432 nucleotide-long open reading frame (ORF) 5 segments of European and North American porcine reproductive and respiratory syndrome viruses and lactate dehydrogenase-elevating virus–P. The sequences correspond to nucleotide 97-526 of ORF5 of the European porcine reproductive and respiratory syndrome virus isolates (provided by T. Stadejek). LDV, lactate dehydrogenase-elevating virus.