Figure 2. Phylogenetic tree based on the spike gene (S) sequence of 112 North American porcine epidemic diarrhea virus strains. Blue represents US non–S INDEL strains; red represents US S INDEL strains; brown represents Mexican strains; purple represents worldwide non–S INDEL strains; and pink represents global S INDEL strains. Bootstrap values are represented at key nodes. Scale bar indicates nucleotide substitutions per site. CH, China; IA, Iowa; S INDEL, insertions and deletions in the spike gene; IN, Indiana; ISU, Iowa State University; MEX, Mexico; MN, Minnesota; USA, United States of America.