Table 3.

Pairwise comparisons of the nucleotide sequences of the S2 subunit of the spike genes between the 4/91 vaccine strain, I1101/16 isolate, and pathogenic 4/91 strain^a.

^aNucleotides shared between the I1101/16 isolate and 4/91 vaccine strain are shown in gray.

^bNucleotide positions corresponding to those in the spike gene in the 4/91 vaccine strain. The GenBank accession number of the pathogenic 4/91 strain is JN192154. The GenBank accession numbers of the other viruses are the same as those shown in Fig. 1.