FIG 3.

Antigenic distance of reference swine N2 to contemporary swine N2. (A) Antigenic map of N2 antigens shows a large antigenic distance exists between N2-98 and N2-02 lineages. The NAI of swine N2 antisera against homologous, reference, and contemporary antigens was determined using the ELLA. Antigenic cartography was used to chart the NAI data in three dimensions and calculate antigenic distances between antigens. (B) Graphical representation of antigenic distances between reference and contemporary antigens. Contemporary antigens are listed on the x axis, and the distances to reference antigens of the N2-98 lineage (bottom) and N2-02 lineage (top) are represented by colored dots. Bold line indicates an antigenic distance of 3 AU.