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. 2022 Sep 23;13:977796. doi: 10.3389/fmicb.2022.977796

FIGURE 4.

FIGURE 4

Heterologous vaccine immunogenicity—the humoral immune response. Immunoglobulin A of (A) bronchoalveolar lavage (BAL), (B) nasal swabs, and (C) serum IgG levels were evaluated at 0 and 14 days post challenge (dpc) via a PRRSV X3 ELISA. The IgA and IgG ELISA S/P ratios were compared within their challenge groups—MOCK (gray), 1-4-4 (NADC30, dark blue), NC174 (red), VR2332 (green), and 1-4-2 (NADC20, light blue). The black bars represent the median values; in addition, individual data points are shown for MOCK vaccinated animals (open diamonds) and MLV vaccinated animals (filled squares). Data were statistically analyzed using a 2-way ANOVA with time and vaccination as the two parameters and Tukey’s multiple comparison test. ****p < 0.0001, ***p < 0.001, **p < 0.01, *p < 0.05. (D) Neutralizing antibody (NA) titers determined via FFN test against the respective challenge strain at 0 and 14 dpc. Since no animals showed FFN titers at 0 dpc, only the 14 dpc data are shown. Titers ≥ 1:4 were considered positive. The titer for each individual PRRSV-challenged pig is shown. Positive NA titers are highlighted in blue (NADC30), red (NC174, not detected), green (VR2332), and light blue (NADC20).