Fig. 6

H&E staining and immunohistochemical staining (IHC) of organs from RDPV-inoculated raccoon dogs at 11 days. Non and Imm represent the non-immunized and immunized raccoon dog groups. a Heart. b Liver. c Spleen. d Lung. e Kidney. f Intestinal tract. g H&E staining of immunized raccoon dog heart. h H&E staining of non-immunized raccoon dog heart. A small amount of myocardial fibers can be seen in the visual field to dissolve, replaced by hyperplastic connective tissue (black arrow), accompanied by lymphocyte punctate infiltration (yellow arrow). i H&E staining of immunized raccoon dog liver. In the visual field, there is more congestion and dilation of liver sinusoids (black arrow), accompanied by a small amount of hemosiderin exudation (yellow arrow), local necrosis of hepatocytes and nuclear fragmentation (red arrow). j H&E staining of non-immunized raccoon dog liver. More hemosiderin can be seen in the visual field (black arrow), and a small amount of hepatocyte chromatin margins can be seen locally (yellow arrow). k H&E staining of immunized raccoon dog spleen. l H&E staining of non-immunized raccoon dog spleen. The number of lymphocytes in the spleen nodules is reduced, and the arrangement is loose (black arrow). A small number of macrophages are visible, and brown particles are visible in the cytoplasm of macrophages (yellow arrows). m, H&E staining of immunized raccoon dog lung. There is a small amount of lymphocyte infiltration in the lung (yellow arrows). n H&E staining of non-immunized raccoon dog lung. The lungs are accompanied by a small amount of lymphocytes and macrophages infiltration (red arrow). Venous congestion and expansion can be seen (yellow arrow). o H&E staining of immunized raccoon dog kidney. p H&E staining of non-immunized raccoon dog kidney. q H&E staining of immunized raccoon dog intestinal tract. r H&E staining of non-immunized raccoon dog intestinal tract. A large area of necrosis and lysis can be seen in the mucosal layer (black arrow), which is replaced by hyperplastic connective tissue (yellow arrow), accompanied by diffuse lymphocyte and macrophage infiltration (red arrow). s Analysis of positive areal density after immunohistochemical staining of organs in group VLPs and group PBS infected with RDPV RPSN. (rabbit anti-RPSN pAb, × 200, data are shown as mean ± SEM. The one-way ANOVA showed a statistically significant difference between group VLPs and group PBS. Single asterisk indicates statistical significance at p < 0.05, and double asterisk indicates p < 0.01