Fig 5. Histopathologic lesions in the inguinal lymph nodes of the flagellin-Cap fusion protein-vaccinated mice after PCV2 challenge.

(A) Mice were challenged with PCV2 strain BJW at 2 weeks after booster and the presence of lymph node lesions was examined at 3 weeks after challenge. (a) Normal morphology of inguinal lymph node section from an unvaccinated unchallenged mouse shows no noticeable germinal centers. (b) Infiltration of histiocytes, depletion of lymphocytes, and apoptotic cells were seen in the prominent germinal centers of inguinal lymph node of an unvaccinated PCV2-challenged mouse. (c) Partial enlargement of panel b, showing large numbers of apoptotic cells (arrows) in germinal centers. (d) No obvious lesions were seen in the inguinal lymph node of a recombinant flagellin-Cap fusion protein-vaccinated PCV2-challenged mouse (10 μg dose). Bars, 80 μm. (B) Histopatholoical lesions were evaluated as a score of 0 to 3 in the inguinal lymph nodes of all the mice after PCV2 challenge. The data show the mean scores of six mice in each group from one of two independently repetitive experiments. Significant difference is expressed as p<0.05 (*) for a comparison of the flagellin-Cap fusion and Cap protein-vaccinated mice, or of the recombinant protein-vaccinated and non-vaccinated mice after PCV2 challenge.