Fig. 3: mRNA-NP vaccination mitigates liver and spleen pathology in Ifnar1^−/− mice following CCHFV infection.

A Hematoxylin and eosin (HE) staining of the liver. Severe liver pathology was observed in LNP control and mRNA-GPC groups, while the mRNA-NP and mRNA-NP + mRNA-GPC groups exhibited mild inflammatory infiltration. Red arrows indicate inflammatory cell infiltration, black arrows indicate hepatocellular necrosis, blue arrows indicate steatosis, and yellow arrows indicate edema. B Immunohistochemistry (IHC) analysis of the liver. High levels of CCHFV antigen were detected in non-immunized control and mRNA-GPC group, whereas little or no antigen was detected in the livers from mRNA-NP or mRNA-NP + mRNA-GPC. C HE staining of spleen. Severe pathological damage was observed in LNP control and mRNA-GPC groups, whereas the mRNA-NP and mRNA-NP + mRNA-GPC groups exhibited minimal histopathological abnormalities. Orange arrows indicate neutrophil infiltration, green arrows indicate hemosiderin deposition, and white arrows indicate reduced small lymphocytes in the white pulp. D IHC analysis of the spleen. High levels of CCHFV antigen were detected in control mice, with moderate levels in the mRNA-GPC group. In contrast, little or no antigen was detected in the spleens from mRNA-NP or mRNA-NP + mRNA-GPC. Scale bars are shown at 100 μm for large lower images, and 20 μm scale bars (inset) for magnified rectangle higher power images.