Fig. 2

Neurotropic virus infections induce axonal degeneration in mouse cortical neurons. (A) Representative immunofluorescence staining images of viral proteins (green), and neurofilament medium chain (Nf-M) (red) in cerebral cortex tissue sections of mice at 5 days post JEV or HSV-1 infection, and 8 days after RABV infection. (B) Quantification of neurofilament immunostaining intensity in the axonal fluorescence images shown in A, indicated by Nf-M antibody. IntDen: Integrated Density. (C) Representative immunohistochemistry staining of beta III tubulin in brain tissue Sect. 5 days post JEV or HSV-1 infection, and 8 days post RABV infection. (D) Degree of axonal degeneration after neurotropic virus infections, quantified as a degeneration index (DI), where a DI of 0.35 or above represents degenerated axons, indicated by a horizontal dotted line. (E) Immunoblot analysis of Nf-M and SARM1 levels in mouse cerebral cortex after JEV, HSV-1, or RABV infection at indicated time points. GAPDH is used as an internal control. (F) Mice were infected by neurotropic viruses JEV, HSV-1 or RABV at the indicated time points, and neurofilament light chain (Nf-L) levels were measured in plasma. All three neurotropic viruses induced increases in plasma Nf-L in a time-dependent manner. Data correspond to means from replicate experiments, and error bars indicate mean ± SEM of data from 6 mice in each group. Student’s t test, ns, P > 0.05; ***P < 0.001