Fig 2: Evaluation of infiltrating macrophages within the area of the rostral reticulospinal tract revealed a significant increase in Mac3+ cells within the cervical segment at 42 dpi, within the cervical and thoracic segment at 98 and 147 dpi as well as within all investigated segments at 196 dpi (A). Assessment of myelin basic protein (MBP) stained slices revealed a significantly reduced MBP positive white matter (WM) area in the thoracic segment at 42 dpi and in all investigated segments at 98, 147, and 196 dpi (B). Moreover, the thoracic segment showed a significant reduction of MBP positive area in the gray matter (GM) at 98 dpi (C). No significant differences between TMEV-infected groups comparing 147 and 196 dpi were detected. Graphs display box and whisker plots. Significant differences between groups detected by Mann–Whitney U-test were indicated by asterisks (* p = 0.05).

Fig 3: Immunophenotyping of inflammatory cells and quantification of TMEV positive cells within the SC following i.s. mock-injection (at 14 dpi; A,D,G,J) and TMEV infection (at 14 dpi; B,E,H,K). Statistical analysis revealed significantly increased numbers of CD3+ (T lymphocytes), CD45R+ (B lymphocytes) and CD107b+ (microglia/macrophages) cells (C,F,I), as well as a spread of virus protein (L) following i.s. TMEV infection. Box-and-whisker plots show median and quartiles. Significant differences between the groups as detected by a Mann–Whitney U-test are indicated by asterisks (* p < 0.05). Bars represent 100 µm in the overviews and 20 µm in the inserts.

Fig 4: Detection and quantification of the SC lesion following i.c. TMEV infection/mock-injection. Immunophenotyping of inflammatory cells as well as detection of virus protein, demyelination and axonal damage at 56 dpi within the thoracic SC following i.c. mock-injection (A,D,G,J,M) and TMEV infection (B,E,H,K,N). Statistical analysis revealed a significantly increasing number of CD3+ T lymphocytes followed by an increased number of CD107b+ microglia/macrophages (C,F). The presence of virus protein (I), as well as progressive demyelination (L) and axonal damage (O) starting at 56 dpi were detected following i.c. TMEV infection. Box-and-whisker plots show median and quartiles. Significant differences between the groups as detected by a Mann–Whitney U-test are indicated by asterisks (* p < 0.05). Bars represent 100 µm in the overviews and 20 µm in the inserts.

Fig 5: Detection of macrophages and myelinophages, TMEV, axonal damage and demyelination at 28 dpi in PN following i.s. mock-injection (A,D,G,J) and TMEV infection (B,E,H,K). Statistical analysis revealed a significant increase in the number of CD107b+ macrophages (C) at all investigated time points. Virus protein was firstly detected at 7 dpi, while significant differences started at 14 dpi (F). Significant axonal damage (I), as well as demyelination (L) following i.s. TMEV infection were initially seen at 28 dpi. Graphs show the average of left and right brachial plexus or sciatic nerves, respectively. Box-and-whisker plots show median and quartiles. Significant differences between the groups as detected by a Mann–Whitney U-test are indicated by asterisks (* p < 0.05). Bars represent 20 µm.