(a) Analysis of tongue by H&E ( × 20), (b) ISH ( × 20), (c) IHC ( × 40) with an in house monoclonal antibody MPV.B9 at week 14 after infection and (d) TEM at week 30, respectively, after viral infection. (a) Koilocytes can be seen in the infected tongue tissue ( × 20, black arrows); (b) some of these infected cells showed strong viral DNA positivity ( × 20, white arrows); (c) viral capsid positive cells are shown with an in-house monoclonal antibody (MPV.B9) targeting denatured viral capsid protein ( × 40, black arrows) and (d) viral particles are seen in infected cells (white arrows).