(A–C) SV40 T-ag expression in an SV40 DNA-positive tonsil from a 14-year-old male. (A) No staining with negative mouse antibody control. (B,C) SV40 T-ag-positive staining with antibody PAb101. (D–F) Negative T-ag staining with antibody PAb101 on other tonsils (D and E are the same specimen). Arrows point to representative T-ag-positive cells in panels B and C. Original magnification for panels A, B and D, 40×; panels C, E and F, 100×.