Figure 1

In situ detection of Epstein–Barr virus (EBV) in breast carcinomas. In situ hybridisation with ³⁵S-labelled RNA probes shows (a) an absence of expression of the EBV-encoded RNAs (EBERs) in a breast carcinoma (note an isolated EBER-positive lymphocyte in the tumour stroma; black grains, arrow), while (b) tumour cells of a nasopharyngeal carcinoma show a strong nuclear labelling indicating EBER expression (black grains). Immunohistochemistry reveals (c) an absence of detectable expression of the EBV-encoded nuclear antigen1 (EBNA1) in a breast carcinoma and (d) the expression of EBNA1 in most nasopharyngeal carcinoma cells (red nuclear staining). Using DNA in situ hybridisation with ³⁵S-labelled probes, (e) an absence of EBV from breast carcinoma cells is demonstrated while (f) EBV DNA is detected in tumour cells of an undifferentiated nasopharyngeal carcinoma (black grains).