FIG. 7.

Immunohistological analysis of virus-lymphoma interrelation in the liver. All IHC stainings were made on liver tissue sections derived on day 21 from infected and lymphoma-bearing mouse 35 of the experiment shown in Fig. 5 and 6. (A [overview] and A* [detail of A]) Two-color IHC staining of intranuclear IE1 protein in infected hepatocytes (red) and membrane CD45R/B220 expressed by the E12E lymphoma cells (black). Arrow, dividing tumor cell in the stage of cytokinesis. (B1 to B3 and B3* [detail of B3]) Serial sections (in 2-μm distances) stained red and black for IE1 and CD45R/B220, respectively (B1), brown for PCNA (B2), and again brown for apoptosis marker active caspase 3 (B3 and B3*). Arrow, group of apoptotic cells within the focus of infection. Note the typical clustering of chromatin in the nuclei. ∗ (B3*), infected but caspase 3-negative hepatocyte bearing the characteristic intranuclear inclusion body. (C1 to C3) Serial sections shown at high magnification after staining for IE1 and CD45R/B220 (C1), PCNA (C2), and active caspase 3 (C3). Twin arrows, infected hepatocyte containing two nuclei with both carrying an intranuclear inclusion body containing viral DNA (visible by in situ hybridization; not shown here [see reference 47]), IE1 protein, and PCNA. Note that this infected hepatocyte did not express cytoplasmic caspase 3. Throughout, sections were counterstained with hematoxylin. Bars, 50 μm.