FIG. 3.

Differentiation of keratinocytes containing wild-type HPV 31 or E4M9 mutant genomes in organotypic rafts. Raft cultures were grown for 13 days, harvested, and fixed in paraformaldehyde. Tissue cross sections were stained with hematoxylin and eosin (A, B, and C) or examined by immunohistochemistry using a polyclonal antibody to HPV31 E1^∧E4 (green staining; D, E, and F). The blue staining in panels D, E, and F corresponds to nuclear staining with DAPI. The closed arrows represent the basal layer.