Acyclovir treatment inhibits mCMV replication and rescues the mCMV-induced abnormal phenotype. β-gal (mCMV) staining is seen throughout E15 + 6 SMGs infected with 50,000 PFU mCMV (A) but is absent from SMGs cultured with mCMV + acyclovir (CMV + Acy) (B). C-F. Histological analysis of control (C), acyclovir-treated (Acy) (D), mCMV-infected (E), and mCMV-infected explants treated with acyclovir (CMV + Acy) (F) SMGs. The epithelial (e) and mesenchymal (m) cellular morphology in CMV + Acy glands (F) is similar to that seen in control (C) and acyclovir-treated (D) SMGs. Note that acyclovir treatment of mCMV-infected SMGs (F) maintained the fibroblastic appearance of the mesenchyme (m); typically, mCMV-infected glands (E) exhibit clusters of large, basophilic abnormal cells (arrows) in the periphery. Bar: A, B: 50 μm; C-F: 20 μm.