FIG.6.

Cell tropism of HCMV strains. (A) Diagram of the UL131-UL128 locus in the Towne, Toledo, FIX, and TR strains of HCMV. The positions of transcriptional start sites and poly(A) cleavage sitesare indicated. Solid boxes represent wild-type ORFs. The point mutation in the Towne UL130 gene and the deletion in the Toledo UL128 gene are shown, and the positions of open reading frames whose expression is disrupted are represented by open boxes. (B) Entry of HCMV strains into MRC-5, HUVEC, HeLa, and ARPE-19 cells. Cells were infected at a multiplicity of 1 PFU/cell, and 48 h later, the cultures were fixed with 2% paraformaldehyde, and infected cells were identified by IE1 expression. (C) Production of infectious progeny by HCMV strains in ARPE-19 cells. Cells were infected at a multiplicity of 1 PFU/cell. Six days (BADrUL131-Y4) or 12 days (all other viruses) later, the cells and media were collected together, samples were frozen and thawed three times, and virus titers were determined by TCID₅₀ assay on MRC-5 cells.