FIG. 6.

The growth defect of UL21a deletion virus is due to the loss of the protein product pUL21a. (A) Diagram of the UL21a locus in UL21a deletion virus (ADsubUL21a), a point mutant virus in which two stop codon mutations were introduced into the UL21a ORF (ADpmpUL21a), and its marker-rescued virus (ADrevpUL21a). (B) Growth kinetic analysis of recombinant HCMV viruses. MRC-5 cells were infected with the indicated viruses at an MOI of 0.01, cell-free viruses were collected at different days postinfection, and their yields were determined by TCID₅₀ assay. Error bars indicate standard deviations. (C) Analysis of viral protein accumulation. MRC-5 cells were infected with ADpmpUL21a or ADrevpUL21a at an input genome number equivalent to 0.25 TCID₅₀ unit of wild-type virus/cell, cells were collected at the indicated times, and total lysate was analyzed by immunoblotting. Shown are representative results from at least two independent experiments.