HCMV persistence in the progeny derived from infected CD34⁺ cells. (A) X-gal staining of the colonies derived from CD34⁺ cells infected with Towne/lox2 in methylcellulose cultures 14 days postinfection. Original magnification × 320. (B) X-gal staining of the progeny derived from CD34⁺ cells infected with Towne/lox2 in suspension cultures 28 days postinfection. Original magnification × 200. (C) Progeny derived from mock-infected CD34⁺ cells stained as in (A) and (B). Original magnification × 200. Cells from the colonies and suspension cultures were stained with X-gal (150 μg/mL) for 6 hours. (D) PCR detection of β-gal DNA in the progeny derived from CD34⁺ cells infected with Towne/lox². PCR products were electrophoretically separated in 1% agarose gels stained with ethidium bromide. The arrow indicates a β-gal DNA PCR product of 900 bp. Lanes 1 through 3, DNA from colonies derived from infected and mock-infected CD34⁺ cells; lanes 4 through 6, DNA from suspension cultures derived from infected and mock-infected CD34⁺ cells. Lanes 1 and 4, DNA from the cultures infected with 95(2); lanes 2 and 5, DNA from the cultures infected with Towne/lox²; lanes 3 and 6, DNA from the cultures derived from mock-infected CD34⁺ progenitors; lane 7, PCR H₂O control; lane m, 100-bp ladder (GIBCO/BRL). Primers used and predicted PCR products are listed in Table 1.