Figure 2
Plaques can be resolved on sub-confluent monolayers of M2-10B4 cells with reduced viscosity CMC. A) 1.25 × 105 M2-10B4 cells were plated in 6 well plates and stained with crystal violet one day later. The representative image covers 1 mm2. B) 1.25 × 105 M2-10B4s were plated in 6-well plates. One day later, cultures were infected with BAC-derived MCMV and overlaid with a high viscosity CMC as in Figure 1. Representative images show plaques 6 days after infection. Sizing bars = 1 mm. C) Either 1.25 × 105 or 6.25 × 105 M2-10B4s were plated and infected with MCMV as above except that cultures were overlaid with an intermediate viscosity CMC. Plaques were resolved 6 days later. Sizing bars = 1 mm. D) 3 x 105 MEFs, generated as described [1], were plated, infected and overlaid as in “C”. Images show plaques 5 days later. Sizing bars = 1 mm. E) Plaque width was measured digitally, with a line drawn across plaque images that was converted to millimeters using the sizing bar. Each point represents a single plaque. (***p < 0.0001, as assessed by a student’s t-test). F) Cultures of M2-10B4s were infected with separate aliquots of a single viral preparation (left three columns, n = 2 to 5 assays per column) or a second viral preparation (right two columns, n = 2 assays per column). (*p = 0.015, **p = 0.005 as assessed by a student’s t-test). G) A single preparation of MCMV V70 [20, 21] (kindly provided by Dr. Ed Mocarski) was assessed by infection of sub-confluent M2-10B4s (1.25 × 105 cells plated, n = 3) or confluent MEFs (3 × 105 cells plated, n = 3). Cultures were overlaid with intermediate viscosity CMC for comparison. Significance was determined by a student's t-test.