Viral clone plaque phenotype assays. BSC40 cells were cultured in a 6-well dish and then infected with VACV clones. Infection was carried out in the presence of 0.5% agarose for 48 h, followed by fixation and staining. All clones of the VACV-BAB2V, VACV-BAHV and VACV-GOB2V presented only small plaques, while VACV-BABV and VACV-GOBV strains presented small plaque clones as well as large plaque clones. VACV-BABV presented two small plaque clones (Clone 1 and 5) and three large plaque clones (Clone 2, 3 and 4). VACV-GOBV presented four small plaque clones (Clone 1, 3, 4 and 5) and one large plaque clone (Clone 2).