A BRBV stock was diluted from 10 −4 to 10−9 in Dulbecco’s Modified Eagle’s medium (DMEM) media. 1 ml of each diluted virus were added in one well of a 6-well plate of Vero cells. After incubation of 1 hour at 37°C, diluted virus-containing media were removed from each well. 2 ml of DMEM with 10% fetal calf serum and 1% methylcellulose overlay were added to each well. After 3 days post-infection, the media was aspirated from each well, and the cells were stained with crystal violet [30]. Plaques, foci of infected cells, are shown as white dots in the stained cell sheet (blue background).