Detection of MERS-CoV pseudovirus infectivity. Cell tropism of MERS-CoV pseudovirus in a variety of target cells from human and non-human hosts. VSV-G and Env- pseudoviruses were used as positive and negative controls, respectively. The data are expressed as mean relative luciferase units (RLU) ± standard deviation (SD) of 4 parallel wells in 96-well culture plates. The experiment was repeated three times, and similar results were obtained.