Discovery of 3 ({5 Chloro-1 [3 (methylsulfonyl)propyl]-1H indol-2 yl}methyl)-1 (2,2,2 trifluoroethyl)-1,3 dihydro-2H imidazo[4,5-c]pyridin-2 one (JNJ-53718678), a potent and orally bioavailable fusion inhibitor of respiratory syncytial virus.