The ability of h-coelenterazine to cross the blood-brain barrier is unknown. To determine whether rZHDNSs-hRLuc can infect the brain, we dissected and soaked the brain in an hcoelenterazine solution and imaged ( Figure 2D ). At 8 h postinfection, the luminescence intensity was ten-fold higher in the brain from infected mice compared to control (10 4 photons/ second/cm 2 /steradian [p/sec/cm 2 /sr] vs. 10 3 p/sec/cm 2 /sr), showing that the RVFV replicated in the brain at an early stage. Light emission increased through 16 h and 34 h post-infection to reach 7610 5 and 7610 6 p/sec/cm 2 /sr, respectively. Importantly, the intensity of luminescence in the brain was ten-to hundred-fold lower compared to the intensities in the thymus, pancreas, spleen, liver, and intestine mesentery, suggesting that the viral load was lower in the brain than in the thoracic and abdominal organs.