To determine whether there was a correlation between the luminescence detected by the camera and the amount of virus genomes in the tissues, rZHDNSs-hRLuc-infected Ifnar1 2/2 living mice were subjected to imaging. Next, the animals were euthanized and the organs harvested and imaged. Total RNAs were extracted from the organs and RVFV RNA copy numbers were measured by quantitative real time RT-PCR. We observed a highly significant correlation between the luminescence emitted by the pancreas in living mice and RVFV RNA copy number ( Figure 4A ). Similarly, luminescence intensity significantly correlated with the RVFV RNA copy number in the harvested pancreas, spleen and liver ( Figure 4B-D) .