To further characterize the LACV infection in weanling mice, an additional group was inoculated intraperitoneally with 100 LD 50 of LACV/human/1960 and selected tissues (serum, muscle, nasal turbinate, brain, and spinal cord) were collected for virus quantitation (n = 5, daily for six days) to confirm titers found in Figure 2 and for histopathological and immunohistochemical (IHC) examination (n = 3, daily for six days), and the data is summarized in Table 1 and Figures 4 and 5. Virus titers for nasal turbinates, brain, spinal cord, muscle, and serum were in agreement with findings in Figure 2 (data not shown). Histopathologic lesions in the brain (including areas of the olfactory bulb, cerebral cortex, thalamus, hippocampus, and medulla oblongata) and spinal cord included perivascular cuffing ( Figure 4A ), neuronal degeneration ( Figure 4B -C), necrosis (either single cell or small foci), and apoptosis (4F). There was an infiltration of CD3+ lymphocytes and macrophages ( Figure 4D -E).