A decreased neurovirulence is observed for rOC/S_G758R variant in 21 day-old BALB/c female mice infected by the intracerebral route.

<p>21 day-old BALB/c mice received 10^2.5 TCID₅₀/10μL of rOC/ATCC or rOC/S_G758R or PBS by the IC route. (A) Survival curves of mice in % during 21 day post-infection. Difference between the two virus variants was significant (* P≤0.05). (B) BALB/c mice were weighed every 2 days during 21 dpi to estimate weight variations, which were expressed in %, compared to day 0 (100%). Differences were significant (*** P≤0.001) when the three conditions (rOC/ATCC, rOC/S_G758R or PBS) were compared between 9 and 11 dpi. Evaluation of the clinical scores (percentage of mice at each level of the scale) of mice infected by rOC/ATCC (C) or rOC/S_G758R (D) based on neurological symptoms described in clinical score scale between level 0 and 3 (see <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1005261#sec011" target="_blank">Materials and Methods</a> section). Production of infectious viral particles was measured in brains (E) and spinal cords (F) every 2 days for 21 dpi. LOD represents the Limit of Detection of infectious viral particles. Results shown are the mean values (with standard deviations) of three independent experiments.