Fig. 2.

Dissemination of poliovirus to the CNS is limited by inefficient retrograde axonal transport, type I IFN responses, and older age. IFNAR+/+ and IFNAR−/− mice were inoculated intramuscularly with 10⁷ PFU total of 10 genetically marked polioviruses, with or without additional muscle damage. Tissues were collected, viral titers were determined by plaque assay, and viral population diversity was determined using a hybridization-based assay (Kuss et al., 2008). Poliovirus titer (A) and viral population diversity (B) in tissues harvested from adult IFNAR+/+ or IFNAR−/− mice with or without muscle damage. Tissues were collected at 72 hpi, prior to disease onset. Poliovirus titer (C) and viral population diversity (D) in tissues harvested from 3-day-old IFNAR+/+ or IFNAR−/− mice. Tissues were collected at 48 hpi in C and D due to the onset of disease. Results are presented as mean +/− standard error of the mean from 4-8 mice per condition. Values that are significantly different, as determined by the Mann-Whitney test, are indicated by asterisks as follows: *, P < 0.05, **, P < 0.005, ***, P < 0.0005. Mus., muscle; ND, none detected.