Figure 1.

Baseline immune parameters associated with West Nile virus (WNV) peripheral restriction. F1 crosses of Collaborative Cross strains were grouped into peripheral restriction (PR) and neuroinvasion, no disease (NND) categories as defined in “Results” and Table 1. Age-matched male mice were euthanized, and spleens were harvested and prepared for flow cytometry staining to determine the frequency of regulatory T cells (Tregs) expressing CTLA-4 or CD44 (A), the frequency of CD3⁺ T cells that are CD8⁺ T cells or CD4⁺ T cells (B), and the frequency of CD8⁺ and CD4⁺ T cells that express CD44 (C). Statistical significance was determined by the unpaired t test. *P ≤ .05, **P ≤ .01, ***P ≤ .001, and ****P ≤ .0001.