Castration restores virus-specific responses and improves viral clearance.

<p>(<b>A</b>) Proportion (left) and number (right) of influenza A viral peptide-specific IFN-γ-expressing CD8⁺ cells in the spleen 10 days after infection. (<b>B</b>) Cytotoxic activity (left) correlated with number of NP₃₆₆-specific CTLs (right) of 2-mth (Young) and 9-mth (Aged) mice. (<b>C</b>) Viral titres 7 days after primary intranasal infection with A/HKx31. Results are expressed as mean±SD of 5–6 mice per group from 2–3 experiments; *p≤0.05 compared to Young; #p≤0.05 compared to ShCx (unpaired two-tailed Student's t test).