M45-specific CD8+ T-cells showed similar responses in both CD73−/− and C57BL/6, peaking at 7 days post infection with a frequency of 10–15% of CD8+ T-cells; this was followed by a rapid decline to a stable level of 0.6–2% of CD8+ T-cells that was maintained over time. The gene discussed is CD8A; the disease is infection.