On day 5 after infection, the day with the largest CD4+/CD8+ ratio (4.0, see above) as well as the nadir of the lymphocyte count in non-vaccinated animals (Fig. 3c), the absolute CD8+ cell count in non-vaccinated animals was reduced by approximately 20 % compared to day 0 (166 ± 34 vs. 202 ± 30 per μL of blood; means and CI95, p = 0.03), while the absolute CD4+ count was similar to the initial level (624 ± 85 vs. 619 ± 66, p = 0.91). Here, CD4 is linked to infection.