CD4 and infection: The course of total cytotoxic T lymphocytes (CD4–CD8α+high cells: 2.5 × 103 cells/μL) as well as of total and activated NK cells (CD3–CD8α+ cells: 1.4 × 103 cells/μL; CD3–CD16+ cells: 1.2 × 103 cells/μL) were not influenced by PCV2 natural infection in vaccinated and unvaccinated animals.