[1] Univ Utrecht, Dept Farm Anim Hlth, Fac Vet Med, NL-3582 CL Utrecht, Netherlands
[2] Univ Utrecht, Dept Infect Dis & Immunol, Fac Vet Med, Div Immunol, NL-3582 CL Utrecht, Netherlands
[3] Univ Utrecht, Inst Risk Assessment Sci, NL-3582 CL Utrecht, Netherlands