[1] Univ Valladolid, Lab Inmunol Mucosas, Valladolid, Spain
[2] HCU Pediat, Valladolid, Spain
[3] HCU Virol, Valladolid, Spain
[4] HGU Gregorio Maranon, Madrid, Spain
[5] UHN, Div Expt Therapeut, Toronto, ON, Canada
[6] HCU Unidad Invest, Valladolid, Spain