[1] Katholieke Univ Leuven, Rega Inst Med Res, Virol Lab, B-3000 Louvain, Belgium
[2] Katholieke Univ Leuven, Rega Inst Med Res, Immunol Lab, B-3000 Louvain, Belgium
[3] Catholic Univ Louvain, Hop Univ St Luc, B-1200 Brussels, Belgium
[4] Akad Ziekenhuis St Jan, Brugge, Belgium