[1] Netherlands Red Cross, Blood Transfus Serv, Cent Lab, Dept Clin Viroimmunol, NL-1066 CX Amsterdam, Netherlands
[2] Univ Amsterdam, Acad Med Ctr, Dept Human Retrovirol, NL-1105 AZ Amsterdam, Netherlands
[3] Univ Amsterdam, Expt & Clin Immunol Lab, Amsterdam, Netherlands