[1] NETHERLANDS RED CROSS, BLOOD TRANSFUS SERV, CENT LAB, DEPT CLIN VIROIMMUNOL, NL-1066 CX AMSTERDAM, NETHERLANDS
[2] UNIV AMSTERDAM, EXPT & CLIN IMMUNOL LAB, AMSTERDAM, NETHERLANDS
[3] UNIV GRONINGEN, ACAD HOSP GRONINGEN, DEPT OBSTET & GYNAECOL, GRONINGEN, NETHERLANDS
[4] UNIV AMSTERDAM, ACAD MED CTR, DEPT HUMAN RETROVIROL, NL-1105 AZ AMSTERDAM, NETHERLANDS
[5] MUNICIPAL HLTH SERV, DEPT PUBL HLTH, AMSTERDAM, NETHERLANDS