[1] INST PASTEUR,BIOL RETROVIRUS LAB,PARIS,FRANCE
[2] SWISS RED CROSS,BLOOD TRANSFUS SERV,DEPT RES,CENT LAB,CH-3000 BERN 22,SWITZERLAND
[3] UNIV BERN,INST MED MICROBIOL,CH-3012 BERN,SWITZERLAND
[4] SWISS RED CROSS,BLOOD TRANSFUS SERV,DEPT MED,CENT LAB,CH-3000 BERN 22,SWITZERLAND