[1] UNIV ZURICH,INST MOLEK BIOL 1,CH-8093 ZURICH,SWITZERLAND
[2] UNIV WURZBURG,INST VIROL & IMMUNOBIOL,D-8700 WURZBURG,FED REP GER
[3] MAX PLANCK INST EXPTL MED,D-3400 GOTTINGEN,FED REP GER
[4] QUEENS UNIV BELFAST,DEPT BIOL,BELFAST BT9 7BL,ANTRIM,NORTH IRELAND
[5] YESHIVA UNIV ALBERT EINSTEIN COLL MED,DEPT CELL BIOL,BRONX,NY 10461
[6] YESHIVA UNIV ALBERT EINSTEIN COLL MED,DEPT MICROBIOL & IMMUNOL,BRONX,NY 10461
[7] YESHIVA UNIV ALBERT EINSTEIN COLL MED,DEPT RADIAT BIOL & BIOPHYS,BRONX,NY 10461