[1] OHIO STATE UNIV, PROGRAM MOLEC CELLULAR & DEV BIOL, COLUMBUS, OH 43210 USA
[2] OHIO STATE UNIV, DEPT MED MICROBIOL & IMMUNOL, COLUMBUS, OH 43210 USA
[3] OHIO STATE UNIV, CTR COMPREHENS CANC, COLUMBUS, OH 43210 USA
[4] INST VIROL, MRC, VIROL UNIT, GLASGOW G11 5JR, SCOTLAND