[1] Robert Koch Inst, D-13353 Berlin, Germany
[2] Univ Dusseldorf, Inst Mol Med, D-40225 Dusseldorf, Germany
[3] Bundesforsch Anstalt Viruskrankheiten Tiere, D-72076 Tubingen, Germany
[4] Univ Giessen, Inst Virol, Fachbereich Vet Med, D-35392 Giessen, Germany
[5] Mt Sinai Sch Med, Dept Microbiol, New York, NY 10029 USA
[6] Mt Sinai Sch Med, Microbiol Grad Sch Training Program, New York, NY 10029 USA