[1] Queen Marys Univ London, Blizard Inst, London, England
[2] MRC Univ Glasgow, Ctr Virus Res, Glasgow, Lanark, Scotland
[3] Univ Nottingham, Virol, Nottingham NG7 2RD, England
[4] Queen Marys Univ London, London, England
[5] Univ Nottingham, Nottingham NG7 2RD, England
[6] Kings Coll Hosp London, London, England