[1] Univ Birmingham, Div Immun & Infect, HPA Antiviral Susceptibil Reference Unit, Birmingham B15 2TT, W Midlands, England
[2] UCL, Royal Free & Univ Coll Med Sch, Dept Sexually Transmitted Dis, London, England
[3] UCL, Royal Free & Univ Coll Med Sch, Dept Virol, London, England
[4] Birmingham Heartlands Hosp, Dept Sexual Med Birmingham, Birmingham B9 5ST, W Midlands, England