[1] Macfarlane Burnet Inst Med Res & Publ Hlth, Ctr Virol, Melbourne, Vic 3004, Australia
[2] Alfred Hosp, Infect Dis Unit, Melbourne, Vic, Australia
[3] Monash Univ, Dept Med, Melbourne, Vic 3004, Australia
[4] Monash Univ, Dept Immunol, Melbourne, Vic 3004, Australia
[5] Baker IDI Heart & Diabet Inst, Melbourne, Vic, Australia
[6] George Washington Univ, Med Ctr, Dept Microbiol Immunol & Trop Med, Washington, DC 20037 USA