[1] Univ Oxford, Dept Zool, Oxford OX1 3PS, England
[2] Univ Edinburgh, Inst Evolutionary Biol, Edinburgh EH9 3JT, Midlothian, Scotland
[3] Univ Florida, Coll Med, Gainesville, FL 32610 USA
[4] Univ Pretoria, Fac Hlth Sci, ZA-0001 Pretoria, South Africa
[5] Ist Super Sanita, Dept Infect Dis, I-00161 Rome, Italy
[6] Bambino Gesu Pediat Hosp, Dept Immunol & Infect Dis, I-00165 Rome, Italy
[7] Spallanzani Inst Infect Dis, I-00149 Rome, Italy
[8] Univ Roma Tor Vergata, Dept Internal Med, I-00133 Rome, Italy
[9] Univ Hosp Geneva, CH-1211 Geneva, Switzerland
[10] Univ Roma Tor Vergata, Dept Biol, I-00133 Rome, Italy
[11] Univ Roma Tor Vergata, Dept Expt Med & Biochem Sci, I-00173 Rome, Italy