[1] Univ Connecticut, Ctr Hlth, Dept Mol Microbial & Struct Biol, Farmington, CT 06030 USA
[2] Yale Univ, Sch Med, Dept Internal Med, Infect Dis Sect, New Haven, CT 06520 USA
[3] Harvard Univ, Sch Med, Dept Biol Chem & Mol Pharmacol, Boston, MA 02115 USA