[1] Duke Univ, Med Ctr, Dept Mol Genet & Microbiol, Durham, NC 27710 USA
[2] Duke Univ, Med Ctr, Dept Pathol, Durham, NC 27710 USA
[3] Duke Univ, Med Ctr, Dept Immunol, Durham, NC 27710 USA
[4] Duke Natl Univ Singapore, Program Emerging Infect Dis, Singapore 169857, Singapore