[1] UNIV COLORADO, HLTH SCI CTR, DEPT MED, DENVER, CO 80262 USA
[2] UNIV COLORADO, HLTH SCI CTR, DEPT MICROBIOL, DENVER, CO 80262 USA
[3] UNIV COLORADO, HLTH SCI CTR, DEPT BIOCHEM, DENVER, CO 80262 USA
[4] BURROUGHS WELLCOME CO, RES TRIANGLE PK, NC 27709 USA
[5] DUKE UNIV, MED CTR, DEPT IMMUNOL, DURHAM, NC 27710 USA
[6] DUKE UNIV, MED CTR, DEPT MICROBIOL, DURHAM, NC 27710 USA