[1] UNIV MONTREAL, INST MICROBIOL, MONTREAL, QUEBEC, CANADA
[2] UNIV MONTREAL, DEPT MICROBIOL & PEDIAT, MONTREAL, QUEBEC, CANADA
[3] ST JUSTINE HOSP, MONTREAL HN7 423, QUEBEC, CANADA
[4] UNIV N CAROLINA, SCH MED, CANC CTR PROGRAM, CHAPEL HILL, NC 27514 USA
[5] UNIV N CAROLINA, DEPT MED, CHAPEL HILL, NC 27514 USA
[6] UNIV N CAROLINA, DEPT BACTERIOL, CHAPEL HILL, NC 27514 USA