[1] UNIV MARYLAND,SCH MED,DEPT MED,CTR VACCINE DEV,BALTIMORE,MD 21201
[2] UNIV BRITISH COLUMBIA,BIOTECHNOL LAB,VANCOUVER,BC V6T 1Z3,CANADA
[3] UNIV BRITISH COLUMBIA,DEPT BIOCHEM & MOL BIOL,VANCOUVER,BC V6T 1Z3,CANADA
[4] UNIV BRITISH COLUMBIA,DEPT IMMUNOL & MICROBIOL,VANCOUVER,BC V6T 1Z3,CANADA