[1] CHILDRENS HOSP MED CTR, DEPT MED, BOSTON, MA 02115 USA
[2] CHILDRENS HOSP MED CTR, DEPT PATHOL, BOSTON, MA 02115 USA
[3] HARVARD UNIV, SCH MED, DEPT MED, BOSTON, MA 02115 USA
[4] HARVARD UNIV, SCH MED, DEPT PATHOL, BOSTON, MA 02115 USA
[5] CTR DIS CONTROL, RESP VIROL SECT, ATLANTA, GA 30333 USA
[6] UNIV CALIF SAN DIEGO, DEPT MED, LA JOLLA, CA 92037 USA
[7] UNIV CALIF SAN DIEGO, DEPT PATHOL, LA JOLLA, CA 92037 USA
[8] VET ADM MED CTR, VIROL LAB, SAN DIEGO, CA USA