[1] Harvard Univ, Sch Med, Dept Microbiol & Mol Genet, Southborough, MA 01772 USA
[2] New England Reg Primate Res Ctr, Southborough, MA 01772 USA
[3] Harvard Univ, Sch Med, Dept Biol Chem & Mol Pharmacol, Boston, MA 02115 USA
[4] Childrens Hosp, Mol Med Lab, Boston, MA 02115 USA
[5] Free Univ Berlin, Dept Biol Chem Pharm, D-1000 Berlin, Germany
[6] Harvard Univ, Sch Med, Dept Pediat, Boston, MA 02115 USA
[7] Childrens Hosp, Perlmutter Lab, Boston, MA 02115 USA