[1] Howard Univ, Ctr Sickle Cell, Washington, DC USA
[2] Howard Univ, Dept Physiol & Biophys, Washington, DC USA
[3] Howard Univ, Dept Med, Washington, DC USA
[4] Howard Univ, Coll Med, Dept Microbiol, Washington, DC USA
[5] Howard Univ, Coll Med, Dept Microbiol, Room 311,520 St NW, Washington, DC 20059 USA