[1] Univ Calif San Diego, Dept Bioengn, La Jolla, CA 92093 USA
[2] Univ Texas Med Branch, Dept Microbiol, Galveston, TX USA
[3] Univ Texas Med Branch, Dept Immunol, Galveston, TX USA
[4] Pacific NW Natl Lab, Biol Sci Div, Richland, WA 99352 USA
[5] Univ Texas Med Branch, Dept Pathol, Galveston, TX USA