[1] NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Houston, TX 77058 USA
[2] Lyndon B Johnson Space Ctr, Enterprise Advisory Serv, Houston, TX 77058 USA
[3] Univ Texas, Med Branch, Dept Pathol, Galveston, TX 77550 USA
[4] Univ Texas, Med Branch, Dept Microbiol, Galveston, TX 77550 USA