[1] Univ Texas, SW Med Ctr, Dept Internal Med, Dallas, TX 75230 USA
[2] Univ Texas, SW Med Ctr, Dept Microbiol, Dallas, TX 75230 USA
[3] Univ New Mexico, Sch Med, Dept Mol Genet, Albuquerque, NM 87131 USA
[4] Univ New Mexico, Sch Med, Dept Microbiol, Albuquerque, NM 87131 USA