1 Department of Obstetrics and Gynecology, Women's Reproductive Health Research Center, Vanderbilt University School of Medicine, Nashville, TN, United States.
2 Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, United States.
3 Department of Microbiology and Immunology, Meharry Medical College, Nashville, TN, United States.
4 VA Tennessee Valley Healthcare System, Nashville, TN, United States.