1. Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama.
2. Department of Comparative Medicine, University of Alabama at Birmingham, Birmingham, Alabama.
3. Department of Surgery, University of Tennessee at Memphis, Memphis, Tennessee.
4. Present address: 131 Fraker Road, Buffalo, Missouri.
5. Department of Obstetrics and Gynecology, University of Michigan, Ann Arbor, Michigan.