1. Department of Biological Responses, Institute for Virus Research, Kyoto University (T.M., Y.S., K.F., J.Y.), Kyoto 606-8397;
2. Department of Obstetrics and Gynecology, Keio University School of Medicine (T.M., Y.Y.), Tokyo 160-0016;
3. Department of Obstetrics and Gynecology, Kyoto National Hospital (Y.K.), Kyoto 612-0861;
4. Department of Obstetrics and Gynecology, Kansai Medical University (H.K.), Osaka 570-0074, Japan