Human papillomavirus deoxyribonucleic acid and ribonucleic acid in seminal plasma and sperm cells**Supported by research grant NSC83-0412-B182-001 from National Science Council of Republic of China and by medical research grant CMRP-343 from Chang Gung College of Medicine and Technology and Memorial Hospital, Taipei, Taiwan, Republic of China, both awarded to C.C.P.