ABSTRACT
Acknowledgments......................................................................................................................... 291 References ..................................................................................................................................... 292
Papillomaviruses (PVs), members of the family Papillomaviridae, are icosahedral nonenveloped double-strand DNA viruses, which infect squamous or mucosal epithelia and produce a range of epithelial neoplasms, both benign and malignant, in most animals and humans (for details see Ref. [1]). PVs along with the polyomaviruses have belonged to former Papovaviridae family. On the basis of the later findings that the two virus groups have different genome sizes, completely different genome organizations, and no major nucleotide or amino acid (aa) sequence similarities, they are now recognized as two independent families. Until now, more than 130 genetically distinct PVs have been identified (for classification of PVs see Ref. [2]). Among them, over 100 different human papillomavirus (HPV) types have been characterized. Some HPV types cause benign skin warts, or papillomas, for which the virus family is named. A subset of HPVs cause virtually all cases of cervical cancer, the second most common cause of death from cancer after breast cancer, killing about 0.25 million women per year. In recent years, a lot of effort has been made for generation of both prophylactic and therapeutic HPV vaccines.
