Genital human papillomavirus infections: current and prospective therapies

Modulation of apoptotic pathways by human papillomaviruses (HPV): mechanisms and implications for therapy

The ability of the host to trigger apoptosis in infected cells is perhaps the most powerful tool by which viruses can be cleared from the host organism. To avoid elimination by this mechanism, human papillomaviruses (HPV) have developed several mechanisms that enable the cells they infect to elude both extrinsic and intrinsic apoptosis. In this manuscript, we review the current literature regarding how HPV-infected cells avoid apoptosis and the molecular mechanisms involved in these events. In particular, we will discuss the modifications in intrinsic and extrinsic apoptotic pathways caused by proteins encoded by HPV early genes. Many of the current efforts regarding anti-cancer drug development are focused on directing tumor cells to undergo apoptosis. However, the ability of HPV-infected cells to resist apoptotic signals renders such therapies ineffective. Possible mechanisms for overcoming the resistance of HPV-infected tumor cells to anticancer drugs will be discussed.

Human papillomavirus proteins as prospective therapeutic targets

Human papillomaviruses (HPV) are the causative agents of a subset of cervical cancers that are associated with persistent viral infection. The HPV genome is an ∼8 kb circle of double-stranded DNA that encodes eight viral proteins, among which the products of the E6 and E7 open reading frames are recognized as being the primary HPV oncogenes. E6 and E7 are expressed in pre-malignant lesions as well as in cervical cancers; hence these proteins have been extensively studied as potential targets for HPV therapies and novel vaccines. Here we review the expression and functions of E6 and E7 in the viral vegetative cycle and in oncogenesis. We also explore the expression and functions of other HPV proteins, including those with oncogenic properties, and discuss the potential of these molecules as alternative therapeutic targets.

Recent progress in the application of nanotechnology for prevention and treatment of human papillomavirus infection

Human papillomavirus (HPV) causes benign and malignant infections of the anogenital tract. Cervical cancer, caused by high-risk HPV types 16, 18, 31, 33, 35, 45, 56 and 58, is the second most common cancer in women and the fifth most common cancer overall. Prevention and treatment of HPV infection may be revolutionized using nanotechnology tools such as vaccines based on virus-like particles and nanoscale drug-delivery systems. Advances in both virus-like particle design and noninvasive delivery of antiviral protein drugs, such as IFNalpha, may provide new opportunities to take on the challenge of global elimination of HPV infections. Biphasic vesicle cream formulation, representing a new class of dermal delivery system for protein drugs, is an alternative to injectable dosage form to deliver IFNalpha for the treatment of HPV infections, showing efficacy in low-grade squamous epithelical lesions of the cervix.

Molecular diagnosis of a laboratory mouse papillomavirus (MusPV)

MusPV, a novel papillomavirus (PV) that naturally infects laboratory mice, was isolated and characterized from a colony of NMRI-Foxn1(nu)/Foxn1(nu) (nude) mice in India. Because MusPV may have been missed during routine pathogen screening of mice in colonies worldwide, a variety of detection methods are described to detect MusPV. The clinical and histologic lesions of productive MusPV infections fit PV-associated features, including papillomas, koilocytes within the stratum granulosum of the hyperplastic/acanthotic papillomatous epithelium, and the presence of intranuclear virus particles in koilocytotic cells visualized by electron microscopy. Antiserum against disrupted PV virions, isolated from another species (canine), identified conserved viral antigens in productively infected cells by immunohistochemistry. A rolling circle technique was used to amplify viral circular DNAs followed by endonuclease restriction enzyme digestion to determine the correct size of PV DNA. Consensus PV degenerative primers, My09/11, commonly used to detect many different types of PVs by polymerase chain reaction (PCR), particularly mucosotropic HPVs, also identified MusPV and all rodent PVs tested. Since there was one nucleotide mismatch between the My09/11 primer set and the MusPV template, a new primer set, MusPV-My09/11, was designed to specifically detect MusPV in latent infections and spontaneous MusPV-induced papillomas. Southern blot analysis verified the presence of full size PV DNA in infected tissues. Virus-like particles (VLPs), generated from MusPV L1 genes, provided a substrate for serological testing of naturally and experimentally infected mice. In summary, a series of diagnostic assays were developed and validated to detect MusPV infection in skin tumors and serological response in laboratory mice.