Research and Development: Human Papilloma Virus Background Information

Sexually Transmitted Viruses Unit Head: Dr John V. Parry
Human Papilloma Virus (HPV) R&D Section Head: Dr Simon Beddows

Papillomaviruses are common double-stranded DNA viruses known to infect almost all mammalian and avian species, with at least 100 types having been documented in humans ( Classification review: de Villiers 2004). Specific HPV types affect the skin and mucosal epithelium to induce papillomas or warts, with the HPV types affecting the mucosa predominantly being transmitted through sexual contact. Most infections are benign and self-limiting and are ultimately cleared by the host immune system. However, the persistence of a subset of mucosal HPV types has been associated with the development of cervical cancer and, in HIV co-infected men who have sex with men, with anal cancer. Globally an estimated 250,000 deaths are attributed annually to cervical cancer and even in countries with a robust cervical cancer screening programme the incidence rates of pre-cancerous lesions and cervical cancer are significant. The introduction of a prophylactic HPV vaccine offers real hope in reducing these rates still further and of making a significant impact in developing countries where screening services do not exist or are inadequate.

WHO website: Papillomaviruses and HPV vaccines

The vaccines are based on the major structural 'capsid' protein of HPV types 16 and 18 (Cervarix ^TM ) or 6, 11, 16 and 18 Merck (Gardasil ^TM ) and are designed to induce functional antibodies to protect the individual from acquiring the virus during intimate contact [ Vaccine review: Lowy & Schiller 2006]. Large multicentre trials have, over ~5 years of observation, demonstrated 90-100% efficacy in preventing the incidence of infection by the vaccine-incorporated HR types, 16 and 18. However, these two HPV types account for only ~70% of cervical cancers and the ability to induce a cross-reactive protective immune response is as yet unclear [ HPV types and cancer: Munoz 2003]. In addition, there is considerable regional and global variation in the prevalence of particular HR HPV types, which may impact on the efficacy of such a vaccine formulation when used on a global scale [ Worldwide HPV types: Clifford 2005]. This may also be reflected in overall vaccine efficacy when administered to recent immigrants from countries where HPV 16 and 18 are not the most prevalent types.

For information on HPV infection and vaccination visit the US Centers for Disease Control HPV website or the Cancer Research UK website.

Last Updated: July 2007

Last reviewed: 5 March 2010