Human papillomavirus (HPV)

Viruses are small, simple micro-organisms. They consist of a small amount of genetic material, often surrounded by an outer protein capsid, which may be protected by an external envelope. As the genetic material of viruses is small and contains few genes, they rely on their host cells to survive and replicate.

The human papillomavirus (HPV) is a very common virus, which is easily transmitted through any sexual activity (Baseman and Koutsky 2005). Approximately 100 types of HPV have now been classified, which can be divided into two main categories: oncogenic and low-risk (Burd 2003; de Villiers et al 2004; Muñoz et al 2003).

(Representation of HPV)

Most HPV infections are transient and clear within a year, but persistent infection with oncogenic HPV types may lead to cervical cancer (Bosch et al 2002). Types 16 and 18 are the most common oncogenic HPV types worldwide, found in over 70% of cervical cancers (Clifford et al 2005b; Muñoz et al 2003; Muñoz et al 2004).

Other diseases caused by oncogenic HPV include less common cancers such as anal, penile, vulvar, vaginal, head and neck cancers (Bjorge et al 1997; Chen et al 2005; Frisch et al 1997; Pow-Sang et al 2002). Low risk mucosal HPV types can cause anogenital warts, or, more rarely, recurrent respiratory papillomatosis (RRP) (Burd 2003; Lee and Smith 2005; Prendiville and Davies 2004b).