Patti E. Gravitt. The Known Unknowns of HPV. J Clin Invest. 2011;121(12):4593-4599. doi:10.1172/JCI57149.
Purpose of the study
The discovery that certain high-risk strains of human papillomavirus (HR-HPV) cause nearly 100% of invasive cervical cancer has spurred a revolution in cervical cancer prevention by promoting the development of viral vaccines.
Although the efficacy of these vaccines has already been demonstrated, a complete understanding of viral latency and natural immunity is lacking, and solving these mysteries could help guide policies of cervical cancer screening and vaccine use.
This was a review series which examined the epidemiological and biological understanding of the natural history of HPV infection, with an eye toward using these studies to guide the implementation of cervical cancer prevention strategies.
Approximately 60% of women with HPV DNA detected will develop serum antibodies against HPV (HPV seropositive), and if cellular samples are collected during peak viral production, mild cytologic abnormalities may be detected on Pap smears.
A minority of HPV infections will persist, and individuals with persistent high-risk HPV are at a substantial risk of developing cervical precancer, or CIN3. The CIN3 lesions are the targets of screening, because more than one-third of these will progress to invasive cervical cancer within 10–20 years. There is continued uncertainty in the natural history of HPV. Namely, it is unclear whether anti-HPV antibody developed following natural HPV infection protects against reinfection, and whether loss of HPV detection reflects virologic clearance or establishment of viral latency.
Implications for practice
This study identifies that a complete understanding of viral latency and natural immunity is lacking. Practitioners should be aware of these limitations when counselling individuals.
For further information
Pubmed link: http://www.ncbi.nlm.nih.gov/pubmed/22133884
Dr. Sylvia Makaroff, Acting Medical Head, Provincial STI/HIV Clinic, Clinical Prevention Services, BCCDC
Avril Spencer, Clinical Nurse Educator, Provincial STI/HIV Clinic, Clinical Prevention Services, BCCDC