Human papillomavirus vaccines: a warty problem

Abstract

Infection of the genital tract with human papillomaviruses (HPVs) is a common occurrence, and manifestations can include genital warts (condyloma acuminata), dysplasia, and invasive cancer. Approaches to diagnose and treat HPV infections are costly and are not fully effective. Even in populations at low risk for sexually transmitted diseases (STDs), HPV infection is severalfold more prevalent than all other STDs combined, and worldwide, uterine cervical cancer remains the most common cancer in women. It should be feasible to develop prophylactic vaccines to prevent HPV infection using the L1 and L2 capsid proteins or therapeutic vaccines to modulate the development or recurrence of disease based on the E6 and E7 oncoproteins or other viral proteins. In favor of success is (a) the relative simplicity of the HPV genome (only two proteins in the viral coat, and a small number of other genes), (b) the lack of genetic variability within types and stability of the genome, and (c) the encouraging results with vaccines against animal PVs. However, it is difficult to provide evidence of the efficacy of HPV vaccines because of the inability to propagate the virus in culture or in animal models and because of the incomplete understanding of the natural history of HPV infection.