HPV 6

Human Papillomavirus (HPV) is a small, non-enveloped DNA virus that infects skin or mucosal cells. Among the more than 100 known HPV genotypes, HPV 6 is classified as a “low-risk” genotype, primarily associated with benign conditions such as genital warts .

HPV has a circular, double-stranded DNA genome approximately 8-kb in length. The genome encodes six early proteins (E1, E2, E4, E5, E6, and E7) responsible for viral replication and two late proteins (L1 and L2), which are the viral structural proteins .

Recombinant technology has been pivotal in the development of HPV vaccines. The L1 protein, a major capsid protein of HPV, can self-assemble into virus-like particles (VLPs) when expressed in a suitable host system, such as yeast or insect cells infected with recombinant baculoviruses . These VLPs resemble the native virus but lack viral genetic material, making them non-infectious .

HPV 6, along with HPV 11, is included in the quadrivalent HPV vaccine (Gardasil®), which also targets HPV types 16 and 18. This vaccine is produced using recombinant technology, where the L1 proteins of these HPV types are expressed and purified from yeast cells . The VLPs are then adsorbed to an amorphous aluminum hydroxyphosphate sulfate adjuvant to enhance the immune response .

The inclusion of HPV 6 in the quadrivalent vaccine is crucial as it helps prevent genital warts, a common and benign condition caused by HPV 6 and 11 . The vaccine has shown high efficacy in inducing serum antibodies against all vaccine-related HPV types in a significant percentage of vaccinated individuals .