HPV18 L1

Human papillomavirus is a DNA virus from the papillomavirus family, of which over 150 types are known. More than 40 types are transmitted through sexual contact and infect the anus and genitals. HPV is typically spread by sustained direct skin-to-skin contact with vaginal and anal sex being the most common methods. L1 forms an icosahedral capsid with a T=7 symmetry and a 50 nm diameter. The capsid is composed of 72 pentamers linked to each other by disulfide bonds and associated with L2 proteins. It binds to heparan sulfate proteoglycans on cell surface of basal layer keratinocytes to provide initial virion attachment. This binding mediates a conformational change in the virus capsid that facilitates efficient infection. The virion enters the host cell via endocytosis. During virus trafficking, L1 protein dissociates from the viral DNA and the genomic DNA is released to the host nucleus. The virion assembly takes place within the cell nucleus. L1 encapsulates the genomic DNA together with protein L2.