HPV : Introduction & Classification

Comments:
Human papillomaviruses (HPV) are small, 55 nm diameter, non-enveloped, double-stranded DNA viruses with icosahedral symmetry. They form a diverse group of viruses belonging to the Papillomaviridae family.

There are five major known HPV genera that infect humans - alpha, beta, gamma, mu, and nu. Each genus has several species which are simply referred to as virus "types." The classification of HPV (HPV type number designation) is based on the nucleotide sequence for the capsid protein L1. Different HPV types are at least 10% dissimilar in the sequence of their L1 genes. Currently, more than 200 HPV types are known.

Any newly discovered HPV is given a unique type number only after the whole genome has been cloned and deposited with the International HPV Reference Center at Karolinksa Institutet in Stockholm, Sweden.

Image author: Dr. Graham Beards / Public Domain.