Copyright information:Taken from "Genetic and phylogenetic evolution of HIV-1 in a low subtype heterogeneity epidemic: the Italian example"http://www.retrovirology.com/content/4/1/34Retrovirology 2007;4():34-34.Published online 21 May 2007PMCID:PMC1892567.performed on near-full length sequences and is based on neighbor joining method. The reliability of the internal branches defining a subtype has been estimated from 1'000 bootstrap replicates and the values are expressed as percentage.