Pervasive HIV recombination limits the utility of circulating recombinant form nomenclature

The naming of HIV-1 circulating recombinant forms (CRFs)—descendent viruses from the same intersubtype recombination events, is along with the designation of ‘subtypes’ and ‘groups’, routinely used to track HIV-1 diversity. However, we argue that continuing to designate all detected CRFs as distinct entities is biologically unjustified, as many represent recombinants of limited epidemiological significance. Indeed, the mechanistic underpinning of HIV-1 recombination highlights the arbitrary nature of naming these incidental recombinants, the majority of which are rarely detected again. This underlines the need to prioritise taxonomically meaningful clades, with a focus on biological significance such as emergence events associated with significant epidemiological spread, phenotypic properties or transmission advantage.