CD4 and infection: For each model, we indicate the number of CD4+ T-cell compartments, the number of virus strains (“v” means it varies as the virus evolves and the number of strains is then denoted by nv), whether the model includes a host anti-viral immune response (and if it does so which type of response) and whether it follows the entire infection and is able to reproduce the slow time scale of CD4+ T-cell decline.