Plasmid contains the entire genome of HIV-1 with a specific mutation in the protease gene, which has been described as a polymorphic mutation. It is unclear, whether it can confer drug resistance to specific HIV-1 PR inhibitors directly. It has been shown in cell culture that the presence of the 63P change leads to higher "replicative fitness" of the virus. The respective mutations have been reported in viruses from HIV-infected individuals on PR inhibitors with virologic therapy failure.