How Do Mutations Occur Before Starting Therapy?
• Natural selection: Soon after HIV enters the body, the virus begins reproducing at a rapid rate – billions of new viruses are produced every day. In the process, HIV produces both perfect copies of itself (wild-type virus) and copies containing errors (mutated virus). In other words, there is no single virus in the body but, instead, a large population of mixed viruses called quasispecies. • Wild-type virus is the most natural and usually most powerful form of HIV and, as a result, reproduces the best. Before therapy is started, wild-type virus is the most abundant in the body and dominates all other quasispecies. • When HIV makes mistakes during copying, mutated viruses – called variants – are produced. Some variants are too weak to survive and/or can’t reproduce. Others are strong enough to reproduce but still can’t compete with the more fit wild-type virus. As a result, their numbers are less than wild-type virus in the body. • Some variants have mutations that allow the virus to
