Question

The human immunodeficiency virus (HIV) reproduces very quickly. A single virus can replicate itself a billion times in one 24-hour period. In a hypothetical treatment situation, a patient’s HIV population consists entirely of drug-resistant viruses after just a few weeks of treatment. How can this treatment result best be explained? How does this explanation illustrate that evolution is an ongoing process?​

Answer 1

When a HIV infected patient takes medication, most of the viruses will not be able to replicate because they are susceptible to the drug. But a few viruses do replicate because they are resistant to that particular drug. These drug resistant viruses are considered to be more fit to survive in the host and become the favored phenotype in natural selection. Hence, these drug resistant viruses replicate and become dominant among the viral population, which proves that evolution is an ongoing process in the case of HIV infection.