Final answer:
An example of virus evolution is the development of resistance to a drug after repeated exposure. Hepatitis A virus, polioviruses, Epstein-Barr virus, herpes simplex virus, rubella virus, yellow fever virus, and HIV-1 are examples of viruses that have evolved over time.
Step-by-step explanation:
An example of virus evolution is the development of resistance to a drug after repeated exposure. This illustrates evolution as an ongoing process because the viruses were able to adapt to changing conditions.
For instance, Hepatitis A virus, polioviruses, Epstein-Barr virus, herpes simplex virus, rubella virus, yellow fever virus, and HIV-1 are examples of viruses that have evolved over time. Some viruses like HIV use antigenic variation to evade the adaptive immune system of human hosts.
Additionally, certain viruses like HIV rapidly change their non-essential antigens to evade the adaptive immune system of human hosts, which is known as antigenic variation.