Evolutionary Medicine

Homework for Chapter 17: Due date is 12/3.
Test 4 (Covers Chapters 13, 14, 17 & 18): Scheduled on 12/8, 12/9, & 12/10.
Key Objective: Understand how evolutionary biology leads to new avenues of disease treatment and prevention.

Vaccines and Viruses: Scientists can utilize evolutionary principles to treat diseases.
- Example of Vaccine Development:
- Viruses used in vaccines evolve to show reduced virulence.
- Virulence: This term describes the ability of a pathogen to cause disease.
- Vaccines’ Goal: Allows the development of a long-lasting immune response to a pathogen without the individual experiencing actual infection.
- Polio Vaccine Development:
  - Scientists create the polio vaccine by mixing polio virus strains with cells from species like monkeys or chimpanzees, where polio viruses do not naturally replicate.
Viruses' Evolution in Nonhuman Cells:
- The viruses replicate slowly within the nonhuman cells (monkeys or chimpanzees).
- As these viruses replicate, they acquire mutations.
- Natural selection favors strains that are better adapted to these specific host cells.
Adaptation and Attenuation:
- As viruses adapt to the nonhuman cells, they become less suited for infecting humans.
- Once the viruses have mutated sufficiently to become weak (attenuated), they can be used as effective vaccines.
Immune Response Activation:
- When these attenuated viruses are injected into humans, they do not cause infection but effectively trigger a robust immune response.

Antibody Binding:
- Conventional antibodies typically bind to the head of the hemagglutinin protein of influenza viruses.
- The Universal Flu Vaccine aims to bind to the base of hemagglutinin instead.
Hemagglutinin Variability:
- The hemagglutinin of different subtypes of influenza viruses exhibits high mutation rates primarily in the head region, while the stalk (base) region is relatively stable.
- Antigenic Drift: This phenomenon refers to the gradual mutations that occur in the head of the hemagglutinin, making the immune response against this region less effective over time.
Stability of the Hemagglutinin Base:
- The base of hemagglutinin remains nearly identical across different flu strains.
- Mutations in this critical part of the protein are typically harmful as they disrupt proper function.
- Any alteration in the shape of the base can compromise its effectiveness.
Theoretical Implications of the Universal Flu Vaccine:
- Antibodies generated from this universal vaccine, targeting the base of hemagglutinin, would theoretically provide protection against any flu strain and offer lasting immunity over the years.

Cancer Rates in Elephants:
- Contrary to expectations, elephants have low rates of cancer despite their large size, which statistically should correlate with higher cancer prevalence.
p53 Gene in Humans vs. Elephants:
- Humans possess one copy of the p53 gene, critical for preventing mutant cells from becoming cancerous.
- Elephants, on the other hand, have evolved to possess 20 copies of the p53 gene, significantly enhancing their cancer resistance.
LIF6 Gene Presence:
- Elephants have a unique gene, LIF6, which is activated by the p53 gene. LIF6 is responsible for inducing the death of cells that contain damaged DNA.
- Researchers are investigating potential drugs that can mimic the LIF6 function in human cells to enhance cancer resistance.

Methods of Developing an Attenuated Vaccine:
- Allow the virus to evolve in nonhuman primate cells until it becomes less adapted to human cells, rendering it too weak for infection.
- Expose the virus to water to induce mutations to the point where it cannot infect humans.
- Utilize computer models to predict which antibodies may provide the most robust immunity against the virus.