Using Molecular Information to Investigate the Evolutionary

Origin of the HIV Virus

HIV vs. AIDS

• HIV: Human Immunodeficiency Virus

• AIDS: Acquired Immune Deficiency Syndrome

Viral Genome

• Look at the viral genomes on your data sheet. What do you see in common, what do you see different?

Let’s use these common genes to see what a virus is made of:

• Env• Pol• Unique viral proteins

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Envelope• Glycoproteins: Identification• Rapidly mutating• Would you use these to look at the evolutionary

origin of HIV?

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Do all viruses have an envelope?

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Genetic Code• What types of

genetic material can viruses have?

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HIV

• A retrovirus:– RNA-->DNA-->cell’s

machinery to make more virus

– Protein reverse transcriptase

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Defense against viruses

• Immune System• Vaccine against a viral

envelop protein.• Why can’t we make a

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Part I. On-line Lab Activities

• Campbell’s Activity 19.2 A and D and 43 A

• Your Choice: Complete one of the Lab Investigations in your notebook

• HIV infects helper T cell, why is this so deadly?

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Part II: Using informatics to discover where HIV came from

• Question: How did HIV become a human retrovirus?

• Write an introduction to this lab summarizing what you know about HIV

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3 Hypotheses

• Another human retrovirus evolved to infect T-cells

• A chimp immunodeficiency virus (SIV) entered the human population.

• A green monkey SIV was accidentally transferred to humans through a vaccine cultivated in green monkey cells

Make your hypothesis

• Now that we’ve discussed the 3 hypotheses, pick one as your likely hypothesis. Draw a cladogram to show the relationship between:

HIV, Chimp SIV, Green Monkey SIV, Human Foamy retrovirus

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Methods

• You will use biology workbench at: workbench.sdsc.edu to determine the relationship among several retroviruses

• Follow the directions on the handout. Record in your lab notebook a generalized summary of how to make a sequence alignment.

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Results: Data and Analysis

• Use your sequence alignment to create a phylogenetic tree.

• Give your phylogenetic tree an appropriate figure description

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Drawing Conclusions

• Is your hypothesis supported by the data? Explain.

• Which hypotheses are/are not supported by the data. Explain

• Did HIV-2 evolve from HIV-1? (Divergent Evolution) or was the evolution of HIV-2 a separate evolutionary event (Convergent evolution). Explain.

Extension

• Summarize what may have happened in Africa in the 1930’s. Read the scenario below:– European and American fishin fleets did extensive

fishing off the West Coast of Africa in the early 20th century. The fishing banks near the shore were significantly depleted by the 1920’s. Many West African nations relied on these fishing banks for a significant portion of the protein in their diet and then had to rely on other protein sources. Can you make a connection between the change in the West African diet and the AIDS epidemic?

Extension 2

• Many governments contribute money to the world AIDS epidemic. Some money is spent on developing vaccines. Other money is spent on educating people how to prevent the spread of viral infections. Suppose an HIV vaccination is created. Should governments stop spending money on virus education? Use the information in the tree to support your answer.

Extension 3

• Wain-Hobson 1998 created a tree showing the evolution of HIV. Compare the data in this tree to the one you created. Discuss similarities and differences. Then draw a conclusion about whether the tree agrees or disagrees with your results.