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Targeting Life-cycle Points

Drugs meant to knock out HIV target the activities of two HIV proteins, the reverse transcriptase and the protease. HAART requires drugs of both types. Drugs called protease inhibitors prevent the viral protease from trimming down the large proteins made late during infection. Without those proteins, the viral shell cannot be assembled. In addition, the proteins that reproduce HIV's genetic information, the reverse transcriptase and the integrase, are not functional.

Drugs that inhibit the reverse transcriptase prevent it from copying the RNA into DNA. These drugs work early in the life cycle of HIV. Reverse transcriptase inhibitors include azidothymidine (AZT), whose structure resembles the DNA nucleotide thymine. When reverse transcriptase builds DNA with AZT instead of thymine, the AZT caps the growing DNA molecule and halts DNA production, due to AZT's slight difference in structure from the thymine that DNA production requires.

Mary Beckman


Janeway, Charles A., et al. "Failures of Host Defense Mechanisms." In Immunobiology: The Immune System in Health and Disease, 4th ed. New York: Current Biology Publications, 1999.

———. HIV Infection and AIDS: An Overview. Washington DC: National Institute of Allergy and Infectious Diseases and U.S. Department of Health and Human Services, 2001.

Shilts, Randy. And the Band Played On: Politics, People, and the AIDS Epidemic. New York: St. Martin's Press, 2000. Stine, Gerald. Acquired Immune Deficiency Syndrome: Biological, Medical, Social and Legal Issues, 3rd ed. New York: Prentice-Hall, 1997.

Additional topics

Medicine EncyclopediaGenetics in Medicine - Part 2HIV - Hiv And Aids, Hiv Life Cycle: Entering Cells, Hiv Life Cycle: Reproduction, Hiv's Immune-system Impairment Mechanism