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The Origins of HIV/AIDS:

The Origins of HIV/AIDS:. Where Did it Come From?. Early Evidence. First described in 1981 Thought to originate in Haiti This idea rapidly discredited Some recent evidence suggests that first appearance in western hemisphere was in Haiti. Recent Thought. Origins in Africa

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The Origins of HIV/AIDS:

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  1. The Origins of HIV/AIDS: Where Did it Come From?

  2. Early Evidence • First described in 1981 • Thought to originate in Haiti • This idea rapidly discredited • Some recent evidence suggests that first appearance in western hemisphere was in Haiti

  3. Recent Thought • Origins in Africa • Means of transmission becoming clearer • HIV is an old infection • So, what is the evidence?

  4. Evidence Favoring West African/Central African Origin • Frequency of infection • Genetic variation—great • Presence in non-human primates

  5. Evidence of non-human primate origin See Hahn et al, Science 2000;287:607-614 • Geographic overlap • Prevalence in chimps • SIV introduced into humans at least 7 times. • SIV—no morbidity or mortality in their hosts • Similarities or identical genome structure in humans and chimps • Phylogenetic relatedness • Transmission routes

  6. Schematic, lineage, HIV-1 and HIV-2 Source: Hahn et al, Science, 2000

  7. Human Exposure to Blood During Bushmeat Preparation

  8. SE Cameroon (red) Leopoldville (Kinshasa)-1896 and 1955 Source: Sharp and Hahn, Nature, 2008

  9. Based on liver , lymph node biopsies, and placental remains

  10. Source: Worobey Et al, Nature 2008

  11. Evidence of Species Jump • SIV-HIV2 similarities • HIV identified in chimps • Intensity of infection in chimps—parallels intensity in humans geographapically

  12. Pan troglodytes troglodytes (chimpanzee)

  13. “Humans are not the natural hosts of either HIV-1 or HIV-2. Instead, these viruses have entered the human population as a result of zoonotic, or cross-species, transmission. We now know of at least 18 distinct primate lentiviruses that naturally infect African primates.”—Hahn et al, Science 2000; 287:607

  14. Infection is Old • Serological (blood) studies • Stored samples 1959-1981 (humans) from Africa • 21 samples HIV positive • 1959—Bantu male, Leopoldville, Belgian Congo (Kinshasa, Democratic Republic of Congo) • Was HIV + • Pt.—Manchester UK, 1959 • Conclusion—present in humans 1959

  15. When Did HIV Originate? • Quite old in primates—subtle genetic variations • Humans— • Analysis of genetic variations • Rates of change • Backwards simulation—as early as 1930 • Very recent-maybe even 1900

  16. Molecular Clock (relaxed) Source: Gilbert et al, PNAS, 2007

  17. Counterarguments • CIA introduced HIV (no evidence) • Introduced by oral polio vaccine • (Ed Hooper, The River • Now discredited • SIV predated oral polio vaccine • Vaccine specimens at Wistar Institute neg for HIV

  18. Pres. Mbeke (South Africa)— • Denies relationship btw. HIV and AIDS • Draws upon work by Duesberg

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