5 ms·

>"What we do know is that this happened 80-140 years ago, why did a virus that infected primates for 50,000 to 2000000 years suddenly jumped species all of a su

by nonbel 10y ago

>"What we do know is that this happened 80-140 years ago, why did a virus that infected primates for 50,000 to 2000000 years suddenly jumped species all of a sudden despite the fact that there was just as much if not more cross species interaction during human history is a better question" Simian AIDS was discovered after human AIDS though: "Examination of the species-specific annual mortality rates of macaques at the center during the previous 4 yr showed a significant increase in deaths in 1980 and 1981" http://www.ncbi.nlm.nih.gov/pmc/articles/PMC393899/ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC393899/ I don't see how people really know whether the problem originated in humans and spread to apes or vice versa. If anything you would expect such issues to be detected in highly monitored animals kept in well controlled research facilities first...

dogma1138 10y ago
Human HIV was discovered probably 5 decades if not more after it jumped. We know it didn't originate in humans, because we can estimate how old SIV and HIV are based on their genetic material and other factors. And we also know how old SIV at least is because we've tested primates on isolated islands and found that they are also infected, so if you find SIV infected primates on an island that was isolated from mainland Africa 30,000 years ago and it's preset within 100% of the primate population you know it's at least that old. Another thing you can do is look at the DNA of the host and see if any viral DNA has been embedded within it, depending on where it is you can also estimate a timeline based on known processes and mutation rates. There is very little to no doubt that HIV originated from SIV, the question is why now. And yes we've discovered SIV later because AIDS happened then we found that it's a virus and not because they are gay, so people started looking at it's source and discovered SIV, FIV, EIAV and others. You also need to understand that viruses are very hard to find, it's not like you just look at blood samples and see them, there are also not that many generic tests that can simply detect if a virus is present or not, it takes years to decades to isolate, classify and then develop methods to identify a virus and it's not like in the 1980's you could just order a full genome to be sequenced at will.
- nonbel 10y ago
  >"we've tested primates on isolated islands and found that they are also infected, so if you find SIV infected primates on an island that was isolated from mainland Africa 30,000 years ago and it's preset within 100% of the primate population you know it's at least that old." This sounds familiar, do you remember the ref? From what I remember the degree of "isolation" was questionable.
  - dogma1138 10y ago
    There were multiple studies some in islands, others in jungles. http://www.nature.com/news/2010/100521/full/news.2010.259.html http://www.nature.com/news/2010/100521/full/news.2010.259.ht... It's important to note that even if the location is not isolated it doesn't matter, and we do have proof that it is, what we look at is the molecular clock of the virus basically it's molecular structure based on the mutation rate of each virus. When you calculate the drift between different strains you can estimate the age, more isolated populations help since they tend to have less types of infections, while it's not common to find a primate with multiple strains on the mainland primates in the deep jungles of south america and on isolated islands off the coast of africa usually only have a single strain due to their relative isolation from other primate populations.
    - nonbel 10y ago
      Not much more time for me to read into this today but I see that the molecular clock estimate is based on the "isolation" estimate. So these are not independent measures: "Crucially, he knew from geological records that the island separated from continental Africa around 12,000 years ago. Assuming that the strains had had at least 12,000 years to evolve apart, he determined that the mutation rate of SIV is much slower than originally thought." I find it difficult to believe that for 10k years a plausible scenario is that nothing happened like eg: A) someone was hunting monkeys from more populated areas and traveled to "isolated" islands/regions to get more. B) monkey on a branch gets thrown out to sea and floats to the island.
      - 10y ago

by nonbel 10y ago

dogma1138 10y ago

Human HIV was discovered probably 5 decades if not more after it jumped. We know it didn't originate in humans, because we can estimate how old SIV and HIV are based on their genetic material and other factors. And we also know how old SIV at least is because we've tested primates on isolated islands and found that they are also infected, so if you find SIV infected primates on an island that was isolated from mainland Africa 30,000 years ago and it's preset within 100% of the primate population you know it's at least that old. Another thing you can do is look at the DNA of the host and see if any viral DNA has been embedded within it, depending on where it is you can also estimate a timeline based on known processes and mutation rates. There is very little to no doubt that HIV originated from SIV, the question is why now. And yes we've discovered SIV later because AIDS happened then we found that it's a virus and not because they are gay, so people started looking at it's source and discovered SIV, FIV, EIAV and others. You also need to understand that viruses are very hard to find, it's not like you just look at blood samples and see them, there are also not that many generic tests that can simply detect if a virus is present or not, it takes years to decades to isolate, classify and then develop methods to identify a virus and it's not like in the 1980's you could just order a full genome to be sequenced at will.

nonbel 10y ago
>"we've tested primates on isolated islands and found that they are also infected, so if you find SIV infected primates on an island that was isolated from mainland Africa 30,000 years ago and it's preset within 100% of the primate population you know it's at least that old." This sounds familiar, do you remember the ref? From what I remember the degree of "isolation" was questionable.
- dogma1138 10y ago
  There were multiple studies some in islands, others in jungles. http://www.nature.com/news/2010/100521/full/news.2010.259.html http://www.nature.com/news/2010/100521/full/news.2010.259.ht... It's important to note that even if the location is not isolated it doesn't matter, and we do have proof that it is, what we look at is the molecular clock of the virus basically it's molecular structure based on the mutation rate of each virus. When you calculate the drift between different strains you can estimate the age, more isolated populations help since they tend to have less types of infections, while it's not common to find a primate with multiple strains on the mainland primates in the deep jungles of south america and on isolated islands off the coast of africa usually only have a single strain due to their relative isolation from other primate populations.
  - nonbel 10y ago
    Not much more time for me to read into this today but I see that the molecular clock estimate is based on the "isolation" estimate. So these are not independent measures: "Crucially, he knew from geological records that the island separated from continental Africa around 12,000 years ago. Assuming that the strains had had at least 12,000 years to evolve apart, he determined that the mutation rate of SIV is much slower than originally thought." I find it difficult to believe that for 10k years a plausible scenario is that nothing happened like eg: A) someone was hunting monkeys from more populated areas and traveled to "isolated" islands/regions to get more. B) monkey on a branch gets thrown out to sea and floats to the island.
    - 10y ago