Brianna Rodriguez
Assignment #1
“The Evolution of HIV and SIV”
The evolution of HIV from SIV is a fairly recent discovery. To this day, researchers are
studying HIV’s phylogeny, or “evolutionary tree,” finding new strands of the virus that can be
linked back to monkeys in Africa (Berkeley, 2008). So, how could such a pandemic occur? It
simply began with innocent interactions between humans and animals.
According to the Berkeley website, in 2010, a group of scientists from the University of
Arizona studied a preserved tissue sample. This sample came from a deceased (1960), HIV
positive woman, who had lived in Kinshasa, a small village in Africa. They then compared it to a
sample from 1959, someone else who had passed from HIV. The researchers then found that the
two samples were completely different, showing that the virus had evolved very rapidly, creating
different strands. This alarmed the researchers because they knew that if there was such a large
gap between the two samples that were only a year apart, it meant that the original virus had
deep roots. By studying a number of additional samples, the scientists were able to come up with
a growth rate for the virus, along with a statistical evolutionary model to figure out different
strands and its origins. With much patience, the scientists found that HIV-1/M, the common
strand of HIV that has infected millions of people, first took its course in 1908.
In an effort to find its common ancestor, HIV has been traced back to Africa because
scientists found that the gorillas and chimps living there were infected with the virus. Having
said this, many chimps in west-central Africa are infected with the virus HIV evolved from: the
Simian Immunodeficiency Virus, or SIV (Berkeley, 2008). Unfortunately in west-central Africa,
along with other places, people hunt and butcher these chimps for food. Scientists found that the
virus must have first made its leap to humans when a hunter came into contact with a chimp in
Cameroon. HIV then made it’s way along the Sangha River to Kinshasa, the place where the
tissue sample taken from the woman in 1960 originated. From there the virus began to evolve
rapidly, and around 1950, through travelling and meat sold in the marketplace, HIV spread
throughout the world!
The evolution of SIV to HIV is important to microbiology because it gave the world,
which at the time was fearful of a “gay disease,” a closer look at what the virus really is, how it
is contracted, and the course it takes in its hosts. By following the phylogeny of SIV/HIV,
scientists have learned how quickly viruses can mutate. Consequently, that is why the search for
a cure has been so difficult. With more and more discoveries on HIV each year, scientists and
researchers are slowly making advances to decode the mysteries of not only HIV, but many other
nasty viruses as well.
Reference
http://evolution.berkeley.edu/evolibrary/news/081101_hivorigins