History of the origin of HIV infection

The origin of the human immunodeficiency virus (HIV) has been the subject of scientific research and debate since its identification in the 1980s. There is now a wealth of evidence about how, when and where HIV first began to cause disease in humans. Read our article and you will learn everything about the origin of HIV infection.

HIV from monkeys?

HIV is a type of lentivirus that attacks the immune system. Similarly, simian immunodeficiency virus (SIV) attacks the immune system of primates.

Research has shown that HIV is related to the simian immunodeficiency virus, and there are many similarities between the two viruses.  Thus, HIV-1 is closely related to the SIV strain found in chimpanzees, and HIV-2 is closely related to the SIV strain found in the smoky mangobey.

In 1999, researchers discovered a strain of SIV (called SIVcpz ) that was almost identical to HIV in humans. Based on this, the researchers concluded that chimpanzees are the source of the HIV-1 virus.

During the same period, scientists conducted additional research into how SIV may have evolved in chimpanzees. They found that the chimpanzees hunted and ate two species of smaller monkeys—smoky mangabeys and white-nosed monkeys. They were the ones who infected chimpanzees with two different strains of SIV.

Then two different strains of SIV combined to form a third virus (SIVcpz), which was carried by chimpanzees. This strain also turned out to be infectious to humans.

How did HIV spread from chimpanzees to humans?

The most common theory is the "hunter" theory. It is based on the fact that the SIVcpz , found in chimpanzees, was transmitted to humans as a result of eating monkey meat or getting chimpanzee blood into cuts or wounds of humans during hunting. Despite the fact that the human body initially fought the simian immunodeficiency virus, the virus gradually adapted to new conditions and turned into HIV-1.

There are 4 main groups of HIV strains (M, N, O and P), each with a slightly different genetic structure. The Hunter theory explains that each time SIV jumped from chimpanzees to humans, it evolved slightly differently in humans and produced different strains. This explains the emergence of more than one strain of HIV-1.  

The most studied strain of the human immunodeficiency virus is group M HIV-1, since this strain has spread throughout the world and is the cause of the vast majority of HIV infections today.

When and where did HIV originate in humans?

Studies of the earliest samples of HIV have given scientists insight into when the virus first appeared in humans and how it evolved. 

The first confirmed case of HIV infection was a blood sample taken in 1959 from a man living in Kinshasa in the Democratic Republic of Congo. The sample was retrospectively analyzed and HIV was detected.  

Using the earliest known sample of HIV, scientists were able to determine where the virus originated. Researchers have concluded that the first case of HIV infection in humans occurred around 1920 in Kinshasa, Democratic Republic of Congo.

It is also in this area that the greatest genetic diversity of HIV strains in the world has been found. Many of the first cases of AIDS were reported there.

In parallel with the active spread of HIV in Kinshasa, the sex trade was gaining momentum in the same city. Thus, by 1937, HIV had reached Brazzaville, about 120 km west of Kinshasa. By 1980, the spread of HIV infection had spread far beyond the Congo.

In the 1960s, subtype B of HIV-1 (subtype M strain) emerged in Haiti. During this time, many Haitian professionals working in the colonial Democratic Republic of the Congo in the 1960s returned to Haiti. Initially, they were blamed for causing the HIV epidemic.

Today, HIV-1 subtype M is the most geographically widespread HIV subtype in the world. By 2014, HIV-1 M caused 75 million infections.