How did AIDS develop?

The origin of AIDS

Where does the AIDS virus (HIV) come from, through what channels it reaches the human body and infects humans, etc., has always puzzled people. Through investigation, research and analytical reasoning, researchers finally gave more confirmation to one of the hypotheses, and various new signs emerged in the development of AIDS.

Origins and Hypotheses

On June 5, 1981, the U.S. Centers for Disease Control and Prevention (CDC) reported that five healthy gay men in the Los Angeles area suffered from Pneumocystis Carinii. parasitic pneumonia (PCP). Later, similar patients were discovered in other parts of the United States. After the CDC cautiously re-evaluated the disease, it believed that it was a new epidemic. By the end of 1982, more than 800 similar cases had been reported in more than 30 states in the United States alone. Related symptoms also included Kaposi's sarcoma (KS), mucosal albicans candidiasis, and disseminated cytomegalovirus infection. Since then, this new disease has spread around the world, and patients have a unique characteristic. The immune system, especially thymic T lymphocytes, has been severely damaged. It was not until 1982 that professionals named this disease that mainly damages the human immune system Acquired Immune Deficiency Syndrome (AIDS). HIV destroys human immunity and causes various clinical symptoms.

Where did HIV originate? There are three main hypotheses, namely the natural theory, the iatrogenic theory and the man-made theory. The natural theory holds that HIV evolved naturally and infected humans by chance. The more popular view is that HIV originated from chimpanzees or green monkeys in Africa. Medical sources believe that humans used contaminated chimpanzee organs and tissues when producing polio vaccines and were infected during vaccination. There are several views on the artificial theory. One is that HIV is a biological weapon created by the CIA, the second is that it is a disaster caused by genetic engineering, and the third is that HIV is a remnant of the Nazis or an attempt by some crazy scientist. The product of committing genocide and establishing a new world order.

However, with the deepening of research and investigation, professionals have denied the latter two statements and affirmed the former one. In the hypothesis that HIV evolved naturally, researchers also believe that HIV-1 came from African chimpanzees, while HIV-2 came from African mangabeys.

Time of origin and HIV-2

There are three early human specimens infected with HIV. They were plasma from an adult male living in the Democratic Republic of the Congo collected in 1959, human tissue specimens from an African-descended man who died in St. Louis, USA, in 1969, and another who died in 1976. Human tissue specimens from Norwegian sailors.

In 1998, the Allen Dimon AIDS Research Center, led by the famous Chinese American scientist Dayi Ho, conducted research and analysis on plasma samples collected in 1959. They believe the HIV found in the man, who lives in the Bantu tribe of Africa, is the ancestor of the HIV subtype currently circulating around the world. Judging from its degree of evolution, HIV should have infected humans not too long ago before 1959. It was around the 1940s or early 1950s.

In January 2000, Dr. Bette Cobb of the Los Alamos National Laboratory in the United States collected various data, established a complex mathematical model, and then used a computer to simulate the evolution process of HIV, and obtained It was concluded that HIV entered the human body between 1910 and 1930. The setting is West Africa. He believes that the time error of his conclusion is 20 years.

Prior to this in 1986, Montagnier of France, one of the discoverers of HIV, had isolated HIV-2 from AIDS patients in West Africa.

On May 12, 2003, Belgian biologist Van Damme analyzed samples from HIV-2 infected people collected from Canchungo, a small town in Guinea-Bissau, and compared them with SIV (Simian Immunodeficiency) of local mangabeys. viruses) and concluded that HIV-2 infected humans in 1940 and 1945. Among them, HIV-2A was transmitted from black and white mangabeys to humans around 1940, while HIV-2B was transmitted from black and white mangabeys to humans around 1945.

Due to historical wars and slave trade, blood transfusions and sex trade were prevalent, which led to the widespread spread of HIV-2. For example, in 1966, the first case of infection due to blood transfusion occurred in Guinea-Bissau. HIV-2 cases. Moreover, Guinea-Bissau's War of Independence (1963-1974) coincided with the beginning of the HIV-2 epidemic.

Where did HIV-1 come from?

On June 13, 2003, American researchers published an article titled "The Mixed Origin of Chimpanzee SIV Viruses" in Science magazine, arguing that The predecessor of HIV-1 is a simian immunodeficiency virus (SIV) in chimpanzees, and SIV may be the product of recombination of two other SIV viruses in different monkeys. Various monkeys in Africa carry different SIV viruses. Scientists from the United States, Britain and France conducted a comparative genome analysis of these viruses and the SIV virus in chimpanzees and found that the SIV virus, the precursor of human AIDS, is likely to be two types of viruses in the red-crowned white-faced monkey and the great spotted nose monkey. Recombinant SIV virus.

The specific pathway is speculated to be that chimpanzees were infected with two SIV viruses by preying on red-crowned white-faced monkeys and great spotted-nosed monkeys. It is possible that these two viruses recombined in chimpanzees to produce new SIV viruses. Humans may have been infected with the SIV virus while hunting chimpanzees, which eventually evolved into HIV-1, which is currently circulating around the world. HIV-2 may have originated directly from the SIV virus in a monkey in West Africa, without going through the chimpanzee link.

Recently, researchers have further confirmed through studies that HIV-1 originated from SIV in chimpanzees in West Africa. Researchers such as Beatrice Hahn of the University of Alabama collected blood samples from a subspecies of chimpanzee in Cameroon. They knew that several captured chimpanzees of this subspecies had been confirmed to carry SIV, which is almost identical to human HIV-1, but they acknowledged that they did not know why the animals had SIV. The discovery confirms long-standing suspicions that wild animals are the natural hosts of HIV, and supports a hypothesis of the origin of AIDS, namely that the first AIDS patients were infected through contact with contaminated blood from chimpanzees in the jungle, and the virus eventually spread from The spread began near Kinshasa in the Democratic Republic of Congo and then spread across the globe.

Hahn and others speculate that the way HIV-1 spreads is that local Africans hunted and slaughtered chimpanzees and were infected with SIV, and SIV evolved into HIV-1 in the human body. This inference is based on biology. SIV in chimpanzees is very similar to HIV-1 in humans, which means humans contracted the virus directly from chimpanzees. This refutes previous inferences by some experts that humans and chimpanzees contracted HIV from monkeys. And how did the chimpanzees become infected with monkey HIV? It can only be inferred that the chimpanzees acquired it when they preyed on monkeys.

In 1959, the first human HIV-positive blood sample was found in Kinsasha, the capital of the Democratic Republic of the Congo. This was the first discovery of HIV-1 in humans. The specific inference can only be that there is a transportation channel from southern Cameroon to Kinshasa, through which many substances from the West African jungle, including wild animals, appear on the market. So SIV came from the jungle to the human world through this way, and evolved into HIV-1. This may be the best explanation at present, but there are still many questions and details in these links, which require more research to confirm in the future.

AIDS may not be an incurable disease

Today, humans have a better understanding of AIDS. The most important thing is that AIDS is not an incurable disease. Because some people Carries HIV but never gets sick. This is also the same characteristic as chimpanzees carrying SIV but not getting sick.

Through analysis of blood samples, Hahn and others discovered the presence of anti-SIV antibodies in chimpanzees and traced the genetic sequence of the virus. On this basis, researchers estimate that about 30% to 35% of chimpanzees are SIV carriers. Surprisingly, these viruses did not cause any AIDS-like illness in the chimpanzees because the captured chimpanzees did not contract immunodeficiency diseases.

Similarly, some people in humans are infected with HIV but do not develop the disease. In the late 1980s, some Canadian and British researchers conducted surveys in the Nairobi area of ??Kenya and found that some women engaged in sexual services were not infected with AIDS despite suffering from syphilis, gonorrhea, etc. A woman named Salome was in her 40s. Her partners who were engaged in sexual services all died of AIDS one by one, and one of Salome's daughters also died of AIDS, but she is still very healthy so far. This shows that Salome's immunity to AIDS is not necessarily hereditary. What is the reason?

Researchers believe that the reason is that their sexual service behavior itself creates resistance to HIV in the reproductive tract. Because once Salome's partners stop working as sex workers and go home, their immunity will decline, and they will contract AIDS when they resume work. At the same time, HIV could also infect their blood samples during the experiment, indicating that they were only immune to sexual transmission. In other words, HIV is eliminated in the reproductive tract before it enters their bloodstream. This leads to a possible explanation that excessive sexual activity can stimulate the reproductive tract to produce powerful antibodies to HIV.

After following a group of Kenyan prostitutes, researchers from the University of Oxford in the UK and the University of Nairobi in Kenya have developed a new vaccine and are conducting trials. However, this vaccine must be injected frequently to be effective. This problem It itself provides a clue that no matter what method is used, it is possible to stimulate the body to produce strong immunity to resist AIDS, so vaccines and drugs can be developed to combat AIDS.

Of course, some people are not susceptible to AIDS due to genetic reasons. For example, the CCR5 gene on the short arm of human chromosome 3 is directly related to the entry of HIV into human immune T cells. When a 32-base deletion occurs after amino acid No. 185 in the CCR5 gene coding region (called CCR5-32 mutation), a shortened, non-functional membrane-penetrating protein will be produced on the cell membrane surface, and HIV cannot enter human cells. Only those who have 32 bases deleted from the CCR5 gene in the human body (CCR5 gene mutation) can obtain a natural barrier against HIV.

All these discoveries provide directions for thinking and action for mankind to ultimately defeat AIDS.

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