For the third time, doctors have managed to rid an HIV patient of the virus through a stem cell transplant. The “Düsseldorf patient” – like the “London patient” and the “Berlin patient” before them – remained virus-free after the therapy. This treatment is only possible for a few patients. Nevertheless, an infection with the dreaded HI virus is no longer a death sentence, at least not in industrialized countries. Antiretroviral drugs give most of those affected a life expectancy comparable to that of people without HIV. So is HIV defeated?
The abbreviation HIV stands for “Human Immunodeficiency Virus”. The HI viruses, which belong to the retroviruses, weaken the body’s own defense system; they mainly affect the CD4+-Helper T cells. Shortly after infection, the pathogens multiply rapidly, often leading to mild, flu-like symptoms, which usually resolve after a few weeks.
As an immune response to the HI virus, the body produces specific antibodies that can usually be detected in the blood no later than three months after infection. This is usually followed by a symptom-free latent phase that can last for months or even years. However, the HI virus multiplies in the body during this time and gradually damages the immune system.
Without treatment, the immune deficiency progresses, with initially non-specific symptoms such as a runny nose, fever or cough. This is followed by so-called opportunistic infections, such as pneumonia, tuberculosis, abscesses – the pathogens use the “good chance” of the weakened immune system to multiply. This final stage of HIV infection, in which an otherwise harmless cold can kill, is known as AIDS (“Acquired Immune Deficiency Syndrome”).
The HI virus is transmitted through bodily fluids such as blood, semen, vaginal secretions or the fluid film on the intestinal mucosa. If such bodily fluids come into contact with mucous membranes – for example, in the vagina, on the penis or in the anus – the viruses can spread from body to body. Therefore, unprotected sex, including anal sex, is the most common route of transmission.
Another major route of transmission is the exchange of syringes or needles during intravenous drug use. Here, HI viruses can enter the blood directly without passing through the mucous membranes. This can also occur as a result of injuries from contaminated medical instruments, posing a particular risk to medical personnel. HI viruses can also enter the blood directly through contaminated blood supplies; this risk is particularly high in countries that do not have the same technical standards as industrialized countries.
Another way of transmission is during pregnancy or breastfeeding from the infected mother to the child. This risk is particularly high during childbirth, but can be greatly reduced with medication and experienced medical personnel.
AIDS was first described as a new clinical picture in 1981, although the cause of the disease was not known at that time. Two years later, Luc Montagnier and Françoise Barré-Sinoussi of the Institut Pasteur in Paris succeeded in isolating HI viruses from a patient’s blood and thus identifying the pathogen. The two virologists were awarded the Nobel Prize in 2008 for this.
The HI virus is most likely a zoonosis, ie a virus that has jumped from animals to humans. It is believed to have spread from monkeys to humans in the early 20th century and then spread through intravenous injection treatment of tropical diseases. The first person in whom an HIV infection could be detected with a blood sample from 1959 came from what was then the Belgian Congo. Only humans get the virus; Chimpanzees can be infected, but do not get sick.
Since the early 1980s, the virus has spread rapidly around the world, causing a pandemic that is estimated to have killed about 40 million people so far. Today (as of 2021) there are 38.4 million people around the world who are infected with the HI virus or who have already developed AIDS. Of these, 28.7 million have access to antiretroviral therapy – significantly more than in 2010, when there were only 7.8 million.
The situation is particularly serious in sub-Saharan Africa. In 2018, approximately 25.6 million people were HIV-positive there. In some African countries, more than 10 percent of 15 to 49-year-olds are infected, in South Africa, Botswana, Eswatini and Lesotho even more than 20 percent. Although the number of new infections is decreasing in Africa, it increased by 29 percent in Central Asia and Eastern Europe between 2010 and 2018.
According to the latest figures, approximately 17,350 people are living with HIV in Switzerland. Of the HIV-infected people living in Switzerland in 2021, 93 percent received a corresponding diagnosis. Of the people who knew about their infection, 96 percent received drug therapy for HIV. 97 percent of people who received such therapy had a viral load below the detection limit – they can no longer pass on the virus.
Antiretroviral therapy can now significantly extend the life expectancy of HIV-infected people. However, it is not possible to completely get rid of the virus with this treatment and thus achieve a cure. Therapy should therefore be continued to prevent the development of resistance.
The treatment is a drug combination therapy consisting of at least three antiretrovirals (highly active antiretroviral therapy, HAART). Their purpose is primarily to prevent the onset of the AIDS syndrome and restore cellular immunity. Successful HAART lowers the concentration of the HI virus in the blood below the detection limit. Then the number of CD4 increases+helper T cells, which steadily decline over the course of untreated HIV infection. The immune system is therefore more resistant to opportunistic infections and other diseases that typically occur in AIDS.
The HI virus quickly develops resistance to individual drugs, so therapy must combine at least three antiretroviral drugs. In current medications, these are combined in one tablet to be taken once a day. Currently, intake should be lifelong and as uninterrupted as possible. The current generation of medicines usually has only minor side effects, such as headache, diarrhea or nausea, which usually pass quickly or can be prevented by changing the combination of active substances.
A major advantage of antiretroviral therapy is that it has a preventive effect against the spread of HIV by lowering the viral load – ie the concentration of HI viruses in the blood. People who are infected with HIV and who are treated successfully no longer pass on the virus.
In contrast to drug-based antiretroviral therapy, complete cure of HIV infection seems possible with stem cell transplantation: this method was the only one that resulted in three patients becoming virus-free. However, it has not been successful in other HIV-infected patients; why is still unclear. Before this procedure can be widely applied, serious obstacles still need to be removed.
As in the other two cases, the “Düsseldorf patient”, whose recovery the research team at the University Hospital of Düsseldorf reported in the journal “Nature Medicine”, had cancer in addition to the HIV infection. Until now, stem cell transplantation has only been used as a high-risk therapy for HIV patients with other life-threatening illnesses. It is an aggressive method with a high risk of serious side effects or even death. This is because the body’s own immune system must first be completely destroyed before the stem cells can be transplanted. In this phase, viruses already present in the body, such as herpes pathogens, can break out. In addition, the stem cell transplant can also target the recipient’s body and cause tissue damage, for example.
As in the other two cases, the stem cells used for the “Düsseldorf patient” had a specific gene mutation called CCR5Δ32. It is a very rare mutation that mainly occurs in people from Northern and Central Europe. As a result, the affected people’s immune cells have no docking point for the HI virus – meaning the virus cannot enter and infect the surface of the cell. Carriers of this mutation are therefore almost completely resistant to HIV.
The transplant transfers this genetic change with the stem cells from the donor to the recipient. The “Düsseldorf patient”, a 53-year-old man, was diagnosed with acute myeloid leukemia in 2011 – three years after his HIV diagnosis. The stem cell transplant he received in 2013 should prevent both blood cancer and HIV infection.
Stem cell therapy even resulted in a reduction of HIV symptoms. Five years after the transplant, the research team was able to discontinue antiviral HIV therapy. Since then, monitoring of the patient’s health has shown that the symptoms are constantly disappearing – doctors say that the man is completely cured.
However, such therapy is currently only possible for a few patients: on the one hand because the number of suitable donors with the mutation is so small; on the other hand, because a stem cell transplant can only be used in the context of the treatment of other life-threatening diseases – such as cancer – because of the many risks involved. Toni Cathomen of Freiburg University Hospital believes that the risk currently associated with a stem cell transplant is unacceptable for HIV-infected people who, thanks to well-adapted therapy, have a life expectancy comparable to that of the general population.
The Düsseldorf research team hopes that their study will show ways to treat HIV in the future through the transplantation of gene-edited stem cells for infected people without cancer. For example, the mutation would be introduced using gene scissors such as Crispr/Cas and combined with strategies that reduce the body’s HIV reservoirs.
According to Jürgen Rockstroh of the University Hospital Bonn, there is still a long way to go. An extension of the therapeutic approach for HIV-infected people without cancer remains unrealistic for the time being. “One problem here seems to be that with the right gene therapy approaches, all cells should then show the CCR5 gene mutation,” explains Rockstroh. However, this is not necessarily achievable for all cells, so that there always remains a reservoir of cells that have not been modified by gene therapy.
Nevertheless, it should show promise to continue gene therapy approaches in research. According to Boris Fehse of the University Hospital Hamburg-Eppendorf, these approaches include protecting blood cells against HIV. It is even conceivable to excise the virus from infected cells.
In any case, the great advantage of the genetic approach would be that healing is possible after a single use of the gene scissors. In this way, the antiretroviral therapy can be discontinued and the patient will not have to take medication for the rest of his life.
With material from the SDA news agency.
source: watson
I’m Maxine Reitz, a journalist and news writer at 24 Instant News. I specialize in health-related topics and have written hundreds of articles on the subject. My work has been featured in leading publications such as The New York Times, The Guardian, and Healthline. As an experienced professional in the industry, I have consistently demonstrated an ability to develop compelling stories that engage readers.
