New progress in AIDS research: Antibodies protect monkeys from HIV for six months

New progress in AIDS research: Antibodies protect monkeys from HIV for six months

Passive immunization prevents the animals from being infected with the HI virus
Scientists from the United States may have made great progress in AIDS research: they injected monkeys with a special HIV antibody, which then protected the animals from being infected with the dreaded virus for several months. German experts rate the results with the news agency "dpa" as promising, because the new approach currently seems to be more effective than the vaccines tested so far.

Monkeys immune for up to 23 weeks
New hope in the fight against the immune deficiency disease AIDS: Scientists from the USA were able to show in a new study the enormous effect that the use of special antibodies can have. For their project, they injected macaques once with a certain type of antibody and then brought them back into contact with a variant of the HI virus every week. This brought an astonishing result because the antibody therapy protected the monkeys from infection. As the researchers led by Malcolm Martin from the National Institute for Allergy and Infectious Diseases in Bethesda (Maryland) report in the journal “Nature”, the animals were immunized for up to 23 weeks.

With passive immunization, the organism remains inactive
One type of antibody, whose half-life was previously extended by chemical changes, was particularly effective, the researchers write. The term “half-life” is the technical term for the time it takes the body to have half of an active ingredient excreted. Macaques that received this substance were therefore immune to the virus for an average of 14.5 weeks. Monkeys that had not been treated, on the other hand, contracted the HIV virus after an average of three weeks.

The method used is called "passive immunization". In contrast to an active vaccination (e.g. against measles or flu), this works without the involvement of the body's defense system. A suitable antibody concentrate is injected here, which ensures immediate immunity to certain pathogens. With this variant, the organism does not have to act itself, but it is protected for a while as if the immune system had formed the antibodies itself. With active immunization, on the other hand, part of the corresponding virus is administered, whereupon the body reacts to the substance (“immune response”) and develops antibodies against it.

Disadvantage: The antibodies must always be re-administered
The problem with passive immunization is "that the antibodies are broken down by the body and have to be given again and again," explains Marcus Altfeld from the Heinrich Pette Institute of the University of Hamburg in an interview with the "dpa". However, if it were possible to develop antibodies with a very high level of resistance, this could be a breakthrough, according to the expert. "The passive transfer of antibodies seems to be more effective than previously tested vaccines," adds Altfeld. Last year, a team of US and German researchers successfully tested human immunotherapy against HIV for the first time. At that time it was shown that the single injection of the broadly neutralizing antibody “3BNC117” was able to significantly reduce the amount of HIV viruses in the blood of the infected test subjects.

Researchers are guided by strategies to protect against hepatitis A
HIV researcher Gerd Fätkenheuer from the University of Cologne also sees the results of the US colleagues and the method of passive immunization as promising: "It is shown here for the first time that a single administration of antibodies can provide long-term protection," the expert told the news agency. Until now, such protection could only be built up if the antibodies were injected directly before contact with the HI virus. When developing their new method, the experts followed successful approaches to protection against hepatitis A as a model.

Research is currently investigating three different options for protection against HIV infection. On the one hand, passive immunization with antibodies that are administered as an infusion and the active vaccination, which triggers a reaction of the immune system. The third approach is the preventive administration of medication, which is already used in high-risk groups in the USA. (No)

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