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New advances in AIDS research Antibodies protect monkeys six months before HIV
Scientists from the United States may have made great progress in AIDS research: They injected monkeys with a specific HIV antibody, which then protected the animals for several months from infection with the dreaded virus. German experts see the results as promising against the news agency "dpa" because the new approach 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 immunodeficiency syndrome AIDS: Scientists from the USA were able to show in a new study, which enormous effect the use of special antibodies can have. For their project they injected macaques once a certain type of antibody and then brought the animals again each week with a variant of the HI virus in contact. This brought an amazing result, because the antibody therapy protected the monkeys from infection. Researchers around Malcolm Martin from the National Institute for Allergy and Infectious Diseases in Bethesda, Maryland, in the journal Nature reported that the animals had been immunized for up to 23 weeks.
Passive immunization with special antibodies could be a medical breakthrough in the fight against AIDS. (Image: jarun011 / fotolia.com) In passive immunization, the organism remains inactive
A particularly high efficacy showed an antibody whose half-life was previously extended by chemical changes, the researchers write. The term "half-life" refers to the period of time the body takes until it has excreted one active ingredient in half. Macaques that had received this substance were therefore immune to the virus for an average of 14.5 weeks. On the other hand, monkeys that had not been treated became infected with the HI virus after three weeks on average.
The method used is called "passive immunization". This works in contrast to an active vaccine (for example against measles or flu) without involvement of the body's defense system. Here a suitable antibody concentrate is injected, which provides for immediate immunity against certain pathogens. The organism does not have to act on this variant itself, but it is for a while as protected as if the immune system had formed the antibodies themselves. In an active immunization, however, a part of the corresponding virus is administered, whereupon the body reacts to the substance ("immune response") and even developed 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 resistance, this could represent a breakthrough, according to the expert. "Passive transmission of antibodies appears to be more effective than previously tested vaccines," adds Altfeld. Already last year, a team of US and German researchers had successfully tested human immunotherapy for HIV for the first time. At that time it was shown that even the single injection of the broadly neutralizing antibody "3BNC117" could significantly reduce the amount of HIV virus in the blood of infected subjects.
Researchers are guided by strategies to protect against hepatitis A.
The HIV researcher Gerd Fätkenheuer from the University of Cologne also regards the results of the US colleagues and the method of passive immunization as promising: "This is the first time that it has been shown that a single dose of antibodies can protect in the longer term," said the expert the news agency. For so far, such a protection could only be established if the injection of the antibody took place directly before the contact with the HI virus. In developing their new method, the experts used successful approaches to protect against hepatitis A..
In the field of research, three different ways to protect against HIV infection are currently being investigated. On the one hand the passive immunization with antibodies, which are administered as an infusion as well as the active vaccination, which triggers an own reaction of the immune system. The third approach is the preventive administration of drugs, which is already used in high-risk groups in the United States. (No)