New Antibody Therapy Permanently Blocks HIV-like SIV Infection in Monkeys


An effective treatment strategy against the HIV-like Simian Immunodeficiency Virus (SIV) in rhesus macaques has been developed by an international research team.

Around 36 million people are infected with HIV and a cure for the deadly virus infection has not yet been found according to the WHO. A new treatment strategy against the HIV-related Simian Immunodeficiency Virus (SIV) has been developed by an international research team that includes scientists from the German Primate Center (DPZ), and the Leibniz Institute for Primate Research in Göttingen.

SIV viruses are regarded as the origin of the Human Immunodeficiency Virus and infect different primate species. SIV-infected rhesus macaques were treated with an anti-retroviral drug for 90 days and in addition they were treated with a specific antibody for 23 weeks in the study. All macaques showed sustained control of the infection as almost no SI viruses could be detected in the blood and gastro-intestinal tissues after finishing the therapy.

The CD4+ T cells that are essential for the immune system were present in sufficient numbers in these tissues after two years of finishing the treatment, the immune systems were intact, and the rhesus macaques healthy. The treatment strategy thus offers a new and promising approach to the therapy of HIV infections in humans (Science).

The currently most frequently used treatment of HIV infections is anti-retroviral therapy. The drugs effectively block the proliferation of the HIV viruses in the infected cells and thus delay the onset of the disease. Since their discontinuation would immediately lead to virus rebound in the body, these drugs have to be administered permanently.

Their continuous administration is accompanied by adverse effects such as chronic inflammation, poisoning symptoms and accelerated aging. “The aim of the study was to find a new therapeutic approach for the treatment of infections with immunodeficiency viruses, which would permanently prevent the proliferation of the viruses even after only temporarily application,” says Lutz Walter, head of the Primate Genetics Laboratory at the DPZ and co-author of the publication.


The study was conducted in the US under the leadership of scientists from the Emory University School of Medicine in Atlanta and the National Institutes of Health (NIH), Bethesda, USA. the rhesus macaques received an anti-retroviral drug identical to the ones given to humans from the fifth to the 18th week after infection. This treatment was combined with a specific antibody therapy, from the ninth week, which was repeated at regular intervals of three weeks.

A control group received only anti-retroviral therapy and an irrelevant control antibody. The anti-retroviral therapy was terminated and only the antibody was administered until the 32nd week, whereupon the treatment of the monkeys was halted. “It is known that the SIV and HIV viruses tend to multiply especially in CD4+ T cells of the intestinal mucosa and thereby establish a chronic infection,” explains Lutz Walter. “The specific antibody prevents the entry of these immune cells into the mucosa.

A further spread of the viruses was thereby effectively stopped and the rhesus macaques have controlled the virus infection since almost two years without further medication.”

The viral load and the amount of CD4+ T cells in the animals were determined after the treatment has ended. the virus load was below the detection threshold and the CD4+ T cells count were stable, in the blood and intestinal tissue, indicating a functional immune system. “We have good reasons to believe that the therapy will work similarly in humans,” says Lutz Walter. “It would be a breakthrough for the future treatment of HIV patients.”

In addition to the scientists of the Emory University School of Medicine, the National Institutes of Health (NIH) and the DPZ, researchers of the Center for the AIDS Program of Research in South Africa, the Georgia Institute of Technology College of Engineering, the John Hopkins School of Medicine, the University of Maryland School of Pharmacy, and the University of Michigan were involved in the project.

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