Scientists have developed an effective treatment strategy against the Simian Immunodeficiency Virus (SIV) in rhesus macaques, an advance that may lead to a new therapy for HIV infection in humans.
Simian Immunodeficiency Virus (SIV) infects different primate species and is regarded as the origin of the HIV.
In the study by an international research team, including scientists from the German Primate Centre (DPZ), SIV-infected rhesus macaques were treated with an antiretroviral drug for 90 days and in addition they were treated with a specific antibody for 23 weeks.
After finishing this therapy, all macaques showed sustained control of the infection as almost no SI viruses could be detected in the blood and gastro-intestinal tissues.
The CD4+ T cells that are essential for the immune system were present in sufficient numbers in these tissues.
Two years after finishing the treatment the viral load remained low, the immune system intact, and the rhesus macaques healthy.
The strategy offers a new and promising approach to the therapy of HIV infections in humans, researchers said.
Antiretroviral therapy is currently the most frequently used treatment of HIV infections. The drugs effectively block the proliferation of the HI viruses in the infected cells and thus delay the onset of the disease.
However, these drugs have to be administered permanently since their discontinuation would immediately lead to virus rebound in the body.
"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," said Lutz Walter, head of the Primate Genetics Laboratory at DPZ.
The focus of the study conducted in the US under the leadership of scientists from the Emory University School of Medicine and the National Institutes of Health (NIH) was on the MHC class I genes as well as the genes of the killer cell immunoglobulin-like receptors (KIR).
Both gene families are essential for a functional immune system as well as for immunological identity of an organism.
The antibody that was used to treat the macaques is a primatised variant of the therapeutic monoclonal antibody that is known as Vedolizumab and has been available since 2014 in the US and Europe.
It is administered to patients to treat chronic inflammatory bowel diseases such as Crohn's and ulcerative colitis where the CD4+ T cells also play an important role.
The scientists are seeking to test the new treatment strategy in clinical trials with HIV patients. A phase-I clinical trial is already underway in the US.
The aim is to find out whether a combination of antiretroviral therapy with Vedolizumab has the same effect in humans, researchers said.
"We have good reasons to believe that the therapy will work similarly in humans. It would be a breakthrough for the future treatment of HIV patients," said Walter.
The study was published in the journal Science.
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