Will broad-spectrum antibodies help to defeat HIV?
American scientists have found a weak link in HIV protection
Copper news
American scientists have managed to identify previously unknown broad-spectrum antibodies in the blood of an HIV-infected patient from Africa that can bind to the shell of a large number of varieties of the immunodeficiency virus, The New Scientist reports. Until recently, scientists have known only four types of such antibodies, and all of them were discovered more than ten years ago.
According to scientists, the antibodies they found bind to the HIV envelope in a new, previously unknown way. These data pave the way for the development of fundamentally new vaccines against HIV infection.
The study, conducted with the support of the International AIDS Vaccine Initiative (International AIDS Vaccine Initiative), included several stages. First, the staff of the California Scripps Research Institute in California collected and studied blood samples of 1800 HIV patients from different regions of the world. A variety of HIV antibodies were found in approximately 10 percent of donors, but most of them protected the human body from only a small number of known varieties of the virus.
After preliminary tests, a blood sample of a patient from Africa was selected for a more thorough examination. Two antibodies, called PG9 and PG16, were isolated from the African's blood. These antibodies neutralized more than 75 percent of the one and a half hundred strains of the immunodeficiency virus tested on them.
As further studies have shown, antibodies produced by the African immune system were bound to a well–known fragment of the envelope of the immunodeficiency virus - glycoprotein gp120, which forms protrusions, or needles, on the surface of the viral particle.
This compound is one of the most stable structures of the virus envelope, so it has long attracted scientists as one of the most likely targets for experimental vaccines against HIV infection. However, the use of such vaccines is complicated by the fact that this fragment of the shell is reliably protected from external influences.
According to the authors of the new study, unlike all currently known antibodies against HIV, PG9 and PG16 interact not with single gp120 molecules, but with a three-dimensional structure formed by three molecules of this glycoprotein. This previously unknown type of interaction allows antibodies to recognize and bind an unusually large number of HIV strains.
According to the coordinator of the research project Wayne Koff (Wayne Koff), a new target for antibodies against HIV is the main discovery of researchers. Using data on the fundamentally new interaction of antibodies with the virus, scientists can find new approaches to the development of vaccines against HIV infection, efforts to create which until recently have been unsuccessful. New and more effective vaccines may stimulate the production of antibodies attacking the three-dimensional structure formed by gp120 molecules.
Scientists believe that taking into account the new data, in the near future they will be able to detect other types of antibodies capable of neutralizing the immunodeficiency virus. Preparation of the relevant study is currently underway at the Scripps Institution. The Institute's staff intend to collect and study as many blood samples as possible from a small subgroup of HIV patients with as yet unexplained resistance to the virus. Unlike the vast majority of patients, these people do not need antiretroviral therapy to prevent the development of AIDS: many years after infection, the concentration of virus particles in their blood remains at a minimum level, which suggests that the immune system of patients somehow suppresses the infection.
The research report is published in the journal Science.
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