Scientists have made several advances in the design of a class of HIV vaccines that could offer a extensive protection against the virus, according to four new research works in which they have developed different methods to obtain broad-spectrum neutralizing antibodies.
The results of these still preliminary studies are published in journals Science, Science Translational Medicine and Science Immunology, and in all four they are described new steps in a sequential vaccination strategy to obtain an effective candidate against the HIV virus.
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The experiments were done in rhesus macaques and in mice, and one of the proposals is in phase 1 of clinical trials. Among the authors There are scientists from the American Scripps Research Institute, the University of Louisville and the University of California, San Diego.
The HIV epidemic has entered its fifth decade and the scientific community has dedicated time and resources to developing candidate vaccines against the virus.
However, health authorities They still lack an effective and approved vaccine that induces broadly neutralizing antibodies, capable of neutralizing the most common circulating strains of HIV, recalls a summary from the Science group.
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One solution is a process called germline selection, in which researchers use a series of proteins directed by the immune system (immunogens) to guide and ‘groom’ young B lymphocytes as they mature in places called germinal centers.
The goal is to induce cells to produce broadly neutralizing antibodies against HIV.
HIV symbol.
EFE
José Alcamí, director of the AIDS Immunopathology Unit of the Carlos III Health Institute, points out that the objective of any preventive vaccine is to induce the production of neutralizing antibodies by the immune system and usually the antigen used must include or be formed by the envelope or surface proteins of the virus.
It is these proteins that interact with entry receptors into the cell, Therefore, its blocking by antibodies neutralizes the virus infection, he tells Science Media Center Spain (SMC), a scientific resources platform.
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The difficulty in obtaining a vaccine is given by the structure of the HIV envelope, which makes it very inaccessible to the action of neutralizing antibodies, details the virologist, who is not involved in the studies.
Given the difficulty of generating neutralizing antibodies against HIV, the authors of these new works guide the immune system to generate a specific type of neutralizing antibodies with different immunogens.
First simpler (so that they can be recognized better) and later more complicated and close to the original envelope protein of HIV, details Julià Blanco, head of the Virology and Cellular Immunology group at the IrsiCaixa AIDS Research Institute.
HIV
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The HIV envelope protein has different regions that are recognized by neutralizing antibodies. For a specific region (the CD4 binding site), this strategy had already been used and has even reached studies in humans.
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Now a second region appears (the base of the V3 loop) that can also be used in a similar way. “If both strategies are combined, a greater quantity and diversity of these neutralizing antibodies could be generated (which would make a potential vaccine more effective).“says Blanco, who does not participate in the studies.
Sequential vaccination can be an excellent strategy, but it may require an excessive number of immunogens, which would make it difficult to convert it into a product that reaches the population most in need. “There is much work ahead“, summarizes SMC.
EFE
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