Found vaccination protects monkeys from HIV infection

Hope for effective protection against HIV infection

02/19/2015

HIV is still one of the most feared infectious diseases. So far, there is no vaccine that protects against infection with the HI virus. Researchers led by Matthew Gardner at The Scripps Research Institute, Jupiter, Florida, have now successfully used a combined protein molecule that docks to the surface of the virus, thereby protecting the host cell from infection, in monkeys. Like the researchers in the trade magazine „Science“ report that the molecule is more effective than so-called broadly neutralizing antibodies, which are also considered promising for vaccination. Macaques have been protected from infection by the protein molecule for months because it has neutralized many HIV-1 variants.

Novel vaccine neutralizes many variants of HIV
An HIV infection proceeds as follows: After the HI viruses have invaded an organism, they bind to certain docking sites on the surface of the host cells. Only then will the cells be infected and the virus propagated. Binding antibodies to different parts of the virus can theoretically protect them from infection. However, as the HI virus permanently changes shape and in this way outwits the immune system, even broadly neutralizing antibodies targeting the immutable regions of the virus and thus effective against a variety of HIV strains can not protect against all types of viruses , This is also one of the main reasons for the difficulties in developing an effective vaccine.

Gardner and his team made a protein that mimics two important docking sites for HI viruses, the CD4 + receptor and the CCR5 coreceptor, on the host cells. The matching binding sites on the virus are two of the least variable structures of the viruses. As it turned out, the new protein the scientists called eCD4-Ig inhibits the multiplication of viruses. It protected the researchers from all HIV-1 variants tested.

Untreated monkeys contracted HIV infection, but not treated animals
After further studies with mice, CD4-Ig was tested on four macaques. However, the animals did not receive the vaccine protein directly, but rather produced it themselves after being given a genetically engineered virus. A total of ten experimental animals received regular doses of monkey immunodeficiency virus with the coat protein of HIV-1 for several weeks.

It turned out that all monkeys that did not previously receive the eCD4-IG protein reacted with an infection. In the treated four macaques, on the other hand, no infection occurred. The protection continued beyond the experimental period of 34 weeks.

„Our data suggest that eCD4-Ig proteins produced by adeno-associated viruses may function as an effective HIV-1 vaccine“, the researchers write „Nature“.Although there were many challenges, their results suggested that eCD4-Ig could provide effective protection against HIV-1.

Further studies on the novel vaccine protection against HIV necessary
US researcher Nancy Haigwood from the Health & Science University at Beaverton, Oregon, is less optimistic about her colleagues' findings. Thus, the number of experimental animals is very low. In addition, the administration of HI viruses was intravenous, which, while the strictest test for the protective effect, but does not reflect the most common natural route of infection via the mucous membranes. It has to be investigated if the protein works there as well.

„I generally think it is a sensible strategy not to develop a classic vaccine, "said Frank Kirchhoff, a virologist and HIV researcher at Ulm University Hospital, to the news agency „dpa“. It was „very elegant ", to have the protein produced in the body, but whether this method also works safely in humans, must be investigated in further studies.