A new way of vaccination completely protected monkeys from HIV despite being injected with four times the dose. This is the first time scientists blocked the virus from infiltrating healthy cells and they are hoping to start a human trial soon.
Previous HIV vaccines failed to stop HIV from spreading to healthy cells because the virus mutates too quickly, but the new method discovered by Michael Farzan, professor of infectious diseases at Scripps Research Institute and his team uses gene therapy to introduce a section of DNA inside the cells. Normally, vaccines only train the immune system to fight an infection, but researchers actually changed the DNA of monkeys to give their cells HIV-fighting properties.
According to the study published in the journal Nature, that new section of DNA gives the cells instructions for manufacturing the tools to neutralize HIV and after that they constantly release the artificial virus killers into the bloodstream. The strategy worked against all of the tested strains, including both HIV-1 and HIV-2 versions that transmit among people, as well as types that only infect monkeys.
The new strategy is based on what experts already know about HIV. The virus looks for a receptor on immune cells called CD4 and locks on it using a specially designed portion of its own viral coat. Then it changes its shape to better slip inside the healthy cell and starts to make more copies of itself. But Farzan’s discovery, called eCD4-Ig, causes the virus to morph prematurely which makes it no longer infectious. The monkeys were protected against very high doses and, so far, the treated monkeys have survived more than a year.
People who already have HIV could be helped to keep levels of HIV down in this way, but it would also protect high-risk individuals from getting infected. But even though the data from the monkeys is encouraging, experts know things change when they deal with humans. The method is still far from being tested on people, as it also needs a different way of introducing the eCD4-Ig complex in the organism.