New HIV treatment shows 100% protection in mice “and humans could be next”
An HIV vaccine may be one step closer, after scientists injected mice with a gene that managed to blocked the virus.
Up till now, researchers have tried to train a person”s immune system to develop effective antibodies, which is the first line of defense against disease.
However, the new technique injects genes that produce disease-beating proteins directly into the muscletissue, using the harmless virus (AAV) as a carrier.
Protector: The crystal structure of the harmless adeno-associated virus that was used to deliver protective antibodies to mice
This method was used on lab rats, who carried human immune cells able to grow HIV, before they were exposed to the virus.
Lead author, Alejandro Balazs, from the California Institute of Technology (Caltech), said: “We expected that at some dose, the antibodies would fail to protect themice, but it never did – even when we gave mice 100 times more HIV than would be needed to infect 7 out of 8 mice.
“All of the exposures in this work were significantly larger than a human being would be likely to encounter.”
One great advantage of the method, called Vectored ImmunoProphylaxis, is that it doesn”t exhaust the body”s natural defenses.
“VIP has a similar effect to a vaccine, but without ever calling on the immune system to do any of the work,” Dr Balazs said.
“Normally, you put an antigen or killed bacteria or something into the body, and the immune system figures out how to make an antibody against it. We”ve taken that whole part out of the equation.”
Human blood samples waiting to be tested for the HIV virus at a medical laboratory
The mice produced high concentrations of protective antibodies for the rest of their lives, as shown by intermittent sampling of theirblood.
They even protected the mice from infection when the researchers exposed them to HIV intravenously.
The scientists, whose paper has been published in the journal Nature, stressed that the leap from mice to humans is large.
Still the fact that the mice could produce large amounts of antibodies, coupled with the finding that a relatively small amount of antibody proved protective in the mice, is promising.
“We”re not promising that we”ve actually solved the human problem,” said researcher leader Nobel Laureate David Baltimore.
“But the evidence for prevention in these mice is very clear.”
Dr Baltimore said team is developing a plan to test their method in human clinical trials.
First identified in 1981, AIDS (the last stage of HIV) has claimed at least 25 million lives, although the annual toll is falling sharply from the peak of the pandemic in response to drug treatment.
However, campaigners say a vaccine is still essential. So far, in clinical trials, only one candidate formula has had even a modest effect, providing a shield of only 31 per cent against the risk of HIV infection.
The study was published to coincide with the eve of World AIDS Day.
The number of people living with HIV currently stands at about 34 million, according to the latest UN figures. Almost 100,000 people are living with the disease in the UK.