DNA mimicry might just do the trick for HIV vaccine
The idea is to fool the body into thinking it has been infected - and trial results look very promising
Using genetically modified DNA to trick the body into thinking it has been infected with HIV is one of the trials now under way to protect people if they ever contracted the virus.
It was announced on Wednesday at the HIV Research 4 Prevention (HIVR4P) conference in Madrid, Spain, that two small trials using DNA vaccines to prevent HIV had early promising results.
Injecting genetically modified DNA into a person's body teaches it to make the proteins similar to those created by the HI virus, and this then tricks the body into thinking it has been infected.
The body’s immune system develops the fight against the “HIV” and creates a shield that would protect the person if they ever were really infected with the virus.
This is the concept of a DNA vaccine.
DNA vaccines are different to all the HIV vaccines currently on trial, which inject substances that mimic what parts of the virus look like.
There is not a single DNA vaccine in use for any disease. But many scientists are trialling them, because they are easy and cheap to manufacture.
A DNA vaccine for the Zika virus spread by mosquitoes is also being tested.
Dr Srilatha Edupuganti, associate professor of medicine at Emory University and protocol chair of the HIV Vaccine Trials Network (HVTN) 098 study (DNA vaccines), told Times Select there was still a lot of promise for DNA vaccines since they were easy to create and manufacture.
But she said a problem was that they didn’t usually do enough to encourage the immune system to develop antibodies to fight the diseases.
“DNA vaccines were not approved in the past because they do not lead to strong immune responses.”
But this time, HVTN scientists reported an experimental HIV DNA given to 111 patients provoked better immune system responses than traditional vaccines.
The DNA injection was given four times over a few months. The scientists also used a new form of delivery for the vaccine, moving away from just using injections.
Edupuganti said: “This is a DNA vaccine that is being given via a special method called electroporation.”
A device called a Biojector is used. It makes cell membranes more permeable to DNA with a pulse of electricity.
The device is used “to encourage cells to take up the DNA vaccine”.
They’re administered with a substance found in the body called Interleukin, which stimulates immune cells.
The researchers found only one‐fifth of the dose was needed when using the Biojector compared with when the vaccine was injected into a person’s muscle.
Asked why the HIV Vaccine Trials Network (a global collaboration to find an HIV vaccine) was trying to invent DNA vaccines when other HIV vaccines were further along in trials, Edupuganti said: “There are no licensed HIV vaccines currently. No one knows if the vaccines that are in current trials will actually work. There is lots of promising data to support that they will work, but it is not proven. Several HIV vaccines have failed in field trials in the past.”
The vaccine trials network said in a statement: “We are on a scientific journey to find a safe and effective HIV vaccine to prevent new HIV infections in the future. There are an estimated 5,000 new HIV infections daily around the world.”
Other research at the conference showed that microbiome – all the bacteria in a person’s gut – influenced the immune response to HIV vaccines. The bacteria act on the human immune system.
“We have further evidence that the microbiome is likely impacting vaccine responses, and that these responses may play a role in whether people are protected from HIV or not,” said James Kublin, executive director of the HVTN and principal staff scientist at the vaccine and infectious disease division at the Fred Hutchinson Cancer Research Centre.
At the start of the conference on Monday, Linda-Gail Bekker, UCT professor and deputy director of the Desmond Tutu Foundation, was given the Desmond Tutu award for her work in the prevention of HIV and TB.
She has been involved in numerous trials to try and help young women prevent HIV with gels and antiretroviral pills, and has worked with sex workers and men who sleep with men (MSM), groups that are at a high risk of contracting the virus.
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