Saturday July 21, 2018

Scientists hopeful of ‘full-length single chain’ AIDS vaccine

0
//
280
www.pbs.org
Republish
Reprint

NewsGram Staff Writer

Robert Gallo, the scientist who first proved in 1984 that HIV triggered the disease AIDS, is again all set to begin the trial of its vaccine in the US. The vaccine which has been developed over the past 15 years by Gallo is a little different and is expected to bear fruitful results.

The initial phase, involving 60 volunteers, will test the safety and immune responses of the vaccine. This study will reveal whether the vaccine is more effective than the other 100+ AIDS vaccines that have been tested over the last three decades. Extensive testing on monkeys have yielded positive results.

Despite the presence of potential vaccines, the challenge with AIDS is that HIV directly infects white blood cells (RBC) called T-cells, so it literally turns our immune system against us. So, once the virus enters a T-cell, it’s invisible to the immune system.

The sole possibility to combat the threat is to pump in antibodies against the HIV surface proteins. However, doing so is equally difficult owing to the fact that the retrovirus can regularly change its viral envelope to hide particular surface proteins.

But Gallo and his team at the Institute of Human Virology in USA believe that they may have now found a moment when the HIV surface protein, known as gp120, is vulnerable to detection – the moment the virus binds with our bodies’ T-cells.

When HIV infects a patient, it first links to the CD4 receptor on the white blood cell. It then transitions, exposing hidden parts of its viral envelope, which allow it to bind to a second receptor called CCR5. Once HIV is attached to both these T-cell receptors, it can successfully infect the immune cell. at this stage, it is impossible to stop its juggernaut.

Gallo’s “full-length single chain” vaccine contains the HIV surface protein gp120, engineered to link to a few portions of the CD4 receptor. The motive is to fuel antibodies against gp120 when it is already attached to CD4 and is in a vulnerable transitional state. The aim of the whole process is effectively stopping it from attaching to the second CCR5 attachment.

Gallo himself admitted to Jon Cohen over at Science that full-length single chain vaccine is a “terrible name”.

The trial is being run in collaboration with Profectus BioSciences, a biotech spin-off from the Institute of Human Virology, and Gallo explained that extreme thorough testing on monkey and getting the fund to develop a human-grade vaccine have resulted in a delay to get to this point.

“Was anything a lack of courage?” he asked Science. “Sure. We wanted more and more answers before going into people.”

Let’s hope that caution pays off, and we may finally have a viable contender for an AIDS vaccine on our hands.

(With inputs from www.sciencealert.com)

Click here for reuse options!
Copyright 2015 NewsGram

Next Story

HIV Drug Is Not Linked to Depression: Study

A new study of a popular HIV drug could ease concerns about its link to depression

0
A doctor draws blood from a man to check for HIV/AIDS at a mobile testing unit in Ndeeba, a suburb in Uganda's capital, Kampala.
A doctor draws blood from a man to check for HIV/AIDS at a mobile testing unit in Ndeeba, a suburb in Uganda's capital, Kampala. VOA

A new study of a popular HIV drug could ease concerns about its link to depression. Researchers in Uganda found that efavirenz, once feared to lead to depression and suicide, did not cause the expected negative side effects in their patients.

Efavirenz is an affordable, once-a-day pill used around the globe to treat and prevent HIV/AIDS. It’s “the treatment of choice” in most of the world, according to Africa Health Research Institute’s Mark Siedner, “especially [in] countries that depend on global aid to treat HIV.”

But some fear that efavirenz may come with a cost.

Some studies in the United States and Europe found the drug increased patients’ risk of depression or suicide, although other studies did not.

The mixed results prompted many doctors in the United States to prescribe more expensive but potentially safer drugs.

Siedner wanted to take another look at the risk of depression, this time in an African population. From 2005 until 2015, he and a team of Ugandan and U.S. doctors tracked 694 patients who took either efavirenz or another antiretroviral medication. They regularly asked the patients whether they experienced depression or suicidal thoughts.

No difference

Their analysis, published in the Annals of Internal Medicine, showed there was no difference between the two treatments. Siedner told VOA, “In other words, efavirenz was not associated with a risk of depression. If anything, there seems to be a signal that potentially it was associated with a decreased risk. But it wasn’t a strong enough [signal] for us to say that.”

The authors also reported that of the 17 participants who died in the course of the study, not a single death was a suicide.

Siedner has two possible explanations for why their findings differed from those in Western countries. “One potential cause is that every single ethnic group in the world, of course, is different, and different in many different ways — different socially, different environmentally, and in this case they may be different genetically.” His team is looking at whether the genes that control metabolism of the drug have a role to play in this story.

HIV Aids is a deadly disease.
HIV virus is Not Linked To Depression. Flickr

A second explanation could be the effectiveness of the drug. Because efavirenz is so potent, it could be keeping people healthier than they expected, so patients are less likely to report negative emotions.

The study is important, said Anthony Fauci, who heads the National Institute of Allergy and Infectious Diseases, because it pushes back against “the initial observation of suicidal ideation and suicide and depression” as caused by efavirenz. He told VOA, “I think now what you’re seeing is that with these conflicting reports, it’s likely someone will come in [with] the proposal to do a randomized study and take a look. So the story isn’t ended with this paper.”

As more research on the safety of efavirenz is conducted, new and cheaper drugs that might replace it are on the horizon. One of them, dolutegravir, might also pose a risk, however. A study in Botswana found dolutegravir was linked to neural tube defects in embryos, meaning it might not be safe for pregnant women. As always, further research is needed to confirm whether this is a common problem or specific to the population studied in Botswana.

Also read: UNAIDS : World Is At A “Defining Moment” In A Battle Against HIV/AIDS

“I think the whole field right now is in a bit of a holding pattern,” Siedner said when asked about dolutegravir and the future of HIV medication. (VOA)