Map of the AIDS pandemic
Thirty years ago, Julie McElrath was a medical resident in Charleston, South Carolina, seeing young patients with rare illnesses, unusual forms of pneumonia or cancer, typically only seen in the elderly with weakened immune systems.
“We were trying to care for these people but we didn’t know what they had,” McElrath said. What they had was AIDS. The epidemic had emerged.
Three decades later, McElrath is one of the world’s leading scientists searching for what many believe is the best, perhaps only, hope of ending the pandemic. A vaccine.
“I do think a vaccine is what we will ultimately need,” she said. Recent studies that have shown that treatment can prevent spreading the infection to others is tremendous news, she said, but the logistics and expense of making that happen are daunting.
Julie McElrath
Today, in her Seattle lab, the HIV Trials Network operated by the Fred Hutchinson Cancer Research Center, she and her colleagues will open precious vials containing white blood cells collected from thousands of Thai research volunteers.
Not that long ago, many had given up on ever finding a vaccine against HIV.
Then, in late 2009, the Thai Prime-Boost vaccine trial (technically known as RV 144) stunned the skeptics, well, okay, almost everybody, by demonstrating that a vaccine could prevent infection. It wasn’t enough protection, but it was protection.
“It gave us hope that this was possible,” McElrath said.
The Thai study – the largest HIV vaccine trial ever done, with 16,000 enrollees — was the first ever to show HIV infection could be prevented. The problem is that it was only about 30 percent protection (not enough to be deemed useful, though this is debated) and it wasn’t at all clear how the vaccine worked.
To make things even more complex, the Thai government hadn’t collected quite enough blood samples to allow scientists to do the standard battery of tests aimed at identifying the specific immune system response that protected against the invading virus. I wrote in greater detail about some of the glitches in the Thai vaccine trial in 2010, as a freelancer, which you can read in this report.
As a result of the lack of adequate sampling (which may have been due to the fact that few really expected this trial to work?), there had been a tussle within the scientific community about how best – and who best – to study these precious samples of blood and plasma.
The fact that McElrath’s lab in Seattle was selected speaks for itself.
“We want to see if there was something unique about the antibodies elicited from the vaccine,” she said. They plan to have results by next fall, to present at the International AIDS Vaccine meeting in Bangkok.
The difficulty in finding a vaccine against HIV stems from the unique nature of this virus, which invades and attacks the very immune system cells that are typically boosted by vaccines to protect against flu, measles or other infectious diseases. McElrath’s job, searching these blood cells for signs of some immune system needle-in-the-haystack, will be difficult.
But even if the scientific analyses don’t reveal an obvious target for an AIDS vaccine, plans are already underway to repeat a version of the Thai prime-boost vaccine approach in Thailand and in South Africa.
“That’s all being discussed right now,” McElrath said. For a variety of reasons, she noted, it won’t be possible to identically repeat the historic Thai vaccine trial.
“To begin with, it would require too many people and take too long,” she said. That’s why it’s so important for scientists to home in on the immune system signals (called “correlates of protection” or “correlates of immunogenicity”) that could help focus these next vaccine trials.
Despite progress made in reducing the rate of new HIV infections and the findings indicating that early treatment can prevent infection, the pandemic is still massive and spreading.
The AIDS pandemic rate of spreading slows, but continues
McElrath’s colleagues at the HIV Trials Network are also advocating a new approach to testing vaccines called “adaptive clinical trial design.” Used in cancer research, AIDS expert and now Fred Hutch president Larry Corey is one of the world’s leading proponents of this attempt to streamline vaccine research.
“The idea is to pick up the pace, evaluate and get results more quickly,” McElrath said. “I think it’s a good approach.”
It is not without its risks and downsides, which could include either missing more subtle signs of efficacy or side effects. But there is little question Seattle is home to many leading efforts aimed at finding an effective HIV vaccine.
The Bill & Melinda Gates Foundation is the leading private contributor to this effort and could also be credited more broadly with reinvigorating the AIDS vaccine research field, going back to one its initial grants in the 1990s to the International AIDS Vaccine Initiative. The foundation has also upset a lot of AIDS vaccine researchers lately, by deciding to put all its well-endowed eggs in the Thai trial basket rather than continue to fund a diversity of strategies.
A lot of hope now rests on the efforts of McElrath and her colleagues, as well as the other scientific teams investigating the Thai blood and plasma samples. It’s right now difficult to imagine a world with an AIDS vaccine, a world freed from this massive killer – a world free of AIDS.
But, for scientists like McElrath, it is now more imaginable than ever.
“I think we’re in a pretty good place right now,” she said. “I’m hopeful.”
