A blood test for analysis of HIV.
Last week, top experts on HIV/AIDS convened in Amsterdam for the 22nd International AIDS conference, and the mood was not great. Even though remarkable advances in treating HIV have led to effective management for many people living with the disease, and its overall incidence has declined, there are signs that the virus could make a troubling comeback.
"In a perfect world, we'd get a vaccine like the HPV vaccine that was 100% effective and I think that's ultimately what we're going to strive for."
Growing resistance to current HIV drugs, a population boom in Sub-Saharan Africa, and insufficient public health resources are all poised to contribute to a second AIDS pandemic, according to published reports.
Already, the virus is nowhere near under control. Though the infection rate has declined 47 percent since its peak in 1996, last year 1.8 million people became newly infected with HIV around the world, and 37 million people are currently living with it. About 1 million people die of AIDS every year, making it the fourth biggest killer in low-income countries.
Leapsmag Editor-in-Chief Kira Peikoff reached out to Dr. Carl Dieffenbach, Director of the Division of AIDS at the National Institute of Allergy and Infectious Diseases, to find out what the U.S. government is doing to develop an HIV vaccine and cure. This interview has been edited and condensed for clarity.
What is the general trajectory of research in HIV/AIDS today?
We can break it down to two specific domains: focus on treatment and cure, and prevention.
Let's start with people living with HIV. This is the area where we've had the most success over the past 30 plus years, because we've taken a disease that was essentially a death sentence and converted it through the development of medications to a treatable chronic disease.
The second half of this equation is, can we cure or create a functional cure for people living with HIV? And the definition of functional cure would be the absence of circulating virus in the body in the absence of therapy. Essentially the human body would control the HIV infection within the individual. That is a much more, very early research stage of discovery. There are some interesting signals but it's still in need of innovation.
I'd like to make a contrast between what we are able to do with a virus called Hepatitis C and what we can do with the virus HIV. Hep C, with 12 weeks of highly active antiviral therapy, we can cure 95 to 100% of infections. With HIV, we cannot do that. The difference is the behavior of the virus. HIV integrates into the host's genome. Hep C is an RNA virus that stays in the cytoplasm of the cell and never gets into the DNA.
On the prevention side, we have two strategies: The first is pre-exposure prophylaxis. Then of course, we have the need for a safe, effective and durable HIV vaccine, which is a very active area of discovery. We've had some spectacular success with RV144, and we're following up on that success, and other vaccines are in the pipeline. Whether they are sufficient to provide the level of durability and activity is not yet clear, but progress has been made and there's still the need for innovation.
The most important breakthrough in the past 5 to 10 years has been the discovery of broad neutralizing monoclonal antibodies. They are proteins that the body makes, and not everybody who's HIV infected makes these antibodies, but we've been able to clone out these antibodies from certain individuals that are highly potent, and when used either singly or in combination, can truly neutralize the vast majority of HIV strains. Can those be used by themselves as treatment or as prevention? That is the question.
Can you explain more about RV144 and why you consider it a success?
Prior to RV144, we had run a number of vaccine studies and nothing had ever statistically shown to be protective. RV144 showed a level of efficacy of about 31 percent, which was statistically significant. Not enough to take forward into other studies, but it allowed us to generate some ideas about why this worked, go back to the drawing board, and redesign the immunogens to optimize and test the next generation for this vaccine. We just recently opened that new study, the follow-up to RV144, called HVTN702. That's up and enrolling and moving along quite nicely.
Carl Dieffenbach, Director of the Division of AIDS at the National Institute of Allergy and Infectious Diseases
(Courtesy)
Where is that enrolling?
Primarily in Sub-Saharan Africa and South Africa.
When will you expect to see signals from that?
Between 2020 and 2021. It's complicated because the signal also takes into account the durability. After a certain time of vaccination, we're going to count up endpoints.
How would you explain the main scientific obstacle in the way of creating a very efficacious HIV vaccine?
Simply put, it's the black box of the human immune system. HIV employs a shield technology, and the virus is constantly changing its shield to protect itself, but there are some key parts of the virus that it cannot shield, so that's the trick – to be able to target that.
So, you're trying to find the Achilles' Heel of the virus?
Exactly. To make a flu vaccine or a Zika vaccine or even an Ebola vaccine, the virus is a little bit more forthcoming with the target. In HIV, the virus does everything in its power to hide the target, so we're dealing with a well-adapted [adversary] that actively avoids neutralization. That's the scientific challenge we face.
What's next?
On the vaccine side, we are currently performing, in collaboration with partners, two vaccine trials – HVTN702, which we talked about, and another one called 705. If either of those are highly successful, they would both require an additional phase 3 clinical trial before they could be licensed. This is an important but not final step. Then we would move into scale up to global vaccination. Those conversations have begun but they are not very far along and need additional attention.
What percent of people in the current trials would need to be protected to move on to phase 3?
Between 50 and 60 percent. That comes with this question of durability: how long does the vaccine last?
It also includes, can we simplify the vaccine regimen? The vaccines we're testing right now are multiple shots over a period of time. Can we get more like the polio or smallpox vaccine, a shot with a booster down the road?
We're dealing with sovereign nations. We're doing this in partnership, not as helicopter-type researchers.
If these current trials pan out, do you think kids in the developed world will end up getting an HIV vaccine one day? Or just people in-at risk areas?
That's a good question. I don't have an answer to that. In a perfect world, we'd get a vaccine like the HPV vaccine that was 100% effective and I think that's ultimately what we're going to strive for. That's where that second or third generation of vaccines that trigger broad neutralizing antibodies come in.
With any luck at all, globally, the combination of antiretroviral treatment, pre-exposure prophylaxis and other prevention and treatment strategies will lower the incidence rate where the HIV pandemic continues to wane, and we will then be able to either target the vaccine or roll it out in a way that is both cost effective and destigmatizing.
And also, what does the country want? We're dealing with sovereign nations. We're doing this in partnership, not as helicopter-type researchers.
How close do you think we are globally to eradicating HIV infections?
Eradication's a big word. It means no new infections. We are nowhere close to eradicating HIV. Whether or not we can continue to bend the curve on the epidemic and have less infections so that the total number of people continues to decline over time, I think we can achieve that if we had the political will. And that's not just the U.S. political will. That's the will of the world. We have the tools, albeit they're not perfect. But that's where a vaccine that is efficacious and simple to deliver could be the gamechanger.
Laika, a gene-edited pig, was named in honor of the first living creature to orbit the earth, a stray dog named Laika.
Untold numbers of animals have contributed to science, in ways big and small. Studying cows and cowpox helped English doctor Edward Jenner create a smallpox vaccine; Ivan Pavlov's experiments on dogs' reactions to external stimuli heavily influenced modern behavioral psychology.
We have these five animals to thank for some of our most important scientific advancements, from space travel to better organ replacement options.
Scientists still work with rats, rabbits, and other mammals to test cosmetics and pharmaceuticals and to conduct infectious disease research. Most of these animals remain nameless and unknown to the public, but over the years, certain individuals have had an outsize effect. We have these five animals to thank for some of our most important scientific advancements, from space travel to better organ replacement options.
1) LAIKA THE DOG
Laika was the first living creature ever to orbit the Earth. In October 1957, the Soviet Sputnik I ship had made history as the first man-made object sent into Earth's orbit; Premier Nikita Khrushchev was keen to gain another Space Race victory by sending up a canine cosmonaut.
Laika ("barker" in Russian), was a stray dog, reportedly a husky-spitz mix, recruited among several other female strays for the trip. Although the scientists put extensive work into preparing Laika and the other canine finalists—evaluating their reactions to air-pressure variations, training them to adapt to pelvic sanitation devices meant to contain waste, and eventually having them live in pressurized capsules for weeks—there was no expectation that the dog would return to Earth, and only one meal's worth of food was sent up with her.
Sputnik II, six times heavier than its predecessor, launched on November 3, 1957. Soviet broadcasts reported that Laika, fitted out with surgically implanted devices to monitor her heart rate, blood pressure, and breathing rates, survived until November 12; the spacecraft stayed in orbit for five more months, burning up when it re-entered the atmosphere.
At the time, the Sputnik II team reassured the world that Laika had died painlessly of oxygen deprivation. It was only decades later, in the 1990s, that Oleg Gazenko—one of the scientists and dog trainers assigned to the mission—revealed that Laika had died 5 to 7 hours after launch from a combination of heat and stress. The capsule had overheated, probably as a result of the rushed preparation; after the fourth orbit, the temperature inside Sputnik was over 90 degrees, and it's doubtful she could have survived much past that. "The more time passes, the more I'm sorry about it. We shouldn't have done it," Gazenko said. "We did not learn enough from the mission to justify the death of the dog."
Yet even the four or five orbits that Laika did complete were enough to spur scientists to press on in the effort to send a human into space.
2) HAM THE CHIMP
Four years after Laika's ill-fated flight, a chimpanzee named Ham entered suborbital flight in the American Project Mercury MR-2 mission on January 31, 1961, becoming the first hominid in space—and unlike Laika, he returned to Earth, alive, after a 16-minute flight.
Even though Ham's flight was not destined for orbit, the spacecraft and booster used on his trip were the same combination intended for the first (human) American's trip later that year. If he came back unharmed, NASA's medical team would be prepared to okay astronaut Alan Shepard's flight.
For approximately 18 months before liftoff, Ham was trained to perform simple tasks, like pushing levers, in response to visual and auditory cues. (If he failed, he received an electric shock; correct performance earned him a treat. Pavlov would have been pleased.)
At 37 pounds, Ham was also the heaviest animal to ever make it to space. His vital signs and movements were monitored from Earth, and after a light electric shock from the ground team reminded him of his tasks, he performed his lever-pushing just a bit slower than he had on Earth, verifying that motion would not be seriously impaired in space.
Less than three months after Ham returned to Earth, on April 12, 1961, Soviet cosmonaut Yuri Gagarin became the first human to complete an orbital flight; Shepard was close behind, successfully crewing the MR-3 mission on May 5. For his part, Ham "retired" to the National Zoo in Washington D.C. for 17 years, before being transferred to the North Carolina Zoological Park; he died of liver failure in 1983 at age 26. His grave is at the International Space Hall of Fame in New Mexico.
3) KOKO THE GORILLA
A western lowland gorilla born at the San Francisco Zoo, Hanabi-ko, or "Koko," became famous in the 1970s for her cognitive and communicative abilities. Psychologist Francine "Penny" Patterson, then a doctoral student at Stanford, chose Koko to work on a language research project, teaching her American Sign Language; by age four, Koko demonstrated the ability both to make up new words and to combine known words to express herself creatively, as opposed to simply mimicking her trainer.
Koko's work with Patterson reflected levels of cognition that were higher than non-human primates had previously been thought to have; by the end of her life, her language skills were roughly equivalent to a young child's, with a vocabulary of around 1,000 signs and the ability to understand 2,000 words of spoken English.
An especially impactful study in 2012 showed that Koko had learned to play the recorder, revealing an ability for voluntary breath control that scientists had previously thought was linked closely to speech and could only be developed by humans. Barbara J. King, a biological anthropologist, suggested that Koko's immersion in a human environment may have helped her develop such a skill, and that it might be misleading to consider similar abilities "innate" or lacking in either humans or non-human primates.
Koko's displays of emotions also fascinated the public, especially those that seemed to closely mirror humans': she cared for pet kittens; appeared on Mr. Rogers' Neighborhood and untied the host's shoes for him; acted playfully with Robin Williams during a visit from him, and later expressed grief when told about the comedian's death. Koko died in her sleep in June 2018, at age 46. Patterson continues to run The Gorilla Foundation, which is dedicated to using inter-species communication to motivate conservation efforts.
4) DOLLY THE SHEEP
Dolly—named after country singer Dolly Parton—was the first mammal ever to be cloned from an adult somatic cell, using the process of nuclear transfer. She was born in 1996 as part of research by scientists Keith Campbell and Ian Wilmut of the University of Edinburgh.
By taking a donor cell from an adult sheep's mammary gland, using it to replace the cell nucleus of an unfertilized, developing egg cell, and then bringing the resultant embryo to term, Campbell and Wilmut proved that even a mature cell (one that had developed to perform mammary gland functions) could revert to an embryonic state and go on to develop into any and all parts of a mammal.
Although cloned livestock are legal in the U.S.—the FDA approved the practice in 2008, after determining that there was no difference between the meat and milk of cattle, pigs, and goats—Dolly has had an even bigger impact on stem cell research. The successful test of nuclear transfer proved that it was possible to change a cell's gene expression by changing its nucleus.
Japanese stem cell biologist Shinya Yamanaka, inspired by the birth of Dolly, won the Nobel Prize in 2012 for his adaptation of the technique. He developed induced pluripotent stem cells (iPS cells) by chemically reverting mature cells back to an embryonic-like blank state that is highly desirable for disease research and treatment. This technique allows researchers to work with such stem cells without the ethically charged complication of having to destroy a human embryo in the process.
5) LAIKA THE PIG
Named in honor of the dog who made it to space, the second science-famous Laika was a genetically engineered pig born in China in 2015 as a result of gene editing carried out by Cambridge, MA startup eGenesis and collaborators.* eGenesis aims to create pigs whose organs—hearts, kidneys, lungs, and more—are safe to transplant into people.
Using animal organs in humans (xenotransplantation) is tricky: the immune system is very good at recognizing interlopers, and the human body can start to reject an organ from another species in as little as five minutes. But pigs are otherwise exceptionally good potential donors for humans: their organs' sizes and functions are very similar, and their quick gestation and maturation make them attractive from an efficiency standpoint, given that twenty Americans die every day waiting for organ donors.
Perhaps unsurprisingly, Dolly the sheep helped move xenotransplantation forward. In the 1990s, immunologist David Sachs was able to use a similar cloning method to eliminate alpha-gal, an enzyme that is produced by most animals with immune systems, including pigs—but not humans. Since our immune systems don't recognize alpha-gal, attacks on that enzyme are a major cause of organ rejection. Sachs' experiments increased the survival time of pig organs in primates to weeks: a huge improvement, but not nearly enough for someone in need of a liver or heart.
The advent of CRISPR technology, and the ability to edit genes, has allowed another leap. In 2015, researchers at eGenesis used targeted gene-editing to eliminate the genes for porcine endogenous retroviruses from pig kidney cells. These viral elements are part of all pigs' genomes and pose a potentially high risk of infecting human cells. (After the HIV/AIDS crisis especially, there was a lot of anxiety about potentially introducing a new virus into the human population.)
The eGenesis lab used nuclear transfer to embed the edited nuclei into egg cells taken from a normal pig; and Laika was born months later—without the dangerous viral genes. eGenesis is now working to make the organs even more humanlike, with the goal of one day providing organs to every human patient in need.
*[Disclosure: In 2019, eGenesis received a series B investment from Leaps By Bayer, the funding sponsor of leapsmag. However, leapsmag is editorially independent of Bayer and is under no obligation to cover companies they invest in.]
[Correction, March 3, 2020: Laika the gene-edited pig was born in China, not Cambridge, and eGenesis is pursuing xenotransplant programs that include heart, kidney, and lung, but not skin, as originally written.]