Quinn Eastman

HIV vaccine design: always a moving target

HIV presents a challenge to vaccine design because it is always changing. If doctors vaccinate people against one variety of virus, will the antibodies they produce stop the virus that they later encounter?

A recently published report on an experimental HIV vaccine’s limited effectiveness in human volunteers illustrates this ongoing puzzle in the HIV vaccine field.

Paul Spearman, now chief research officer for Children’s Healthcare of Atlanta and vice chair for research for Emory’s Department of Pediatrics, began overseeing the study when he was at Vanderbilt. The report is in the April 15 issue of the Journal of Infectious Diseases.

Paul Spearman, MD

The vaccine was designed to elicit both antibody and T cell responses against HIV and in particular, to generate broadly neutralizing antibodies. Unfortunately, it didn’t work. Volunteers who received the vaccine made antibodies that could neutralize the virus in the vaccine, but not related viruses thought to be like what participants in a larger study might encounter.

“High levels of neutralizing antibodies can be raised against HIV, while at the same time, breadth of neutralization has never yet been achieved in a vaccine,” Spearman says. “The essential problem is that the antibodies raised have a narrow specificity, while the virus is extremely variable. In contrast, about 20% of HIV-infected individuals will demonstrate neutralization breadth.”

Last year, scientists demonstrated a method for identifying these broadly neutralizing antibodies in HIV-infected individuals. However, having a vaccine hit that target reliably is still elusive.

Spearman reports that he is in charge of a new trial that will be boosting the same individuals that participated in the previous trial with HIV protein from a clade C virus, starting later this year. Clade C is the predominant HIV subtype in southern Africa, while clade B, used in the published trial, is the predominant subtype in North America and Western Europe.

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Indispensable cilia

Cilia are tiny hair-like structures on the outside of cells. Your memory of cilia may extend back to biology class, when you saw a picture of a paramecium or lung tissues, where cilia keep surfaces free of dirt and mucus.

Ciliated cells in the human oviduct

In the last few years, scientists have been learning more about cilia’s many roles in the body. Nearly all mammalian cells have cilia, and they are thought to act more like antennae, sending and receiving signals. Defects in cilia have been connected to lung, heart, kidney and eye diseases. Accordingly, Emory’s 15th BCMB training grant symposium focuses on cilia, beginning Thursday evening with a keynote talk by Susan Dutcher from Washington University, St. Louis and extending all day Friday.

At Emory, cell biologist Winfield Sale’s laboratory uses the model system of the alga Chlamydomonas to study dynein, a molecular motor that drives the functions of cilia. In addition, geneticist Tamara Caspary’s laboratory is studying how defects in cilia can lead to altered embryonic development. Ping Chen’s group has been examining cilia in the context of inner ear development.

This week’s program is sponsored by Emory’s graduate program in Biochemistry, Cell and Developmental Biology, the Departments of Cell Biology, Biochemistry, Pharmacology, Biology, Microbiology and Immunology, Physics, the Graduate Division of Biological and Biomedical Sciences and the Woodruff Health Sciences Center.

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A milestone in treating hemophilia

Hematologist Pete Lollar has devoted his career to developing treatments for hemophilia A, which is caused by a lack of blood clotting factor VIII. Lollar is a professor of pediatrics in Emory School of Medicine and director of hemostasis research at Children’s Healthcare of Atlanta. Last week, Lollar was honored by Emory’s Office of Technology Transfer for setting in motion research that has progressed to a phase III clinical trial of a new product, OBI-1, a special form of factor VIII.

John "Pete" Lollar, MD

Along with this milestone came a dramatic story, described by OTT’s assistant director Cale Lennon. The first patient to enroll in the clinical trial did so in November 2010 because of what appeared to be acquired hemophilia, which led to severe uncontrolled hemorrhaging. As a result of treatment with OBI-1, developed by Lollar and his research team at Emory, the patient’s bleeding was brought under control and it saved his life. He was treated at Indiana Hemophilia and Thrombosis Center in Indianapolis.

Acquired hemophilia is a challenge for doctors to deal with because it is such a surprise. Unlike people with inherited hemophilia, those with acquired hemophilia do not have a personal or family history of bleeding episodes. Their immune systems are somehow provoked into making antibodies against their own clotting factor VIII. These antibodies also appear over time in about 30 percent of patients with inherited hemophilia who take standard clotting factors.

OBI-1, a special form of clotting factor VIII, is less of a red flag to the immune system. This allows treatment of patients who cannot benefit from standard clotting factor VIII, because of the presence of auto-antibodies.

Emory originally licensed OBI-1 to Octagen Corporation, a “homegrown” startup company founded in 1997. Octagen sublicensed the OBI-1 technology to a French biotechnology firm, Ipsen Biopharm in 1998. Over the next decade, Octagen and Ipsen pursued preclinical and initial clinical studies and completed a phase II clinical trial in 2006. Ipsen purchased the OBI-1 program outright in May 2008.

In January 2010, Ipsen developed a partnership agreement with Inspiration Biopharmaceuticals, which was founded by two businessmen whose children have hemophilia. Under the agreement’s terms, Inspiration licensed OBI-1 from Ipsen and is responsible for its clinical development, regulatory approval and commercialization.

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The next generation of biomedical engineering innovators

Congratulations to the winners of the InVenture innovation competition at Georgia Tech. The competition aired Wednesday night on Georgia Public Broadcasting. The winners get cash prizes, a free patent filing and commercialization service through Georgia Tech’s Office of Technology Transfer.

Several of the teams have Emory connections, through the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory, and the Atlanta Clinical & Translational Science Institute.

Emergency medical professionals know that intubation can be rough. The second place ($10,000) MAID team created a “magnetic assisted intubation device” that helps them place a breathing tube into the trachea in a smoother way. The MAID was designed by Alex Cooper, Shawna Hagen, William Thompson and Elizabeth Flanagan, all biomedical engineering majors. Their clinical advisor was Brian Morse, MD, previously a trauma fellow and now an Emory School of Medicine surgical critical care resident at Grady Memorial Hospital.

“When I first saw the device that the students had developed, I was blown away,” Morse told the Technique newspaper. “It’s probably going to change the way we look at intubation in the next five to 10 years.”

The AutoRhexis team, which won the People’s Choice award ($5,000), invented a device to perform the most difficult step during cataract removal surgery. It was designed by a team of biomedical and mechanical engineering majors: Chris Giardina, Rebeca Bowden, Jorge Baro, Kanitha Kim, Khaled Kashlan and Shane Saunders. They were advised by Tim Johnson, MD, who was an Emory medical student and is now a resident at Columbus Regional Medical Center.

The finalist Proximer team, advised by Emory surgeon Albert Losken, MD, developed a way to detect plastics in the body, which can help breast cancer survivors undergoing reconstruction.

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The Scientist ranks Emory one of top 15 best places to work for postdocs

This year, the readers of The Scientist magazine have ranked Emory University as the 11th best place to work for postdocs in the United States. Among Emory’s strengths, respondents cited training and mentoring, and career development opportunities.

The top U.S. institution was the Whitehead Institute for Biomedical Research in Cambridge, Massachusetts. The top international institution was University College, London. Emory has previously ranked as high as number 4 (in 2006) in The Scientist’s best places to work for postdocs survey.

The ranking was based on responses from 2,881 nontenured life scientists working in academia, industry or noncommercial research institutions. 76 institutions in the United States and 17 international institutions were included.

Emory employs nearly 700 postdoctoral fellows in laboratories in the School of Medicine, Yerkes National Primate Research Center, Emory College, the Graduate School of Arts and Sciences, Rollins School of Public Health and Nell Hodgson Woodruff School of Nursing.

After receiving their PhD degrees, life sciences graduates launch their research careers by working for several years as postdoctoral fellows in the laboratories of established scientists. In addition to engaging in sometimes grueling laboratory research, many postdocs teach, mentor graduate and undergraduate students and apply for their own funding on a limited basis.

 

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One reason why SIV-infected sooty mangabeys can avoid AIDS

Sooty mangabeys are a variety of Old World monkey that can be infected by HIV’s cousin SIV, but do not get AIDS. Emory immunologist and Georgia Research Alliance Eminent Scholar Guido Silvestri, MD, has been a strong advocate for examining non-human primates such as the sooty mangabey, which manage to handle SIV infection without crippling their immune systems. Silvestri is division chief of microbiology and immunology at Yerkes National Primate Research Center.

Research shows sooty mangabeys have T cells that can do the same job as those targeted by SIV, even if they don't have the same molecules on their surfaces

A recent paper in the Journal of Clinical Investigation reveals that sooty mangabeys have T cells that perform the same functions as those targeted by SIV and HIV, but have different clothing.

Silvestri and James Else, the animal resources division chief at Yerkes, are co-authors on the paper, while Donald Sodora at Seattle Biomedical Research Institute is senior author.

One main target for SIV and HIV is the group of T cells with the molecule CD4 on their surfaces. These are the “helper” T cells that keep the immune system humming. Doctors treating people with HIV infections tend to keep an eye on their CD4 T cell counts.

In the paper, the scientists show that sooty mangabeys infected with SIV lose their CD4 T cells, without losing the ability to regulate their immune systems. What’s remarkable here is that sooty mangabeys appear to have “double negative” or DN T cells that can perform the same functions as those lost to SIV infection, even though they don’t have CD4.

CD4 isn’t just decoration for T cells. It’s a part of how they recognize bits of host or pathogen protein in the context of MHC class II (the molecule that “presents” the bits on the outside of target cells). Somehow, the T cells in sooty mangabeys have a way to get around this requirement and still regulate the immune system competently. How they do this is the topic of ongoing research.

The authors write:

It will be important to assess DN T cells in HIV-infected patients, particularly to determine whether these cells are preserved and functional in long-term nonprogressors. These efforts may lead to future immune therapies or vaccine modalities designed to modulate DN T cell function. Indeed, the main lesson we have learned to date from this cohort of SIV-infected CD4-low mangabeys may be that managing immune activation and bolstering the function of nontarget T cells through better vaccines and therapeutics has the potential to contribute to preserved immune function and a nonprogressive outcome in HIV infection even when CD4+ T cell levels become low.

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Emory/Georgia Tech: partners in creating heart valve repair devices

Vinod Thourani, associate professor of cardiac surgery at Emory School of Medicine, along with Jorge Jimenez and Ajit Yoganathan, biomedical engineers at Georgia Tech and Emory, have been teaming up to invent new devices for making heart valve repair easier.

At the Georgia Bio and Atlanta Clinical and Translational Science Institute’s second annual conference on academic/industry partnerships, Thourani described how he and his colleagues developed technology that is now being commercialized.

Apica Cardiovascular co-founders (l-r) James Greene, Vinod Thourani, Jorge Jimenez and Ajit Yoganathan

Apica Cardiovascular was founded based on technology invented by Jimenez, Thourani, Yoganathan and Thomas Vassiliades, a former Emory surgeon.

Thourani is associate director of the Structural Heart Program at Emory.

Yoganathan is director of the Cardiovascular Fluid Mechanics Laboratory at Georgia Tech and the Center for Innovative Cardiovascular Technologies.

The technology simplifies and standardizes a technique for accessing the heart via the apex, the tip of the heart’s cone pointing down and to the left. This allows a surgeon to enter the heart, deliver devices such as heart valves or left ventricular assist devices, and get out again, all without loss of blood or sutures.

Schematic of transapical aortic valve implantation. The prosthesis is implanted within the native annulus by balloon inflation.

At the conference, Thourani recalled that the idea for the device came when he described a particularly difficult surgical case to Jimenez.  Thourani said that a principal motivation for the device came for the need to prevent bleeding after the valve repair procedure is completed.

With research and development support from the Coulter Foundation Translational Research Program and the Georgia Research Alliance VentureLab program, the company has already completed a series of pre-clinical studies to test the functionality of their device and its biocompatibility.

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Brain chemical linked to migraines could be anxiety target

Neuroscientist Michael Davis, PhD, and his colleagues have devoted years to mapping out the parts of the brain responsible for driving fear and anxiety. In a recent review article, they describe the differences between fear and anxiety in this way:

Fear is a generally adaptive state of apprehension that begins rapidly and dissipates quickly once the threat is removed (phasic fear). Anxiety is elicited by less specific and less predictable threats, or by those that are physically or psychologically more distant (sustained fear).

Michael Davis is an investigator at Yerkes National Primate Research Center and Emory School of Medicine

A host of their studies suggest that one part of the brain, the amygdala, is instrumental in producing “phasic fear,” while the bed nucleus of the stria terminalis (BNST) is important for “sustained fear.”

In a new report in the Journal of Neuroscience, Davis’ team describes the effects of a brain communication chemical, which is known primarily for its role in driving migraine headaches, in enhancing anxiety.

“This is the first study to show a role of this peptide, in a brain area we’ve identified as being important for anxiety.  This could lead to new drug targets to selectively reduce anxiety,” Davis says.

His team found that introducing calcitonin gene-related peptide (CGRP) into rats’ BNSTs can increase the anxiety they experience from loud noises or light, in that they startle more and avoid well-lit places. This peptide appears to activate other parts of the brain including the amygdala, hypothalamus and brainstem, producing fear-related symptoms.

Slice of rat brain showing the bed nucleus of the stria terminalis (BNST) and the central amygdala (Ce)

If Davis and his colleagues block CGRP’s function by introducing a short, decoy version of CGRP into the BNST, the reverse does not happen: the rats are not more relaxed. However, the short version does block the startle-enhancing effects of a smelly chemical produced by foxes that scientists use to heighten anxiety-like behavior in rats. This suggests that interfering with CGRP can reduce fear-related symptoms in situations where the rats are already under stress.

“Blockade of CGRP receptors may thus represent a novel therapeutic target for the treatment of stress-induced anxiety and related psychopathologies such as post-traumatic stress disorder,” says the paper’s first author, postdoctoral fellow Kelly Sink.

In fact, experimental drugs that work against CGRP are already in clinical trials to treat migraine headaches. But first, Sink reports that she and her colleagues are examining the relationship between CGRP and the stress hormone CRF (corticotropin-releasing factor) — another target of pharmacological interest — in the parts of the brain important for fear responses.

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Another avenue of HIV trickery reveals opportunity

Emory and University of Rochester researchers have discovered an extra way by which HIV adapts to survive in a hiding spot in the human immune system. The results are published in the Journal of Biological Chemistry.

A team led by Baek Kim from the University of Rochester and Raymond Schinazi from Emory found that when HIV faces a shortage of the building blocks it usually uses to replicate, the virus adapts by using different building blocks. The discovery may offer scientists a new way to try to stop the virus.

One of HIV’s favorite hiding spots is an immune cell called a macrophage, whose job is to chew up and destroy foreign invaders and cellular debris. One can think of macrophages as worker bees: they don’t reproduce because they’re focused on getting stuff done.

Raymond Schinazi, PhD, DSc, is director of the Laboratory of Biochemical Pharmacology at Emory's Center for AIDS Research

Normally, HIV uses “dNTPs” (building blocks of DNA), but dNTPs are found at very low levels in macrophages because they’ve stopped dividing and making new DNA. Current drugs generally target dNTPs, and aim at the infection in a different type of cells: T cells.

Macrophages do have high levels of RNA building blocks (“rNTPs”). The team found that HIV uses primarily rNTPs instead of dNTPs to replicate inside macrophages. When the team blocked the ability of the virus to interact with rNTPs, its ability to replicate in macrophages was cut by more than 90 percent.

“The first cells that HIV infects in the genital tract are non-dividing target cell types such as macrophages,” Kim says. “Current drugs were developed to be effective only when the infection has already moved beyond these cells. Perhaps we can use this information to help create a microbicide to stop the virus or limit its activity much earlier.”

Compounds that interfere with the use of rNTPs already exist and have been tested as anti-cancer drugs.

“We are now developing new anti-HIV drugs jointly based on this novel approach that are essentially non-toxic and can be used to treat and prevent HIV infections,” Schinazi says.

Baek Kim, PhD

The first authors of the paper are graduate students Edward Kennedy from Rochester and Christina Gavegnano from Emory. Other authors include graduate students Laura Nguyen, Rebecca Slate and Amanda Lucas from Rochester, and postdoc Emilie Fromentin from Emory.

The research was funded by the National Institute of Allergy and Infectious Disease and the Department of Veterans Affairs.

University of Rochester press release

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Reassuring news on viral immunity + HIV vaccine

A recent paper in Journal of Immunology suggests that a platform for an HIV vaccine developed by Yerkes National Primate Research Center scientists won’t run into the same problems as another HIV vaccine. Postdoc Sunil Kannanganat is the first author of the JI paper, with Emory Vaccine Center researcher Rama Amara as senior author.

Harriet Robinson, MD and Rama Rao Amara, PhD

Many HIV vaccines have been built by putting genes from HIV into the backbone of another virus. Some have used a modified cold virus (adenovirus 5). The vaccine developed at Yerkes uses modified vaccinia Ankara (MVA), a relative of smallpox and chicken pox.

Read more

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