The surprising finding that an antibody treatment can push SIV-infected monkeys into prolonged remission, even after antiviral drugs are stopped, continues to rumble across the internet.
Blue circles show how viral levels stayed low even after antiretroviral drugs were stopped.
The Science paper was featured on NIH director Francis Collins’ blog this week. NIAID director Anthony Fauci has been giving presentations on the research, which emerged from a collaboration from his lab and Tab Ansari’s at Emory. Fauci’s talk at the recent HIV prevention meeting in Chicago is viewable here.
At Lab Land, we were pleased to see that the watchdogs at Treatment Action Group had this to say:
“Media coverage of the paper has generally been accurate, but has had to wrestle with the uncertainty that exists among scientists regarding how ART-free control of viral load should be described.”
HIV pioneer Robert Gallo noted in an article accompanying the Science paper that the anti-integrin antibody treatment represents an emerging alternative to the vaunted “shock and kill” strategy, which he termed “soothe and snooze.” Note to reporters: the upcoming “Strategies for an HIV cure” conference at NIH in mid-November might be a good chance to compare the different strategies and put them in perspective.
An ongoing collaboration between the Emory Vaccine Center and the ICGEB (International Centre for Genetic Engineering and Biotechnology) in New Delh, investigating immune responses to dengue virus, is getting some attention.
A Journal of Virology paper published by the collaboration was highlighted by Nature Asia. In that paper, the researchers show that in dengue infection, the group of antiviral immune cells known as CD8+ T cells undergoes a massive expansion. That could be dangerous if all of the CD8 T cells were making inflammatory cytokines, but they do not. Only a small fraction are making cytokines.
The authors point out that this phenomenon is “somewhat reminiscent of T-cell exhaustion seen under the conditions of prolonged antigenic stimulus in chronic viral infections [which has been studied in detail by Rafi Ahmed and colleagues] or closely resembles the ‘stunned’ phenotype reported in febrile phase of other acute infections such as HIV and viral hepatitis… The IFN-γ unresponsiveness acquired during the massive antigen-driven clonal expansion is likely to ensure that these cells do not cause excessive inflammation at the time that their numbers are high during the febrile phase of dengue disease.” Read more
Immune cells that serve as antibody production factories, also known as plasma cells, are the focus of a recent Nature Immunology paper from Jeremy Boss and colleagues.
Plasma cells also appear in Ali Ellebedy and Rafi Ahmed’s recent paper on the precursors of memory B cells and Eun Lee’s work on long-lived antibody-producing cells. In addition, plasma cells appear prominently in Larry Boise’s studies of myeloma, because myeloma cancer cells are thought to come from plasma cells and have a similar biology.
The Boss lab’s paper focuses on patterns of methylation, modifications of DNA that usually help turn genes off. In comparison with resting B cells, plasma cells need to turn on lots of genes, so their DNA methylation level goes down when differentiation occurs (see graph). PC = plasma cells, PB = plasmablasts. DNAme indicates the extent of DNA methylation. Read more
Are you experienced? Your immune system undoubtedly is. Because of vaccinations and infections, we accumulate memory T cells, which embody the ability of the immune system to respond quickly and effectively to bacteria or viruses it has seen before.
Not so with mice kept in clean laboratory facilities. Emory scientists think this difference could help explain why many treatments for sepsis that work well in mice haven’t in human clinical trials.
Mandy Ford has teamed up with Craig Coopersmith to investigate sepsis, a relatively new field for her, and the collaboration has blossomed in several directions
“This is an issue we’ve been aware of in transplant immunology for a long time,” says Mandy Ford, scientific director of Emory Transplant Center. “Real life humans have more memory T cells than the mice that we usually study.”
Sepsis is like a storm moving through the immune system. Scientists studying sepsis think that it has a hyper-inflammatory phase, when the storm is coming through, and a period of impaired immune function afterwards. The ensuring paralysis leaves patients unable to fight off secondary infections.
In late-stage sepsis patients, dormant viruses that the immune system usually keeps under control, such as Epstein-Barr virus and cytomegalovirus, emerge from hiding. The situation looks a lot like that in kidney transplant patients, who are taking drugs to prevent immune rejection of their new organ, Ford says.
Ford’s team recently found that sepsis preferentially depletes some types of memory T cells in mice. Because T cells usually keep latent viruses in check, this may explain why the viruses are reactivated after sepsis, she says. Read more
HIV researchers are becoming increasingly bold about using the “cure” word in reference to HIV/AIDS, even though nobody has been cured besides the “Berlin patient,” Timothy Brown, who had a fortuitous combination of hematopoetic stem cell transplant from a genetically HIV-resistant donor. Sometimes researchers use the term “functional cure,” meaning under control without drugs, to be distinct from “sterilizing cure” or “eradication,” meaning the virus is gone from the body. A substantial obstacle is that HIV integrates into the DNA of some white blood cells.
HIV cure research is part of the $35.6 million, five-year grant recently awarded by the National Institutes of Health to Yerkes/Emory Vaccine Center/Emory Center for AIDS Research. Using the “shock and kill” approach during antiviral drug therapy, researchers will force HIV (or its stand-in in non-human primate research, SIV) to come out of hiding from its reservoirs in the body. The team plans to test novel “latency reversing agents” and then combine the best one with immunotherapeutic drugs, such as PD-1 blockers, and therapeutic vaccines.
The NIH also recently announced a cluster of six HIV cure-oriented grants, named for activist Martin Delaney, to teams led from George Washington University, University of California, San Francisco, Fred Hutchinson Cancer Research Center, Wistar Institute, Philadelphia, Beth Israel Deaconess Medical Center and University of North Carolina. Skimming through the other teams’ research plans, it’s interesting to see the varying degrees of emphasis on “shock and kill”/HIV latency, enhancing the immune response, hematopoetic stem cell transplant/adoptive transfer and gene editing weaponry vs HIV itself.
Zika virus can infect and replicate in immune cells from the placenta, without killing them, scientists have discovered. The finding may explain how the virus can pass through the placenta of a pregnant woman, on its way to infect developing brain cells in her fetus.
Infected placental macrophages. Zika antigens visible in red. From Quicke et al (2016).
The results were published in Cell Host & Microbe.
“Our results substantiate the limited evidence from pathology case reports,” says senior author Mehul Suthar, PhD, assistant professor of pediatrics at Emory University School of Medicine. “It was known that the virus was getting into the placenta. But little was known about where the virus was replicating and in what cell type.”
Scientists led by Suthar and Emory pediatric infectious disease specialist Rana Chakraborty, MD, found that Zika virus could infect placental macrophages, called Hofbauer cells, in cell culture. The virus could also infect another type of placental cell, called cytotrophoblasts, but only after a couple days delay and not as readily. Other researchers recently reported that syncytiotrophoblasts, a more differentiated type of placental cell than cytotrophoblasts, are resistant to Zika infection.
The cells for the experiments were derived from full-term placentae, obtained from healthy volunteers who delivered by Cesarean section. The level of viral replication varied markedly from donor to donor, which hints that some women’s placentae may be more susceptible to viral infection than others. Read more
Third in a series on malaria immunology from graduate student Taryn McLaughlin. Sorry for the delay last week, caused by technical blog glitches.
It’s easy for me to find reasons to brag when it comes to research here at Emory. However, even an unbiased person should be excited about the malaria vaccine platform being developed by Alberto Moreno at the Emory Vaccine Center.
His vaccine is based on a chimeric protein (a protein that is a combination of bits and pieces of multiple proteins, a la the creature from Greek mythology) that should get your immune system to target multiple stages of the Plasmodium vivax life cycle. Part of it targets the infectious sporozoite, part of it targets the blood stage merozoite, and part of it will even target the transmitted gamete in future versions. This seems like a no brainer. Of course we should be targeting multiple stages!
Continuing from Monday’s post, IMP graduate student Taryn McLaughlin explains why the most advanced malaria vaccine is actually not that great.
Malaria has plagued humans for thousands of years. And while we have known the causative agents of the disease- for 150 years, malaria remains scientifically frustrating. In fact, one of the most common treatments for the disease is simply a derivative of a treatment used in ancient China.
One of the most frustrating features is that there is no sterilizing immunity. In other words, for many diseases once you are infected with the microbe responsible, you develop an immune response and then never get the disease again. Not so with malaria. Compounded with terrible treatment and the impracticality of ridding the world of mosquitos, a vaccine sounds like pretty much our only hope. And yet this has been scientifically challenging and unsuccessful for many many reasons.
In fact a number of vaccine candidates have come along in the last few decades that have seemed SO promising only to go on and break our hearts in clinical trials. The most recent of which is a vaccine that goes by the name RTS,S (named for the different components of the vaccine).
As a quick refresher, Plasmodium enters the body via mosquitos as a sporozoite. It then migrates through the skin going into the blood and eventually making itâ€™s way to the liver. Here it goes inside liver cells where it replicates and turns into merozoites (such that one sporozoite becomes thousands of merozoites). This stage of the disease is asymptomatic. Some time later, all those merozoites burst out of your liver cells causing mayhem and invading your red blood cells. Here, they once again replicate and metamorphose. Fun times. Anyways, during the last stage, some of those plasmodium become gametes which get eaten by mosquitos thus completing the life cycle. Read more
In recognition of World Malaria Day, Lab Land will have a series ofÂ posts from Taryn McLaughlin, a graduate student in Emoryâ€™s IMP program. Her posts will set the stage for upcoming news about malaria research at Emory and Yerkes. Taryn is part of Cheryl Dayâ€™s lab and is also an associate producer with theÂ AudiSci podcast.
Those of us in the US are fortunate to not have to consider malaria in our day-to-day lives. Globally though, malaria is a serious public health threat with nearly 3.2 billion people at risk and close to half a million deaths every year. The scientific community has been developing malaria vaccines for decades. Yet a robust vaccine still remains elusive. Why?
IMP graduate student Taryn McLaughlin
One set of barriers comes from economics:Â malariaâ€™s strongest impact is in developing countries. But there is just as strong a case to be made for scientific obstacles. Frankly, the parasite (technically a bunch of species of microbes that I’ll just lump together under the umbrella term Plasmodium) that causes malaria is just smarter than we are.
I’m only kidding, but it is a fascinating organism. Its complexity makes it difficult to pin down and also interesting to write about. But before we talk about why Plasmodium is such a pain, let’s first discuss what exactly makes an effective vaccine. Read more