http://www.cosmosmagazine.com/node/3918/full

Gene Therapy Targets CCR5 in CD4 Precursor Stem Cells

[...] By targeting the CCR5 gene in the stem cells that give rise to the CD4s, Cannon, who is also working with Sangamo, thinks she ultimately has a better chance of achieving an effective and durable cure. To test the idea, Cannon's lab transplants human stem cells into one group of mice that serve as controls. A second group of mice receive human stem cells that have been modified with the zinc-finger nuclease. The researchers then infect the mice with HIV. Experiments on numerous groups of mice show that the virus initially does equally well in all the animals, but after a few weeks, viral levels nosedive in the treated mice. The zinc-finger nucleases successfully mangle the CCR5 gene in only about 5% of the mouse immune cells. But HIV selectively kills the cells whose CCR5 receptors are intact. Thus, Cannon contends, the proportion of cells with a broken CCR5 receptor will increase over a few weeks, until the virus can no longer spread: even if a latently infected cell starts churning out HIV, it has nowhere to go. So the treated mice remain infected, but at such low levels that they suffer no ill effects. [...] Cannon is confident that the human studies will prove the merits of the idea, even if it's only on a modest scale at first. "Our little piece of the puzzle is that we're trying to get zinc-finger nucleases to work in stem cells and not do any harm," she says. If her research group can crack open the door, she predicts, colleagues will come rushing in to help find more effective, safer, cheaper ways to functionally cure HIV-infected people of all ages everywhere. "There's nothing like success to galvanise the community," she says. "If we can produce a one-shot treatment that basically means people don't have to take antiretrovirals, it's going to spread like wildfire."

http://www.npr.org/blogs/health/2012/07/26/15...w-transplants-doctors-say

Two More Nearing AIDS 'Cure' After Bone Marrow Transplants, Doctors Say

The so-called Berlin patient is famously the only person in the world who has been cured of HIV. But he may soon have company. Two people in Boston also seem to be free of HIV after undergoing bone marrow transplants for cancer, just as the Berlin patient did five years ago. The crucial difference is that the Boston patients have not yet stopped taking anti-HIV drugs — although that may happen in the coming months.

Harvard researchers got an enthusiastic response from an overflow crowd when they presented the first report on the patients at the 19th International AIDS Conference in Washington, D.C. "As far as we've been able to measure, we can't find evidence of HIV infection in the patients' blood or blood plasma, and their antibody levels against HIV are dropping," Dr. Daniel Kuritzkes of Brigham and Women's Hospital told Shots. "The antibody evidence tells us there is little if any persisting HIV protein to trigger an anti-HIV response." [...]

It's been widely assumed that the magic in [Berlin patient] Brown's cure resides in the stem cells he got from a bone marrow donor. Those donor cells lack a receptor called CCR5 that HIV uses to enter immune cells. Not necessarily, the Boston researchers say. The donor cells their patients got did not lack the receptor. So what's happening with them must be different from the Berlin patient.

The Boston researchers think their might-be-cures are due to two factors: [1] The patients got a milder form of pre-transplant chemotherapy. As a result, they were able to stay on their anti-HIV drugs. That protected the transplanted donor cells from becoming infected with any HIV that might have been hiding out in their bodies.
The donor cells most likely killed off the patients' own HIV-infected immune cells as the bone marrow transplants took effect. [2] This second phenomenon is called graft-versus-host disease. The donor cells see the patients' native cells as foreigners and attack them. "The success of a bone marrow transplant depends on having the right amount of graft-versus-host disease," Kuritzkes says. "You need a little bit. You hope not to have so much that you get clinically sick from it."

The Berlin patient also had episodes of graft-versus-host disease. That could help explain why his HIV infection was extinguished — or driven to such low levels that his new immune system is able to control it. It's possible that the lack of CCR5 receptors on the donor cells did contribute to the Berlin patient's cure. But scientists are excited by the possibility that a cure may not require donor cells lacking CCR5 receptors. That would widen the donor pool, since very few people are lucky enough to lack CCR5. [...]

http://www.huffingtonpost.com/2012/07/25/timo...in-patient_n_1703941.html

Timothy Ray Brown, Man Believed Cured Of AIDS, Says He's Still Cured
By JOSH LEDERMAN 07/24/12 12:45 PM ET

WASHINGTON -- The first person believed to have been cured of AIDS says reports he still has the HIV virus are false.

Timothy Ray Brown, also known as the "Berlin patient," says doctors have told him he's "cured of AIDS and will remain cured." [...]

http://www.sciencedaily.com/releases/2012/08/120803110827.htm

Researchers Invent New Tool to Study Single Biological Molecules

ScienceDaily (Aug. 3, 2012) — By blending optical and atomic force microscope technologies, Iowa State University and Ames Laboratory researchers have found a way to complete 3-D measurements of single biological molecules with unprecedented accuracy and precision. Existing technologies allow researchers to measure single molecules on the x and y axes of a 2-D plane. The new technology allows researchers to make height measurements (the z axis) down to the nanometer -- just a billionth of a meter -- without custom optics or special surfaces for the samples. [... Here's how] the new microscope technology -- called standing wave axial nanometry (SWAN) -- [...] works: Researchers attach a commercial atomic force microscope to a single molecule fluorescence microscope. The tip of the atomic force microscope is positioned over a focused laser beam, creating a standing wave pattern. A molecule that has been treated to emit light is placed within the standing wave. As the tip of the atomic force microscope moves up and down, the fluorescence emitted by the molecule fluctuates in a way that corresponds to its distance from the surface. That distance can be compared to a marker on the surface and measured. [...] measurements of a molecule's height are accurate to less than a nanometer. It also reports that measurements can be taken again and again to a precision of 3.7 nanometers. [...]

http://media.caltech.edu/press_releases/13546

PASADENA, CA - A team led by scientists at the California Institute of Technology (Caltech) have made the first-ever mechanical device that can measure the mass of individual molecules one at a time. [...] The device - €”which is only a couple millionths of a meter in size - €”consists of a tiny, vibrating bridge-like structure. When a particle or molecule lands on the bridge, its mass changes the oscillating frequency in a way that reveals how much the particle weighs. "As each particle comes in, we can measure its mass," says Michael Roukes, the Robert M. Abbey Professor of Physics, Applied Physics, and Bioengineering at Caltech. "Nobody's ever done this before." [...]

Traditionally, molecules are weighed using a method called mass spectroscopy, in which tens of millions of molecules are ionized - €”so that they attain an electrical charge - €”and then interact with an electromagnetic field. By analyzing this interaction, scientists can deduce the mass of the molecules. The problem with this method is that it does not work well for more massive particles€ - like proteins or viruses - €”which have a harder time gaining an electrical charge. As a result, their interactions with electromagnetic fields are too weak for the instrument to make sufficiently accurate measurements. The new device, on the other hand, does work well for large particles. In fact, the researchers say, it can be integrated with existing commercial instruments to expand their capabilities, allowing them to measure a wider range of masses.

The researchers demonstrated how their new tool works by weighing a molecule called immunoglobulin M (IgM), an antibody produced by immune cells in the blood. By weighing each molecule - which can take on different structures with different masses in the body - €”the researchers were able to count and identify the various types of IgM. Not only was this the first time a biological molecule was weighed using a nanomechanical device, but the demonstration also served as a direct step toward biomedical applications. Future instruments could be used to monitor a patient's immune system or even diagnose immunological diseases. For example, a certain ratio of IgM molecules is a signature of a type of cancer called Waldenstrom macroglobulinemia.

In the more distant future, the new instrument could give biologists a view into the molecular machinery of a cell. Proteins drive nearly all of a cell's functions, and their specific tasks depend on what sort of molecular structures attach to them - €”thereby adding more heft to the protein€ - during a process called posttranslational modification. By weighing each protein in a cell at various times, biologists would now be able to get a detailed snapshot of what each protein is doing at that particular moment in time.

Another advantage of the new device is that it is made using standard, semiconductor fabrication techniques, making it easy to mass-produce. That's crucial, since instruments that are efficient enough for doctors or biologists to use will need arrays of hundreds to tens of thousands of these bridges working in parallel. "With the incorporation of the devices that are made by techniques for large-scale integration, we're well on our way to creating such instruments," Roukes says. This new technology, the researchers say, will enable the development of a new generation of mass-spectrometry instruments. [...]