Tag Archives: genetic mutation

STD Awareness: Can Gene Editing Cure HIV?

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For the first time in history, someone with HIV has been treated with cells edited in the lab. It was a bold attempt to try to replicate previous successes in “curing” HIV through bone marrow transplants, but the results were a mixed bag.

Your DNA is like a book, and each sentence is a gene. Imagine a word is misspelled. Sometimes, a misspelling won’t affect your ability to understand the sentence, but other times, it will be so bad that you’ll have trouble figuring out the intended meaning. Think of the difference between “I drive a car” and “I driv a car,” or “I like food” and “I like flod.” You might not be able to tell what that last sentence is even trying to say! Those misspellings are mutations, and sometimes mutations are relatively benign (“I driv a car”), while other times they can cause diseases (“I like flod”).

A mutated version of the CCR5 gene confers near-immunity to HIV — but increases susceptibility to other viruses.

CRISPR, pronounced crisper, is a powerful new technology that can edit genes. By cutting DNA at a specific location and replacing some of the letters in the genetic alphabet, CRISPR can edit genes like you can edit a document using “find and replace.” The hope is that, someday, CRISPR could be used to fight disease by tweaking faulty genes. Continue reading →

STD Awareness: Searching for an HIV Vaccine

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Ever since the dawn of the AIDS era, researchers have worked nonstop to develop an HIV vaccine. In 1984, Margaret Heckler of the U.S. Department of Health and Human Services famously (over)promised that a vaccine would be ready for testing in two years. But it’s taken much, much longer. This Saturday, May 18, is HIV Vaccine Awareness Day, a celebration of the patients, community members, and scientists who are hard at work bringing this vaccine into existence.

Only one vaccine — still in the experimental stage — has shown any effectiveness against HIV.

Hiding from the Immune System

Vaccines are inspired by our own bodies’ ability to fight disease. Usually, when our immune system encounters a threat, it takes note of the viral “antigens,” which are like facial features — a button nose, say, or dramatically arched eyebrows — that make it instantly recognizable. It creates “antibodies,” weapons that can target those antigens like guided missiles. Often, the immune system can remember the distinguishing facial features so it’s ready to attack if the enemy ever returns — giving us immunity, possibly for life.

Vaccines take advantage of our natural ability to create these immune memories by exposing our immune systems to antigens without actually exposing us to infectious viruses. Think of it as a “wanted” poster that helps the immune system recognize “bad guys” before it actually sees them on the street, enabling it to attack and destroy them before they cause disease. Continue reading →

STD Awareness: Can HIV Be Cured Now?

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In 1991, when Timothy Ray Brown was in his 20s, he moved from the United States to Europe in search of adventure. His travels brought him to Berlin, where he put down roots and became a translator — but this newfound stability was quickly disrupted. A former boyfriend told him he had been diagnosed with HIV, the virus that causes AIDS, and suggested Brown be tested as well. The results were positive. Brown calculated he had about two more years left to live.

His fortunes changed the next year when antiretroviral drugs transformed HIV from a death sentence to a manageable chronic disease. Life went on. But 10 years later, in 2006, he started noticing changes. While he usually made a 14-mile round trip on his bike to and from work, a quick ride to a café one mile away left him so winded he had to stop halfway through.

We still don’t have an HIV cure that works for everyone.

He was diagnosed with leukemia, a type of cancer that affects certain types of blood cells. He immediately began chemotherapy, a taxing regimen that nearly killed him when an infection forced his doctors to induce a coma. And when the cancer came back, his doctors recommended a bone marrow transplant, which involved wiping out his immune system with drugs and radiation. A year later, after his leukemia came back, he received a second bone marrow transplant. Recovery was grueling. He descended into delirium, nearly went blind, and was temporarily paralyzed. He had to undergo physical therapy to relearn how to walk and talk.

Miraculously, he came out of this near-death experience in full remission from leukemia. But the bone marrow transplants hadn’t just gotten rid of his leukemia. They had gotten rid of his HIV infection, too. The media dubbed him the “Berlin patient.” Continue reading →

STD Awareness: The Future of Treatment for HIV/AIDS

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This scanning electron micrograph shows HIV particles (colored yellow) infecting a human T cell. Image: National Institute of Allergy and Infectious Diseases, National Institutes of Health

This scanning electron micrograph shows HIV particles (colored yellow) infecting a human T cell. Image: National Institute of Allergy and Infectious Diseases, National Institutes of Health

In 2006, an HIV-positive man was diagnosed with leukemia. First he received chemotherapy, and when the cancer returned his doctor recommended a stem-cell transplant with tissues obtained from a bone-marrow donor. After finding an unusually high number of compatible donors, his doctor, Gero Hütter, had a simple idea that would change the course of HIV research. Dr. Hütter knew of a rare genetic mutation that confers immunity to many strains of HIV, including the strain that infected his cancer patient. And new blood cells, including immune cells, are manufactured by bone marrow. What if he could find a bone-marrow donor with this mutation? What effect would it have on the HIV infection?

Five years after his cancer diagnosis, the man, known as the Berlin patient and recently identified as Timothy Ray Brown, is in remission from cancer … and the most sensitive tests have been unable to detect HIV anywhere in his body, despite the discontinuation of antiretroviral drugs. Scientists are a cautious lot, careful not to make grand statements without qualifying them with words like “seem” and “suggest.” But more and more, researchers are starting to say that Brown could be the first case in which a cure for HIV was attained.

Human immunodeficiency virus, or HIV, has been the focus of intense research since the 1980s, when it was identified as the causative agent of AIDS. Many anti-HIV drugs have been developed since then, though worldwide, less than a third of people who need the drugs have access to them. Those with access, however, have significantly improved health outcomes and longer life expectancy. Continue reading →