Tag Archives: immune system

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: Trichomoniasis, the Pear-Shaped, Blood-Sucking, Silent Scourge

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What’s shaped like a pear, hangs with a posse of bacteria, and is a silent scourge upon millions of urogenital tracts? I hope you guessed Trichomonas vaginalis, the single-celled parasite that causes trichomoniasis, or trich (pronounced “trick”). Trich is the most common curable sexually transmitted disease out there — currently afflicting around 3.7 million Americans and 156 million Earthlings.

These single-celled creatures pack a punch, but the body fights back.

When trich causes symptoms, sufferers might experience vaginal discharge (which sometimes has a bad odor), penile burning or discharge, spotting, and itching or swelling in the genital area. But around 70 percent of infections have no symptoms at all, making it a mostly “silent” disease. Based on the totality of the evidence, the Centers for Disease Control and Prevention (CDC) doesn’t currently recommend routine screening for trich in people without symptoms.

But it’s the subject of some debate. Since both symptoms and screenings are rare, and the disease isn’t reportable, some health experts worry that trich could be doing a lot of damage right under our noses. An infection during pregnancy could increase risk for preterm labor or low birth weight. It can increase risk for both acquiring and transmitting HIV from or to a partner. Women with trich are more likely to acquire an HIV infection when sexually exposed to the virus — in fact, one study estimated that 6.2 percent of all HIV infections among U.S. women could be attributed to trich. It’s also easier to catch HIV from a man with trich than from a man without trich. 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: How Common Is Herpes?

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Those of you with an eye for weird news might have noticed recent headlines about wild monkeys in Florida suffering from a herpes epidemic.

Two things in that sentence might have tripped you up. One, Florida has wild monkeys? Yup. In the late 1930s, after a Tarzan movie was wrapped, three male and three female rhesus monkeys were released into the Florida wilds, giving rise to an estimated 1,000 monkeys roaming the Sunshine State today.

Both oral herpes and genital herpes are on the decline.

The second thing that might have given you pause: Monkeys can get herpes? Yes again! The Herpesviridae family is huge, with at least 100 members infecting mammals, birds, reptiles, bony fish, amphibians, and oysters — even dinosaurs are thought to have been infected by herpesviruses! The virus has been evolving alongside us since before the dawn of humanity, so it knows us like the back of its hand (metaphorically speaking), allowing it to stow away in our bodies and hide from the immune system.

The “Tarzan” monkeys suffer from a type of herpesvirus called herpes B, which can be deadly in humans, though it’s rare — just try not to find yourself on the receiving end of a monkey bite or scratch. Not so rare in humans are human herpesviruses, of which there are eight types. Types 1 and 2 — aka herpes simplex virus (HSV) 1 and 2 — can both cause genital herpes, one of the most common sexually transmitted diseases (STDs). HSV-1 mostly causes cold sores, but can also infect the genitals to cause genital herpes, while HSV-2 mostly causes genital herpes, but can also infect the facial area to cause cold sores. (A little confusing, I know.) Continue reading →

STD Awareness: The Long Road to a Chlamydia Vaccine

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Earlier this year, television personality John Oliver was the butt of an elaborate prank orchestrated by actor Russell Crowe. It started with an auctioned jock strap, and ended with Crowe funding the John Oliver Koala Chlamydia Ward at the Australia Zoo. If you want the full story, check out the video below (beware explicit language).

Despite Oliver playing it for laughs, koala chlamydia is very real and very serious. At least half of wild koalas are infected with a chlamydia type that’s related to the human version. As in humans, koalas can transmit these bacteria through sexual contact. And, similar to the havoc it wreaks in our species, in koalas chlamydia can cause blindness, urinary tract infections, and female infertility — and can be passed from mother to infant. Along with other factors, chlamydia is said to be responsible for plummeting koala populations in many parts of Australia. Continue reading →

STD Awareness: Is HPV Now a “Men’s Disease”?

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Human papillomavirus, or HPV, is most notorious for causing cervical cancer — making it, in many people’s minds, a “women’s disease.” But this gender-blind sexually transmitted virus can cause cancer in any cell it infects, and is associated with cancers of the cervix, anus, vagina, vulva, penis, and mouth and throat — aka oropharyngeal cancer.

While oropharyngeal cancers used to be caused mostly by tobacco, as people quit smoking an increasing proportion is caused by HPV. In the 1980s, only 15 percent of oropharyngeal cancers were caused by HPV, but nowadays the virus is behind 70 percent of them. A 2011 study predicted that the number of HPV-positive oropharyngeal cancers will surpass cervical cancers by 2020.

HPV is rapidly gaining prominence among men.

It’s only 2017, but we’re ahead of schedule. Earlier this year, researchers reported that, in the United States, oropharyngeal cancer is more common among men than are cervical cancers among women — and oropharyngeal cancer rates are increasing in the male population, while they are relatively stagnant among women. These rates are projected to continue climbing, which will skew oropharyngeal cancer even more heavily toward the male population. But, in the public’s imagination, HPV is most well-known for its association with cervical cancer — while most people haven’t even heard of oropharyngeal cancer.

Oropharyngeal Cancer and HPV

Oropharyngeal cancer can strike the inside of your mouth and throat. Risk factors include tobacco (including cigarettes, snuff, and chewing tobacco), marijuana use, alcohol, and oral infection with HPV. HPV can be spread by most sexual activities — including vaginal, anal, and oral sex, as well as “French kissing” and rubbing genitals together. There are many strains of HPV, which come in two main categories: low-risk HPV, which can cause genital warts; and high-risk HPV, which can cause cancer. Continue reading →