Tag Archives: DNA

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: Is Mouthwash a Match for Gonorrhea’s Superpowers?

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Since the 1930s, we’ve enjoyed around eight decades of easily cured gonorrhea — at least in places with easy access to antibiotics — but experts fear those days are numbered. In the past year or so, cases of untreatable gonorrhea have occasionally made headlines.

Thanks to the powers of evolution, some bacteria have acquired the multiple genes necessary to withstand the onslaught of the pills and shots administered by doctors. Gonococci, the bacteria that cause gonorrhea, are starting to win this “arms race” with humans, whose antibiotic arsenals are losing effectiveness. And with gonorrhea on the rise, gonococci may be evolving at an ever-quickening clip.

In 1879, Listerine claimed to cure gonorrhea. Today, scientists are finally testing that claim. We await the results.

Oral Gonorrhea: The Silent Scourge

Many experts believe oral gonorrhea is a key driver of antibiotic resistance. These infections usually don’t cause symptoms, and without symptoms people usually don’t seek treatment. Without treatment, gonococci can hang out in a throat for up to three months.

After transmission by oral sex — and possibly even by kissing  — gonococci can set up camp in the throat, which is an ideal environment for acquiring antibiotic resistance. They might not be causing symptoms, but they’re not sitting there twiddling their thumbs, either. If there’s one thing gonococci love to do, it’s collecting genes like some of us collect trading cards, and the throat is a gathering place for closely related bacteria species that hand out antibiotic-resistance genes for their expanding collections.

Gonococci can easily scavenge DNA from their surroundings — say, from a dead bacterium — and patch long segments of these genes into their own DNA, creating genetic hybrids between themselves and other organisms. Last month, scientists from Indiana University caught this phenomenon on video for the first time.

Continue reading →

Some Good News About Three Sexually Transmitted Viruses

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Scientists are hard at work finding ways to improve your health!

With so much bad news emblazoned across headlines in every newspaper you look at, the world might seem like a gloomy place. So let’s take one depressing subject — disease — and peel away the sad outer layer to find silver linings of optimism.

When it comes to infections, a lot of us blame one thing: germs, also known as “bugs” — “pathogens” if we’re fancy. Some people might not think of infectious diseases as being that big of a deal — after a round of antibiotics, you’ll be on the mend. Unfortunately, antibiotics only work for bacteria, but a lot of diseases are caused by other types of germs — for which antibiotics are no match. One type of germ is called a virus, and they can’t be cured. Sometimes they can be prevented with vaccines or treated with drugs. For example, the major strains of human papillomavirus (HPV) can be prevented with a vaccine called Gardasil, herpes simplex virus can be suppressed with antiviral drugs, and HIV can be controlled with antiretroviral drugs — but none of these infections can be cured. HPV is usually defeated by the immune system, but herpes and HIV are with you for life.

But it’s not all bad. Around the world, individual scientists have picked their “favorite” viruses and are devoting their lives to finding better prevention strategies, better treatments, and even cures. Let’s check in with some of the latest headlines touting the successes of science.

New Hope for a Herpes Vaccine

A herpes vaccine would be a blockbuster — given how common this sexually transmitted infection is, a preventive shot could help a lot of couples discuss their herpes status without as much fear of judgment and stigma.

Herpes might cause an “outbreak” — unpleasant symptoms that include genital sores — but afterward the virus goes dormant in the nerve cells, hiding from the immune system. In some people, the virus can come out of its dormancy to cause flare-ups of symptoms, but once it’s had its fun it retreats back to the nerve cells.

Earlier this year, media reported on a promising new candidate for a herpes vaccine. Using a completely different strategy than previous, failed herpes vaccines, the researchers behind this breakthrough targeted the part of the virus that allows it to hide from our immune systems. If this vaccine works as hoped, recipients will be able to mount an immune defense when exposed to the virus, blocking it from establishing a permanent home in nerve cells. It might even suppress outbreaks in people who already have herpes. Continue reading →

STD Awareness: Genetics and the Gonococcus

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Image: CDC

Ever since the discovery of effective antibacterial therapies less than a century ago, humans have been able to easily cure gonorrhea, the sexually transmitted scourge that laid waste to fallopian tubes and robbed newborns of vision. Most of us in the developed world have forgotten that this disease was once a leading cause of infertility in women and blindness in babies — and still is in much of the developing world.

Unfortunately, gonococci — the species of bacteria that cause gonorrhea — have been evolving resistance to every antibiotic we’ve thrown at them, including sulfonamides, penicillins, tetracyclines, macrolides, fluoroquinolones, and narrow-spectrum cephalosporins. We have one remaining first-line gonorrhea treatment left: extended-spectrum cephalosporins, which include cefixime, which is taken orally, and ceftriaxone, which is administered as a shot — and resistance is emerging to those drugs, as well.

Gonococci don’t swap potato salad recipes at family reunions — they swap genetic material!

The emergence of antibiotic-resistant gonorrhea is considered one of the most pressing problems in infectious disease — just two years ago, the Centers for Disease Control and Prevention named it an “urgent threat,” and indeed, gonorrhea seems to be evolving resistance to drugs at quite a rapid clip. Gonococci can acquire resistance to antibiotics in three ways.

First, a genetic mutation can endow bacteria with special antibiotic-fighting powers, making it harder for a drug like penicillin to attach to their cells and destroy them. Such a mutant is more likely to gain evolutionary traction if it finds itself in an antibiotic-drenched environment in which resistance to that drug allows it to “outcompete” other bacteria. Indeed, antibiotic resistance was first documented in the 1940s, just years after sulfonamides and penicillin were introduced as the first effective cures for gonorrhea. Continue reading →

STD Awareness: The Next Generation of Gardasil Is Coming!

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noisemakersIt’s January, which means it’s time to festoon our surroundings with streamers, throw around the confetti, break out the noisemakers, and shout Happy Cervical Health Awareness Month!

And, in 2015, we have something huge to celebrate: Last month, the Food and Drug Administration (FDA) approved Gardasil 9, the next-generation HPV vaccine, which provides broader protection than the current version. Next month, the new and improved vaccine will start to be shipped to health care providers, and the Advisory Committee on Immunization Practices is expected to give the Centers for Disease Control and Prevention the green light to recommend the vaccine, after which insurance plans and the Vaccines for Children program should start covering it.

The newest version of Gardasil protects against the seven strains of human papillomavirus that together cause 90 percent of cervical cancers.

Why is this news so exciting for people who care about cervical health? Because, while the current version of Gardasil, which debuted in 2006, protects recipients from the two HPV strains that cause 70 percent of cervical cancers, Gardasil 9 will protect against seven strains of HPV that collectively cause 90 percent of cervical cancers. On top of that, both versions of Gardasil protect against the two HPV strains that are together responsible for 90 percent of genital warts.

Gardasil 9 has been shown to be highly effective in clinical studies, and it is safe to use, which means Gardasil just became an even more potent weapon against cancers caused by HPV. Not only that, but vaccination against HPV will also reduce the frequency of precancerous lesions, which are cellular abnormalities that can be treated before progressing into full-fledged cancer. Less pre-cancer means less time, money, and anxiety spent dealing with followup procedures after an abnormal Pap test, for example. Continue reading →

STD Awareness: The Herpes Virus and Herpes Medications

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herpes medicationOne of the most common sexually transmitted diseases (STDs) is herpes, which affects an estimated 1 out of 6 Americans between the ages of 14 and 49. Herpes is caused by a virus, and one reason that it’s so widespread is that the herpesvirus is ancient. Prehistoric, even — dinosaurs are thought to have been infected by herpesviruses! The Herpesviridae family is huge, with at least 100 members infecting mammals, birds, reptiles, bony fish, amphibians, and oysters.

Herpes drugs from the acyclovir family physically block herpes DNA from replicating — which is pretty amazing!

Humans can suffer from both oral herpes and genital herpes, which are caused by two types of the herpes simplex virus (HSV-1 and HSV-2). Recent genetic analysis reveals that the virus that causes cold sores, HSV-1, has been evolving with us since before we were Homo sapiens, diverging from the viruses that infected our common ancestors 6 million years ago. Interestingly, we didn’t acquire HSV-2 — which mostly causes genital herpes — until our Homo erectus ancestors caught it from early chimpanzees 1.6 million years ago, well before the emergence of modern Homo sapiens around 200,000 years ago.

Most people know what the virus does — genital herpes can involve blisters, pain, and itching — but most people don’t know how the virus works. Luckily, scientists have uncovered a lot of the virus’ secrets — which has allowed them to develop some pretty effective drugs that we can use to foil herpes’ plans. Continue reading →

Are Pap Tests Accurate?

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If you follow health news, you might have noticed some controversy over certain cancer-screening methods: Does the evidence support mammograms as a tool to reduce breast cancer deaths? Are PSA tests effective in saving lives from prostate cancer? These are questions that we are beginning to answer as more and more evidence comes in. But don’t let these questions dissuade you from all cancer screening.

With regular Pap testing, cervical cancer is almost 100 percent preventable.

In fact, although we’re reevaluating data for other cancer-screening methods, we have mountains of solid evidence that the Pap test is one of the best cancer-screening methods out there. Because it detects signature mutations that mark cells as headed toward becoming cancerous, Pap testing detects “pre” cancer while other cancer-screening techniques, like mammography, only detect cancer.

Cervical cancer used to be a top killer in developed nations — and it remains a major cause of death in countries without widespread health-care access — but in the last 50 years, cervical cancer deaths fell by 70 percent in the United States, transforming cervical cancer from the leading cause of cancer death among American women to a less common, nearly preventable cancer. Despite this, you might hear people complain that the Pap test isn’t accurate, citing the possibility of receiving “false positive” or “false negative” results.

A Pap test looks for abnormalities in cervical cells, and you can receive one of these four results:

True Positive: Cellular abnormalities are detected, and they are in fact present. True Negative: Cellular abnormalities are not detected, and in fact the cells are normal.
False Positive: Cellular abnormalities are detected, but the cells are actually normal. False Negative: Cellular abnormalities are not detected, but are actually present.

When we receive a true positive result, we can receive treatment for precancerous lesions that in fact might otherwise lead to cancer. Likewise, when we receive a true negative result, no further treatment is needed. Continue reading →