Scientists Use the Tweaked Genes of a Virus to Halt Vision Loss

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iStock

What if you could tweak the genes of a virus to turn its ability to invade cells into a delivery system for eyesight therapy? That’s what researchers at Johns Hopkins School of Medicine say they’ve done by modifying an adenovirus, a type of virus that can infect tissue linings. The cutting edge gene therapy was developed to help those who suffer vision loss from a particular eye disorder—wet age-related macular degeneration (AMD).

Approximately 1.6 million Americans have AMD, the number one cause of vision loss. The disease is characterized by the growth of abnormal blood vessels that leak retinal fluid into the eye and destroy the macula, an area near the retina important for high acuity vision. This gene therapy both reduces fluid buildup and improves vision loss in humans, according to study results published in The Lancet.

The best current treatment for the disease requires injections of antibodies into the retina to suppress vascular endothelial growth factor (VEGF), a protein that is responsible for the growth of blood vessels—which in turn cause leaking fluid. But the problem is that patients must obtain these injections at four- to six-week intervals, or else the disease symptoms return and worsen over time. Peter Campochiaro, a professor of ophthalmology and neuroscience at Johns Hopkins Medicine's Wilmer Eye Institute and one of the authors of the study, explains that during this treatment, if a patient takes too long to get their next injection, the abnormal blood vessel net grows larger and recruits other cells. “That scarring causes permanent decrease in vision,” he tells Mental Floss. So over time, it’s common even for patients in treatment to “end up with less vision.”

His team has been working to make a form of injections that last longer, so patients don’t have to come in as frequently. For phase one of this trial, Campochiaro’s team recruited 19 participants to participate in a 52-week study. He was looking for people “who don’t have great visual potential, but have evidence of the disease process that you can measure in effect,” he says.

Since viruses are naturally good at getting into cells and depositing their genetic material, the researchers decided to modify a virus to deposit a gene that codes for a protein called sFLT01. sFLT01 blocks the factor that causes the abnormal vessels and fluid production. When the modified virus is injected into the eye, “the viral vector enters cells and deposits the gene, and the gene begins to produce the [sFLT01] protein,” he says. The protein binds to VEGF, preventing it from causing vessel growth and subsequent fluid leakage.

The 19 participants were divided into five different groups and given increasing doses of the viral vector. After determining there was no toxicity at the dose-limit of the first three groups, they proceeded to increase the dosage to its highest level.

Of the 11 participants with symptoms judged to be reversible, six showed “a substantial reduction in the fluid,” and four of those six saw “a pretty dramatic effect.” Those patients had big pockets of fluid in their retinas decrease, Campochiaro says. Better yet, the treatment lasted throughout the yearlong study, though the protein numbers peaked at 26 weeks, and then declined slightly (although not enough to reactivate disease symptoms).

In assessing why five patients saw no reduction in fluid, the scientists discovered those patients had pre-existing antibodies to the virus. They theorize that in these patients, the immune system may have killed the viral vector before it could deposit the genes, though they will have to do more research to prove this. This could be a problem in using this particular virus—a carrier virus called AAV2—since some 60 percent of patients tend to have these antibodies.

A possible solution might be to give resistant patients a surgical injection instead. During this procedure, scientists could take out the vitreous—a gel-like substance that gives your eye its round shape—and inject the vector surgically under the retina instead. While patients might prefer not to have surgery, “our data suggests that it doesn’t matter if there’s pre-existing antibodies [with this method],” he says.

Alternately, other viral vectors have proven to be more effective than AAV2, including a variation on the virus, AAV8, which provides better infections of the virus into the cell. Even more promising, the researchers recently finished a four-year study on a lentiviral vector (a totally different group of viruses) “that take [the genes] into the nucleus of the cell and inserts the gene right into the chromosomes,” Campochiaro explains.

His next steps will be to retest the treatment with a longer study period to identify just how long-lasting the effects are, as well as to test higher doses of the viral vector.

But right now, he is just excited that the gene therapy works. “We injected this gene, the gene is producing a protein, and you can measure that protein in the eye over time,” he says.

6 Protective Mask Bundles You Can Get On Sale

pinkomelet/iStock via Getty Images Plus
pinkomelet/iStock via Getty Images Plus

Daily life has changed immeasurably since the onset of COVID-19, and one of the ways people have had to adjust is by wearing protective masks out in public places, including in parks and supermarkets. These are an essential part of fighting the spread of the virus, and there are plenty of options for you depending on what you need, whether your situation calls for disposable masks to run quick errands or the more long-lasting KN95 model if you're going to work. Check out some options you can pick up on sale right now.

1. Cotton Face Masks; $20 for 4

Protective Masks with Patterns.
Triple7Deals

This four-pack of washable cotton face masks comes in tie-dye, kids patterns, and even a series of mustache patterns, so you can do your part to mask germs without also covering your personality.

Buy it: $20 for four (50 percent off)

2. CE- and FDA-Approved KN95 Mask; $50 for 10

A woman putting on a protective mask.
BetaFresh

You’ve likely heard about the N95 face mask and its important role in keeping frontline workers safe. Now, you can get a similar model for yourself. The KN95 has a dual particle layer, which can protect you from 99 percent of particles in the air and those around you from 70 percent of the particles you exhale. Nose clips and ear straps provide security and comfort, giving you some much-needed peace of mind.

Buy it: $50 for 10 (50 percent off)

3. Three-Ply Masks; $13 for 10

Woman wearing a three-ply protective mask.
XtremeTime

These three-ply, non-medical, non-woven face masks provide a moisture-proof layer against your face with strong filtering to keep you and everyone around you safe. The middle layer filters non-oily particles in the air and the outer layer works to block visible objects, like droplets.

Buy it: $13 for 10 (50 percent off)

4. Disposable masks; $44 for 50

A batch of disposable masks.
Odash, Inc.

If the thought of reusing the same mask from one outing to the next makes you feel uneasy, there’s a disposable option that doesn’t compromise quality; in fact, it uses the same three-layered and non-woven protection as other masks to keep you safe from airborne particles. Each mask in this pack of 50 can be worn safely for up to 10 hours. Once you're done, safely dispose of it and start your next outing with a new one.

Buy it: $44 for 50 (41 percent off)

5. Polyester Masks; $22 for 5

Polyester protective masks.
Triple7Deals

These masks are a blend of 95 percent polyester and 5 percent spandex, and they work to block particles from spreading in the air. And because they're easily compressed, they can travel with you in your bag or pocket, whether you're going to work or out to the store.

Buy it: $22 for five (56 percent off)

6. Mask Protector Cases; $15 for 3

Protective mask case.
Triple7Deals

You're going to need to have a stash of masks on hand for the foreseeable future, so it's a good idea to protect the ones you’ve got. This face mask protector case is waterproof and dust-proof to preserve your mask as long as possible.

Buy it: $15 for three (50 percent off)

At Mental Floss, we only write about the products we love and want to share with our readers, so all products are chosen independently by our editors. Mental Floss has affiliate relationships with certain retailers and may receive a percentage of any sale made from the links on this page. Prices and availability are accurate as of the time of publication.

Tear Gas vs. Pepper Spray: What’s the Difference?

This is probably pepper spray.
This is probably pepper spray.
Siberian Photographer/iStock via Getty Images

Pepper spray and tear gas are both non-lethal irritants that cause extreme burning of the eyes, nose, and throat—but there are a few key differences between the two substances.

For one, they’re created from different chemicals. According to biohazard remediation company Aftermath, the active ingredient in pepper spray is oleoresin capsicum, which comes from the compound that makes hot peppers so hot: capsaicin. If you’ve ever accidentally rubbed your eyes after chopping a chili pepper, you’ve gotten a very tiny taste of what it’s like to be sprayed with pepper spray. Tear gas, on the other hand, contains 0-Chlorobenzylidenemalononitrile (CS), 2-chlorobenzalmalononitrile (CN), or a similar artificial chemical. At room temperature, both of those chemicals are powdery solids, not gases—they’re mixed with liquids or gases so they can be dispersed in the air.

Delivery methods differ, too. Pepper spray often comes in an aerosol can, which shoots it in a stream, a mist, or some other relatively direct path (though it’s also available as a gel or foam). As the Berkeley Science Review explains, tear gas is mainly dispersed with a grenade, which releases the substance over a wide area when it explodes. Since the grenades can cover so much ground, law enforcement officers are more likely to use tear gas to try to break up a crowd, and civilians are more likely to carry pepper spray as a personal safety measure.

The immediate effects of the two substances are similar—burning sensation in mucous membranes, rise in blood pressure, difficulty breathing, runny nose, etc.—but tear gas can also cause nausea and vomiting in higher concentrations.

For more on tear gas, including what to do if you’re exposed to it, head here.

[h/t Aftermath]