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Scientists Make Progress Toward a Safe, Effective Zika Vaccine

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A biologist releases genetically modified Aedes Egypti mosquitoes in Piracicaba, Brazil, in February 2016. The modified mosquitoes, which cannot transmit Zika, compete with wild mosquitoes. Image Credit: Victor Moriyama/Getty Images

 
Zika virus has spread to almost 60 countries since early 2016. Almost 5000 cases have been identified in the United States, including more than 200 infections transmitted in Florida and Texas. Though the virus often causes only mild symptoms (or may not cause any symptoms at all), the link between Zika infection, microcephaly, and other developmental abnormalities has been strengthened with additional studies over the past year. However, a vaccine is still unavailable.

New research led by investigators at the University of Pennsylvania may move us closer to the goal of a safe, effective vaccine for the virus. The findings were published today in the journal Nature.

The scientists used a novel type of vaccine to immunize mice and monkeys, taking RNA molecules that code for viral proteins (messenger RNA, or mRNA). Because these RNA molecules would usually be quickly cleared by the body, the RNA in the Zika vaccine was modified by the addition of a modified nucleoside. The nucleoside is a nucleotide—the building blocks of DNA—lacking a phosphate group, which previous studies have shown helps to “hide” the mRNA from the host and allow replication. The mRNA was also packaged within lipid nanoparticles, encouraging protein expression. This vaccine therefore allows the mRNA to enter cells and induce production of the viral protein, causing a host immune response similar to that seen with a live virus vaccine. Researchers found that a single dose of the mRNA vaccine effectively protected animals against Zika virus.

Senior author Drew Weissman, of the University of Pennsylvania, relayed the advantages of this approach in a phone call with mental_floss. “The main advantages of our RNA vaccine is that only a single administration is needed. For all of the DNA and inactivated vaccines, they have to immunize twice to get protection, so we get much higher levels of neutralization with a single immunization. The only other vaccine that had protection after a single immunization was the live virus adenovirus vaccine.”

Live vaccines are difficult for a number of reasons, including potential side effects, and cannot be used in pregnant women—a main risk group for Zika infections due to the virus’s effects on the developing fetus. Weissman also noted the mRNA vaccine is inexpensive to produce, which could facilitate widespread use even in resource-limited countries.

Scientists hope to start human clinical trials with the Zika mRNA vaccine in 12 to 18 months. In the interim, additional experiments are planned in order to begin studying whether this Zika vaccine could potentially lead to increased illness with a related flavivirus: dengue. Dengue infection can lead to a phenomenon called “antibody-dependent enhancement,” where antibodies make disease worse instead of protecting the host from infection. There is concern that those vaccinated for Zika could experience more severe dengue infections in areas where both viruses circulate.

To examine whether their Zika vaccine could cause this effect, Weissman says, “We’re taking two approaches. We want to look at antibody-dependent enhancement between different flaviviruses. We’re also working on a combination vaccine that includes all of the flavivirus RNAs together, and the hope there is that with a single vaccine we can immunize against Dengue, West Nile, Zika, Japanese encephalitis, or whatever flaviviruses we want to include.”

Weissman and his collaborators are not the only ones hoping to move a Zika vaccine from the lab to the clinic. A number of different groups have worked to develop a Zika vaccine over the last year. A Phase I clinical trial, to investigate vaccine safety, began last August of a DNA vaccine developed at the National Institutes of Health. And while investigators are hopeful that one of the vaccines in development could be ready for use by 2018, vaccines for pregnant women may be delayed until several years after that, due to the difficulties of demonstrating safety in that population.

The components of the mRNA vaccine also provide hope the vaccine could be used during pregnancy. Weissman explains, “The RNA they use is identical to what’s in our bodies. The nanoparticles also contain mostly physiological lipids. We’ve seen no adverse events from any of our immunizations, so we’re thinking that will probably be easy to give to a pregnant woman.”

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Medicine
Why Haven't We Cured Cancer Yet?
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Walkathons, fundraisers, and ribbon-shaped bumper stickers raise research dollars and boost spirits, but cancer—the dreaded disease that affects more than 14 million people and their families at any given time—still remains bereft of a cure.

Why? For starters, cancer isn't just one disease—it's more than 100 of them, with different causes. This makes it impossible to treat each one using a one-size-fits-all method. Secondly, scientists use lab-grown cell lines cultivated from human tumors to develop cancer therapies. Living masses are far more complex, so potential treatments that show promise in lab experiments often don't work on cancer patients. As for the tumors themselves, they're prone to tiny genetic mutations, so just one growth might contain multiple types of cancer cells, and even unique sub-clones of tumors. These distinct entities might not respond the same way, or at all, to the same drug.

These are just a few of the challenges that cancer researchers face—but the good news is that they're working to beat all of them, as this TED-Ed video explains below.

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Health
Skipping Breakfast Could Be Bad for Your Heart
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There are mountains of evidence supporting the claim that breakfast really is the most important meal of the day. Getting something in your stomach in the first hours of the morning can regulate your glucose levels, improve your cognition, and keep your hunger in check. Now new research published in the Journal of the American College of Cardiology points to another reason not to wait until lunchtime to break last night’s fast. As TIME reports, people who skip breakfast are at an increased risk for atherosclerosis, a disease caused by plaque buildup in the arteries.

Researchers surveyed over 4000 men and women between the ages of 40 and 54 living in Spain. After looking at the dietary habits of each participant, they broke them into three groups: people who consumed more than 20 percent of their daily calories in the morning; those who got 5 to 20 percent; and those who ate less than 5 percent.

The subjects who ate very little in the a.m. hours or skipped breakfast all together were 2.5 more likely to have generalized atherosclerosis. This meant that plaque was starting to collect on the walls of their arteries, hardening and narrowing them and increasing the risk for heart attack or stroke. People who fell into the 5 to 20 percent calorie category were also more likely to show early signs of the disease, while those who ate the most calories in the morning were the healthiest.

These results aren’t entirely surprising. Previous studies have shown a connection between skipping breakfast and health problems like high blood pressure, high cholesterol, diabetes, and unwanted weight gain. A possible explanation for this trend could be that waiting several hours after waking up to eat your first meal of the day could trigger hormonal imbalances. The time between getting into and out of bed is the longest most of us go without eating, and our bodies expect us to consume some calories to help kickstart our energy for the day (drinking straight coffee doesn’t cut it). Another theory is that people who don’t eat in the morning are so hungry by the time lunch rolls around that they overcompensate for those missing calories, which is why skipping breakfast doesn’t make sense as a diet strategy.

But of course there are many breakfast skippers who aren’t motivated by health reasons either way: They just don’t think they have the time or energy to feed themselves in the morning before walking out the door. If this describes you, here are some simple, protein-packed meals you can prepare the night before.

[h/t TIME]

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