Scientists Get Closer to a Zika Vaccine

On June 2, 2016, in Recife, Brazil—the heart of the Zika outbreak—mothers ride the bus with their children, both born with microcephaly, or an abnormally small head. The birth defect is linked to the Zika virus. Image credit: Mario Tama/Getty Images

Zika virus exploded across the world earlier this year, causing a large outbreak of disease in Brazil and spreading to almost 50 countries and territories. While the typical Zika infection is mild, recent reports have strengthened the link between virus infection during pregnancy and the development of microcephaly, a rare neurological condition which leads to a small head and brain in the developing fetus. Zika also has been linked to the development of Guillan-Barre syndrome [PDF], a neurological disorder that can lead to weakness or paralysis.

New research from investigators at Harvard Medical School and collaborators at the University of Sao Paulo, Walter Reed Army Institute of Research, and Ragon Institute has suggested that we’re one step closer to a vaccine to protect vulnerable individuals against Zika virus. The researchers published their findings this week in the journal Nature.

Scientists tested two types of Zika vaccines in mice: a DNA vaccine and an inactivated, whole-virus vaccine. In DNA vaccination, the host's cell takes up the foreign DNA, and the cell then makes the proteins encoded by the DNA included in the vaccine. With an inactivated virus, the host responds directly to the injected proteins that the killed virus produced.

Lead author Dan Barouch, of Harvard Medical School's Center for Virology and Vaccine Research, explained in a press-only teleconference on July 27, “These two vaccine candidates both provided complete protection against Zika virus challenge in mice. To the best of our knowledge, this is the first report of Zika virus vaccine protection in an animal model.”

Importantly, the mice were protected against Zika after a single immunization without any need for a booster. To date, these vaccines have not been tested in pregnant mice, but Barouch notes these studies are ongoing.

The researchers caution that “care should be taken extrapolating from this mouse study to potential human efficacy.” Ben Neuman, a virologist at the University of Reading who was not involved with the study, agrees. He tells mental_floss that “while DNA vaccines work really well in mice, they tend to be a bit hit or miss in other animals, and DNA vaccines have not been particularly effective in people to this point.” No DNA vaccines are currently approved for human use in the U.S.; one is approved for horses against West Nile virus. To date, only one human DNA vaccine has been approved, for Japanese encephalitis virus in Australia.

While this study represents a step forward in the hunt for a Zika vaccine, moving a Zika vaccine from concept to clinic is a difficult prospect. While DNA vaccines may be a long shot, the prospects are also murky for other types of vaccines that have been used for humans, such as attenuated vaccines (live but weakened forms of the virus), which weren’t tested in this study. To create an inactivated vaccine for Zika, enough of the virus would need to be grown in cell cultures to be able to provide a high dose of vaccine to recipients. For a live vaccine, we would have to be careful to be sure that it wouldn’t cause any of the possible developmental or neurological effects that we see with wild-type Zika virus, including microcephaly or Guillain-Barré syndrome.

Another concern for a Zika vaccine is the potential to make other diseases, caused by related viruses, more serious. Zika is a Flavivirus and related to other viruses in this genus, including West Nile, yellow fever, Japanese encephalitis, and dengue. A second infection with dengue can actually be worse than the first, due to a phenomenon called antibody-dependent enhancement of infection. There is concern that there is potential for a Zika vaccine to induce this response.

“Antibodies are sticky molecules that float around in the blood, and many cells are covered with molecules that can catch passing antibodies," Neuman explains. "A virus like Zika may miss its chance to infect a host cell that it is poorly adapted to recognize. But if it is covered in antibodies, the virus has a better chance to infect because the antibody acts as a bridge—the cell holds onto the antibody, which sticks to the virus. This is why dengue virus is usually more severe the second or third time you catch it—the virus gets an infectious boost from antibodies left over from earlier infections. It would be wise to have a better idea of how antibodies will affect Zika virus before we start vaccinating lots of people.”

This unwelcome outcome could happen in reverse as well: The recently released dengue vaccine may make infection with Zika virus more serious, as recent laboratory models have suggested.

We’ll soon have a better idea of antibody production due to Zika vaccines in human trials. Co-author Col. Nelson Michael, of the Walter Reed Army Institute of Research, confirms to mental_floss via email that trials of the inactivated vaccine tested in this research will be moving into Phase I human trials in October—so these vaccines may soon become a reality.

Emery Smith
Stones, Bones, and Wrecks
The 'Alien' Mummy Is of Course Human—And Yet, Still Unusual
Emery Smith
Emery Smith

Ata has never been an alien, but she's always been an enigma. Discovered in 2003 in a leather pouch near an abandoned mining town in Chile's Atacama Desert, the tiny, 6-inch mummy's unusual features—including a narrow, sloped head, angled eyes, missing ribs, and oddly dense bones—had both the “It's aliens!” crowd and paleopathologists intrigued. Now, a team of researchers from Stanford University School of Medicine and UC-San Francisco has completed a deep genomic analysis that reveals why Ata looks as she does.

As they lay out in a paper published this week in Genome Research, the researchers found a host of genetic mutations that doomed the fetus—some of which have never been seen before.

Stanford professor of microbiology and immunology Garry Nolan first analyzed Ata back in 2012; the mummy had been purchased by a Spanish businessman and studied by a doctor named Steven Greer, who made her a star of his UFO/ET conspiracy movie Sirius. Nolan was also given a sample of her bone marrow; his DNA analysis confirmed she was, of course, human. But Nolan's study, published in the journal Science, also found something very odd: Though she was just 6 inches long when she died—a typical size for a midterm fetus—her bones appeared to be 6 to 8 years old. This did not lead Nolan to hypothesize an alien origin for Ata, but to infer that she may have had a rare bone disorder.

The current analysis confirmed that interpretation. The researchers found 40 mutations in several genes that govern bone development; these mutations have been linked to "diseases of small stature, rib anomalies, cranial malformations, premature joint fusion, and osteochondrodysplasia (also known as skeletal dysplasia)," they write. The latter is commonly known as dwarfism. Some of these mutations are linked to conditions including Ehlers-Danlos syndrome, which affects connective tissue, and Kabuki syndrome, which causes a range of physical deformities and cognitive issues. Other mutations known to cause disease had never before been associated with bone growth or developmental disorders until being discovered in Ata.

scientist measures the the 6-inch-long mummy called Ata, which is not an alien
Emery Smith

"Given the size of the specimen and the severity of the mutations … it seems likely the specimen was a pre-term birth," they write. "While we can only speculate as to the cause for multiple mutations in Ata's genome, the specimen was found in La Noria, one of the Atacama Desert's many abandoned nitrate mining towns, which suggests a possible role for prenatal nitrate exposure leading to DNA damage."

Though the researchers haven't identified the exact age of Ata's remains, they're estimated to be less than 500 years old (and potentially as young as 40 years old). Genomic analysis also confirms that Ata is very much not only an Earthling, but a local; her DNA is a nearest match to three individuals from the Chilote people of Chile.

In a press statement, study co-lead Atul Butte, director of the Institute for Computational Health Sciences at UC-San Francisco, stressed the potential applications of the study to genetic disorders. "For me, what really came of this study was the idea that we shouldn't stop investigating when we find one gene that might explain a symptom. It could be multiple things going wrong, and it's worth getting a full explanation, especially as we head closer and closer to gene therapy," Butte said. "We could presumably one day fix some of these disorders."

Just Two Cans of Soda a Day May Double Your Risk of Death From Heart Disease

If you've been stocking your refrigerator full of carbonated corn syrup in anticipation of warmer weather, the American Heart Association has some bad news. The advocacy group on Wednesday released results of research that demonstrate a link between consumption of sugary drinks—including soda, fruit juices, and other sweetened beverages—and an increased risk of dying from heart disease.

Study participants who reported consuming 24 ounces or more of sugary drinks per day had twice the risk of death from coronary artery disease of those who averaged less than 1 ounce daily. There was also an increased risk of death overall, including from other cardiovascular conditions.

The study, led by Emory University professor Jean Welsh, examined data taken from a longitudinal study of 17,930 adults over the age of 45 with no previous history of heart disease, stroke, or diabetes. Researchers followed participants for six years, and examined death records to determine causes. They observed a greater risk of death associated with sugary drinks even when they controlled for other factors, including race, income, education, smoking habits, and physical activity. The study does not show cause and effect, the researchers said, but does illuminate a trend.

The study also noted that while it showed an increased risk of death from heart disease, consumption of sugary foods was not shown to carry similar risk. One possible explanation is that the body metabolizes the sugars differently: Solid foods carry other nutrients, like fat and protein, that slow metabolism, while sugary drinks provide an undiluted influx of carbohydrates that the body must process.

The news will likely prove troublesome for the beverage industry, which has long contended with concerns that sugary drinks contribute to type 2 diabetes and tooth decay. Some cities, including Seattle, have introduced controversial "soda tax" plans that raise the sales tax on the drinks in an effort to discourage consumption.


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