Scientists closer to universal flu vaccine after pandemic 'natural experiment'

Sep. 22, 2013 — Scientists have moved closer to developing a universal flu vaccine after using the 2009 pandemic as a natural experiment to study why some people seem to resist severe illness.

Researchers at Imperial College London asked volunteers to donate blood samples just as the swine flu pandemic was getting underway and report any symptoms they experienced over the next two flu seasons.

They found that those who avoided severe illness had more CD8 T cells, a type of virus-killing immune cell, in their blood at the start of the pandemic.

They believe a vaccine that stimulates the body to produce more of these cells could be effective at preventing flu viruses, including new strains that cross into humans from birds and pigs, from causing serious disease.

The findings are published in Nature Medicine.

Professor Ajit Lalvani from the National Heart and Lung Institute at Imperial College London, who led the study, said: "New strains of flu are continuously emerging, some of which are deadly, and so the Holy Grail is to create a universal vaccine that would be effective against all strains of flu."

Today's flu vaccines make the immune system produce antibodies that recognise structures on the surface of the virus to prevent infection with the most prevalent circulating strains. But they are usually one step behind as they have to be changed each year as new viruses with different surface structures evolve.

Previously, experimental models had suggested that T cells may protect against flu symptoms but until now this idea has not been tested in humans during a pandemic.

Professor Lalvani's team rapidly recruited 342 staff and students at Imperial to take part in their study in autumn 2009. The volunteers donated blood samples and were given nasal swabs. They were sent emails every three weeks asking them to fill in a survey about their health. If they experienced flu symptoms, they took a nasal swab and sent it back to the lab.

They found that those who fell more severely ill with flu had fewer CD8 T cells in their blood, and those who caught flu but had no symptoms or only mild symptoms had more of these cells.

Professor Lalvani said, "The immune system produces these CD8 T cells in response to usual seasonal flu. Unlike antibodies, they target the core of the virus, which doesn't change, even in new pandemic strains. The 2009 pandemic provided a unique natural experiment to test whether T cells could recognise, and protect us against, new strains that we haven't encountered before and to which we lack antibodies.

"Our findings suggest that by making the body produce more of this specific type of CD8 T cell, you can protect people against symptomatic illness. This provides the blueprint for developing a universal flu vaccine.

"We already know how to stimulate the immune system to make CD8 T cells by vaccination. Now that we know these T cells may protect, we can design a vaccine to prevent people getting symptoms and transmitting infection to others. This could curb seasonal flu annually and protect people against future pandemics."

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Balloon-borne astronomy experiment X-Calibur racing to hit wind window

Sep. 13, 2013 — In a few days, a balloon-borne telescope sensitive to the polarization of high-energy "hard" X-rays will ascend to the edge of the atmosphere above Fort Sumner, N.M., to stare fixedly at black holes and other exotic astronomical objects.

When X-Calibur, as the polarimeter is called, looks to the skies, it will see things that have never been seen before because it is looking at characteristics of high-energy light that astronomers are just beginning to explore.

X-Calibur differs from other instruments in that it can measure the polarization degree and direction of X-rays, which provide information not available in other ways. For example, when it looks at black holes and their plasma outflows, it will be able to tell how fast the black holes are spinning.

"Whenever you look at the sky at a different wavelength, you see something completely different," said Henric Krawczynski, PhD, professor of physics in Arts & Sciences at Washington University in St. Louis and principal investigator of the X-Calibur experiment.

The beauty of balloon flights is that they can be used to test new instruments like X-Calibur at very low cost, but the drama of them is that the experiment flies at the mercy of the wind.

X-Calibur, like other experiments flown from NASA's Columbia Scientific Balloon Facility in Fort Sumner, has to catch a ride on what is called a stratospheric turnaround event.

At mid-latitudes, stratospheric winds reverse direction twice each year: in the early spring and in late summer. If the winds are favorable, the balloon will travel west in the morning and return east in the evening.

"This way you can put it in the air for 30 hours, if you're lucky," Krawczynski said. If the wind doesn't turn around, the balloon flight will be short. When balloons drift outside the allowed operational area, flight safety officers fire guillotines that separate the parachute from the balloon, dropping the payload.

What could possibly go wrong? The WUSTL polarimeter will be carried aloft by an X-ray pointing telescope, called InFOCuS, that was designed and built by NASA's Goddard Space Flight Center.

A team of 15 people is working 12-hour days -- essentially living in the NASA hangar at Fort Sumner -- to make sure the telescope will be ready on time to catch the favorable winds.

One crucial task is to make sure the X-rays are concentrated on the center of the polarimeter, which is 8 meters from the mirror. The two components have to be aligned within one-sixtieth of a degree or the X-rays either won't hit the collimator at the center of the polarimeter or they'll hit it off-axis, both of which are bad, Krawczynski said.

"The X-rays are hitting the collimator but a bit off to one side. We still need to tilt the mirror by half an arc-minute or so to focus the beam on the center of the collimator," he said.

Everything else has to be carefully checked out as well. A reaction wheel that has worked for 25 years has suddenly started to wobble and must be replaced. And difficulties arose when the telescope was rotated through 90 degrees in the NASA hangar that hadn't been apparent when it was rotated through 30 degrees in the lab.

But in fact, Krawczynski isn't so much worried as excited. "When something doesn't work, we have to troubleshoot and try to figure out what to do. It's detective work, which is fun," he said.

"I'm pretty confident we'll make the window for these turnaround flights," he said during a brief return to St. Louis. "It looks like we'll be ready in the middle of the window, but maybe we can make up a few days' time."

Armchair observers can watch near-real-time video of the launch at the Columbia Scientific Balloon Facility. While the balloon is aloft, it will be tracked on a Google Earth map?. X-Calibur is a team effort. Washington University in St. Louis, led by Henric Krawczynski, is in charge of the X-ray polarimeter and overall mission; NASA's Goddard Space Flight Center, led by Scott Barthelmy, a WUSTL graduate, is responsible for the gondola, X-ray telescope and the pointing system; the X-ray mirror and star trackers were contributed by Nagoya University in Japan; Gianluigi De Geronimo of Brookhaven National Laboratory oversees the electronic components; and Guarino Engineering Services the mechanical ones.

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