Physics professor fights viruses

Credit: Maria Raffaele/Art Staff Credit: Maria Raffaele/Art Staff

Every year thousands of people get shots to prevent the flu. The flu is something very commonplace in our society, but sometimes complications can lead to death; the Centers for Disease Control estimates that the H1N1 flu in 2009 took more than 12,000 lives. The flu is caused by a virus; the virus is protected by an outer coat of protein known as a capsid.

This capsid is the focus of the research group led by Alex Evilevitch, an associate professor of physics, who is working on accurately manipulating the pressure in the capsid of viruses that attacks human cells. According to Evilevitch, this has numerous applications in science and medicine and opens a wide range of possibilities of curing diseases like the flu that occur because of viruses.

Viruses are extremely small infectious agents that attack normal cells and then replicate within them, many times causing diseases. Viruses are “ultramicroscopic” entities, meaning that they are too small to be seen through a traditional microscope. In fact, the average virus is about a hundredth the size of a bacterium, or one-millionth of a meter in diameter.

Viruses attack cells and inject their genetic material (DNA or RNA) into the cells. This forces the cells to make multiple copies of the virus and release them, causing diseases in the process. One example of a virus is HIV, which causes the widely known disease AIDS.

Evilevitch explained that, in the capsid of the virus, “there is a lot of DNA packaged in a very small space. So what happens when we push all that DNA inside the capsid? DNA has a lot of negative charges on it, and it is a very stiff molecule. That causes a lot of repulsion between the DNA strands.” Because of all this repulsion inside, the capsid is constantly under pressure.

According to Evilevitch, this pressure can reach 100 atmospheres (atm), whereas a champagne bottle is normally five or 10 atm. Most viruses use this property when injecting their DNA into host cells, as the pressure difference causes the DNA to “shoot out like a bullet” into the cells.

In Evilevitch’s lab, one of the things researchers do is measure the energy changes that result as the DNA shoots into the cells and causes a small change in heat energy. This is accomplished through microcalorimetry, which measures minute changes in temperature at the level of cells and viruses.

The researchers at the lab are working on changing the pressure inside viral capsids so that the viruses become ineffective. This is accomplished by measuring effects of salts on the DNA pressure inside the capsid, as the ions from the salts can permeate into the capsid.

There is a question about the practicality of changing the pressure in viruses to render them ineffective in the future. It is not realistic to inject salts directly into one’s bloodstream.

Evilevitch explained that injections do not have to be salts; they merely have to be positively or negatively charged particles that can permeate the capsid structure and change the pressure. Even then, the pressure does not have to change dramatically. He said, “It is not the matter of changing the pressure from 100 atm to 0 atm, but instead, it is the matter of changing the pressure slightly to stop the virus from injecting or packaging its genome.”

Evilevitch’s lab is making progress toward the cure for multitudes of diseases caused by viruses. About the future, he said, “We are just about to publish a paper showing that we need to change the density inside of internal capsid charge by 1 percent and viruses will inject into the cell, but it will not repackage [the] genome into virus capsids.”

This is a major discovery because it means that the virus could be rendered ineffective with only a slight pressure change. Though this pressure-changing process is dependent on many factors, it is a major step toward a day when viruses may not be such a menace to society; perhaps the common flu could be wiped out.