Virus Research ?????

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www.LiveScience.com/health

05 February 2008

New Way to Kill Viruses: Shake Them to Death

By Schirber, Special to LiveScience

Scientists may one day be able to destroy viruses in the same way

that opera singers presumably shatter wine glasses. New research

mathematically determined the frequencies at which simple viruses

could be shaken to death.

" The capsid of a virus is something like the shell of a turtle, " said

physicist Otto Sankey of Arizona State University. " If the shell can

be compromised [by mechanical vibrations], the virus can be

inactivated. "

Recent experimental evidence has shown that laser pulses tuned to the

right frequency can kill certain viruses. However, locating these so-

called resonant frequencies is a bit of trial and error.

" Experiments must just try a wide variety of conditions and hope that

conditions are found that can lead to success, " Sankey told

LiveScience.

To expedite this search, Sankey and his student Dykeman have

developed a way to calculate the vibrational motion of every atom in

a virus shell. From this, they can determine the lowest resonant

frequencies.

As an example of their technique, the team modeled the satellite

tobacco necrosis virus and found this small virus resonates strongly

around 60 Gigahertz (where one Gigahertz is a billion cycles per

second), as reported in the Jan. 14 issue of Physical Review Letters.

A virus' death knell

All objects have resonant frequencies at which they naturally

oscillate. Pluck a guitar string and it will vibrate at a resonant

frequency.

But resonating can get out of control. A famous example is the Tacoma

Narrows Bridge, which warped and finally collapsed in 1940 due to a

wind that rocked the bridge back and forth at one of its resonant

frequencies.

Viruses are susceptible to the same kind of mechanical excitation. An

experimental group led by K. T. Tsen from Arizona State University

have recently shown that pulses of laser light can induce destructive

vibrations in virus shells.

" The idea is that the time that the pulse is on is about a quarter of

a period of a vibration, " Sankey said. " Like pushing a child on a

swing from rest, one impulsive push gets the virus shaking. "

It is difficult to calculate what sort of push will kill a virus,

since there can be millions of atoms in its shell structure. A direct

computation of each atom's movements would take several hundred

thousand Gigabytes of computer memory, Sankey explained.

He and Dykeman have found a method to calculate the resonant

frequencies with much less memory.

In practice

The team plans to use their technique to study other, more

complicated viruses. However, it is still a long way from using this

to neutralize the viruses in infected people.

One challenge is that laser light cannot penetrate the skin very

deeply. But Sankey imagines that a patient might be hooked up to a

dialysis-like machine that cycles blood through a tube where it can

be hit with a laser. Or perhaps, ultrasound can be used instead of

lasers.

These treatments would presumably be safer for patients than many

antiviral drugs that can have terrible side-effects. Normal cells

should not be affected by the virus-killing lasers or sound waves

because they have resonant frequencies much lower than those of

viruses, Sankey said.

Moreover, it is unlikely that viruses will develop resistance to

mechanical shaking, as they do to drugs.

" This is such a new field, and there are so few experiments, that the

science has not yet had sufficient time to prove itself, " Sankey

said. " We remain hopeful but remain skeptical at the same time. "

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