by VR Sreeraman on  July 28, 2007 at 4:14 PM Research News
Visible Light Pulses Helps to Eliminate Viruses More Effectively
US scientists have found that an intense pulse of visible light kills viruses lurking in biological samples more effectively and safely than other alternative methods, including therapies with UV irradiation or microwaves.

The researchers say the pulse produces mechanical vibrations in the virus shell, also called capsid, as a result of which, the virus is irreversibly damaged and disintegrated.

They say that the new technique may help destroy human immunodeficiency virus (HIV) and Hepatitis C.

The traditional UV irradiation technique can cause mutations, which eventually make the microorganisms resistant. UV light can also damage the DNA of surrounding healthy cells.

Microwaves, on the other hand, are even less promising as the water surrounding in and around a microorganism absorbs the energy from the radiation, and it does not reach the virus.

But visible light can overcome this problem, Kong-Thon Tsen of Arizona State University and his colleagues at Johns Hopkins School of Medicine have discovered. They say that just a single pulse of light is enough to destroy the viruses completely.

The researchers have already tested the efficacy of the technique in experiments in which they applied pulses of purple-coloured light, lasting just 10-15 seconds, to viruses called M13 bacteriophages.

The "power density" of the laser was just 50 megawatts per square centimetre, low enough to leave surrounding human cells and tissue undamaged, but high enough to produce large-amplitude vibrations in a virus's capsid. It was also too low to cause genetic mutations, meaning the virus would not build up resistant to the treatment over time.

According to researchers, the technique may be used to disinfect blood or other biological samples in hospitals.

"In addition, we believe that the method may be especially important in designing novel treatments for blood-borne viral diseases," the New Scientist quoted Tsen as saying.

"For example blood dialysis allows us to irradiate a patient's blood outside the body and potentially cleanse it of infectious virus particles before reintroducing it into the patient. In this way, we could reduce mortality associated with diseases like hepatitis C and AIDS," he added.

The researchers are now contemplating testing the efficacy of the technique in killing a wide range of deadly viruses including HIV and hepatitis C.

"We also plan to conduct further tests on the effects of the low-power visible laser on mammalian cells to determine any potential side effects and confirm that it selectively kills viruses," said Tsen.

Source: ANI

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