Shattering Viruses

A new study is trying to establish the intrinsic vibration modes of capsids---the protein shells of virus particles that package its genetic material---with a view toward rupturing them and thereby killing the pathogenic virus. If the capsid resonant frequencies could be determined, then possibly light or sound waves might be used to shatter the capsids the way the opera singer Enrico Caruso supposedly shattered wine glasses by sustaining a note at exactly the resonant frequency of the glass. This approach to attacking viruses is alternative to treating them with chemicals, which is not always effective; furthermore, the chemicals can do damage to healthy cells, or the viruses can mutate and defeat chemical defenses. Hence the importance of attempting to undo viruses with mechanical means.

Eric Dykeman and Otto Sankey, physicists at Arizona State University, are modeling capsid vibrations at the atomic level for comparisons with experiments being performed by K.T. Tsen at ASU in which picosecond laser pulses are scattered from capsids. The capsids, which are mostly made of complex protein assemblies, will typically absorb some of the laser light, a process which causes them to vibrate. The rest of the laser beam, its energy somewhat depleted, will be downshifted in frequency. This allows observers to deduce the resonant frequency of the capsids. By staging the short laser pulse in different ways, a whole catalog of capsid resonant frequencies can be made. Sankey (otto.sankey@asu.edu, 480-965-4334) says that the simulations performed so far suggest that resonant frequencies for their chosen virus, the satellite tobacco necrosis virus (see vibration movie at http://www.aip.org/png/2008/292.htm) are in the vicinity of 60 to 90 GHz. (Dykeman and Sankey, Physical Review Letters, upcoming article)