Studies of inactivation mechanism of non-enveloped icosahedral virus by a visible ultrashort pulsed laser
- Equal contributors
1 Department of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
2 US Department of Agriculture, Agricultural Research Service, Food Safety and Intervention Technologies Research Unit, James W. W. Baker Center, Delaware State University, Dover, Delaware 19901, USA
3 Department of Physics, Arizona State University, Tempe, Arizona 85287, USA
4 Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
5 Department of Biomedical Engineering, Washington University School of Medicine, St. Louis, Missouri 63110, USA
6 U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, Wyndmoor, PA 19038, USA
7 Departments of Pathology, Johns Hopkins School of Medicine, Baltimore, MD 21231, USA
8 Departments of Oncology, Johns Hopkins School of Medicine, Baltimore, MD 21231, USA
9 Departments of Obstetrics and Gynecology, Johns Hopkins School of Medicine, Baltimore, MD 21231, USA
10 Departments of Molecular Microbiology and Immunology, Johns Hopkins School of Medicine, Baltimore, MD 21231, USA
11 Center for Biophysics, Arizona State University, Tempe, Arizona 85287, USA
Virology Journal 2014, 11:20 doi:10.1186/1743-422X-11-20Published: 5 February 2014
Low-power ultrashort pulsed (USP) lasers operating at wavelengths of 425 nm and near infrared region have been shown to effectively inactivate viruses such as human immunodeficiency virus (HIV), M13 bacteriophage, and murine cytomegalovirus (MCMV). It was shown previously that non-enveloped, helical viruses such as M13 bacteriophage, were inactivated by a USP laser through an impulsive stimulated Raman scattering (ISRS) process. Recently, enveloped virus like MCMV has been shown to be inactivated by a USP laser via protein aggregation induced by an ISRS process. However, the inactivation mechanism for a clinically important class of viruses – non-enveloped, icosahedral viruses remains unknown.
Results and discussions
We have ruled out the following four possible inactivation mechanisms for non-enveloped, icosahedral viruses, namely, (1) inactivation due to ultraviolet C (UVC) photons produced by non-linear optical process of the intense, fundamental laser beam at 425 nm; (2) inactivation caused by thermal heating generated by the direct laser absorption/heating of the virion; (3) inactivation resulting from a one-photon absorption process via chromophores such as porphyrin molecules, or indicator dyes, potentially producing reactive oxygen or other species; (4) inactivation by the USP lasers in which the extremely intense laser pulse produces shock wave-like vibrations upon impact with the viral particle. We present data which support that the inactivation mechanism for non-enveloped, icosahedral viruses is the impulsive stimulated Raman scattering process. Real-time PCR experiments show that, within the amplicon size of 273 bp tested, there is no damage on the genome of MNV-1 caused by the USP laser irradiation.
We conclude that our model non-enveloped virus, MNV-1, is inactivated by the ISRS process. These studies provide fundamental knowledge on photon-virus interactions on femtosecond time scales. From the analysis of the transmission electron microscope (TEM) images of viral particles before and after USP laser irradiation, the locations of weak structural links on the capsid of MNV-1 were revealed. This important information will greatly aid our understanding of the structure of non-enveloped, icosahedral viruses. We envision that this non-invasive, efficient viral eradication method will find applications in the disinfection of pharmaceuticals, biologicals and blood products in the near future.