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Studies of inactivation mechanism of non-enveloped icosahedral virus by a visible ultrashort pulsed laser.

Tsen SW, Kingsley DH, Poweleit C, Achilefu S, Soroka DS, Wu TC, Tsen KT - Virol. J. (2014)

Bottom Line: 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.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics, Arizona State University, Tempe, Arizona 85287, USA. tsen@asu.edu.

ABSTRACT

Background: 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.

Conclusion: 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.

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Typical TEM images of MNV-1. (a): without laser irradiation (the control); (b): with laser irradiation at a power density of 1.1 ± 0.2 MW/cm2 (here, for the sake of clarity, only one inactivated MNV-1 is shown); (c): with laser irradiation at a power density of 100 ± 10 MW/cm2. The spherical structure with a diameter of around 30 nm in (a) represents the presence of MNV-1 in the control. At the intermediate laser power density, (b) shows that the inactivated MNV-1 particle forms cracks at the structural links of the capsid. At the high laser power density, (c) demonstrates the disintegration of the capsid of the inactivated MNV-1 into spherical structures with a diameter of around 10 nm.
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Figure 3: Typical TEM images of MNV-1. (a): without laser irradiation (the control); (b): with laser irradiation at a power density of 1.1 ± 0.2 MW/cm2 (here, for the sake of clarity, only one inactivated MNV-1 is shown); (c): with laser irradiation at a power density of 100 ± 10 MW/cm2. The spherical structure with a diameter of around 30 nm in (a) represents the presence of MNV-1 in the control. At the intermediate laser power density, (b) shows that the inactivated MNV-1 particle forms cracks at the structural links of the capsid. At the high laser power density, (c) demonstrates the disintegration of the capsid of the inactivated MNV-1 into spherical structures with a diameter of around 10 nm.

Mentions: Typical transmission electron micrographs of the control and laser-irradiated MNV-1 samples are shown in Figure 3. The spherical structure of diameter about 30 nm in Figure 3(a) shows the presence a MNV-1 particle in the control. Figure 3(b) shows that, after laser irradiation with a power density of 1.1 ± 0.2 MW/cm2, the capsid of the inactivated MNV-1 becomes cracked, presumably along the weak structural links, but remains intact, as evidenced by the appearance of smaller structures of about 10 nm in diameter on the capsid (here, for the sake of clarity, only one inactivated MNV-1 is shown). This transmission electron microscope image clearly reveals the locations of weak structural links on the capsid of a non-enveloped, icosahedral virus – MNV-1. Figure 3(c) shows that as the laser power density increases to 100 ± 10 MW/cm2, the capsid of the inactivated MNV-1 becomes disintegrated and separated into small pieces of diameter about 10 nm.


Studies of inactivation mechanism of non-enveloped icosahedral virus by a visible ultrashort pulsed laser.

Tsen SW, Kingsley DH, Poweleit C, Achilefu S, Soroka DS, Wu TC, Tsen KT - Virol. J. (2014)

Typical TEM images of MNV-1. (a): without laser irradiation (the control); (b): with laser irradiation at a power density of 1.1 ± 0.2 MW/cm2 (here, for the sake of clarity, only one inactivated MNV-1 is shown); (c): with laser irradiation at a power density of 100 ± 10 MW/cm2. The spherical structure with a diameter of around 30 nm in (a) represents the presence of MNV-1 in the control. At the intermediate laser power density, (b) shows that the inactivated MNV-1 particle forms cracks at the structural links of the capsid. At the high laser power density, (c) demonstrates the disintegration of the capsid of the inactivated MNV-1 into spherical structures with a diameter of around 10 nm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3924410&req=5

Figure 3: Typical TEM images of MNV-1. (a): without laser irradiation (the control); (b): with laser irradiation at a power density of 1.1 ± 0.2 MW/cm2 (here, for the sake of clarity, only one inactivated MNV-1 is shown); (c): with laser irradiation at a power density of 100 ± 10 MW/cm2. The spherical structure with a diameter of around 30 nm in (a) represents the presence of MNV-1 in the control. At the intermediate laser power density, (b) shows that the inactivated MNV-1 particle forms cracks at the structural links of the capsid. At the high laser power density, (c) demonstrates the disintegration of the capsid of the inactivated MNV-1 into spherical structures with a diameter of around 10 nm.
Mentions: Typical transmission electron micrographs of the control and laser-irradiated MNV-1 samples are shown in Figure 3. The spherical structure of diameter about 30 nm in Figure 3(a) shows the presence a MNV-1 particle in the control. Figure 3(b) shows that, after laser irradiation with a power density of 1.1 ± 0.2 MW/cm2, the capsid of the inactivated MNV-1 becomes cracked, presumably along the weak structural links, but remains intact, as evidenced by the appearance of smaller structures of about 10 nm in diameter on the capsid (here, for the sake of clarity, only one inactivated MNV-1 is shown). This transmission electron microscope image clearly reveals the locations of weak structural links on the capsid of a non-enveloped, icosahedral virus – MNV-1. Figure 3(c) shows that as the laser power density increases to 100 ± 10 MW/cm2, the capsid of the inactivated MNV-1 becomes disintegrated and separated into small pieces of diameter about 10 nm.

Bottom Line: 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.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics, Arizona State University, Tempe, Arizona 85287, USA. tsen@asu.edu.

ABSTRACT

Background: 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.

Conclusion: 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.

Show MeSH
Related in: MedlinePlus