Sociedade Portuguesa de Microbiologia

Portuguese Society of Microbiology

PhD highlights: Liliana Costa

Title: Photoinactivation of viruses by porphyrins

Abstract: Microbial photodynamic inactivation (PDI) has been successfully used to inactivate microorganisms. PDI has already been studied under different conditions for different microorganisms; however, there is still scarce information about bacteriophage inactivation. The goal of this study was to elucidate and evaluate several aspects of viral PDI: (i) effect of different light sources, doses and intensities on phage inactivation; (ii) photoinactivation efficiency on DNA- and RNA-type bacteriophages, (iii) main mechanism by which phage photosensitization takes place, (iv) effect of PDI on phage proteins; and (v) possibility of resistance development and viability recovery after consecutive phototreatments.

From this study it can be concluded that: (i) phage photoinactivation was significantly higher when low fluence rates were used at long irradiation times (Costa et al, 2012b); (ii) phages were efficiently inactivated to the detection limit (reductions of 6-7 log)(Costa et al., 2011); (iii) RNA-type phages were much more easily inactivated than the DNA-type ones (sooner and with ten times less porphyrin concentration than that used for DNA-type phages) (Costa et al., 2012b); (iii) type II mechanism (production of singlet oxygen) was the main mechanism by which photosensitization took place (Costa et al., 2013); (iv) IR spectroscopy represents a promising and fast-screening methodology to study damage induced by photosensitization on phage proteins; and (v) after ten consecutive photodynamic cycles, T4-like phage did not exhibit any resistance to PDI nor recovered its viability (Costa et al., 2010).

In conclusion, viral PDI is a very efficient technology for inactivation of non-enveloped DNA- and RNA-type phages (Costa et al., 2012a); it may be used as an alternative to conventional antiviral treatments, even at low light fluence rates, without emergence of viral resistance.

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Acknowledgments: Thanks are due to the Univ. de Aveiro, FCT, FEDER and to CESAM.

References:

Costa L, Faustino MAF, Tomé JPC, Neves MGPS, Tomé AC, Cavaleiro JAS, Cunha A, Almeida A. (2013), Involvement of type I and type II mechanisms on the photoinactivation of non-enveloped DNA and RNA bacteriophages. J. Photochem. Photobiol. B: Biol. 120:10-16.

Costa L, Neves MGPS, Cavaleiro JAS, Cunha A, Faustino MAF, Almeida A.(2012a), Susceptibility of non-enveloped DNA- and RNA-type viruses to photodynamic inactivation. Photoch. Photobio. Sci. 11:1520-1523.

Costa L, Faustino MAF, Neves MGPS, Cunha A, Almeida A. (2012b), Photodynamic inactivation of mammalian viruses and bacteriophages. Viruses 4:1034-1074.

Costa L, Tomé JPC, Neves MGPS, Tomé AC, Cavaleiro JAS, Faustino MAF, Cunha A, Almeida A. (2011), Evaluation of resistance development and viability recovery by a non-enveloped virus after repeated cycles of aPDT. Antiviral Res. 91:278-282.

Costa L, Carvalho CMB, Tomé JPC, Faustino MAF, Neves MGPS, Tomé AC, Cavaleiro JAS, Cunha A, Almeida A. (2010), Sewage bacteriophage inactivation by cationic porphyrins: influence of light parameters. Photoch. Photobio. Sci. 9:1126-1133.

PhD Degree:  Biologia, ramo Microbiologia; Year of conlusion: 2012

Institution: Universidade de Aveiro, Portugal

Supervision(s): Adelaide Almeida (Dep. Biologia, Univ Aveiro) and Amparo Faustino (Dep, Química, Univ Aveiro)

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This entry was posted on 28/03/2013 by in Magazine SPM and tagged .

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