Mechanisms of inactivation of bacteriophage φX174 and its DNA in aerosols by ozone and ozonized cyclohexene

Abstract

The mechanisms of inactivation of aerosolized bacteriophage phiX174 in atmospheres containing ozone, cyclohexene, or ozonized cyclohexene were studied by using 32P-labelled phage. The inactivation of the aerosolized phage in clear air or in air containing cyclohexene is due to damage of the protein coat since the deoxyribonucleic acid (DNA) extracted from the inactivated phage retains its biological activity. Inactivation of the phage in air containing ozonized cyclohexene is due both to protein and DNA damage. Sucrose gradient analysis shows that aerosolized inactivated phiX174 releases unbroken DNA. In contrast, the DNA from phage phiX174 inactivated by ozonized cyclohexene is broken. The inactivation of aerosolized phage phiX174-DNA was studied in the same atmospheres using 32P-labelled DNA. phiX174-DNA aerosolized in clear air or air containing cyclohexene at 75% r.h. is inactivated by a factor of 2 in 30 min. The inactivated DNA is broken. Ozone as well as ozonized cyclohexene inactivates KNA very fast causing breaks in the molecule. This is in contrast with the intact bacteriophage in which ozone does not produce breaks in the DNA.

Ozone for Inactivation of Aerosolized Bacteriophages

“…0.05). Furthermore, our results of ozone doses for phi X174 were similar to those evaluated at a long exposure time of 30 min (Demik and Degroot 1977). Our findings demonstrated that the germicidal effects of ozone for airborne virus inactivation depended on ozone dose, and were not individually influenced by ozone concentration or the contact time.…”

“…The vehicle transmission pathways include respiratory transmission by droplets and aerosols. To reduce infection risk from viruscontaining aerosols, there are many control techniques including filtration (Demers 2001), ultraviolet germicidal irradiation (UVGI) (Jensen 1964;Tseng and Li 2005a), and ozone (Demik and Degroot 1977;Kekez and Sattar 1997) have been extensively researched. Among these methods, ozone is known in decreasing the viral load (Berrington and Pedler 1998) and used as a potent oxidizing agent in food and other industries (Kim et al 1999).…”

“…Up to now, only limited data has been available on the inactivation of airborne viruses by ozone (Demik and Degroot 1977;Kekez and Sattar 1997). At a long exposure time of 30 min, the use of ozone could inactivate 3 logs of airborne phi X174 phage at an ozone concentration of 0.04 ppm (Demik and Degroot 684 C.-C. TSENG AND C.-S. LI 1977).…”

“…In addition, phi X174 was observed to retain biological activity of extracted DNA after 30 min. Therefore, ozone may primarily inactivate the protein capsid, and then the naked nucleic acid may be secondarily inactivated (Demik and Degroot 1977;Kim et al 1980). In virus inactivation, ozone concentration, contact time, and the type of viral capsid protein are suggested to play critical roles.…”

Effects of ozone treatment on cell growth and ultrastructural changes in bacteria.

“…The oxygen atom, being a strong oxidizer, appears to be a good agent for sterilization by the oxidation process. This property, therefore, becomes very useful for antioxidant protection system in arterial diseases and the immune system (Jakab et al, 1995;Peden and Dailey, 1995;Verrazzo et al, 1995) and in the inactivation of microorganisms (Broadwater et al, 1973;De Mik and De Droot, 1977;Foegeding, 1985;Ishizaki et al, 1986;Komanapalli and Lau, 1998). The use of ozone is applied in decontamination of microorganisms in biocleaned rooms (Masaoka et al, 1982), food preservation (Chen et al, 1992;Rice et al, 1982;Sheldon and Brown, 1986) and drinking water (Boyce et al, 1981;Glaze, 1987;Katzenelson and Biedermann, 1976).…”