Liquid-phase study of ozone inactivation of Venezuelan equine encephalomyelitis virus

A critical mini-review on challenge of gaseous O3 toward removal of viral bioaerosols from indoor air based on collision theory

COVID-19, a pandemic of acute respiratory syndrome diseases, led to significant social, economic, psychological, and public health impacts. It was not only uncontrolled but caused serious problems at the outbreak time. Physical contact and airborne transmission are the main routes of transmission for bioaerosols such as SARS-CoV-2. According to the Centers for Disease Control (CDC) and World Health Organization (WHO), surfaces should be disinfected with chlorine dioxide, sodium hypochlorite, and quaternary compounds, while wearing masks, maintaining social distance, and ventilating are strongly recommended to protect against viral aerosols. Ozone generators have gained much attention for purifying public places and workplaces' atmosphere, from airborne bioaerosols, with specific reference to the COVID-19 pandemic outbreak. Despite the scientific concern, some bioaerosols, such as SARS-CoV-2, are not inactivated by ozone under its standard tolerable concentrations for human. Previous reports did not consider the ratio of surface area to volume, relative humidity, temperature, product of time in concentration, and half-life time simultaneously. Furthermore, the use of high doses of exposure can seriously threaten human health and safety since ozone is shown to have a high half-life at ambient conditions (several hours at 55% of relative humidity). Herein, making use of the reports on ozone physicochemical behavior in multiphase environments alongside the collision theory principles, we demonstrate that ozone is ineffective against a typical bioaerosol, SARS-CoV-2, at nonharmful concentrations for human beings in air. Ozone half-life and its durability in indoor air, as major concerns, are also highlighted in particular.

Effects of temperature and PM2.5 on the incidence of hand, foot, and mouth in a heavily polluted area, Shijiazhuang, China

The influence of weather and air pollution factors on hand, foot, and mouth disease (HFMD) has received widespread attention. However, most of the existing studies came from lightly polluted areas and the results were inconsistent. There was a lack of relevant evidence of heavily polluted areas. This study aims to quantify the relationship between weather factors and air pollution with HFMD in heavily polluted areas. We collected the daily number of hand, foot, and mouth disease in Shijiazhuang, China from 2014 to 2018, as well as meteorological and air pollutant data over the same period. The generalized linear model combined with the distributed lag model was used to study the effect of meteorological factors and air pollutants on the daily cases of HFMD and its hysteresis effect. We found that the dose-response relationship between temperature, PM_2.5, and the risk of hand-foot-mouth disease was non-linear. Both low temperature and high temperature increased the risk of hand-foot-mouth disease. The cumulative effect of high temperature reached the maximum at 0-10 lag days, and the cumulative effect of low temperature reached the maximum at 0-3 lag days. The concentration of PM_2.5 between 76 and 200 μg/m³ has a certain risk of the onset of hand, foot, and mouth disease, but the extreme PM_2.5 concentration has a certain protective effect. In addition, low humidity, low wind speed, and low-O₃ can increase the risk of HFMD. Risks of humidity and low concentration of O₃ increased as lag days extended. In conclusion, our study found that climate factors and air pollutants exert varying degrees of impact on HFMD. Our research provided the scientific basis for establishing an early warning system so that medical staff and parents can take corresponding measures to prevent HFMD.

Short-Term Effects of Meteorological Factors and Air Pollutants on Hand, Foot and Mouth Disease among Children in Shenzhen, China, 2009-2017

BACKGROUND

A few studies have explored the association between meteorological factors and hand, foot, and mouth disease (HFMD) with inconsistent results. Besides, studies about the effects of air pollutants on HFMD are very limited.

METHODS

Daily HFMD cases among children aged 0-14 years in Shenzhen were collected from 2009 to 2017. A distributed lag nonlinear model (DLNM) model was fitted to simultaneously assess the nonlinear and lagged effects of meteorological factors and air pollutants on HFMD incidence, and to further examine the differences of the effect across different subgroups stratified by gender, age and childcare patterns.

RESULTS

The cumulative relative risk (cRR) (median as reference) of HFMD rose with the increase of daily temperature and leveled off at about 30 °C (cRR: 1.40, 95%CI: 1.29, 1.51). There was a facilitating effect on HFMD when relative humidity was 46.0% to 88.8% (cRR at 95th percentile: 1.18, 95%CI: 1.11, 1.27). Short daily sunshine duration (5th vs. 50th) promoted HFMD (cRR: 1.07, 95%CI: 1.02, 1.11). The positive correlation between rainfall and HFMD reversed when it exceeded 78.3 mm (cRR: 1.41, 95% CI: 1.22, 1.63). Ozone suppressed HFMD when it exceeded 104 µg /m3 (cRR at 99th percentile: 0.85, 95%CI: 0.76, 0.94). NO₂ promoted HFMD among infants and the cRR peaked at lag 9 day (cRR: 1.47, 95%CI: 1.02, 2.13) (99th vs. 50th). Besides, children aged below one year, males and scattered children were more vulnerable to high temperature, high relative humidity, and short sunshine duration.

CONCLUSIONS

Temperature, relative humidity, sunshine duration, rainfall, ozone and NO₂ were significantly associated with HFMD, and such effects varied with gender age and childcare patterns. These findings highlight the need for more prevention effort to the vulnerable populations and may be helpful for developing an early environment-based warning system for HFMD.

A reasonable Approach for the Treatment of HIV Infection in the Early Phase with Ozonetherapy (Autohaemotherapy). How 'Inflammatory' Cytokines may have A therapeutic Role

Immunoregulatory cytokines produced by the TH1 subset and by CD8⁺ T lymphocytes appear to brake naturally and sometimes arrest the progress of HIV infection in the early phase. It appears reasonable to assume that a mild and equilibrated stimulation of the immune system may prevent or delay the fatal transition towards the prevalent production of TH2-type cytokines. The problem is how to stimulate the immune system in a physiological fashion. In the last 7 years we have clarified the main mechanisms of action of an unorthodox immunotherapeutic method first used 40 years ago. Optimized autohaemotherapy after a brief exposure ofblood to ozone may today afford the trick of reprogramming the immune system to keep HIV at bay. The autohaemotherapeutic procedure is simple, safe, inexpensive and most likely is more effective than conventional approaches.

The Clinical Application of Ozonetherapy

The reader may be eager to examine in which diseases ozonetherapy can be proficiently used and she/he will be amazed by the versatility of this complementary approach (Table 9 1). The fact that the medical applications are numerous exposes the ozonetherapist to medical derision because superficial observers or sarcastic sceptics consider ozonetherapy as the modern panacea. This seems so because ozone, like oxygen, is a molecule able to act simultaneously on several blood components with different functions but, as we shall discuss, ozonetherapy is not a panacea. The ozone messengers ROS and LOPs can act either locally or systemically in practically all cells of an organism. In contrast to the dogma that “ozone is always toxic”, three decades of clinical experience, although mostly acquired in private clinics in millions of patients, have shown that ozone can act as a disinfectant, an oxygen donor, an immunomodulator, a paradoxical inducer of antioxidant enzymes, a metabolic enhancer, an inducer of endothelial nitric oxide synthase and possibly an activator of stem cells with consequent neovascularization and tissue reconstruction.

Virion disruption by ozone-mediated reactive oxygen species

It is well documented in the scientific literature that ozone-oxygen mixtures inactivate microorganisms including bacteria, fungi and viruses (Hoff, J.C., 1986. Inactivation of microbial agents by chemical disinfectants. EPA 600 S2-86 067. Office of Water, U.S. Environmental Protection Agency, Washington, DC; Khadre, M.A., Yousef, A.E., Kim, J.-G., 2001. Microbiological aspects of ozone applications in food: a review. J. Food Sci. 66, 1242-1252). In the current study, delivery and absorption of precisely known concentrations of ozone (in liquid media) were used to inactivate virus infectivity. An ozone-oxygen delivery system capable of monitoring and recording ozone concentrations in real time was used to inactivate a series of enveloped and non-enveloped viruses including herpes simplex virus type-1 (HHV-1, strain McIntyre), vesicular stomatitis Indiana virus (VSIV), vaccinia virus (VACV, strain Elstree), adenovirus type-2 (HAdV-2), and the PR8 strain of influenza A virus (FLUAVA/PR/8/34/H1N1; FLUAV). The results of the study showed that ozone exposure reduced viral infectivity by lipid peroxidation and subsequent lipid envelope and protein shell damage. These data suggest that a wide range of virus types can be inactivated in an environment of known ozone exposure.

Effects of ozone exposure on inactivation of intra- and extracellular enterovirus 71

In this study, the potential of ozone in inactivating enterovirus 71 (EV71) free particles was investigated using either various ozone flow rates of 100, 80 or 60 mg/h or a constant flow rate of 80 mg/h, given to culture medium or various pH culture media containing EV71, respectively. Results demonstrated that EV71 inactivation by ozone was related to the kinetics of ozone solubility, approximately 99% inactivation being obtained in the exponential phase of ozone solubility. However, the inactivation rate was dependent on the ozone input flow rate and positively enhanced at acidic pH. Inactivation of intracellular EV71 was also studied. At a constant ozone supply of 60 mg/h, a significant reduction of intracellular virus titer (> or =99%, p < 0.01) was obtained after 45 or 60 min exposure but with low cell viability. Upon 30 min exposure, however, 45% cell viability was retained. The results indicate that the inactivating effect of ozone on intracellular EV71 virus is dependent on exposure duration.

Bactericidal effects of ozone at nonspermicidal concentrations

A study was conducted to assess the use of ozone (O3) to control pathogens or contaminants of concern to animal breeders and regulatory officials. In separate experiments, samples of fresh bovine semen and Pseudomonas aeruginosa, Escherichia coli, or Campylobacter fetus subsp. venerealis were diluted with antibiotic-free milk (10(6) sperm and 10(6) organisms/mL of diluted semen), exposed in the previous day to a constantly monitored level of 5, 10, 15, or 20 micrograms/mL of O3 for 3-5 min. After 10 min at 30 degrees C, sperm motility was assessed and the samples cooled to 5 degrees C. Two and 18 h after the beginning of cooling, aliquots of each semen sample were evaluated for motility and cultured for organisms. Reductions were observed in P. aeruginosa and E. coli colony counts of 2 logs, and in C. fetus of 5 logs, after exposure for 2 h to O3 at a concentration of 5 micrograms/mL that had a moderate effect on sperm motility (reduction of 20%). Fewer than 100 colonies, i.e., a 4 logs reduction of all bacteria, were counted after dilution with ozonized-treated milk at 20 micrograms/mL of O3. However, this concentration of O3 reduced sperm motility by 50% 10 min after dilution. The results of these experiments indicate that a concentration and exposure time to O3 can be selected to reduce P. aeruginosa, E. coli, and C. fetus in contaminated bull semen diluted with milk while having only minimal effects on sperm motility.

Ozone disinfection dynamics of enteric viruses provide evidence that infectious titer reduction is triggered by alterations to viral colloidal properties

The inactivation dynamics of three enteric virus species (polio-, rota- and parvovirus) were analysed in different aqueous suspensions by using O3 under continuous flow conditions. A mathematical model for the reaction rate of infectious titer reduction was proposed, based on the thermodynamic principles of phase behaviour of colloids suspended in aqueous environments. Up to a certain threshold dosage of residual ozone (RO), and depending on the type of test virus and the ionic or organic load in the stock suspension, the logarithm of the reaction rate constant of viral inactivation rate was observed to vary in a rather sigmoidal manner with log RO concentration. Data from photon correlation spectroscopy, electron microscopy and tensiometric analysis suggested that below the threshold RO, the pattern of virus inactivation dynamics reflects the varying potential of different-sized viral particles (VPs) to adsorb to the cellular monolayer. There is strong evidence that oxidant-induced surface activity of organic matter causes redistribution of VP infectivity. This hypothesis was statistically corroborated inasmuch as experimental inactivation data proved to be satisfactorily fitted by a logistic equation. It was concluded that viral infection, and thus viral inactivation, is a complex process which is governed largely by the classical laws of colloidal behaviour. The latter is suggested to appreciably determine the capability of inoculated VPs to infect host cultures. This notion may especially be cause for concern when regulatory requirements for virus disinfection are being based on titration results from in vitro testing procedures.

Autohaemotherapy after treatment of blood with ozone. A reappraisal

Autohaemotherapy, involving bland treatment ex vivo of blood with ozone and prompt reinfusion into the donor, is a procedure mainly performed in central Europe, which is claimed to have therapeutic value in circulatory disorders, viral diseases and cancer. This practice is mostly performed in private clinics, and good clinical trials have not been published, which has understandably given rise to prejudice and scepticism. By analysing possible mechanisms of action and current hypotheses, this report attempts to explain how this procedure can be useful in such disparate diseases. The current state of the art is presented objectively, the lack of toxicity is documented, and the rationale and therapeutic advantages are discussed, with the aim of eliciting interest in carrying out controlled clinical trials.

Ozone inactivates HIV at noncytotoxic concentrations

The inactivation of human immunodeficiency virus (HIV) and cytotoxic properties of ozone-treated serum and serum-supplemented media were examined. The titer of HIV suspensions in human serum was reduced in a dose-dependent manner when treated with total reacted ozone concentrations at a range of 0.5 to 3.5 micrograms/ml-1. Complete inactivation of HIV suspensions was achieved by 4.0 micrograms/ml-1 of ozone in the presence or absence of H-9 cells. In contrast, cellular metabolism, as measured by MTT dye cleavage, and DNA replication, as measured by BUdR incorporation, were enhanced in H-9 cells grown in media treated with quantities of ozone that completely inactivate HIV. The permissively HIV-infected cell line HXB/H-9 was cultured in ozone-treated media for six days with culture supernatants being sampled and assayed on alternate days for HIV p24 core protein. HIV p24 was reduced in all treated cultures compared to control cultures, with an average reduction of 46% [p24].