Modeling the Transport of Human Rotavirus and Norovirus in Standardized and in Natural Soil Matrix-Water Systems

Interactions Between Infectious Foodborne Viruses and Bacterial Biofilms Formed on Different Food Contact Surfaces

Bacterial biofilms contribute to contamination, spoilage, persistence, and hygiene failure in the food industry, but relatively little is known about the behavior of foodborne viruses evolving in the complex communities that make up biofilm. The aim of this study was to evaluate the association between enteric viruses and biofilms on food contact surfaces. Formed biofilms of mono- and multispecies cultures were prepared on glass, stainless steel, and polystyrene coupons and 10⁵ pfu/ml of murine norovirus, rotavirus, and hepatitis A virus were added and incubated for 15 min, 90 min, and 24 h. The data obtained clearly demonstrate that the presence of biofilms generally influences the adhesion of enteric viruses to different surfaces. Many significant increases in attachment rates were observed, particularly with rotavirus whose rate of viral infectious particles increased 7000 times in the presence of Pseudomonas fluorescens on polystyrene after 24 h of incubation and with hepatitis A virus, which seems to have an affinity for the biofilms formed by lactic acid bacteria. Murine norovirus seems to be the least influenced by the presence of biofilms with few significant increases. However, the different factors surrounding this association are unknown and seem to vary according to the viruses, the environmental conditions, and the composition of the biofilm.

Fate and Transportation of Viruses from Reclaimed Water into a Floatation System

The fate and transport of viruses in floatation systems is considerably important for accurate determination of the safety of reusing reclaimed water in the flotation process. Herein, simulation experiments on the floatation, adsorption and desorption were performed to examine the effect of initial virus concentration, pH and floatation reagents on the adsorption of viruses ΦΧ174 and MS2 onto copper–molybdenum ores. The transport of viruses in the flotation systems was also investigated. The viruses in the reclaimed water were rapidly adsorbed onto the ore particles, suggesting that tailing wastewater can be safely reused for floatation. However, the adsorbed viruses in the concentrates, middlings and tailings may pose health risks at certain exposure levels. The transport of viruses was dominated by their attachment to ore particles, with most being inactivated or irreversibly adsorbed. The removal and adsorption rates decreased as the initial virus concentration increased, and the removal rate decreased as pH was increased from 7.5 to 9.5. In comparison with MS2, ΦΧ174 was removed more effectively. This suggested that electrostatic repulsion is an important mechanism because MS2 has a greater negative charge. The attachment of both ΦΧ174 and MS2 onto the mineral particles increased significantly in the presence of PJ053 and CaO.

Attenuation and transport of human enteric viruses and bacteriophage MS2 in alluvial sand and gravel aquifer media-laboratory studies

Potable groundwater contamination by human enteric viruses poses serious health risks. Our understanding of virus subsurface transport has largely depended on studying bacteriophages as surrogates. Few studies have compared the transport behaviour of enteric viruses, especially norovirus, with phage surrogates. We conducted laboratory column experiments to investigate norovirus and bacteriophage MS2 (MS2) filtration in alluvial sand, and rotavirus, adenovirus and MS2 filtration in alluvial gravel aquifer media in 2 mM NaCl (pH 6.6-6.9) with pore velocities of 4.6-5.4 m/day. The data were analysed using colloid filtration theory and HYDRUS-1D 2-site attachment-detachment modelling. Norovirus removal was somewhat lower than MS2 removal in alluvial sand. The removal of rotavirus and adenovirus was markedly greater than MS2 removal in alluvial gravel. These findings concurred with the log₁₀ reduction values, mass recoveries, attachment efficiencies and irreversible deposition rate constants. The modelling results suggested that the MS2 detachment rates were in the same order of magnitude as norovirus, but they were 1 order of magnitude faster than those of rotavirus and adenovirus. The attachment of viruses and MS2 was largely reversible with faster detachment than attachment rates, favouring free virus transport. These findings highlight the risk associated with continual virus transport through subsurface media if viruses are not inactivated and remobilising previously attached viruses could trigger contamination events. Thus, virus attachment reversibility should be considered in virus transport predictions in subsurface media. Further research is needed to compare surrogates with enteric viruses, especially norovirus, regarding their transport behaviours under different experimental conditions.

Make it clean, make it safe: A review on virus elimination via adsorption

Recently, the potential dangers of viral infection transmission through water and air have become the focus of worldwide attention, via the spread of COVID-19 pandemic. The occurrence of large-scale outbreaks of dangerous infections caused by unknown pathogens and the isolation of new pandemic strains require the development of improved methods of viruses' inactivation. Viruses are not stable self-sustaining living organisms and are rapidly inactivated on isolated surfaces. However, water resources and air can participate in the pathogens' diffusion, stabilization, and transmission. Viruses inactivation and elimination by adsorption are relevant since they can represent an effective and low-cost method to treat fluids, and hence limit the spread of pathogen agents. This review analyzed the interaction between viruses and carbon-based, oxide-based, porous materials and biological materials (e.g., sulfated polysaccharides and cyclodextrins). It will be shown that these adsorbents can play a relevant role in the viruses removal where water and air purification mostly occurring via electrostatic interactions. However, a clear systematic vision of the correlation between the surface potential and the adsorption capacity of the different filters is still lacking and should be provided to achieve a better comprehension of the global phenomenon. The rationalization of the adsorption capacity may be achieved through a proper physico-chemical characterization of new adsorbents, including molecular modeling and simulations, also considering the adsorption of virus-like particles on their surface. As a most timely perspective, the results on this review present potential solutions to investigate coronaviruses and specifically SARS-CoV-2, responsible of the COVID-19 pandemic, whose spread can be limited by the efficient disinfection and purification of closed-spaces air and urban waters.