Inactivation of potato virus Y in water by hydrodynamic cavitation

Z vodo se poleg človeških in živalskih patogenih virusov prenašajo tudi rastlinski. Eden od virusov, za katerega je bila možnost prenosa z vodo potrjena, je virus Y krompirja (PVY). PVY je eden od najnevarnejših virusov krompirja, saj uničuje pridelek ene najpomembnejših poljščin. Poleg krompirja napada tudi druge rastline v družini razhudnikovk (Solanaceae) npr. paradižnik. Zaradi vse večjega pomanjkanje čiste vode in varčevanja z njo, se v kmetijstvu, ki porablja za namakanje ogromne količine vode, vse bolj uveljavljajo zaprti namakalni sistemi z reciklirano vodo. Pred ponovno uporabo moramo iz take vode odstraniti patogene organizme. Za njihovo odstranjevanje razvijamo nove, okolju prijaznejše metode, kot je hidrodinamska kavitacija za inaktivacijo virusov v vodi. V raziskavi smo vodovodni vodi dodali PVY in jo nato obdelali s hidrodinamsko kavitacijo. Po različnih časih obdelave smo testirali virusno infektivnost. Pokazali smo, da po 500 kavitacijskih prehodih pod tlačno razliko 700 000 Pa, virus ne more več okužiti rastlin tobaka, v nekaterih poskusih pa smo virusno inaktivacijo dosegli že po krajših časih obdelave. Virusno infektivnost smo testirali na testnih rastlinah, ki smo jih okuževali z odvzetimi alikvoti obdelanega vzorca v različnih časovnih točkah. Poleg virusne infektivnosti smo z metodo RT-PCR preverjali tudi, če je prišlo do razgradnje RNA. Po vizualizaciji z agarozno gelsko elektroforezo smo v nekaterih primerih opazili le manjši vpliv na genomsko RNA in tako sklepali, da hidrodinamska kavitacija vpliva na različne virusne strukture. Inaktivacija virusa naj bi bila posledica poškodb virusne kapside, kar smo opazili s transmisijsko elektronsko mikroskopijo. Da je inaktivacija virusa v glavnem posledica mehanskih učinkov kavitacije, smo dokazali z dodatkom lovilcev prostih radikalov, ki niso imeli vpliva na virusno infektivnost.Human, animal, and even plant pathogens can be transmitted through water. One of the plant pathogenic viruses, for which the possibility of transmission through water has been confirmed, is potato virus Y (PVY). PVY is one of the most important potato viruses because it can destroy a large proportion of crops, causing major agricultural losses. PVY can also destroy some other plants in the Solanaceae family, such as tomato. Lack of clean water is a major global problem, and since agriculture consumes large amounts of it, closed irrigation systems that recycle water are being used. In order to prevent the spread of viruses with water, we need to remove or inactivate them. Therefore, new environmentally friendly methods are being developed to serve this purpose. One of these new methods is hydrodynamic cavitation. In this study, we treated tap water contaminated with PVY using hydrodynamic cavitation and observed the ability of the virus to infect plants after different treatment times. We showed that after 500 cavitation passes below a pressure difference of 700 000 Pa, the virus was no longer able to infect tobacco plants. In some experiments, the virus lost this ability after shorter treatment times. Viral infectivity was tested with test plants that were infected with aliquots of the treated sample. In addition to viral infectivity, we also tested RNA degradation using RT-PCR and its visualization using agarose gel electrophoresis. In some cases, only minor effect of cavitation on viral RNA was observed, suggesting that cavitation affects various viral structures to different extents, but viral inactivation is due to damage to the viral capsid, which was also observed by transmission electron microscopy. By adding radical scavengers, we showed that the radicals known to be generated during cavitation did not affect viral infectivity, suggesting that viral inactivation is likely caused by the mechanical effects of cavitation

Hydrodynamic cavitation efficiently inactivates potato virus Y in water

Waterborne plant viruses can destroy entire crops, leading not only to high financial losses but also to food shortages. Potato virus Y (PVY) is the most important potato viral pathogen that can also affect other valuable crops. Recently, it has been confirmed that this virus is capable of infecting host plants via water, emphasizing the relevance of using proper strategies to treat recycled water in order to prevent the spread of the infectious agents. Emerging environmentally friendly methods such as hydrodynamic cavitation (HC) provide a great alternative for treating recycled water used for irrigation. In the experiments conducted in this study, laboratory HC based on Venturi constriction with a sample volume of 1 L was used to treat water samples spiked with purified PVY virions. The ability of the virus to infect plants was abolished after 500 HC passes, corresponding to 50 min of treatment under pressure difference of 7 bar. In some cases, shorter treatments of 125 or 250 passes were also sufficient for virus inactivation. The HC treatment disrupted the integrity of viral particles, which also led to a minor damage of viral RNA. Reactive species, including singlet oxygen, hydroxyl radicals, and hydrogen peroxide, were not primarily responsible for PVY inactivation during HC treatment, suggesting that mechanical effects are likely the driving force of virus inactivation. This pioneering study, the first to investigate eukaryotic virus inactivation by HC, will inspire additional research in this field enabling further improvement of HC as a water decontamination technology

Inactivation of the enveloped virus phi6 with hydrodynamic cavitation

The COVID −19 pandemic reminded us that we need better contingency plans to prevent the spread of infectious agents and the occurrence of epidemics or pandemics. Although the transmissibility of SARS-CoV-2 in water has not been confirmed, there are studies that have reported on the presence of infectious coronaviruses in water and wastewater samples. Since standard water treatments are not designed to eliminate viruses, it is of utmost importance to explore advanced treatment processes that can improve water treatment and help inactivate viruses when needed. This is the first study to investigate the effects of hydrodynamic cavitation on the inactivation of bacteriophage phi6, an enveloped virus used as a SARS-CoV-2 surrogate in many studies. In two series of experiments with increasing and constant sample temperature, virus reduction of up to 6.3 logs was achieved. Inactivation of phi6 at temperatures of 10 and 20 °C occurs predominantly by the mechanical effect of cavitation and results in a reduction of up to 4.5 logs. At 30 °C, the reduction increases to up to 6 logs, where the temperature-induced increased susceptibility of the viral lipid envelope makes the virus more prone to inactivation. Furthermore, the control experiments without cavitation showed that the increased temperature alone is not sufficient to cause inactivation, but that additional mechanical stress is still required. The RNA degradation results confirmed that virus inactivation was due to the disrupted lipid bilayer and not to RNA damage. Hydrodynamic cavitation, therefore, has the potential to inactivate current and potentially emerging enveloped pathogenic viruses in water at lower, environmentally relevant temperatures