90. Peppermint extract – a natural-derived disinfectant, effective against African swine fever virus Małgorzata Juszkiewicz1 , Marek Walczak1 , Anna Szczotka-Bochniarz1 1) National Veterinary Research Institute, Partyzantów 57 avenue, 24-100 Puławy, Poland Corresponding author: malgorzata.juszkiewicz@piwet.pulawy.pl
Introduction: African swine fever (ASF) is one of the most dangerous and fatal swine diseases, described for the first time roughly a hundred years ago. Even now, there is neither a commercially approved vaccine nor treatment available. The only way to hinder further spread of the disease is by culling the affected herds and applying prevention based mainly on proper biosecurity. Due to growing awareness of the potential ASF threat among pig producers, disinfection processes are considered as one of the most important preventive measures. Currently, a variety of chemical compounds are applied for the disinfection of pig farms. Meanwhile, these chemicals may pose a potential risk, due to their toxic, irritant or corrosive effect. Environmental degradation, among others, is caused by overexploitation of its resources, overpopulation and contamination by detergents and chemicals. Ideally, natural virucidal compounds should be safe for both humans and animals, biodegradable, easily available and inexpensive. Therefore the aim of the study was to determine whether any plantbased natural compounds may show a virucidal effect against African swine fever virus (ASFV), and simultaneously be depleted of some of the side effects typical for chemical compounds. Material and methods: Fourteen plant extracts (pure extracts n=5, hydroglycerin-based n=6, hydroglycolic-based n=3, namely: black currant, black chokeberry, strawberry, raspberry, thyme, field horsetail, peppermint, aloe vera, asiatic pennywort, lime Lemon balm, cucumber, common nettle, fenugreek) were selected and screened for their virucidal effect against ASFV. The examination was carried out using the suspension test inspired by the PN-EN 14675: 2015 European Standard procedure. All tested plant extracts were analysed in triplicate, diluted with water of standardized hardness, to obtain three dilutions of each extracts. The tested mixture contained 1 part of virus stock, 1 part of interfering substance at low or high soiling level (BSA - bovine albumin 3.0g/l or BSA + YE bovine albumin 10g/l, plus a yeast extract 10g/l, respectively) and 8 parts of selected plant-extract. The obtained mixture was incubated at 10 ± 1°C for 30 min ± 10 s. Determination of 50% endpoint titer was assumed using Spearman–Kärber method. A 10-fold serial dilution was done in 96-well plates (in quadruplicates) containing Vero cell culture. The presence of cytopathic effect was observed after 7 day-incubation (37 °C ± 2 °C, 5% CO 2). If the difference between tested extract and virus control was ? 4 log (TCID50/ml), the extract was considered as virucidal against ASFV. Results: Our research showed that peppermint extract (1.05%) shows virucidal activity against ASFV, with the mean log reduction (±SD) at 4.41 (±0.23) – BSA and 4.17 (±0.11) – BSA+YE. The remaining thirteen plant extracts showed low or moderate virucidal activity against ASFV, reducing the virus titre from 0,08 to 2,58 log10. In case of extracts suspended in a hydroglycolic medium, the effect of high virus titre reduction resulted only from medium composition. High soiling was shown to have a significantly negative impact on disinfection effectiveness, which confirms the crucial role of precleaning prior to proper disinfection. Conclusion: Our research has proven the existence of a naturally-derived disinfectant, effective against the ASF virus, which may be safe for animals, humans and the environment, which is additionally ecological, biodegradable, inexpensive and easily available.
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