Enteric Viral Surrogate Reduction by Chitosan

Abstract

Enteric viruses are a major problem in the food industry, especially as human noroviruses are the leading cause of nonbacterial gastroenteritis. Chitosan is known to be effective against some enteric viral surrogates, but more detailed studies are needed to determine the precise application variables. The main objective of this work was to determine the effect of increasing chitosan concentration (0.7-1.5% w/v) on the cultivable enteric viral surrogates, feline calicivirus (FCV-F9), murine norovirus (MNV-1), and bacteriophages (MS2 and phiX174) at 37 °C. Two chitosans (53 and 222 kDa) were dissolved in water (53 kDa) or 1% acetic acid (222 KDa) at 0.7-1.5%, and were then mixed with each virus to obtain a titer of ~5 log plaque-forming units (PFU)/mL. These mixtures were incubated for 3 h at 37 °C. Controls included untreated viruses in phosphate-buffered saline and viruses were enumerated by plaque assays. The 53 kDa chitosan at the concentrations tested reduced FCV-F9, MNV-1, MS2, and phi X174 by 2.6-2.9, 0.1-0.4, 2.6-2.8, and 0.7-0.9 log PFU/mL, respectively, while reduction by 222 kDa chitosan was 2.2-2.4, 0.8-1.0, 2.6-5.2, and 0.5-0.8 log PFU/mL, respectively. The 222 kDa chitosan at 1 and 0.7% w/v in acetic acid (pH 4.5) caused the greatest reductions of MS2 by 5.2 logs and 2.6 logs, respectively. Overall, chitosan treatments showed the greatest reduction of MS2, followed by FCV-F9, phi X174, and MNV-1. These two chitosans may contribute to the reduction of enteric viruses at the concentrations tested but would require use of other hurdles to eliminate food borne viruses.

Survival of Human Norovirus Surrogates in Water upon Exposure to Thermal and Non-Thermal Antiviral Treatments

“…Initial treatment with 0.01% CM (0-h contact time) did not appear to be effective against murine norovirus; however, it resulted in 2.9 log reduction in MS2 infectious particles. These results are consistent with previous studies showing a higher sensitivity of MS2 compared with murine norovirus to either a 222-kDa chitosan dissolved in acetic acid or a 53-kDa chitosan dissolved in water [40,41]. Considering the reduction in infectivity of MS2, the antiviral activity of CM against this virus does not seem to be improved over contact times.…”

“…Chitosan is recognized for its broad antibacterial activity with industrial and medical applications [36][37][38][39], but its activity in acidic conditions limits its application in the natural environment. Studies investigating the impact of chitosan on stability of human norovirus surrogates have generated mixed results, and the effectiveness of the compound may be linked to particle size [40,41]. Recent advancements in generating chitosan particles at micro and nanoscales has enabled the successful in vivo and in vitro elimination of pathogenic bacteria in cattle [42] and in crop irrigation ponds [43].…”

Foodborne viruses: Detection, risk assessment, and control options in food processing

“…phenolic acids and flavonoids, showed antiviral effects against rotavirus and FCV (Matemu et al, 2011;Katayama et al, 2013). Chitosan, a positively charged polysaccharide composed of glucosamine and acetyl-glucosamine, has been shown to have antiviral effects on MNV, MS2 and FCV (Su et al, 2009;Davis et al, 2012Davis et al, , 2015. Grape seed and green tea extracts can be incorporated into edible chitosan films with a 5% grape seed extract reducing MNV titres by 4.0 log 10 after 3 h. Edible films enriched with Preserved raw crab product in soy sauce MNV 1.6 (20%) 1.4 (15%) 1.0 (10%) 0.6 (5% salt) (Park and Ha, 2015) Soy sauce containing 20, 15, 10, 5% salt for 3 days at 10°C…”

Natural bioactive substances for the control of food-borne viruses and contaminants in food

“…Chitosan, a biopolymer produced by the deacetylation of chitin derived from the exoskeleton of crustaceans, is one of the most widely used materials in this field (Davis et al 2012). Previous research has found that watersoluble chitosan could inhibit enteric viruses by interfering with viral replication or damaging the structure of viruses (Davis et al 2012;Davis et al 2015). Chitosan extracted from crab processing discards decreased the ion contaminants in water via metal chelation (Gamage and Shahidi 2007).…”