Treatment Effect of Various Concentration of Plant Extracts on Murine Norovirus

Abstract

Noroviruses are positive-sense, single-stranded, non-enveloped RNA virus that measures approximately 27 - 35 nm in diameter. It affects humans of all ages and races causing most cases of viral gastroenteritis worldwide. Infection results from ingestion of contaminated food or water as well as causing diarrhea and vomiting in humans. Extracts from plants are known to have antioxidant, anti-inflammatory, and adhesive properties which are associated with barrier functions. The aim of this study was to elucidate whether plaque reduction was due to an effect of methanolic plant extract directly on the virus, whether the extract affects viral replication, and lastly, whether the extract disrupts the cell surface binding with the virus. The plant extracts of interest were the calyces of Hibiscus sabdariffa (HS) and the seeds of Zanthoxylum armatum (ZA). Antiviral activities of these extracts were determined against murine norovirus. The logarithmic viral reduction per plaque-forming unit was (22 log10) PFU/ml (control), (15 log10) PFU/ml (treated HS), and (12 log10) PFU/ml (treated ZA) with a significant reduction (68% and 55% respectively) when compared with the control for the direct effect on the virus. The role of extracts on virus replication showed (25 log10) PFU/ml (control) as against the HS treated-virus-infected cells (9 log10) PFU/ml and ZA treated-virus-infected cells (5 log10) PFU/ml (36% and 20% respectively). Finally, effect of the extract on the viral attachment showed (31 log10) PFU/ml (control), (12 log10) (HS-treated) and (9 log10) PFU/ml (ZA-treated), (39% and 29% respectively. Extract treatment with HS and ZA has shown evidence of a reduced number of plaques formation with the latter having fewer plaques. Both extracts have proven potential to reduce the viral multiplication process by interfering with the replication process. This study shows that Hibiscus sabdariffa (calyces) and Zanthoxylum armatum (seed) extracts disrupt murine norovirus from consistent viral replication.