Newcastle disease virus is a paramyxovirus which causes Newcastle disease in birds. Investigation was done on the effect of leaf extract of Phyllanthus amarus against Newcastle disease virus (NDV) using an in-ovo assay. Nine to eleven day-old viable embryonated chicken eggs (ECE) were used for the assay, these were divided into six groups of six eggs each. Methanol, aqueous and n-hexane extracts of the plant leaves were administered to the various groups at concentrations varying from 50 to 5 mg/ml. Embryonated eggs were incubated and embryo survival was monitored daily. Negative control and diluents control groups received phosphate buffer saline (PBS) and dimethly suphoxide (DMSO), respectively. The other group was uninoculated while a virus control group received 100 EID50/0.1 ml NDV alone. Bacteria free allantoic fluid from the embryonated eggs in different treatment groups were harvested and collected for spot hemagglutination (HA) test and HA assay to detect the presence of NDV viral particles and the viral titre, respectively. Leaf extracts were assayed for presence of phytochemicals and antioxidant potentials. It was observed from the results that the extract was toxic to the embryo at a concentration above 50 mg/ml and further results showed that the HA viral titre reduction was directly proportional to increasing extract concentration. The phytochemical assays of leaf extract revealed the presence of phytochemicals including alkaloids, tannins, saponins, flavonoids, phenols, steroids, glycosides. The current findings have demonstrated that leaf extract from P. amarus has potentials of medicinal value as well as antiviral activity against NDV in-ovo. Further experimental assays using live animal models are recommended to validate the use of P. amarus plant extract in therapeutic measure in chickens.
Key words: Antiviral, Phyllanthus amarus, Newcastle disease virus (NDV), embryonated chicken eggs (ECE).
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