An Alternative Antiviral Therapy of Newcastle Disease in Broiler Chickens: A Clinical Study of Methanolic Neem Leaves Extract

Abstract

Newcastle disease (ND) is an important viral disease that threatens the global poultry industry. The urgent need for a safe and effective antiviral alternative prompted us to evaluate neem methanolic leaf extract against Newcastle disease virus (NDv) in broilers. A total of Sixty Cobb chicks (day old) were allocated randomly into 4 equal groups; group A was a control negative, and group B was a control positive. Groups C and D received a methanolic neem leaf extract (MNLE) in drinking water for five days at 500 and 1000 µg/kg BW, respectively. At 25th days old, chicks in groups B, C and D were challenged via the oculonasal route with 0.2 ml of virulent NDv. The use of MNLE in groups C and D significantly reduced morbidity and mortality as well as the macroscopic and microscopic scoring lesions of all examined organs compared to the infected untreated group B. The high dose of MNLE (1000 µg/ kg BW; group D) was more efficient and significant in relieving the clinical and pathological abnormalities caused by ND challenge compared with the low dose (500 µg/ kg BW; group C). Moreover, positive effects of the herbal treatment on the experimentally ND-infected chickens were evidenced by reducing viral RNA concentrations in the oropharyngeal swabs at 3, 5, and 7 days post challenge and the infectivity titer of the virus isolated from the trachea, spleen, and cecal tonsils at 7 days post challenge. In conclusion, MNLE possesses potential antioxidant to have a power to control NDv shedding and infection. So, MNLE could be a source of inspiration for new alternative antivirals.