Antiviral Efficacy of Neem, Garlic, and Ginger Extracts on Newcastle Disease Virus in Poultry: Impact of Concentration and Heat Treatment

Aims: Newcastle disease virus (NDV) is a paramyxovirus that causes significant mortality rates in poultry, often known as Newcastle disease or Ranikhet. This virus has the potential to inflict serious economic losses on farmers. As there is no effective therapy for NDV infection, the current research investigated the efficiency of medicinal plant extracts against this virus.

Place and Duration of Study: The experiment was conducted at the Department of Physiology, Biochemistry, and Pharmacology and the Department of Microbiology and Veterinary Public Health, Chittagong Veterinary and Animal Sciences University (CVASU), Bangladesh, during a period from January to April 2017.

Methodology: Plant samples (neem bark, neem leaf, garlic, and ginger) were collected from the medicinal garden of CVASU. Samples were ground, and 300 g of ground samples were mixed with distilled water in a 1:5 ratio. Mixtures were stirred for 1 hour by an electric stirrer (1000 rpm) and left overnight. All the mixtures were filtrated through Whatmanno. 1 filter paper separately. Finally, aqueous extracts were prepared from the filtrated sample with the help of a round bottom flask of a rotator vacuum evaporator. Then, the extracts were categorized into different groups to determine the possible effects of extract concentration and heat treatment on the antiviral potential of plant extracts. The plant extract was mixed with viable NDV (8 HA; field strain) and kept at 27.3 °C for 30 minutes. To determine virus inactivation, a 0.2-ml mixture was inoculated into nine-day-old embryonated chicken eggs and incubated. After 48 hours, the allantoic fluid was harvested, and a hemagglutination (HA) assay was performed to determine the virus HA titer.

Results: The antiviral effect of plant extract is described in terms of HA titers, specifically the geometric mean titer (GMT). The lower GMT titer value of the plant extract showed higher antiviral activity. However, Neem is more efficient against NDV than other extracts (garlic and ginger). The antiviral activities of these extracts can vary due to the concentration and heat treatment (autoclave) of the extracts. The antiviral potency of all plant extracts declines with decreasing concentration. Heat treatment significantly (p = 0.02) decreases the plant's extract antiviral efficacy.

Conclusion: This study suggests the potential use of common local medicinal plants to treat Newcastle disease in poultry, although active compounds of those plants have not yet been studied. Finally, these plants can be a promising source for developing antiviral drugs against Newcastle disease.