The Newcastle Disease (ND) is highly contagious, implying high economic impact, caused by the Newcastle Disease Virus (NDV) of the Paramyxoviridae family, Rubulavirus genus. 

The virus  is a pleomorphic enveloped virus around 200–300 nm in diameter. The viral particle is formed by an enveloped nucleocapsid with fusion (F) protein spicules and hemaglutinine-neuramidase (HN) protein. The virus has a non-segmented, negative sense, single stranded RNA genome. Pathogenicity of the virus varies greatly and the disease may range from a light respiratory tract infection to a 100% mortality rate. 

Immunization against ND has been conducted with either live or inactivated virus. Live Newcastle Disease vaccine, with low virulence strain, has the advantage of mass administration and induces both local and cell immune response. Inactivated virus vaccine induces low levels of protection. 

Infection by Newcastle Disease virus may occur through either inhalation or ingestion: the virus is present in the air exhaled by the birds, in their faeces and all over the bird carcass during acute infection and death. Due to the occurrence of such diseases, sanitary barriers are established in domestic and foreign trade of birds and their by-products, ensuing large economic losses for countries where the diseases are recorded. Given the economic importance of such pathogens, availability of vaccines is essential to immunize susceptible organisms.