Newcastle Disease Virus

Abstract

Newcastle disease virus (NDV), a member of the Avulavirus genus in the Paramyxoviridae family, has a ribonucleic acid (RNA) genome that is negative sense, nonsegmented and single‐stranded. The genome codes for six structural proteins: nucleocapsid, phosphoprotein (P), matrix, fusion, hemagglutinin–neuraminidase and the RNA‐directed RNA polymerase, in addition to the nonstructural V protein that is produced by a frame shift in the P coding region. Virulent forms of NDV (vNDV) contain multiple basic amino acids in the fusion cleavage site along with a phenylalanine (F) at position 117, are found worldwide and are endemic in some countries. Infections of poultry species with vNDV lead to trade restrictions. Although all NDV strains are of one serotype, their genomes evolve over time, becoming more diverse. Strains of NDV have been used as viral vectors to formulate vaccines for other infectious diseases and experimentally to treat human cancers. The virus causes conjunctivitis in humans. Key Concepts: Virulent NDV (vNDV) is the aetiological agent of one of the most prevalent and virulent avian diseases in the world, and causes millions of birds to die, and significantly affects the poultry industries of many countries in Africa, Asia and South America. Lentogenic NDV (loNDV) is widely distributed in wild birds where it does not cause significant disease or clinical signs. Isolates of NDV are genetically diverse with at least two classes of viruses, each divided into 10 genotypes. Depending on the virulence of the NDV isolate and the immune status of the host, Newcastle disease produces a large range of clinical signs. The fusion protein cleavage site is a key determinant of virulence and a key element utilised for modern diagnostics and classification. Because all NDV isolates are of a single serotype vaccines prepared with any NDV isolate should protect against disease from any other NDV infection. Neutralising antibodies to the Fusion (F) and hemagglutinin–neuraminidase (HN) proteins of NDV are known to be important in preventing morbidity and morality from Newcastle disease. Even vaccinated birds with high antibody titre to NDV will become infected when exposed to virulent NDV and these vaccinated birds will shed virulent NDV in oral secretion and fecal matter. The genome of NDV has been used as a vaccine vector to carry foreign genes of other organisms for use in both animals and humans.

Comparative Evaluation of the Protective Efficacy of Different Vaccination Programs Against a Virulent Field Strain of the Newcastle Disease Virus in Broilers

“…in different countries (Patti & Koch, 2013). In most areas of Iran where NDV is endemic, vaccination is mandatory for commercial and backyard poultry.…”

Newcastle Disease Virus Detection from Chicken Organ Samples Using Reverse Transcriptase Polymerase Chain Reaction

“…The cleavage site of the F protein differs in arrangement of multiple basic amino acids depending on the degree of virulence. Miller et al (2010) NDV is highly contagious, with reports stating that even low pathogenic viral strains (lentogens) that cause mild infections of the respiratory tract can greatly increase its pathogenicity even during a single passage (Rabalski et al, 2014).…”

Newcastle Disease Viruses Causing Recent Outbreaks Worldwide Show Unexpectedly High Genetic Similarity to Historical Virulent Isolates from the 1940s

“…Chickens infected with NDV show a wide spectrum of clinical signs that vary with different virus strains (3). Hanson and Brandly (4) categorize ND viruses into three main pathological groups: lentogens are avirulent and cause mild enteric, respiratory, or subclinical disease (5); mesogens cause disease and death primarily for chickens younger than 8 weeks and produce mainly respiratory disease (6); velogens induce severe systemic infections with high mortality rates (7). According to the World Organisation for Animal Health (OIE) (8), virulent NDV strains, which include both mesogenic and velogenic strains, must meet one of the following criteria: (i) have an intracerebral pathogenicity index (ICPI) in day-old chicks (Gallus gallus) of 0.7 or greater; or (ii) have multiple basic amino acids at the C terminus of the F2 protein and phenylalanine at residue 117, which is the N terminus of the F1 protein.…”

“…The term "multiple basic amino acids" refers to the presence of at least three arginine or lysine residues from positions 113 through 116. More information about NDV characteristics can be found in a comprehensive review that has been published recently (7).…”

“…Evidence suggests the existence of epidemiological links between field isolates recovered from wild birds and those obtained from poultry (7,28,29). Additionally, there is evidence for spillover of both lentogenic and velogenic viruses from poultry into wild birds (11,30).…”