Newcastle disease (ND) define as viral disease which caused by Newcastle disease virus (NDV) under the family of paramyxoviridae. Its nonsegmented negative sense RNA virus. Its caused disease in poultry specially chicken, pigeon etc.
Definition of ND
Definition of Newcastle disease broadly announced by two ways in worldwide which is most most acceptable.
(a) According to OIE (Formerly The Office International des Epizooties OIE)
Newcastle disease (ND) is defined as an infection of birds caused by a virus of avian paramyxovirus serotype- 1 (APMV-1) that should meets one of the following criteria for virulence:
⦁ Newcastle disease virus has an intracerebral pathogenicity index (ICPI) in day-old chicks (Gallus gallus) of 0.7 or greater.
⦁ NDv is a disease of birds caused by strains of avian paramyxovirus type 1, significantly more virulent than lentogenic strains.
⦁ Virulence of NDV virus depends on multiple basic amino acid in virus structurestructure (either directly or by deduction) at C & N terminus.Multiple basic amino acid shows at the C-terminus of F2 protein & phenylalanine (F) at residue 117 which is the N-terminus of the F1 protein.
The term multiple basic amino acids refers to at least 3 arginine or lysine residues between residues 113 and 116.
In this definition, amino acid residues are numbered from the N-terminus of the amino acid sequence deduced from the nucleotide sequence of the F0 gene, and 113–116 corresponds to residues –4 to –1 from the cleavage site.
⦁ Newcastle disease is a disease of poultry caused by a virus of avian paramyxovirus serotype 1 (APMV-1) which has an intracerebral pathogenicity index (ICPI) in day-old chicks of 1.2 or greater.
⦁ Virulent virus can also be confirmed by the presence of multiple basic amino acids at the at the C-terminus of the F2 protein and F (phenylalanine) at residue 117, the N-terminus of the F1 protein If NDV virus unable to demonstrate the unique pattern of amino acid residues as explain above would require characterization of the isolated virus by an ICPI test.
2) According to European Union (EU):
“an infection of poultry caused by an avian strain of the paramyxovirus 1 with an intracerebral pathogenicity index [ICPI] in day-old chicks greater than 0.7”.
Definition in Pigeon
In addition, variant APMV-1 isolates from pigeons are referred to as pigeon paramyxovirus type 1 (PPMV-1). Based on the OIE definition, by containing multiple amino acids in the fusion cleavage site, the PPMV-1 isolates are vNDV and upon infection of poultry are defined as ND and are reportable to the OIE.
However, only some PPMV-1 cause signs of clinical disease in chickens, giving IPCI values of less than 0.7, but increasing in virulence after multiple passages in chickens.
Types Of Newcastle Disease
There are two types of newcastle disease found world wide
virulence Newcastle disease virus (vNDV)
Its defined as ND inection which meet criteria according to OIE for Newcastle disease. Common criteria are
- Virus should hashas an intracerebral pathogenicity index (ICPI) in day-old chicks (Gallus gallus) of 0.7 or greater
- NDV shows basic amino acid in virus structure. etc
Common vNDV pathotypes are velogenic & Mesogenic strain
Low virulence Newcastle disease virus (loNDV)
Its defined as asymptomatic or NDV of low virulence will be referred as loNDV. This types of NDV found in reservoir host or natural host.Common natural host are Pigeon. domisticared chicken, comrants, Live newcastle disease vaccine