Virulence of pigeon-origin Newcastle disease virus isolates for domestic chickens

• Published in: Avian diseases 2001-10, Vol.45 (4), p.906-921
• Main Authors: Kommers, G.D, King, D.J, Seal, B.S, Brown, C.C
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; amino acid sequences; Animals; Antibodies, Monoclonal - immunology; Base Sequence; Birds; Brain - pathology; Brain - virology; Chick Embryo; Chickens; clinical aspects; Columbidae; Heart - virology; histopathology; Hypertension; Immunohistochemistry - veterinary; Inoculum; lesions; Molecular Sequence Data; Mortality; Myocardium - pathology; Newcastle disease; Newcastle Disease - mortality; Newcastle Disease - pathology; Newcastle Disease - virology; Newcastle disease virus; Newcastle disease virus - classification; Newcastle disease virus - genetics; Newcastle disease virus - immunology; Newcastle disease virus - pathogenicity; nucleotide sequences; pathogenesis; pathotypes; Phylogeny; Pigeons; Poultry Diseases - mortality; Poultry Diseases - pathology; Poultry Diseases - virology; Respirovirus; Reverse Transcriptase Polymerase Chain Reaction - veterinary; Rubulavirus; Serial Passage - veterinary; Specific Pathogen-Free Organisms; Viral Fusion Proteins - chemistry; Virulence; Viruses
• ISSN: 0005-2086; 1938-4351
• DOI: 10.2307/1592870

The virulence of six pigeon-origin isolates of Newcastle disease virus (NDV) was evaluated before and after passage in white leghorn chickens. Four isolates were defined as pigeon paramyxovirus-1 (PPMV-1) and two isolates were classified as avian paramyxovirus-1 (APMV-1) with NDV monoclonal antibodies. The four PPMV-1 isolates were passaged four times in chickens, and the APMV-1 isolates were passaged only once. Infected birds were monitored clinically and euthanatized. Tissues were collected for histopathology, in situ hybridization with a NDV matrix gene digoxigenin-labeled riboprobe, and immunohistochemistry with an anti-peptide antibody to the nucleoprotein. Mean death time, intracerebral pathogenicity index, and intravenous pathogenicity index tests performed before and after passage in chickens demonstrated increased virulence of the passaged PPMV-1 isolates and high virulence of the original isolates of APMV-1. Sequence analysis of the fusion protein cleavage site of all six isolates demonstrated a sequence typical of the virulent pathotype. Although the pathotyping results indicated a virulence increase of all passaged PPMV-1 isolates, clinical disease was limited to depression and some nervous signs in only some of the 4-wk-old specific-pathogen-free white leghorns inoculated intraconjunctivally. However, an increased frequency of clinical signs and some mortality occurred in 2 wk olds inoculated intraconjunctivally with passaged virus. Histologically, prominent lesions in heart and brain were observed in birds among all four groups inoculated with the PPMV-1 isolates. The behavior of the two pigeon-origin APMV-1 isolates when inoculated into chickens was characteristic of velogenic viscerotropic NDVs and included necro-hemorrhagic lesions in the gastrointestinal tract.