On the origin and diversity of Newcastle disease virus in Tanzania

• Published in: Onderstepoort journal of veterinary research Vol. 78; no. 1; p. 312
• Main Authors: Yongolo, Mmeta G, Christensen, Henrik, Handberg, Kurt, Minga, Uswege, Olsen, John E
• Format: Journal Article
• Language: English
• Published: South Africa ARC-Onderstepoort Veterinary Institute - Agricultural Research Council 01.01.2011; AOSIS
• Subjects: Agriculture, Dairy & Animal Science; Anatomy & Morphology; Animals; Base Sequence; Biochemistry & Molecular Biology; Birds; Chickens; fusion protein; Genotype; Newcastle Disease - epidemiology; Newcastle Disease - transmission; Newcastle Disease - virology; Newcastle disease virus; Newcastle disease virus - classification; Newcastle disease virus - isolation & purification; Pharmacology & Pharmacy; Phylogeny; Physiology; Poultry Diseases - epidemiology; Poultry Diseases - transmission; Poultry Diseases - virology; rural chickens; Sequence Analysis, DNA; Tanzania; Veterinary Sciences; virulence; Tanzania
• ISSN: 0030-2465; 2219-0635; 2219-0635
• DOI: 10.4102/ojvr.v78i1.312

Free-range rural chickens (FRCs) dominate the poultry industry in developing countries and chickens are exposed to multi-host infections, including Newcastle disease virus (NDV). The knowledge about the characteristics of NDV from FRCs is limited. This study investigated the persistence, spread and risks of NDV from FRCs. NDV isolates (n = 21) from unvaccinated FRCs in Tanzania were characterised by conventional intracerebral pathogenicity index (ICPI) and sequence analysis of a partial region of the deduced fusion protein encompassing the cleavage site. Results showed that five isolates were screened as lentogenic, nine as mesogenic and six as velogenic. Phylogenetic analysis of the 21 isolates compared to reference sequences revealed three, four, nine and five isolates in genotypes 1, 2, 3c and 4a, respectively. Genotype 3c also included published sequences of Tanzanian isolates obtained from exotic birds and chicken isolates from Uganda. The analysis showed that NDV were persistently present among chicken populations and possibly spread through live chicken markets or migration of wild birds. Differences in amino acid sequences detected around the cleavage site separated the isolates in six types. However, cleavage site pattern could not fully differentiate mesogenic isolates from velogenic isolates.