Original Research

On the origin and diversity of Newcastle disease virus in Tanzania

Mmeta G. Yongolo, Henrik Christensen, Kurt Handberg, Uswege Minga, John E. Olsen
Onderstepoort Journal of Veterinary Research | Vol 78, No 1 | a312 | DOI: https://doi.org/10.4102/ojvr.v78i1.312 | © 2011 Mmeta G. Yongolo, Henrik Christensen, Kurt Handberg, Uswege Minga, John E. Olsen | This work is licensed under CC Attribution 4.0
Submitted: 20 December 2010 | Published: 30 September 2011

About the author(s)

Mmeta G. Yongolo, Department of Virology, Ministry of Livestock Development, Tanzania, United Republic of
Henrik Christensen, Department of Veterinary Disease Biology, University of Copenhagen, Denmark
Kurt Handberg, Department of Clinical Microbiology, University Hospital of Aarhus, Denmark
Uswege Minga, Faculty of Science, Technology and Environmental Studies, Open University of Tanzania, Tanzania, United Republic of
John E. Olsen, Department of Veterinary Disease Biology, University of Copenhagen, Denmark

Abstract

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.

Keywords

fusion protein; Newcastle disease virus; phylogeny; rural chickens; virulence

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