Genetic diversity of newcastle disease virus involved in the 2021 outbreaks in backyard poultry farms in Tanzania
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Date
2023
Journal Title
Journal ISSN
Volume Title
Publisher
MDPI
Abstract
Newcastle disease virus is a significant avian pathogen with the potential to decimate
poultry populations all over the world and cause enormous economic losses. Distinct NDV genotypes
are currently causing outbreaks worldwide. Due to the high genetic diversity of NDV, virulent strains
that may result in a lack of vaccine protection are more likely to emerge and ultimately cause
larger epidemics with massive economic losses. Thus, a more comprehensive understanding of
the circulating NDV genotypes is critical to reduce Newcastle disease (ND) burden. In this study,
NDV strains were isolated and characterized from backyard poultry farms from Tanzania, East
Africa in 2021. Reverse-transcription polymerase chain reaction (RT-PCR) based on fusion (F) gene
amplification was conducted on 79 cloacal or tracheal swabs collected from chickens during a
suspected ND outbreak. Our results revealed that 50 samples out 79 (50/79; 63.3%) were NDV-
positive. Sequencing and phylogenetic analyses of the selected NDV isolates showed that 39 isolates
belonged to subgenotype VII.2 and only one isolate belonged to subgenotype XIII.1.1. Nucleotide
sequences of the NDV F genes from Tanzania were closely related to recent NDV isolates circulating
in southern Africa, suggesting that subgenotype VII.2 is the predominant subgenotype throughout
Tanzania and southern Africa. Our data confirm the circulation of two NDV subgenotypes in
Tanzania, providing important information to design genotype-matched vaccines and to aid ND
surveillance. Furthermore, these results highlight the possibility of the spread and emergence of new
NDV subgenotypes with the potential of causing future ND epizootics.
Description
Journal Article
Keywords
Newcastle disease virus (NDV), Tanzania, East Africa, Poultry, Genotypes, Phylogenetic analyses