Molecular Characterisation of Newcastle Disease Virus from Different Agro-Ecological Zones in Ghana

Abstract

Although Newcastle disease is reported to be endemic in Ghana, little information has been documented on the molecular epidemiology and the genotype distribution of the Newcastle disease viruses (NDVs) in the country. In this study, a total of four NDV isolates were sequenced and analysed. NDVs recovered were from outbreaks in backyard and commercial poultry farms between 2018 and 2019. A full genome sequence of all four isolates was performed. A commonly used region of the virus genome that spans nucleotide 61 to nucleotide 374 of the Fusion protein, including the cleavage site was targeted. Based on sequence analysis, two of the sequences were classified under Genotype XIV and the other two classified under Genotype XVIII. Phylogenetic analysis, amino acid sequence determination of the F0 cleavage site as well as pairwise distance analysis of the full fusion protein gene sequences were done. Results showed close genetic similarities between circulating strains within the West African sub-region. The emergence and identification of different genotypes could give an insight into the high rate of mutations occurring in NDV strains in Ghana or importation and transmission of strains from other countries, which also raises concerns about the efficacy of current NDV control measures in the country. The amino acid sequence identity of the Ghanaian strains and the NDV- I2 vaccine strain ranged from 82 – 83%. The genetic relatedness of some of the Ghanaian NDV strains to the NDV I2 vaccine strain makes the isolated Ghanaian strains prime candidates for the production of an NDV vaccine. Thus, there is the need for continuous surveillance and characterization of NDV in Ghana to monitor the emergence of new genotypes within the Ghanaian poultry industry.