Evolution and Spread of Regionally Adapted Newcastle Disease Virus Isolates From Live Bird Markets in Nigeria, 2023-2024.

Abstract

Newcastle disease (ND) virus (NDV) infection ranks among the most important poultry diseases globally. In Nigeria, ND remains a persistent menace to poultry production, marked by recurrent outbreaks. However, there is limited understanding of the evolutionary changes and transmission dynamics of the virus in the region. A molecular epidemiological study was conducted to elucidate the evolutionary and transmission patterns of NDV in Nigeria. Phylogenetic analysis of seven NDV isolates from cases recorded between 2023 and 2024 in four Northeastern states exhibited genetic diversity and formed distinct clusters that correspond to the prevailing subgenotype XIV.2. The maximum clade credibility (MCC) tree suggests sustained local circulation of the dominant NDV lineage, likely preceded by an international introduction from Southeast Asia. The fusion genes of the Nigerian genotype XIV and another important genotype XVII are mainly under negative selection, but codons 516 (XIV) and 114 (XVII) consistently show positive selection. The Nextstrain analysis reveals ongoing local evolution and genetic diversity of NDV in West Africa, and Central Nigeria acting as a key transmission hub, with evidence of reintroductions from neighboring countries. These findings have implications for NDV control and prevention strategies in Nigeria, highlighting the need for enhanced NDV surveillance, transboundary transmission control, and development of a vaccine tailored to the circulating NDV genotypes. The study also contributes to the understanding of regional spread pattern of NDV and informs evidence-based policies for mitigating the impact of the disease on poultry production.