Fowlpox virus from backyard poultry in Plateau State Nigeria: isolation and phylogeny of the P4b gene compared to a vaccine strain

Abstract

Fowlpox is a viral infection that cause nodular and diphtheritic lesions on the skin and mucous membrane of the digestive and respiratory tracts of birds. It is a disease of economic importance in domestic and wild birds especially in tropical and subtropical countries. Despite its endemicity, there is limited literature on the genetic diversity of field virus circulating in Nigeria. In this study, cutaneous tissue samples were aseptically collected from suspected poultry flocks through passive surveillance conducted in Plateau state Nigeria from 2009 to 2013. Fowlpox virus was isolated in chorion allantoic membrane of embryonated chicken eggs and identified with Agar Gel Immuno Diffusion test using homologous reference antigen and antisera. Genomic DNA amplification and cycle sequencing of the P4b gene locus of seven selected field isolates along with a local vaccine strain was done and analysed alongside published sequences of FPV P4b gene using MEGA 5 software. Nucleotide analysis of our isolates and a vaccine strain showed 100% similarity and also shared 72 – 100% homology with selected sequences from the GenBank while clustering on the phylogenetic tree in clade A, subclade A1. This study represents the first available fowl poxvirus sequences (KP987207-KP987214) from the West and Central Africa regions in the GenBank. Full genome sequences and comparative molecular analysis of circulating field and vaccine strain is critical for the design and implementation of target oriented control programme.

Keywords: Fowlpox, Isolation, Nigeria, Phylogeny, Virus