Molecular characterization and phylogenetic analysis of Marek's disease virus in chickens from Ogun State, Nigeria

Authors: OLUWAYINKA, ENIOPE - Federal University Of Agriculture, Abeokuta; OTESILE, EBENEZER - Federal University Of Agriculture, Abeokuta; ONI, OLUWOLE - Federal University Of Agriculture, Abeokuta; AJAYI, OLUSOLA - Federal University Of Agriculture, Abeokuta; Dunn, John

Submitted to: Avian Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/31/2023
Publication Date: 8/22/2023
Citation: Oluwayinka, E.B., Otesile, E.B., Oni, O.O., Ajayi, O.L., Dunn, J.R. 2023. Molecular characterization and phylogenetic analysis of Marek's disease virus in chickens from Ogun State, Nigeria. Avian Pathology. 52(6):401-411. https://doi.org/10.1080/03079457.2023.2243838.
DOI: https://doi.org/10.1080/03079457.2023.2243838

Interpretive Summary: Marek’s disease (MD) is a disease that causes tumors in chickens caused by MD virus serotype 1 (MDV1). While frequently diagnosed in Nigeria, there is very little information on the molecular characteristics. This study was aimed at characterizing three virulence genes of MDV1 from chickens in Ogun state, Nigeria. A total of 230 blood samples, 185 feather tips, and 22 tumor samples from 59 different flocks of chickens on 44 commercial poultry farms in Ogun State, Nigeria, were analyzed. Thirteen samples were MDV1 positive and their sequences showed 100% identity. Comparison to other know sequences revealed that the Nigerian strains clustered with strains from Egypt, India, and Israel. Evaluating the virulence of the viruses in chickens is recommended to fully characterize the genotype and phenotype of MDV1 circulating in Nigeria.

Technical Abstract: Marek’s disease (MD) is caused by oncogenic MD virus serotype 1 (MDV1) and is characterized by lymphoproliferative lesions, high morbidity, and mortality in chickens. Despite being ubiquitous on chicken/poultry farms, there is a dearth of information on its molecular characterization in Ogun State, Nigeria. This study was aimed at characterizing three virulence genes (Meq, pp38, and vIL-8) of MDV1 from chickens in Ogun state, Nigeria. A total of 230 blood samples, 185 feather tips, and 22 tumor samples from 59 different flocks of chickens on 44 commercial poultry farms in Ogun State, Nigeria, were pooled and spotted on 106 FTA cards. The samples were screened for MDV1 by polymerase chain reaction (PCR) and positive samples were sequenced. Phylogenetic analysis of Nigeria Meq, pp38, and vIL-8 genes with the published references of MDV1 was carried out. Thirteen samples were MDV1 positive and the nucleotide sequences of the three genes from these positive samples showed 100% identity. The Meq genes contained 399 amino acids (aa) with three PPPP motifs in the transactivation domain and two interruptions of the PPPP motifs due to proline to arginine substitutions at positions 176 and 217 resulting in a 20.88% proline composition. Phylogenetic analysis revealed that the Nigerian strains clustered with strains from Egypt while pp38 and vIL-8 genes clustered with strains from Egypt, India, and Israel. In vivo pathotyping is therefore recommended to specifically ascertain the pathotype of Nigeria's MDV1.