title: Molecular characterization of field infectious bursal disease virus isolates from Nigeria.
abstract: OBJECTIVE
  To characterize field isolates of infectious bursal disease virus (IBDV) from outbreaks in nine states in Nigeria through reverse transcription polymerase chain reaction (RT-PCR) and sequence analysis of portions of the VP2 and VP1 genes and to determine the presence or absence of reassortant viruses.
  
  
  METHODS
  A total of 377 bursa samples were collected from 201 suspected IBD outbreaks during 2009 to 2014 from nine states in Nigeria. Samples were subjected to RT-PCR using VP2 and VP1 gene specific primers, and the resulting PCR products were sequenced.
  
  
  RESULTS
  A total of 143 samples were positive for IBDV by RT-PCR. These assays amplified a 743 bp fragment from nt 701 to 1444 in the IBDV VP2 hypervariable region (hvVP2) of segment A and a 722 bp fragment from nt 168 to 889 in the VP1 gene of segment B. RT-PCR products were sequenced, aligned and compared with reference IBDV sequences obtained from GenBank. All but one hvVP2 sequence showed similarity to very virulent IBDV (vvIBDV) reference strains, yet only 3 of the VP1 67 VP1 sequences showed similarity to the VP1 gene of vvIBDV. Phylogenetic analysis revealed a new lineage of Nigerian reassortant IBDV strains.
  
  
  CONCLUSIONS
  Phylogenetic analysis of partial sequences of genome segment A and B of IBDV in Nigeria confirmed the existence of vvIBDV in Nigeria. In addition, we noted the existence of reassortant IBDV strains with novel triplet amino acid motifs at positions 145, 146 and 147 in the reassorted Nigerian IBDV.
authors.affiliation: Department of Virology, Viral Research Division, National Veterinary Research Institute, Vom, Plateau State, Nigeria; Department of Applied Microbiology and Brewing, Faculty of Biosciences. Nnamdi Azikiwe University Awka, Anambra State, Nigeria; Department of Veterinary Preventive Medicine, Food Animal Health Research Program, Ohio Agricultural Research and Development Center, The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691, USA.
authors.forename: Ijeoma O
authors.initials: IO
authors.lastname: Nwagbo
authors.affiliation: Department of Virology, Viral Research Division, National Veterinary Research Institute, Vom, Plateau State, Nigeria.
authors.forename: Ismaila
authors.initials: I
authors.lastname: Shittu
authors.affiliation: Department of Virology, Viral Research Division, National Veterinary Research Institute, Vom, Plateau State, Nigeria.
authors.forename: Chika I
authors.initials: CI
authors.lastname: Nwosuh
authors.affiliation: Department of Veterinary Microbiology and Parasitology, College of Veterinary Medicine, Micheal Okpara University of Agriculture Umudike, Abia State, Nigeria.
authors.forename: George O
authors.initials: GO
authors.lastname: Ezeifeka
authors.affiliation: Department of Applied Microbiology and Brewing, Faculty of Biosciences. Nnamdi Azikiwe University Awka, Anambra State, Nigeria.
authors.forename: Frederick J C
authors.initials: FJ
authors.lastname: Odibo
authors.affiliation: Department of Veterinary Preventive Medicine, Food Animal Health Research Program, Ohio Agricultural Research and Development Center, The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691, USA.
authors.forename: Linda O
authors.initials: LO
authors.lastname: Michel
authors.affiliation: Department of Veterinary Preventive Medicine, Food Animal Health Research Program, Ohio Agricultural Research and Development Center, The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691, USA.
authors.forename: Daral J
authors.initials: DJ
authors.lastname: Jackwood
keywords: Nigeria; infectious bursal disease virus; novel; reassortant; very virulent