The genome segment B encoding the RNA-dependent RNA polymerase protein VP1 of very virulent infectious bursal disease virus (IBDV) is phylogenetically distinct from that of all other IBDV strains.
A full-length cDNA clone of the segment B of the very virulent infectious bursal disease virus (IBDV) strain BD 3/99 was constructed and the full-length nucleotide sequence was established. The nucleotide sequence encoding VP1, an RNA-dependent RNA polymerase, of BD 3/99 was aligned with that of 17 other IBDV strains including six very virulent, three classical virulent, five classical attenuated, one antigenic variant and two serotype 2 strains. The VP1 genes of all very virulent strains were 97.5% to 99.8% identical. With the exception of an atypical Australian strain, 002-73, all of the classical virulent or attenuated and antigenic variant strains were also 97.5% to 100% identical. Serotype 2 strains showed only 4-6% divergence from serotype 1 classical virulent or attenuated strains; in contrast, however, the very virulent strains were 10.5% to 12.5% divergent from the classical virulent or attenuated strains as well as serotype 2 strains. Analysis of the deduced amino acid sequence of VP1 revealed 17 common, including 8 unique amino acid substitutions in the very virulent strains. In the phylogenetic tree the very virulent strains formed a distinct cluster and all other strains including classical virulent, attenuated and antigenic variant strains and even serotype 2 strains were grouped together. It is suggested that the VP1 of very virulent IBDV is phylogenetically distinct from that of all other IBDV strains and probably originated from a hitherto unidentified source.
Islam
M R
MR
Institute of Virology, Faculty of Veterinary Medicine, University of Leipzig, Germany.
Zierenberg
K
K
Müller
H
H
D000595:Amino Acid Sequence; D000818:Animals; D018175:Birnaviridae Infections / Q000821:virology; D002645:Chickens; D003001:Cloning, Molecular; D018076:DNA, Complementary; D016679:Genome, Viral; D007243:Infectious bursal disease virus / Q000145:classification / Q000235:genetics / Q000472:pathogenicity*; D008969:Molecular Sequence Data; D010802:Phylogeny; D011201:Poultry Diseases / Q000821:virology*; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D015678:Viral Structural Proteins / Q000737:chemistry / Q000235:genetics*; D014774:Virulence
D018076:DNA, Complementary; C107669:VP1 protein, infectious bursal disease virus; D015678:Viral Structural Proteins; D012324:RNA-Dependent RNA Polymerase