Both genome segments contribute to the pathogenicity of very virulent infectious bursal disease virus

Olivier Escaffre, Cyril Le Nouën, Michel Amelot, Xavier Ambroggio, Kristen M. Ogden, Olivier Guionie, Didier Toquin, Hermann Müller, Mohammed R. Islam, Nicolas Eterradossi

Research output: Contribution to journalArticlepeer-review

54 Scopus citations


Infectious bursal disease virus (IBDV) causes an economically significant disease of chickens worldwide. Very virulent IBDV (vvIBDV) strains have emerged and induce as much as 60% mortality. The molecular basis for vvIBDV pathogenicity is not understood, and the relative contributions of the two genome segments, A and B, to this phenomenon are not known. Isolate 94432 has been shown previously to be genetically related to vvIBDVs but exhibits atypical antigenicity and does not cause mortality. Here the full-length genome of 94432 was determined, and a reverse genetics system was established. The molecular clone was rescued and exhibited the same antigenicity and reduced pathogenicity as isolate 94432. Genetically modified viruses derived from 94432, whose vvIBDV consensus nucleotide sequence was restored in segment A and/or B, were produced, and their pathogenicity was assessed in specific-pathogen-free chickens. We found that a valine (position 321) that modifies the most exposed part of the capsid protein VP2 critically modified the antigenicity and partially reduced the pathogenicity of 94432. However, a threonine (position 276) located in the finger domain of the virus polymerase (VP1) contributed even more significantly to attenuation. This threonine is partially exposed in a hydrophobic groove on the VP1 surface, suggesting possible interactions between VP1 and another, as yet unidentified molecule at this amino acid position. The restored vvIBDV-like pathogenicity was associated with increased replication and lesions in the thymus and spleen. These results demonstrate that both genome segments influence vvIBDV pathogenicity and may provide new targets for the attenuation of vvIBDVs.

Original languageEnglish (US)
Pages (from-to)2767-2780
Number of pages14
JournalJournal of virology
Issue number5
StatePublished - Mar 2013
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology
  • Immunology
  • Insect Science
  • Virology


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