Submitted to: Proceedings of Southern Conference on Avian Diseases
Publication Type: Abstract Only
Publication Acceptance Date: 12/1/2004
Publication Date: 1/31/2005
Citation: Petkov, D.I., Linnemann, E., Kapczynski, D.R., Sellers, H.S. 2005. Infectious bursal disease virus full-length sequence analysis. Proceedings of Southern Conference on Avian Diseases. p. 32.
Technical Abstract: Chickens infected with infectious bursal disease virus (IBDV) are immunosuppressed and predisposed to opportunistic infections. We expect to identify with full-length IBDV sequence analysis regions involved in the pathogenicity. Segments A and B of field isolate 9109, Lukert, Edgar cell-culture adapted (CCA), and Edgar chicken embryo-adapted (CEA) strains were sequenced. The amino acid sequences were aligned with previously published IBDV sequences followed by phylogenetic analysis using recently reported cleavage sites and RNA-dependent, RNA-polymerase (RdRp) motifs. The most conserved protein was VP5. Phylogenetic analysis of the RdRp motif and VP4 proteins revealed conserved branching pattern. The VP1 protein from cell-culture adapted Lukert and Edgar CCA, and Edgar CEA and field isolates 9109 has different amino acid length. Lukert, Edgar CCA and CEA have amino acid substitutions at VP3 protein within the self- and dsRNA-binding domains and 9109 isolate at the VP3 carboxyl domain which is important vvIBDV pathogenic determinant. The VP4 substitutions at 541 (I) in 9109 within motif I is present in OKYM and variant E. Mutations in the protease may affect the polyprotein cleavage and play role in the viral adaptation and pathogenicity. Our analysis revealed that most of our predicted VP2 antigenic regions are located outside of the previously proposed major and minor regions. Extensive amino acid substitutions in the VP2 processing site were present only in the Edgar CCA and CEA strains. Amino acid determinants in VP2 for tissue-culture adaptation at position 253 and 284 were conserved in Edgar CCA and Lukert. The US variant determinants at amino acid position 222 and 249 were observed in 9109 isolate. While segment B was highly conserved, full-length segment A analysis is needed for complete IBDV characterization. Lukert, Edgar CCA and CEA strains have sequence characteristics of the classical strains. The 9109 isolate has both, very virulent and US variant characteristics. Our analysis did not reveal regions other than VP2 predicted antigenic domains that could be linked to the pathogenicity.