Full-length sequence analysis of four IBDV strains with different pathogenicities

Area of Science:

• Virology
• Molecular Biology
• Genomics

Background:

• Infectious bursal disease virus (IBDV) causes significant economic losses in poultry.
• Accurate molecular typing of IBDV strains is crucial for disease control and vaccine development.
• Previous studies often relied on partial genomic information for strain characterization.

Purpose of the Study:

• To characterize field isolate 9109 and adapted strains (Lukert, Edgar CCA, CEA) of serotype 1 IBDV.
• To compare full-length genomic sequences and deduce amino acid sequences with existing IBDV strains.
• To evaluate the utility of specific viral proteins and genomic regions for molecular typing.

Main Methods:

• Sequencing of IBDV genomic segments A and B from selected strains.
• Nucleotide and deduced amino acid sequence comparison with previously reported IBDV strains.
• Phylogenetic analysis of viral proteins (VP1, VP3, VP4) and non-coding regions.

Main Results:

• Viral protein VPX and specific regions of VP2 (aa 202-451, 210-473) best represent the IBDV genome.
• Greatest variability observed in VP2 and the 5' non-coding region of segment B.
• Isolate 9109 exhibits characteristics of classical, very virulent, and variant IBDV strains, highlighting complex genetic makeup.

Conclusions:

• Full-length genomic sequencing is essential for accurate molecular characterization of IBDV strains.
• Partial sequence analysis may be insufficient for definitive classification as very virulent, classical, or variant.
• The study underscores the importance of comprehensive genomic data for understanding IBDV evolution and epidemiology.