Restriction fragment profiles of genome segment A of infectious bursal disease virus correlate with serotype and geographical origin of avibirnaviruses

Previous analysis of the two serotypes of infectious bursal disease virus (IBDV) have demonstrated the correlation between antigenicity and similarities of nucleotide and amino acid sequences of the VP2 coding region in genome segment A. Restriction fragment profiles of genomic segment A cDNA of five IBDV isolates (QC-2 and QT-1 of serotype 1, SK9, and Nos. 39 and 52 of serotype 2) were determined in order to establish the genetic relationship of these viruses to other avibirnaviruses. The restriction fragment profiles using three of seven restriction enzymes (SacI which cuts in the VP2 region, DraIII which cuts in the VP3 region, and EcoRI which cuts in the VP4 region) were used to place QC-2, QT-1, SK9, No. 39, and No. 52 within the phylogenetic tree among seven other avibirnaviruses of known sequence. The two IBDV serotypes corresponded to two genotypes on the basis of the presence or absence of the SacI restriction site. The serotype 1 cluster of strains was further differentiated into five minor clusters on the basis of the PstI, EcoRI, BamHI, HindIII, DraIII, and Bsu361 restriction sites, which emphasized the geographical origins of the strains. It is concluded that restriction analysis of cDNA of the whole viral genomic segment A allows differentiation of IBDV isolates on the basis of their antigenicity and geographical origin.