Kibenge F S, Dhama V
Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Canada.
Arch Virol. 1997;142(6):1227-36. doi: 10.1007/s007050050154.
The VP1 encoded by genomic segment B of birnaviruses is generally known to exist as a genome-linked protein (VPg) and as a "free" polypeptide of 90 kDa in virus particles. The guanylylation activity associated with infectious bursal disease virus (IBDV) was demonstrated by incubating purified virus in presence of [alpha 32P] GTP; optimum activity in the 90 kDa form of VP1 was seen in low salt concentration in the presence of 4 mM magnesium ions over a wide range of incubation temperatures. The IBDV VP1 was shown to lack guanyl transferase activity. Northwestern (RNA-protein) blot analysis of purified virus using a radiolabelled cDNA probe consisting of 3' and 5' ends of genomic segment B indicated that both forms of virion-associated VP1 contained viral RNA sequences of which those linked to VPg corresponded to the two genome segments and those linked to the 90 kDa VP1 were probably a short oligonucleotide of the terminal viral RNA sequences.
