Sequence analysis of the variable VP2 gene of infectious bursal disease viruses passaged in Vero cells.
Korean field infectious bursal disease viruses (IBDVs) were isolated from IBDV suspected commercial chickens. A previous study revealed that these IBDV field isolates were virulent or very virulent IBDVs. The isolates were passaged three times in the chorioallantoic membrane of specific-pathogen-free embryonated chicken eggs and four times in Vero cells. After passage, viral RNAs were isolated and purified to determine the genetic changes. The hypervariable regions of the VP2 gene were amplified by reverse transcriptase-polymerase chain reaction (RT-PCR). To confirm the genetic changes, PCR products were cloned, sequenced and compared to the sequences of the parental IBDVs and published IBDV strains. By sequencing analysis, the passaged IBDVs had amino acid changes at positions 253 (Q --> H), 279 (D or N --> N) and 284 (A --> T) which were commonly found in the attenuated IBDV strains. Two serines in the serine-rich heptapeptide (residue 326-332) were substituted into other amino acids which were similar to the IBDV vaccine strains.
Kwon
Hyuk Moo
HM
Laboratory of Veterinary Microbiology, Department of Veterinary Medicine, Kangwon National University, Chunchon 200-701, Republic of Korea; kwonhm@kangwon.ac.kr
Kim
Soo Joung
SJ
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D017931:DNA Primers; D007243:Infectious bursal disease virus / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D012692:Serial Passage; D014709:Vero Cells; D015678:Viral Structural Proteins / Q000737:chemistry / Q000235:genetics*
D017931:DNA Primers; C082513:VP2 protein, infectious bursal disease virus; D015678:Viral Structural Proteins