Submitted to: International Marek's Disease Symposium Abstracts and Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 7/14/2004
Publication Date: 7/14/2004
Citation: Niikura, M., Dodgson, J., Cheng, H.H. 2004. Characterization and complete sequence of an infectious Marek's disease virus bacterial artificial chromosome clone generated from a virulent strain [abstract]. International Marek's Disease Symposium Abstracts and Proceedings. Paper No. P.17.
Technical Abstract: An infectious bacterial artificial chromosome (BAC) clone that generates a partially virulent Marek's disease virus (MDV) has been isolated. MDV produced from this clone grew similarly in vitro compared to the parental virus strain Md11. In infected chickens, BAC-derived MDV replicated to levels comparable to the Md11 strain in the early phase of infection but not in the later stages. This clone maintained the potential to cause lymphomas in infected animals, though the incidence was significantly lower than observed with Md11. The BAC vector sequence was not the cause of this reduced virulence, since removal of the vector had no effect. To elucidate the cause of the decreased oncogenicity, the complete sequence of this MDV-BAC clone was determined. The cloned MDV sequence was found to be very similar to the published sequence of the Md5 strain except for two structural differences. The terminal repeat short (TRS) segment in the clone was replaced by a novel sequence. Also, the structure of the a-like sequences in the BAC differed slightly from others previously reported. Furthermore, 15 non-synonymous nucleotide differences in 13 potential open reading frames were found between Md5 and Md11 sequences. However, 13 of these differences were found to be strain specific. One difference in UL41, viral host shutoff protein, was a difference between the BAC and Md11. Another difference found in ICP4 represented one of two alleles co-existing in Md11 population.