Comparison of 1.8kb gene family of Marek’s Disease Viruses of Different Pathotypes
Abstract: In this study, sequences of the 1.8kb gene family of 12 different strains of Marek′s disease vivuses were compared. These strains covered 4 different pathotypes, i.e, vaccine, virulent, very virulent, and very virulent plus strains, plus three field strains isolated in China. The results demonstrated that the homology of the upstream regulating sequences of the gene family was more than 92.5% among 12 strains, vaccine strain CVI988/Rispens had more mutations especially with a “CTCGG" deletion between TATA box and a SP1 enhancer. There were 3-7 consecutive repeats of 132 bp in the 1.8 kb gene family of vaccine strain CVI988/Rispens, but only 2 copies were detected in the left strains of all pathotypes. However, there were also only 2 copies of 132 bp repeats found even in Chinese vaccine strain 814, indicating that expansion of 132 bp repeat copies did not have an important role as suggested before. The homology of 1.8 kb gene family was more than 97% among different strains. There were 2 ORF in the 1.69 kb no