›› 2015, Vol. 42 ›› Issue (2): 285-291.doi: 10.16431/j.cnki.1671-7236.2015.02.007

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Molecular Identification of Self-excision of Bacterial Artificial Chromosome Sequence in Meq-null Marek's Disease Virus

SUN Peng1, SU Shuai1, LI Yan-peng2, DING Jia-bo3, CUI Zhi-zhong1   

  1. 1. College of Animal Science and Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, China;
    2. Institute of Animal Sciences, Chinese Academy of Agricultural Sciences(CAAS), Beijing 100193, China;
    3. China Institute of Veterinary Drug Control, Beijing 100081, China
  • Received:2014-09-09 Online:2015-02-20 Published:2015-02-13

Abstract: The test was aimed to study the molecular identification of self-excision of bacterial artificial chromosome in meq-null Marek's disease virus (MDV) clone genome.SC9-1 recombinant plasmid containing cre recombinase expression cassette was transfected into chickens embryo fibroblast (CEF) to rescue SC9-1 recombinant virus.SC9-1 recombinant virus was passaged on CEF cells continuously,using cre recombinase knocked out BAC sequence in process of virus passaged.Extracting 1 to 10 generations DNA of SC9-1 recombinant virus as template,PCR detected BAC sequence of viral genome by specific primers.Using specific primers for the BAC sequence of gpt gene,the MDV conserved gene pp38 as an internal standard,the content of BAC sequences in the viral genome of different passages were detected by fluorescence quantitative PCR.The residual sequence of both sides of loxp site were amplified by PCR,and future verifying the knockout of BAC sequence by sequencing.The results showed that,using the BAC sequence specific primers to detect BAC sequence of different generations in the viral genome, the first five generation of virus DNA could amplify 600 bp specific band meaning the viral genome contained the BAC sequence.The 6 to 10 generationes of virus DNA couldn't amplify 600 bp specific band meaning the viral genome didn't contain the BAC sequence.The result of fluorescence quantitative PCR showed that the content of BAC sequence in viral genome decreased gradually with the passage of the virus and couldn't detect BAC sequence completely until the sixth generation.In the process of the knockout of BAC sequence,PCR identifying the residual sequence of both sides of loxp site,the results showed only one loxp site left after the knockout of BAC sequence and the sequence homology was above 99.7%.The experiment confirmed that the cre/loxp system could delete the BAC sequence in MDV meq-null mutant SC9-1 completely by culturing virus on CEF cells for 6 generation of batches and the knockout of BAC sequence had high degree of consistency.

Key words: Marek's disease; meq gene; bacterial artificial chromosomes; knockout; identification

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