Abstract Two fragments in the non-essential region of Marek's disease virus (MDV) were amplified by PCR from the genome of MDV CVI988 strain, and cloned into pUC19 for generating the 5.5 kb homologous recombinant arms. A transfer vector pUS-gpt-GFP was constructed by inserting the expressing cassettes of the CMV-gpt-ployA or CMV-GFP-polyA, respectively, into the unique BglⅡsite of US2 region in the recombinant arms. The transfer vector was transiently transfected into CHO cells and the expression of the green fluorescence protein was observed under the fluorescence microscope. This transfer vector was then transfected into CEF infected with MDV CVI988 strain. The recombinant CVI988 viruses expressing foreign genes, named rMDVgptGFP, were cloned by purifying the plagues expressing GFP in the MX-HAT selection medium. The purified recombinant viruses were further confirmed by PCR detection and growth of recombinant virus in selective and nonselective media.
