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Diversity (polymorphism) of the meq gene in the attenuated Marek's disease virus serotype I and the transformed cell lines by MDVa Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan, b Department of Poultry disease, Faculty of Veterinary Medicine, South Valley University, Egypt, e-mail: monuma@vetmed.hokudai.ac.jpABSTRACT: Marek's disease virus (MDV) induces malignant lymphomas in chickens. One of the candidate oncogenes, meq, which encodes a 339-amino-acid bZIP transactivator protein, has been identified in the MDV1 genome, and suggested to play a key role in transformation by MDV1. The transactivation domain of the meq gene is characterized by six proline-rich repeats (PRR). High proline content of the transactivation domain is related to transactivation and transrepression activity. To analysis the PRR region of the transactivation domain in the meq gene, PCR is performed using a primer set which is designed to amplify the transactivation domain. In the attenuated MDV1, JM, prepared by prolonged passage in vitro, the MSB1 and MTB cell lines which are derived from MD tumors, and PBMC and spleen cells from chickens infected with different strains of MDV1, 0.8-kb long meq (L-meq) was mainly detected by PCR using the primer set. In addition, other DNA fragments including 0.6-kb meq, 0.5-kb short meq (S-meq), and 0.3-kb very short meq (VS-meq) were detected. In another MDV1, Md5, attenuated by prolonged passage in vitro, the 0.6-kb meq is always detected, and 0.5-kb S-meq is occasionally detected. L-meq encodes 399-a.a. bZIP protein in which 60 amino acids are inserted to MEQ. The transactivation domain of L-MEQ is characterized by nine PRR in which 3 PRR are added to 6 PRR of MEQ. S-meq encodes 298-a.a. bZIP protein in which 41 amino acids are deleted from MEQ. The transactivation domain of S-MEQ is composed of 4 PRR. VS-meq encodes 247-a.a. bZIP protein in which 92 amino acids are deleted from MEQ. The transactivation domain of S-MEQ is composed of only two PRR. These results are confirmed by Southern blot analysis using a S-meq specific probe. Thus, multiple forms of the meq genes are present in the attenuated MDV1 and the MDV transformed cell lines. For more information, contact kschangs@hanmail.net Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Paris, France; February 9 - 12, 2002; in the section on Viral Oncogenesis. |
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