潜伏期马立克氏病病鸡血清I型病毒L-meq、meq基因的比较及遗传分析

Meq gene and L-meq gene of MDV serotype Ⅰ were amplified from the genome in the lymphoid tissues of MDV latently infected chickens by PCR technique. The PCR product was cloned into the cloning vector pMD18-T. Sequence analysis showed that L-meq gene and meq gene were relatively conservative except that there was a 180-bp insertion into meq gene. But only meq gene was obtained in latently infected chicken. In order to explore the reason of diappearance of L-meq during its onset period. These two amino acids of meq and L-meq were compared. The result showed that meq contained six proline-rich-repeats (PRR) while L-meq had nine PRR, in which 3 PRR were added. Thus, it was concluded that PRR may have both transacting and modulating functions of viral DNA. The 180-bp nucleotide sequence might be the reason why MDV is not oncogenic during its onset period. Moreover, L-meq may be necessary for the maintance of its latent period.