Department of Disease Control, Faculty of Veterinary Medicine, Hokkaido University, Kita-18, Nishi-9, Kita-ku, Sapporo, 060-0818, Japan.
Department of Advanced Pharmaceutics, Faculty of Veterinary Medicine, Hokkaido University, Kita-18, Nishi-9, Kita-ku, Sapporo, 060-0818, Japan.
Virol J. 2020 Nov 23;17(1):186. doi: 10.1186/s12985-020-01456-1.
Marek's disease virus (MDV) causes malignant lymphomas in chickens (Marek's disease, MD). MD is currently controlled by vaccination; however, MDV strains have a tendency to develop increased virulence. Distinct diversity and point mutations are present in the Meq proteins, the oncoproteins of MDV, suggesting that changes in protein function induced by amino acid substitutions might affect MDV virulence. We previously reported that recent MDV isolates in Japan display distinct mutations in Meq proteins from those observed in traditional MDV isolates in Japan, but similar to those in MDV strains isolated from other countries.
To further investigate the genetic characteristics in Japanese field strains, we sequenced the whole genome of an MDV strain that was successfully isolated from a chicken with MD in Japan. A phylogenetic analysis of the meq gene was also performed.
Phylogenetic analysis revealed that the Meq proteins in most of the Japanese isolates were similar to those of Chinese and European strains, and the genomic sequence of the Japanese strain was classified into the Eurasian cluster. Comparison of coding region sequences among the Japanese strain and MDV strains from other countries revealed that the genetic characteristics of the Japanese strain were similar to those of Chinese and European strains.
The MDV strains distributed in Asian and European countries including Japan seem to be genetically closer to each other than to MDV strains from North America. These findings indicate that the genetic diversities of MDV strains that emerged may have been dependent on the different vaccination-based control approaches.
马立克氏病病毒（MDV）可引起鸡的恶性淋巴瘤（马立克氏病，MD）。MD 目前通过疫苗接种来控制；然而，MDV 株有增加毒力的倾向。MDV 的 Meq 蛋白（致癌蛋白）存在明显的多样性和点突变，表明氨基酸取代引起的蛋白质功能变化可能影响 MDV 的毒力。我们之前报道，日本最近的 MDV 分离株的 Meq 蛋白与日本传统 MDV 分离株观察到的不同，但与其他国家分离的 MDV 株相似。
为了进一步研究日本田间株的遗传特征，我们对从日本 MD 鸡中成功分离的 MDV 株进行了全基因组测序。还对 meq 基因进行了系统发育分析。
系统发育分析表明，大多数日本分离株的 Meq 蛋白与中国和欧洲株相似，日本株的基因组序列被归入欧亚群。与其他国家的 MDV 株相比，日本株与中国和欧洲株的编码区序列比较显示，日本株的遗传特征与中国和欧洲株相似。
包括日本在内的亚洲和欧洲国家分布的 MDV 株似乎比北美的 MDV 株在遗传上更为接近。这些发现表明，新兴的 MDV 株的遗传多样性可能取决于不同的基于疫苗的控制方法。
