Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo 060-0818, Japan.
Virus Res. 2013 Dec 26;178(2):404-10. doi: 10.1016/j.virusres.2013.09.012. Epub 2013 Sep 23.
Influenza virus A/Hong Kong/483/97 (H5N1) (HK483-K) has the PB2 with lysine at position 627 (PB2-627K) and is highly pathogenic in chickens and mice. On the other hand, the pathogenicity of mutant virus (HK483-E), which was generated by substituting lysine with glutamic acid at the position of the PB2, is lower than that of HK483-K in mice, but is highly pathogenic in chickens. The PB2 is one of the components of heterotrimeric polymerase complex, which plays roles in the transcription and replication of virus genes. Cell-free polymerase assay revealed that intrinsic transcription activity of the polymerase complex with PB2-627K is higher than that of glutamic acid (PB2-627E). In chicken cells, transcription efficiency of the polymerase complex with PB2-627E was not lower than those with PB2-627K, indicating that transcription of virus genes is modulated by some host factors in chicken cells, resulting in high growth. Polymerase complex with PB2-627K efficiently transcribes and replicates virus polymerase genes in mouse cells, leading to high growth of HK483-K compared with that of HK483-E. The results of our experiments clearly suggest that efficient transcription and replication of virus genes by polymerase complex result in the higher pathogenicity in mice.
甲型流感病毒 A/香港/483/97（H5N1）（HK483-K）的 PB2 蛋白在 627 位具有赖氨酸（PB2-627K），对鸡和小鼠具有高致病性。另一方面，突变病毒（HK483-E）的致病性较低，其在 PB2 位置上的赖氨酸被谷氨酸取代，在小鼠中的致病性低于 HK483-K，但在鸡中具有高致病性。PB2 是异源三聚体聚合酶复合物的组成部分之一，在病毒基因的转录和复制中发挥作用。无细胞聚合酶测定表明，具有 PB2-627K 的聚合酶复合物的固有转录活性高于具有谷氨酸（PB2-627E）的聚合酶复合物。在鸡细胞中，具有 PB2-627E 的聚合酶复合物的转录效率不低于具有 PB2-627K 的聚合酶复合物，表明病毒基因的转录受到鸡细胞中某些宿主因子的调节，从而导致高生长。具有 PB2-627K 的聚合酶复合物在小鼠细胞中有效地转录和复制病毒聚合酶基因，导致 HK483-K 的生长速度高于 HK483-E。我们的实验结果清楚地表明，聚合酶复合物高效地转录和复制病毒基因导致了在小鼠中的高致病性。
