Kirisawa R, Hosoi Y, Yamaya R, Taniyama H, Okamoto M, Tsunoda N, Hagiwara K, Iwai H
Department of Veterinary Microbiology, Rakuno Gakuen University, Ebetsu, Hokkaido, Japan.
Arch Virol. 2005 Dec;150(12):2549-65. doi: 10.1007/s00705-005-0587-9. Epub 2005 Jul 14.
We isolated a variant equine herpesvirus-1 (EHV-1), strain 5089, from the lung of a dead neonatal foal in Japan and characterized the biological nature of the virus. The virus spread in cultured cells mainly by cell-to-cell infection, unlike wild-type EHV-1, which spreads efficiently as a cell-free virus. The virus titer in cultured supernatant and the intracellular virus titer were low compared to those of wild-type EHV-1. Heparin treatment of the virus had no effect on viral infectivity in cell culture. Glycoprotein C (gC) was not detected by Western blotting and fluorescent antibody tests in 5089 virions and 5089-infected cells, respectively. RT-PCR analysis revealed that the expression level of 5089 gC mRNA was reduced considerably compared to that of wild-type EHV-1. Sequencing analysis of the 5089 gC coding region showed a point mutation in the promoter region of the gC open reading frame. However, the mutation did not affect the promoter activity. These results suggested that the lack of gC in 5089 virions might be one of the reasons for spread of the virus by cell-to-cell infection and that gC mRNA expression might not be activated efficiently due to factors other than the mutation in the gC promoter region.
我们从日本一匹死亡新生马驹的肺中分离出一株变异的马疱疹病毒1型（EHV-1），5089株，并对该病毒的生物学特性进行了表征。与野生型EHV-1不同，野生型EHV-1能作为无细胞病毒高效传播，而该病毒在培养细胞中主要通过细胞间感染进行传播。与野生型EHV-1相比，培养上清液中的病毒滴度和细胞内病毒滴度较低。用肝素处理该病毒对其在细胞培养中的感染性没有影响。分别在5089病毒粒子和5089感染细胞中，通过蛋白质免疫印迹法和荧光抗体试验未检测到糖蛋白C（gC）。逆转录聚合酶链反应（RT-PCR）分析显示，与野生型EHV-1相比，5089 gC mRNA的表达水平大幅降低。对5089 gC编码区的测序分析表明，gC开放阅读框的启动子区域存在一个点突变。然而，该突变并未影响启动子活性。这些结果表明，5089病毒粒子中缺乏gC可能是该病毒通过细胞间感染传播的原因之一，并且由于gC启动子区域突变以外的因素，gC mRNA表达可能未被有效激活。
