Young Virginia A, Dillon Patrick J, Parks Griffith D
Department of Microbiology and Immunology, Wake Forest University School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157-1064, USA.
Virology. 2006 Jun 20;350(1):90-102. doi: 10.1016/j.virol.2006.01.006. Epub 2006 Feb 15.
Our previous results have shown that the parainfluenza virus SV5 is a poor inducer of proinflammatory cytokines interleukin-8 (IL-8) and macrophage chemoattractant protein 1 (MCP-1). By contrast, an engineered P/V mutant rSV5-P/V-CPI- and a naturally-occurring variant WF-PIV (Wake Forest-Parainfluenza Virus) are both potent activators of IL-8 and MCP-1. In the present study, we addressed the question of why rSV5-WT is such a poor inducer of host cytokine responses relative to the two SV5 variants, and we used the CC chemokine RANTES as a measure of host responses. Time course experiments showed high-level secretion of IL-6 and RANTES following infections of human A549 lung epithelial cells with the P/V-CPI- mutant and WF-PIV. By contrast, SV5-WT induced very low cytokine responses, with the notable exception of moderate induction of RANTES. The mechanism of RANTES induction by the two SV5 variants shared common properties, since RANTES secretion from infected cells had similar kinetics, depended on virus replication, correlated with increased RANTES mRNA levels and promoter activation, and was reduced by inhibitors of the p38 MAPK, ERK, and PI3K pathways. Despite the similar mechanisms of RANTES induction, the two SV5 variants differed dramatically in their growth and gene expression kinetics. By comparison to the P/V mutant rSV5-P/V-CPI- which has accelerated viral gene expression, WF-PIV infection showed a prolonged delay in viral replication, and infected cells did not show high-level viral RNA and protein expression until approximately 12-24 hpi. Sequence analysis revealed that the N, P, V, and M genes from WF-PIV differed by 3, 8, 5, and 10 amino acids compared to rSV5-WT, respectively. Chimeric viruses harboring the WF-PIV P/V or M genes in the context of the other rSV5 genes had growth properties similar to rSV5-WT but had a RANTES-inducing phenotype similar to that of the bone fide WF-PIV virus. Our data indicate a role for both the P/V and the M gene products as determinants of RANTES induction in response to SV5 infection.
我们之前的研究结果表明，副流感病毒SV5是促炎细胞因子白细胞介素-8（IL-8）和巨噬细胞趋化蛋白1（MCP-1）的低效诱导剂。相比之下，一种经基因工程改造的P/V突变体rSV5-P/V-CPI-和一种天然存在的变体WF-PIV（维克森林副流感病毒）都是IL-8和MCP-1的强效激活剂。在本研究中，我们探讨了相对于这两种SV5变体，rSV5-WT为何是宿主细胞因子反应的如此低效诱导剂这一问题，并使用CC趋化因子RANTES作为宿主反应的一个指标。时间进程实验表明，用P/V-CPI-突变体和WF-PIV感染人A549肺上皮细胞后，会出现高水平的IL-6和RANTES分泌。相比之下，SV5-WT诱导的细胞因子反应非常低，只有对RANTES的中度诱导是个明显的例外。两种SV5变体诱导RANTES的机制具有共同特性，因为受感染细胞中RANTES的分泌具有相似的动力学，依赖于病毒复制，与RANTES mRNA水平的升高和启动子激活相关，并且会被p38 MAPK、ERK和PI3K途径的抑制剂所抑制。尽管RANTES诱导机制相似，但两种SV5变体在生长和基因表达动力学方面存在显著差异。与具有加速病毒基因表达的P/V突变体rSV5-P/V-CPI-相比，WF-PIV感染显示病毒复制存在长时间延迟，并且受感染细胞直到感染后约12 - 24小时才显示高水平的病毒RNA和蛋白质表达。序列分析显示，与rSV5-WT相比，WF-PIV的N、P/V和M基因分别有3、8、5和10个氨基酸不同。在其他rSV5基因背景下携带WF-PIV P/V或M基因的嵌合病毒具有与rSV5-WT相似的生长特性，但具有与正宗WF-PIV病毒相似的RANTES诱导表型。我们的数据表明，P/V和M基因产物在响应SV5感染时作为RANTES诱导的决定因素发挥作用。
