流感病毒神經(jīng)氨酸酶（Neuraminidase，NA）是由流感病毒的RNA6編碼的一個(gè)主要的表面抗原,，屬于II型膜蛋白,。NA是一種糖苷外切酶，可以從α-糖苷鍵上除去唾液酸殘基,，這一功能對(duì)病毒粒子脫離宿主細(xì)胞以及防止病毒粒子聚集是非常重要的,。NA在流感病毒形態(tài)發(fā)生和病毒粒子成熟過程中也發(fā)揮重要作用。此外,，NA還為流感病毒感染時(shí)清理通道,，在病毒接觸宿主細(xì)胞中發(fā)揮作用?；谶@些功能,，NA與流感病毒的宿主特異性以及病毒致病力密切相關(guān)。迄今為止,，NA仍然是抗流感病毒藥物的最佳靶標(biāo),。然而,，NA在宿主細(xì)胞內(nèi)轉(zhuǎn)運(yùn)過程和機(jī)理迄今仍不清楚,，哪些宿主因子參與了NA向細(xì)胞膜轉(zhuǎn)運(yùn)過程仍一無所知，因此限制了針對(duì)NA唾液酸結(jié)合位點(diǎn)外的藥物開發(fā),。

中國(guó)科學(xué)院微生物研究所陳吉龍研究員領(lǐng)導(dǎo)的病毒感染與腫瘤發(fā)生機(jī)理研究組通過microarray技術(shù)篩選到宿主因子ARHGAP21,，發(fā)現(xiàn)在流感病毒感染A549細(xì)胞后,，ARHGAP21表達(dá)水平發(fā)生了明顯變化，而小G蛋白Cdc42與ARHGAP21又是緊密關(guān)聯(lián)的,，通過一系列的生化與分子生物學(xué),、以及細(xì)胞生物學(xué)等實(shí)驗(yàn)，證實(shí)了Cdc42和ARHGAP21參與了流感病毒NA蛋白向細(xì)胞膜轉(zhuǎn)運(yùn)的調(diào)控,，從而影響了流感病毒的復(fù)制過程,。

此外，陳吉龍研究組還發(fā)現(xiàn)了甲型流感病毒可以直接感染特異亞群的淋巴細(xì)胞,，并進(jìn)一步證實(shí)了宿主細(xì)胞內(nèi)Itk信號(hào)通路在流感病毒感染這些細(xì)胞的過程中起重要作用,。

此項(xiàng)研究揭示了宿主因子小G蛋白Cdc42、ARHGAP21對(duì)流感病毒NA蛋白轉(zhuǎn)運(yùn)調(diào)控作用,，闡明了宿主細(xì)胞內(nèi)Itk信號(hào)通路對(duì)流感病毒感染與復(fù)制的影響,。這些結(jié)果加深了人們對(duì)流感病毒生命周期(life cycle)以及病毒致病機(jī)理的理解，為徹底闡明流感病毒感染與復(fù)制的整個(gè)調(diào)控網(wǎng)絡(luò)提供了幫助,。另外,，此項(xiàng)研究對(duì)新型抗流感病毒藥物的設(shè)計(jì)具有重要的參考意義。

相關(guān)研究論文已在線發(fā)表于國(guó)際重要學(xué)術(shù)刊物The Journal of Biological Chemistry及Journal of General Virology上,。（生物谷Bioon.com）

doi:10.1074/jbc.M111.312959
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Transport of influenza A virus neuraminidase (NA) to host cell surface is regulated by ARHGAP21 and Cdc42

Song Wang1, Hua Li1, Yuhai Chen1, Haitao Wei1, George F. Gao1, Hongqiang Liu1, Shile Huang2 and Ji-Long Chen1,*

Influenza virus neuraminidase (NA) is transported to the virus assembly site at the plasma membrane and is a major viral envelope component that plays a critical role in the release of progeny virions and in determination of host range restriction. However, little is known about the host factors that are involved in regulating the intracellular and cell surface transport of NA. Here we identified the Cdc42-specific GAP, ARHGAP21 differentially expressed in host cells infected with influenza A virus using cDNA microarray analysis. Furthermore, we have investigated the involvement of Rho family GTPases in NA transport to the cell surface. We found that expression of constitutively active or inactive mutants of RhoA or Rac1 did not significantly affect the amount of NA that reached the cell surface. However, expression of constitutively active Cdc42 or depletion of ARHGAP21 promoted the transport of NA to the plasma membranes. By contrast, cells expressing shRNA targeting Cdc42 or overexpressing ARHGAP21 exhibited a significant decrease in the amount of cell surface-localized NA. Importantly, silencing Cdc42 reduced influenza A virus replication, whereas silencing ARHGAP21 increased the virus replication. Together, our results reveal that ARHGAP21 and Cdc42-based signaling regulates the NA transport and thereby impacts virus replication.

doi:10.1099/vir.0.041228-0
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Role of Itk signaling in the interaction between influenza A virus and T cells

Kewei Fan1, Yinping Jia1, Song Wang1, Hua Li1, Defeng Wu2, Guoshun Wang3 and Jilong Chen1,4

Although T cell-mediated immune response to influenza virus has been extensively studied, little information is available on direct interaction between influenza virus and T cells that pertains to severe diseases in humans and animals. To address these issues, we utilized the BALB/c mouse model combined with primary T cells infected with A/WSN/33 influenza virus to investigate whether influenza virus has an affinity for T cell in vivo. We observed that small portions of CD4+ T cells and CD8+ T cells in spleen and thymus expressed viral proteins in infected mice. A significant proportion of mouse primary T cells displayed expression of alpha-2,6 sialic acid-linked influenza virus receptor and was directly infected by influenza A virus. These experiments reveal that there exists a population of T cells that is susceptible to influenza A virus infection. Furthermore, we employed human Jurkat T cell to investigate the virus/T cell interaction with particular emphasis on understanding of whether Interleukin-2-inducible T cell kinase (Itk), a Tec family tyrosine kinase that regulates T cell activation, is involved in viral infection of T cell. Interestingly, influenza virus infection resulted in an increased expression of Itk recruited to the plasma membrane and an increased level of PLC-γ1 phosphorylation, suggesting that Itk/PLC-γ1 signaling is activated by the viral infection. We demonstrated that depletion of Itk inhibited the replication of influenza A virus, whereas overexpression of Itk increased viral replication. These results indicate that Itk is required for efficient replication of influenza virus in infected T cells.