生物谷報(bào)道：現(xiàn)在也許你也像千百萬(wàn)人一樣被流感困擾,，咳嗽,，打噴嚏,。病毒通過(guò)感染細(xì)胞引起普通感冒或埃博拉出血熱等疾病,。一個(gè)科學(xué)新聞中心的錄像報(bào)告展示了病毒感染細(xì)胞的詳細(xì)過(guò)程,。
一張圖片強(qiáng)過(guò)千言萬(wàn)語(yǔ)
科學(xué)家制作了一張令人驚奇的病毒卡通圖片，讓人覺(jué)得像出自科幻電影,。圖片展示了比針尖還小一萬(wàn)倍的病毒感染細(xì)胞的一瞬間,，同時(shí)展示了它的結(jié)構(gòu),。圖片由一名生物學(xué)家及其同事完成,。圖片是對(duì)高倍顯微下的真實(shí)病毒和對(duì)病毒感染細(xì)胞的最新的理解,。
科學(xué)家通過(guò)聯(lián)合使用晶體和低溫電子顯微成像技術(shù)，得到了成千張T4病毒感染大腸桿菌的圖片。晶體成像技術(shù)可進(jìn)行原子水平的顯像,，而低溫電子顯微技術(shù)再使病毒水平成像,，二者聯(lián)合可以同時(shí)得到微觀和相對(duì)整體的圖像。了解T4感染大腸桿的機(jī)制,，有利于了解機(jī)制相似的其他病毒感染細(xì)胞的過(guò)程和機(jī)制,。
科學(xué)家發(fā)現(xiàn)，感染發(fā)生時(shí)T4與細(xì)胞表面接觸的基板形狀改變,。其蜂窩狀六角形基板打開(kāi)變成星狀,，以刺破大腸桿表面,，釋放DNA進(jìn)入細(xì)胞?？赡苁堑鞍组g的滑動(dòng)造成了這種變形,。
回歸基礎(chǔ)
有趣的是，研究小組發(fā)現(xiàn)了解自然的過(guò)程就是回歸基礎(chǔ)科學(xué)問(wèn)題的過(guò)程,。從理論上了解世界上最小生物體是如何完成復(fù)雜任務(wù)的,，為科學(xué)家在許多研究領(lǐng)域打開(kāi)了視野,。
研究T4病毒是如何感染細(xì)胞有利于人們對(duì)疾病的研究,。T4病毒可以作為健康DNA載體系統(tǒng)轉(zhuǎn)染疾病細(xì)胞,，達(dá)到基因治療的作用,。針對(duì)帕金森病和老年癡呆病的基因治療研究正在進(jìn)行。但真正應(yīng)用T4病毒作為載體的基因治療方法還離我們有一段距離,。
關(guān)于T4病毒的研究還在繼續(xù)進(jìn)展中，科學(xué)家希望更多的了解構(gòu)成T4病毒基板的蛋白。通過(guò)T4人們對(duì)病毒的認(rèn)識(shí)已經(jīng)提高了很多,，包括對(duì)西尼羅河，登革熱和流感等病毒的認(rèn)識(shí)（http://www.bioon.com/）,。
How Viruses Infect
You may be coughing or sneezing out millions of them right now. Viruses, whether the common cold or Ebola, do their harm by infecting cells. As this ScienCentral News video reports, scientists have now shot detailed images revealing how one virus does it.
A Picture is Worth a Thousand Words
Looking like something out of a science fiction movie, a remarkable animation created by researchers at Purdue University, in collaboration with the Institute of Bioorganic Chemistry in Moscow and The Tokyo Institute of Technology, illustrates a virus ten thousand times smaller than the head of a pin infecting a living cell.
Structural biologist Michael Rossmann, Purdue's Hanley Distinguished Professor of Biological Sciences, and his colleagues, created the animation based on actual, never before seen, high-resolution images they captured of the virus. The new understanding they have gained about how viruses infect other cells could help science fight viral diseases and deadly bacterial infections, or potentially one day be harnessed for medical benefit.
Combining two different imaging techniques, crystallography and cryoelectron microscopy, Rossmann and his team took thousands of pictures of a virus called T4 as it infected E. coli bacteria, a variety of which is commonly associated with food poisoning. "The crystallography technique is able to obtain the structure of individual proteins at an atomic resolution where we can see individual atoms and see their relationship to each other," Rossmann explains. "The electron microscopy enables us to look at larger units such as the whole virus."
The high-resolution images came from their effort to understand, in new detail, the intricate workings of how these cell-killing machines wreak their havoc. "Many viruses—even most viruses—will use the same kind of mechanism by which they infect cells," Rossmann explains. "By looking at T4, looking at these details, we are therefore able to tell quite a bit about how many viruses infect cells."
This is an artist's rendition of a T4 virus infecting a bacteria cell.
They found that the 'docking bay' or baseplate of T4, which latches onto the surface of other cells, changes shape. The proteins that form the normally hexagonal, honeycomb-shaped baseplate rearrange themselves, causing it to open in to a star shape. This enables the virus to infect the E. coli by piercing its outer surface and injecting its DNA into the cell. "The proteins kind of slither and slide across each other in undergoing very large structural changes," Rossmann says.
Back to Basics
Interested, basically, in understanding how nature works, the group's research is a step forward in fundamental scientific knowledge. Viruses are among the tiniest of biological entities, yet nature has designed them to perform very complicated tasks—understanding their behavior will open doors for scientists in many disciplines. Rossmann likens their work to looking under the hood of a car in order to understand what makes it run. "That's really what we're doing, we're opening the hood and seeing inside how these biological systems work and understand what they do," he says.
Understanding how T4 infects cells will help science and medicine to fight diseases around the world. The virus could also be used as a nano-sized DNA injection machine, delivering healthy DNA into cells whose genetic material has been damaged by injury or disease. This so-called gene therapy is being developed more and more to prevent and treat genetically-based diseases, such as Parkinson's disease and Alzheimer's disease, where parts of the DNA in the cells of the patient are not functioning properly. "In knowing how T4 injects its genomic material into a cell, we might be able to adapt T4 to target human cells," Rossmann explains. "So you've now got a virus which can target a specific cell and introduce a specific gene into the cell which it requires." Gene therapy using T4 remains a distant possibility.
Through his ongoing work with T4, Rossmann hopes to learn more about the proteins that make up the T4 baseplate, as well was studying the infection process in other viruses. Along with T4, Rossmann and his international team of researchers have increased scientists' understanding of many other viruses, including those that cause Dengue fever, West Nile and the common cold.
Rossmann's research appeared in the August 20, 2004 issue of Cell, and was funded by the National Science Foundation, the International Human Frontier Science Program and the Howard Hughes Medical Institute.
