DNA疫苗（DNA vaccine)（名词解释)

听力原文： Chinese scientists administered an experimental AIDS vaccine on Saturday, to some volunteers. The vaccinations launched the second phase of clinical testing for AIDS DNA vaccine.

The AIDS vaccine consists of two gene vaccines, one containing DNA of the AIDS virus and the other carting poxvirus.

The AIDS DNA vaccine is aimed at helping the body's antibodies and cells to form. immunity to HIV, the AIDS virus, and the poxvirus vaccine is aimed at strengthening the immunity, the developers said.

The safety of the two gene vaccines was tested in the first phase of trials. The second phase is to examine their combined safety, which means vaccinating volunteers twice with each vaccine.

The poxvirus vaccine is aimed to ______

A．form. immunity to HIV and AIDS virus

B．help the body's antibodies

C．help the body' s cells

D．strengthen the body' s immunity

Volunteers are being recruited(征募) to eat raw potatoes in the first human trials of a vaccine grown in genetically engineered vegetables. Researchers in Texas hope that people who eat the potatoes will be protected against common gut(肠，肠子) infections. They believe this technique could prove to be a cost-effective way of growing vaccines in developing countries where such diseases are still killers.

Other researchers previously succeeded in using similar techniques to produce potential vaccines Now Hugh Mason and his colleagues at Texas A & M University(得克萨斯农业及机械大学) their plant vaccines on mice and plan to recruit 15 volunteers for a human trial.

The team first tested the technique in tobacco plants. They took a strain of Escherichia coli(大肠杆菌) bacteria that causes food poisoning, and identified the part of the poison which binds to its victims gut cells. They then used a modified plant bacterium called Agrobacterium tumefasciens to transfer the segment of DNA which manufactures the binding protein into the tobacco plant. Under normal circumstances, these bacteria transfer packets of DNA into plant cells to force the plant to manufacture the nutrients they need.But in the modified bacteria, the DNA package includes the gene to pro- duce the binding protein.

Once the foreign DNA segment was incorporated(结合，合并) into the tobacco's own DNA, the bacteria were killed off with antibiotics. Mason's team then grew these modified tobacco plants and found that they produced the E. coli binding protein.

Proof of success came when the tobacco leaves were mashed up(捣碎) and squirted into the stomachs of mice. Mason says that within days the mice started producing specific antibodies to the E. coli poison, but suffered no ill effects from digesting the binding protein. Mason then produced genetically engineered potatoes and fed these to mice, with similar results.

Mason's team have used plants to produce vaccines against a number of other infectious agents. For example, they have made a vaccine using a protein from the shell of the Norwalk virus, which causes diarrhoea(腹泻) in children.

A third vaccine has also been produced in tobacco using a surface protein from the hepatitis B virus. But Mason says that so far they have only been able to produce small amounts of it in potatoes. Although a vaccine already exists against hepatitis B, a cheaper plant version could make mass immunisation(群众性免疫) possible.

One problem with growing potatoes to produce vaccines is that cooking tends to destroy the protein component of the vaccine, so they must be eaten raw. Mason thinks that bananas may be a better option. "One banana could potentially produce a whole host of different vaccines," says Mason.

The purpose of this text is______。

A．to prove that doctors don't like vegetables

B．to amuse the reader by telling some funny things

C．to describe how vegetables can grow vaccines for their own use

D．to tell the reader about a cheaper way of growing vaccines

翻译附件 文本如下：STARTING IN HUMANS (PHASE 1) mRNA-1273: The front-runner in the U.S., which is backed by the NIAID and developed by Moderna Therapeutics, is based upon a specific type of genetic material, mRNA. This vaccine, mRNA-1273, codes for a specific protein on the novel coronavirus -- the “spike protein” – the key into a human cell. An mRNA-based virus has never been approved for use in humans, but animal studies have been promising. This particular vaccine, however, was rushed to human trials before it was even tested in animals -- skipping a step in traditional vaccine development. A Phase I trial testing the vaccine’s safety in 45 healthy adult volunteers began earlier this month at Kaiser Permanente Washington Health Research Institute in Seattle. The participants will receive two injections of low, medium or high doses of the vaccine and be monitored for any adverse events or immune response. The company is hopeful that it may have a vaccine as early as fall 2020 for some particularly vulnerable groups, such as health care workers. The Phase I safety study should be completed by June 2021. Ad5-nCoV: The front-runner across the globe, Ad5-nCoV, was developed by the Beijing Institute of Biotech and CanSino Biologics, a Chinese biopharmaceutical company. This vaccine uses a viral vector, a virus that has been engineered to not contain its infectious properties and instead delivers genetic material to the recipient. Phase I testing of this vaccine is underway at Hubei Provincial Center for Disease Control and Prevention, where 108 healthy adult volunteers will receive one of three doses of the vaccine to assess for safety. Ad5-nCoV is perhaps the most promising because CanSino has already produced a nearly identical vaccine, Ad5-EBOV, to protect against Ebola. The Ebola vaccine has already entered Phase II testing, meaning it’s even further along. Still, the official anticipated completion date for Ad5-nCOV safety testing is December 2020, with all testing completed by 2022. ChAdOx1: The University of Oxford is one of the most recent groups to bring its vaccine candidate into human studies -- a major milestone. The vaccine is simultaneously being tested for both safety (Phase I) and efficacy (Phase II) by injecting 510 healthy participants with either vaccine or placebo. This vaccine uses an inactivated (non-infectious) virus that contains genetic material for the key protein on the novel coronavirus, similar to Ad5-nCoV in China. This viral vector, however, was derived from chimpanzees which, the researchers argue, creates an even more robust response than other viruses to which humans may have already been exposed. This vaccine is being funded by the United Kingdom government and is moving quickly. Still, its anticipated completion date of this phase isn’t until May 2021.STILL IN LABORATORY (PRECLINICAL) BNT162: Biopharmaceutical giant Pfizer, along with partner company BioNTech, is working on an mRNA-based vaccine that is similar to Moderna’s model. The duo was already working on an influenza vaccine using this scientific strategy so their vaccine candidate, “BNT162,” is moving particularly fast. Clinical trials are anticipated to begin in April in both the U.S. and Germany. INO-4800: An entirely different technology is being developed by Inovio Pharmaceuticals, a company that uses a proprietary platform for “activation immunotherapy.” This vaccine delivers DNA, another genetic material, into a host’s cells by utilizing a hand-held smart device “CELLECTRA.” The DNA is translated into proteins that activate an individual’s immune system to generate a targeted immune response. While that may sound like science fiction, the company has used the same technology to rapidly advance vaccines against MERS, a closely related coronavirus, and HPV-related cervical precancer, among others. None of these, however, have completed their trial phase and entered the market. Trials for the COVID-19 specific vaccine, INO-4800, are anticipated to begin in April. Sanofi recombinant DNA vaccine (unnamed): Last month, Sanofi Pasteur announced that it was partnering with the U.S. Department of Health and Human Services to create a DNA-based vaccine. Their vaccine, which is yet to be named, relies on recombinant (engineered) DNA that encodes for proteins found on COVID-19 surface -- the same basic principle of many of the other candidates. The company had been previously working on a vaccine for SARS, a close relative of the novel coronavirus, which showed promise in animal models. More importantly, however, Sanofi has proved immensely successful in the vaccine market: they have influenza vaccines, including Flublok and Fluzone, that are widely in use today. They claim that their technique -- and their experience with mass production of their products -- would allow a COVID-19 vaccine to be introduced much more quickly than traditional production methods. Still, human trials are yet to begin but will likely start in April.

第一篇

Volunteers are being recruited(征募) to eat raw potatoes in the first human trials of a vaccine grown in genetically engineered vegetables. Researchers in Texas hope that people who eat the potatoes will be protected against common gut(肠，肠子) infections. They believe this technique could prove to be a cost-effective way of growing vaccines in developing countries where such diseases are still killers.

Other researchers previously succeeded in using similar techniques to produce potential vaccines Now Hugh Mason and his colleagues at Texas A & M University(得克萨斯农业及机械大学) their plant vaccines on mice and plan to recruit 15 volunteers for a human trial.

The team first tested the technique in tobacco plants. They took a strain of Escherichia coli(大肠杆菌) bacteria that causes food poisoning, and identified the part of the poison which binds to its victims gut cells. They then used a modified plant bacterium called Agrobacterium tumefasciens to transfer the segment of DNA which manufactures the binding protein into the tobacco plant. Under normal circumstances, these bacteria transfer packets of DNA into plant cells to force the plant to manufacture the nutrients they need. But in the modified bacteria, the DNA package includes the gene to pro- duce the binding protein.

Once the foreign DNA segment was incorporated(结合，合并) into the tobacco's own DNA, the bacteria were killed off with antibiotics. Mason's team then grew these modified tobacco plants and found that they produced the E. coli binding protein.

Proof of success came when the tobacco leaves were mashed up(捣碎) and squirted into the stomachs of mice. Mason says that within days the mice started producing specific antibodies to the E. coli poison, but suffered no ill effects from digesting the binding protein. Mason then produced genetically engineered potatoes and fed these to mice, with similar results.

Mason's team have used plants to produce vaccines against a number of other infectious agents. For example, they have made a vaccine using a protein from the shell of the Norwalk virus, which causes diarrhoea(腹泻) in children.

A third vaccine has also been produced in tobacco using a surface protein from the hepatitis B virus. But Mason says that so far they have only been able to produce small amounts of it in potatoes. Although a vaccine already exists against hepatitis B, a cheaper plant version could make mass immunisation(群众性免疫) possible.

One problem with growing potatoes to produce vaccines is that cooking tends to destroy the protein component of the vaccine, so they must be eaten raw. Mason thinks that bananas may be a better option. "One banana could potentially produce a whole host of different vaccines," says Mason.

The purpose of this text is______。

A. to prove that doctors don't like vegetables

B. to amuse the reader by telling some funny things

C. to describe how vegetables can grow vaccines for their own use

D. to tell the reader about a cheaper way of growing vaccines