How Cold Viruses Are Being Used in COVID-19 Vaccine Candidates
2020-09-05
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1Modified common cold viruses are being used to create COVID-19 vaccine candidates in China and Russia.
2Such viruses have been studied for over 30 years, but are still not widely used.
3They are now driving the vaccine research from Russia's Gamaleya Institute and China's CanSino Biologics.
4The COVID-19 vaccine candidates are called adenovirus vector vaccines.
5They use modified adenovirus type 5, or Ad5, viruses.
6Unlike most viruses, modified viruses will not cause infection because they cannot reproduce on their own.
7Ad5 viruses can be used as vectors to carry genes from the virus that causes COVID-19 into the body.
8The human cells will then create proteins to activate the body's natural defenses to guard against the virus.
9In the 1970s, Frank Graham of Canada was the first researcher to work with Ad5 viruses.
10At the time, he was working at a laboratory in The Netherlands.
11Graham planned to use the viruses to study natural processes responsible for cancer.
12He also wanted to provide the human kidney cell line that makes them, called HEK293, to researchers all over the world.
13"The cells became tremendously widespread and popular" among researchers, said Graham, who is now retired and lives in Italy.
14In early gene therapy, Ad5 vectors were tested to replace a missing or damaged gene.
15Researchers stopped using them after an 18-year-old died in 1999 when the patient's natural defense system overreacted.
16The patient had received a large dose of Ad5 vectors during a gene therapy test.
17However, they believe much smaller doses would have been a good choice to use in developing a vaccine.
18At McMaster University in Canada, Graham and other researchers developed several Ad5 vectors, including one for a rabies vaccine used on wild raccoons.
19They began developing an Ad5-based vaccine against Severe Acute Respiratory Syndrome (SARS) in 2003 and published early test results.
20The project was set aside when the SARS outbreak ended.
21In 2011, CanSino Biologics developed an experimental tuberculosis vaccine based on Ad5 from the McMaster researchers.
22The Chinese company then turned its attention to an Ad5-based Ebola vaccine at the request of the Chinese military.
23The Ebola vaccine was approved for military use in 2017.
24In June of this year, the Chinese military approved emergency use of CanSino's COVID-19 vaccine without Phase 3 testing.
25Under Phase 3 trials, an experimental vaccine is tested on tens of thousands of volunteers to measure its effectiveness.
26The Gamaleya Research Institute, which developed Russia's coronavirus vaccine, also used Ad5 vectors to develop an Ebola vaccine.
27The institute said that vaccine has been given to about 2,100 people.
28For COVID-19, Russian researchers are combining Ad5 with another modified adenovirus called Ad26.
29On August 11, Russian President Vladimir Putin announced that his country was the first to approve a vaccine for COVID-19.
30The approval came less than two months after the start of human testing of the vaccine.
31And the treatment has yet to complete Phase 3 trials.
32Scientists around the world have questioned whether its quick approval without extensive testing will lead to a safe vaccine.
33I'm Jonathan Evans.
1Modified common cold viruses are being used to create COVID-19 vaccine candidates in China and Russia. Such viruses have been studied for over 30 years, but are still not widely used. They are now driving the vaccine research from Russia's Gamaleya Institute and China's CanSino Biologics. 2Adenovirus type 5 (Ad5) 3The COVID-19 vaccine candidates are called adenovirus vector vaccines. They use modified adenovirus type 5, or Ad5, viruses. Unlike most viruses, modified viruses will not cause infection because they cannot reproduce on their own. 4Ad5 viruses can be used as vectors to carry genes from the virus that causes COVID-19 into the body. The human cells will then create proteins to activate the body's natural defenses to guard against the virus. 5Has Ad5 been successful in the past? 6In the 1970s, Frank Graham of Canada was the first researcher to work with Ad5 viruses. At the time, he was working at a laboratory in The Netherlands. 7Graham planned to use the viruses to study natural processes responsible for cancer. He also wanted to provide the human kidney cell line that makes them, called HEK293, to researchers all over the world. 8"The cells became tremendously widespread and popular" among researchers, said Graham, who is now retired and lives in Italy. 9In early gene therapy, Ad5 vectors were tested to replace a missing or damaged gene. Researchers stopped using them after an 18-year-old died in 1999 when the patient's natural defense system overreacted. The patient had received a large dose of Ad5 vectors during a gene therapy test. However, they believe much smaller doses would have been a good choice to use in developing a vaccine. 10At McMaster University in Canada, Graham and other researchers developed several Ad5 vectors, including one for a rabies vaccine used on wild raccoons. They began developing an Ad5-based vaccine against Severe Acute Respiratory Syndrome (SARS) in 2003 and published early test results. The project was set aside when the SARS outbreak ended. 11COVID-19 vaccine with Ad5 in China, Russia 12In 2011, CanSino Biologics developed an experimental tuberculosis vaccine based on Ad5 from the McMaster researchers. The Chinese company then turned its attention to an Ad5-based Ebola vaccine at the request of the Chinese military. The Ebola vaccine was approved for military use in 2017. 13In June of this year, the Chinese military approved emergency use of CanSino's COVID-19 vaccine without Phase 3 testing. Under Phase 3 trials, an experimental vaccine is tested on tens of thousands of volunteers to measure its effectiveness. 14The Gamaleya Research Institute, which developed Russia's coronavirus vaccine, also used Ad5 vectors to develop an Ebola vaccine. The institute said that vaccine has been given to about 2,100 people. 15For COVID-19, Russian researchers are combining Ad5 with another modified adenovirus called Ad26. 16On August 11, Russian President Vladimir Putin announced that his country was the first to approve a vaccine for COVID-19. The approval came less than two months after the start of human testing of the vaccine. And the treatment has yet to complete Phase 3 trials. 17Scientists around the world have questioned whether its quick approval without extensive testing will lead to a safe vaccine. 18I'm Jonathan Evans. 19Hai Do wrote this story for Learning English with additional reporting from Reuters. George Grow was the editor. 20________________________________________________________________ 21Words in This Story 22modify - v. to change some parts of something while not changing other parts 23vector - n. a virus that carries germs that cause disease 24therapy - n. the treatment 25dose - n. the amount of medicine or drug taken at one time 26outbreak - n. a sudden start or increase of disease