[ti:Search for COVID-19 Vaccine Includes Animal Tests] [by:pzw8555.cn] [00:00.00]更多听力请访问pzw8555.cn [00:00.04]Scientists say they are carrying out tests on monkeys, [00:05.56]ferrets and other animals in the search for a vaccine for COVID-19. [00:14.84]The testing can help researchers learn about how the vaccine [00:20.56]affects the immune system, the body's natural defense against disease. [00:28.72]If a vaccine causes the immune system to react in the wrong way, [00:34.84]it could worsen existing disease. [00:39.84]Researchers have already been seeking tens of thousands of human subjects [00:46.56]to take part in large COVID-19 vaccine studies. [00:53.40]Efforts to find a vaccine to prevent COVID-19 have quickly increased [01:00.36]as the disease continues spreading in a worldwide pandemic. [01:07.52]Scientists have also turned to animals to help answer important questions [01:14.44]about the development of a vaccine. [01:19.20]Ralph Baric is a coronavirus expert [01:23.16]at the University of North Carolina, Chapel Hill. [01:28.72]His laboratory is testing several possible vaccines in animals. [01:36.32]Animal testing lets scientists see how the body reacts to vaccines [01:42.40]in ways studies involving people never can, [01:47.08]said Kate Broderick, chief of research at U.S.-based Inovio Pharmaceuticals. [01:55.80]With animals, "we're able to perform autopsies [01:59.92]and look specifically at their lung tissue and get a really deep dive [02:06.48]in looking at how their lungs have reacted," Broderick told The Associated Press. [02:14.12]Broderick has been awaiting results from mice, ferrets and monkeys [02:20.68]that were given the virus after receiving Inovio's vaccine. [02:26.96]Three species were chosen to expand research results. [02:33.56]Some progress has been reported involving vaccine safety. [02:40.24]The first animal data from several research teams [02:44.48]has found no signs of a worrisome side effect called disease enhancement. [02:53.04]Disease enhancement happens when a vaccine causes a body [02:58.88]to produce antibodies that cannot fully block infection. [03:04.16]The weak antibodies instead help strengthen the disease. [03:11.40]The first case of this happened in the 1960s, [03:16.12]with a failed vaccine for respiratory syncytial virus, or RSV. [03:24.28]More recently, it has led to difficulties in vaccine development efforts for dengue. [03:32.48]And some attempted vaccines for SARS, which is similar to COVID-19, [03:39.76]caused disease enhancement in animal testing. [03:44.84]Such problems were not reported in three recently reported vaccine studies [03:52.12]involving monkeys tested using different methods. [03:57.88]The studies used shots developed by Britain's Oxford University [04:03.48]and the Chinese drug company Sinovac. [04:08.64]The three studies were small, [04:11.20]but none of the monkeys showed evidence of immune-enhanced disease [04:16.88]when the scientists put the virus directly into their bodies. [04:23.08]Some of the best evidence yet that a vaccine might work [04:27.84]comes from the monkey studies, in which Oxford and Sinovac [04:33.64]created very different kinds of COVID-19 vaccines. [04:39.48]In separate studies, each team reported vaccinated monkeys [04:44.84]were protected from the dangerous lung condition pneumonia. [04:50.04]The researchers said the untreated monkeys in the studies got sick. [04:57.56]But protection against severe disease is just a first step. [05:03.52]Could a vaccine also stop the spread of the virus? [05:09.08]The Oxford study raises some questions about that issue. [05:14.52]The researchers found just as much virus remained [05:19.16]in the vaccinated monkeys' noses as in the unvaccinated. [05:26.44]The kind of vaccine may make a difference. [05:30.12]Researchers at Beth Israel Deaconess Medical Center in Boston [05:36.64]designed six versions of a COVID-19 vaccine. [05:42.92]Some only partly protected monkeys [05:46.64]- but one fully protected eight monkeys from any sign of the virus. [05:52.84]Those results were reported by Dr. Dan Barouch, [05:57.88]who is working with America's Johnson & Johnson company [06:02.32]on developing a COVID-19 vaccine. [06:07.88]I'm Bryan Lynn. 更多听力请访问pzw8555.cn