a researcher who pricked with a needle containing the Ebola Zaire virus last month is expected to return to work at the Institute Bernard Nocht in Hamburg, Germany, after Easter. Scientists are now planning an extensive series of tests to determine her reaction to an experimental vaccine precipitated in Canada after the accident. But they can never know for sure if the shots have saved his life.
The researcher, whose name was not made public, was released from the hospital Thursday, said Stephan Günther, head of the virology department of the Institute. The Hamburg health authorities allowed him to leave exactly 3 weeks after the start of the event, which is the maximum incubation period for Ebola known, pictured above courtesy of the NIH.
Within 48 hours after the accident, the researcher was inoculated with an experimental vaccine against the Ebola Zaire virus, developed at Canada's National Microbiology Laboratory in Winnipeg, but never tested in humans before . The vaccine is based on a pathogen of cattle virus called vesicular stomatitis, which has been modified to express a glycoprotein also present on the envelope of the Ebola virus.
The patient, physician, and other scientists called to consult on the matter had chosen this candidate vaccine over several others because a similar vaccine against Marburg based on stomatitis, a close cousin of the Ebola virus, offered the same protection when administered after exposure to the virus. They reasoned that the same would be true for the vaccine against the Ebola virus.
But if the vaccine actually prevented infection is hard to say, said Günther. One problem is that, unlike for example in monkey studies, in which a fixed amount of virus is injected it is unclear whether the viral particles are actually entered the body of the researcher; they may not have left the needle in the accident, for example. In this case, there was nothing to protect against.
The antibody tests might normally be that the researcher was exposed to the virus, but standard tests look for antibodies against the Ebola glycoprotein, which is the same in the virus and the vaccine. This means that even if these antibodies are found, scientists can not be sure if they were triggered by the virus itself or by the vaccine, said virologist at Boston University Thomas Geisbert, who tested the vaccine in monkeys the US Army Medical Research Institute of infectious diseases in Fort Detrick, Maryland.
the only way for researchers to conclude with certainty that the virus has entered the body of the researcher is to find an immune response that may have been triggered by the virus itself, for example, against nuclear proteins Ebola or a so-called matrix protein known as VP40. The detection of these antibodies is difficult; Günther says he will contact other laboratories in Ebola to see if they can help provide analysis.
If we find these telltale signal of the exhibition, however, they would strongly that the vaccine has saved the lives of women, because injection appears to be a particularly deadly route of entry for the virus, said Geisbert. In past experience, as in the 1976 Ebola outbreak in Zaire, very few patients known to have been infected by needle survived accidents, he said.
Whatever road researchers take, they will need to ensure judicious use of blood taken after the accident, said Geisbert. "You do not want to burn through these precious samples with tests that are not well validated," he said. "The urgency is gone, we are left with academic issues now," says Günther. "This will take some time."
The scientist is still on leave, stress and anxiety recovery brush with one of the most deadly viruses, Günther said. She declined numerous interview requests, he said.
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