There are less than a year, Zika seemed too trivial for anyone with hard measures against developing. The virus spread by mosquitoes has been racing across the countries of the southern hemisphere, but, at worst, it seemed to cause a mild fever and a rash. No more: On 1 February the World Health Organization (WHO) said cluster "extraordinary" microcephaly and other neurological complications that have now been linked to Zika "international scope of public health emergency." and vaccinemakers large and small, began the race to head off. they have a good chance of success, many experts say, but they cautioned that vaccine development requires years of testing.
isolated in 1947, Zika caused the first serious concern in May 2015 after arriving in South America and suspicions grew that the infection during pregnancy could be the cause of microcephaly harmful brain in babies. the link, the WHO Director-General Margaret Chan in Geneva, Switzerland, the stresses, is "strongly suspected but not yet scientifically proven," as a potential link to Guillain-Barre syndrome, can cause temporary paralysis in adults. With viral propagation increasingly, a vaccine is now a priority.
Vaccine pioneer Stanley Plotkin of the University of Pennsylvania predicted "a single development path" for a vaccine. He noted that Zika belongs to the flavivirus family, and vaccines exist for many of his relatives, including dengue fever, yellow fever and Japanese encephalitis. "I see no technical issues such as those that obviously exist for vaccines against HIV, tuberculosis, and many other agents," said Plotkin, who consults several vaccinemakers.
However, "there are a lot of puzzles," said Thomas Monath, a virologist who studied Zika in wild monkeys in Nigeria in the 1970s and is now chief scientist in chief to NewLink Genetics in Devens, Massachusetts, contributed to the development of a promising Ebola vaccine. For Zika, an unknown is whether the infection leads to life protection, a key feature of diseases for which vaccines are most effective, such as yellow fever. Another question is whether the natural immunity or induced by the vaccine against other related viruses, including yellow fever could offer a measure of "cross-protection", which could confuse efforts to assess vaccine Zika . have not yet researchers developed a monkey model much needed to allow comparisons of candidate vaccines.
The approaches have proliferated. Monath, who developed vaccines against several flaviviruses, said NewLink pursue a traditional strategy that inactivates or kills the virus with a chemical so it can not replicate in the body. He thinks an inactivated vaccine has the best chance to win regulatory approval for a product that pregnant women can use.
At nonprofit Butantan Institute in Sao Paulo, Brazil, however, immunologist and director Jorge Kalil is betting that weakened, live vaccine can be safe and potentially more effective than the killed virus. His team plans to exploit a technology that researchers from the US National Institute of Allergy and Infectious Diseases (NIAID) used to make a vaccine against dengue fever, which Butantan licensed and is currently being tested in a test 'efficiency. To weaken the virus, the researchers deleted genes so it can copy but not cause illness. "Maybe we can mitigate the Zika virus using the same cuts of the same sites," Kalil said, noting that Butantan likely would partner with NIAID to develop its vaccine. The Brazilian Institute has a key advantage: Unlike almost all other non-profit in the world who does research on vaccines, it has a year of manufacture on an industrial scale plants last, the institute cranked 40 million doses of flu vaccine, so it might be able to provide enough product for Brazil without needing help from big pharma.
NIAID Director Anthony Fauci in Bethesda, Maryland, said his institute has a "head start" with a different technology, used to make an experimental vaccine for West Nile, another flavivirus. The manufacturing process begins with a "plasmid" circular DNA which contains the essential viral genes. When inserted in bacterial cells, they produce "particles" viruslike that are similar to an inactivated vaccine, because they can not replicate. (The West Nile vaccine worked well in early human studies, but NIAID could not find a commercial partner to advance it.)
Inovio Pharmaceuticals Plymouth Meeting, Pennsylvania, boasts that it already has an experimental vaccine Zika nothing containing a plasmid made Zika genes. With the help of an electric zap the skin, plasmid goes directly into human cells, which then Zika of proteins that stimulate the immune system. CEO Joseph Kim says his team has already started tests on mice. But although researchers can quickly make such simple DNA vaccines, they lost their luster over the past 20 years because it did not trigger strong immune responses against other diseases. "There are very good people in the field who have lost faith in this technology," admits Kim. "I want to prove that this technology is viable and perhaps the best option for these types of homes."
The small Jenner Institute in Oxford, UK, is to Zika the surface protein of adenovirus innocuous chimpanzee, which serve as a "vector" -an approach similar to that used in the Ebola vaccine GlaxoSmithKline, which was tested during the outbreak in West Africa. Protein Sciences Vaccinemakers Meriden, Connecticut and Hawaii Biotech Honolulu, both of which specialize in the production of viral proteins in insect cell lines also have ongoing projects.
predict when a vaccine will be marketed is the game of a cup, but Fauci NIAID think animal studies could be completed in a few months and small human studies to evaluate the safety and immune responses could start the end of 2016. While promising candidate surfaces, large-scale efficacy trials are probably years away, he said. Getting a vaccine approved and provide millions of doses could take a large manufacturer resources. Among the four major pharmaceutical companies that make vaccines, only Sanofi Pasteur of Lyon, France, which produces all three existing vaccines-a flavivirus Zika launched a program, although others say they are closely monitoring the field.
As an emergency measure for pregnant women, Kalil said Butantan hopes to produce a protective serum that the institute already for several diseases, injecting Zika virus in horses and harvesting antibodies animals do. "It will take a little over a year," says Kalil. "This is the best course of time, if you are very, very optimistic."
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