After a successful trial in rhesus monkeys, a team of researchers, including doctors from Beth Israel Deaconess Medical Center, is ready to start testing a Zika virus vaccine in humans, they announced Thursday.
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In addition, passive protection was also tested by using antibodies from vaccinated monkeys to protect Zika-naïve mice and monkeys.
Fauci said that DNA plasmid vaccines have multiple advantages, including being “very convenient and easily scaleable”.
In another experiment, the researchers administered two doses of an experimental DNA vaccine, one dose of an experimental adenovirus vector vaccine, or a placebo injection to three groups of four monkeys each. A month after the booster, the monkeys got a dose of Zika virus.
The vaccine study using purified killed virus vaccine was conducted on 16 rhesus monkeys.
“They’ve been proven to be safe and effective and have been licensed by major regulatory agencies”, said senior co-author Colonel Stephen Thomas, a vaccinologist who specializes in such viruses.
The second and third used harmless strands of DNA taken from the Zika virus – one in an enclosure of harmless DNA (called a plasmid) and the other in a type of virus called an adenovirus. But they may not be as practical for Zika, said study author Colonel Nelson Michael, who co-leads the Walter Reed Institute’s Zika program.
The NIAID plans to initiate a phase II trial in early 2017 if those data are promising – and if it has the money.
Compared with the DNA vaccine, far less of the inactivated-virus vaccine was needed for it to be effective, he said. Findings from the new preclinical study confirm and extend these prior studies by demonstrating robust protection in nonhuman primates. In contrast, eight other monkeys that had gotten a sham vaccine became infected. “In order to make it a reasonable concentration to put into a human’s arm, it’s nearly like syrup”, Michael said.
“Results from both mouse and nonhuman primate testing are encouraging and support a decision to move forward with our US government, industry and regulatory partners to advance our ZPIV vaccine candidate to human trials”, said Col. Stephen Thomas, an infectious disease Army physician and a vaccinologist specializing in flaviviruses such as Zika and dengue.
Human trials are set to begin, according to Barouch. “But remember, they fast-tracked the Ebola vaccine, too, and here we are two years later and we’re still waiting and wanting”, he said.
“Under ordinary circumstances it can take 10-years or more before a vaccine starts clinical testing and makes it to market”, Neuzil said.
Just 2,000 doses or so are needed for testing, but 100 million are needed to address a crisis such as Zika in a country like Brazil, he said. The partnership with Sanofi-which has produced vaccines for dengue, yellow fever, and Japanese encephalitis-will be key to scaling up production.
“This is a really, really good marriage”, he said.
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On the cusp of the Olympic Games’ opening ceremony in Rio de Janeiro, the Zika virus – which started tearing through Brazil late previous year, causing the rare but devastating disorder of microcephaly in babies – has been transmitted in more than 50 countries and territories, according to the Centers for Disease Control and Prevention.
