Two experimental Zika vaccines have been 100% successful in testing on mice, US researchers have said. The tests could provide a promising sign that similar vaccines under development for humans will protect against the mosquito-borne virus.
The study, published in the journal Nature, was led by Dr Dan Barouch, of Beth Israel Deaconess Medical Center and Harvard Medical School.
His team tested two different vaccine candidates in a strain of mice that develops Zika symptoms.
Mice given either type of vaccine were 100% protected from Zika after a single shot, the study said.
Unvaccinated mice that were exposed to the virus all developed symptoms.
Professor Adrian Hill, director of Oxford University’s Jenner Institute, which is also developing Zika vaccines, called the US study an “encouraging first step”.
“This new mouse model should be useful for comparative assessments of the large range of vaccine candidates now being designed.”
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Separately, US scientists said they have developed a model of the Zika virus in monkeys.
Researchers at the University of Wisconsin said on Tuesday that tests on infected rhesus macaques suggest the monkeys developed antibodies that protected them against a second case of Zika.
Scientists said the findings were a promising sign that humans may similarly be able to develop protective antibodies against the virus.
However, Mr Hill stressed there are still years of testing needed before a finished vaccine will be available for humans.
The mosquito-borne Zika virus has swept through the Americas and Caribbean since last fall.
It has been linked to thousands of cases of microcephaly, a birth defect marked by unusually small head size, as well as to neurological disorders.
The World Health Organisation (WHO) declared Zika a global health emergency in February.
At least 15 companies and academic groups are racing to develop Zika vaccines, according to the WHO.