Hopes of developing a vaccine against Zika have taken a small step forward as Inovio Pharmaceuticals Inc said its experimental shot had induced a robust and durable response in mice.
Shares in the US biotech firm, which expects to test its product in humans before the end of the year, jumped seven percent in premarket trading on the prospect of it developing a vaccine against the mosquito-borne disease.
At least 15 companies and academic groups are currently racing to develop Zika vaccines, according to the World Health Organization (WHO), spurred on by growing public concern over the virus sweeping across the Americas.
Zika, whose symptoms include mild fever and rash, has been linked to brain damage in thousands of babies in Brazil, although the connection is not yet proven.
There is no proven treatment or vaccine for the disease, a close cousin of the viruses that cause dengue, chikungunya and West Nile fever.
Inovio said in a statement that mice given its vaccine showed the development of antibodies and generated a response from T-cells, which play an important role in immunising the body.
"We will next test the vaccine in non-human primates and initiate clinical product manufacturing. We plan to initiate Phase I human testing of our Zika vaccine before the end of 2016," Inovio Chief Executive Joseph Kim said.
Phase I is the first stage in a three-step process of testing new medicines and involves giving an experimental product to healthy volunteers.
Other organisations with relatively advanced Zika vaccine projects include India's Bharat Biotech, which said earlier this month that its experimental vaccine would start pre-clinical trials in animals imminently.
The US National Institutes for Health is also working on another DNA vaccine, while France's Sanofi, which makes the world's first vaccine for dengue, said on February 2 it was launching a Zika project.
Despite the accelerated work program, however, the WHO estimates it will still be at least 18 months before any Zika vaccines are ready to be tested in large-scale clinical trials.