Researchers have identified neutralizing antibodies against Zika virus from an infected patient that fully protected mice from infection, adding to the current arsenal of antibodies in development for much needed antiviral therapies and vaccines.

Unlike other human antibodies under investigation that recognize both Zika and the closely related dengue virus, the antibodies used in this study exclusively target Zika, demonstrating a high specificity that could be important in avoiding potential side effects -- such as enhanced dengue infection in regions where both viruses are endemic.

The 2015 outbreak of Zika virus disease, a mosquito-borne infection linked to a birth defect known as microcephaly in babies, has spread to more than 80,000 people in 69 countries and regions worldwide. Zika is fortunately no longer considered an international public health emergency, according to the World Health Organization, but an urgent need for preventative and treatment approaches, none of which has been clinically approved, remains.

Here, Qihui Wang and colleagues isolated 13 monoclonal antibodies from the blood of a Zika virus-infected patient returning from Venezuela to China.

Two of these antibodies (known as Z23 and Z3L1) potently eliminated Zika virus in vitro, without cross-reacting with dengue virus strains, and shielded mice completely from Zika virus infection.

Structural analysis suggests that the antibodies block infection by targeting sites on the virus' envelope protein, which aids viral entry into cells. Further analysis is necessary to better understand how Z23 and Z3L1 specifically offer protection, the authors say.