Novel assay could discriminate Zika infection from related flaviviruses

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A new test to detect Zika infection has been labelled the ‘best-to-date’ in differentiating Zika from related viruses. The antibody-based assay, which has been developed by researchers at the University of California Berkley (CA, USA) and biotech company Humabs BioMed (Bellinzona, Switzerland), could help with identification of Zika patients in simple and cost-effective way.

A high level of cross-reactivity between Zika and related flaviviruses has complicated serological detection of the virus, causing current assays to have limited abilities in differentiating between them. In addition, many assays can only detect Zika virus for a short time after infection. These obstacles in diagnosis have caused difficulties in determining the true prevalence of Zika, and there is a need for a specific serological assay to discriminate Zika infections.

Utilizing its proprietary CellClone discovery technology, Humabs had previously generated a human monoclonal antibody against Zika nonstructural protein 1 (NS1). In this study, the NS1-antibody was then used to develop the new diagnostic test, which is a blockade-of-binding ELISA assay.  The team suggested the new antibody and protocol give this test a superior specificity and sensitivity.

The assay was implemented in laboratories across five countries and tested on clinical samples from both travelers and patients from endemic areas. The researchers demonstrated that the assay appeared to have a high sensitivity, at 91.8% and a high specificity, at 95.9%, in detecting Zika.

Study author, Eva Harris (University of California Berkely), commented: “The whole world has been in urgent need of a serological method to distinguish dengue virus from Zika virus infections, and this the first to have such high sensitivity and specificity in dengue-endemic regions.”

The assay is currently in the licensing process, and the team hope it will be available for use soon. Additional studies are also being undertaken in order to further simplify the protocol.

Davide Corti, Chief Scientific Officer of Humabs BioMed, concluded: “These results support that the antibody-based assay that we have developed is highly effective in detecting both recent and past Zika virus infections and in discriminating Zika from other flavivirus infections. This novel assay has the potential to become an effective, simple and low-cost solution for Zika surveillance programs, prevalence studies and clinical intervention trials in flavivirus-endemic areas.”

Sources: Balmaseda A, Stettler K, Medialdea-Carrera R et al. Antibody-based assay discriminates Zika virus infection from other flaviviruses. Proc. Natl Acad. Sci. doi:10.1073/pnas.1704984114 (2017) (Epub ahead of print); http://news.berkeley.edu/2017/07/18/new-test-distinguishes-zika-from-similar-viral-infections/

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