ELISA kit Offers Enhanced Diagnosis of Zika Virus Infection

An ELISA kit that measures anti-Zika virus antibodies of both the IgM and IgA classes was shown to accurately diagnose the acute phase of the infection even in patients with prior flavivirus exposure.

Specific anti-Zika virus IgM response may be absent in individuals who have had previous contact with a flavivirus through infection or vaccination against dengue, yellow fever, tick-borne encephalitis, Japanese encephalitis, or West Nile viruses. In such cases, determination of specific IgA can facilitate diagnosis of acute Zika virus infection.

To this end, EUROIMMUN AG (Luebeck, Germany) developed the Anti-Zika Virus IgAM ELISA kit. The rationale behind the assay was based on findings that while some patients with an acute Zika virus infection did not exhibit both specific IgM and IgA antibodies, all tested samples were reactive for at least one of the two parameters. Therefore, combined testing for both IgM and IgA would be beneficial for reliable diagnostics of acute Zika virus infections.

Serum samples from 31 patients with confirmed acute Zika virus infections from the Dominican Republic (where Zika and dengue viruses are endemic) and 40 patients from Vietnam with acute dengue virus infection were tested with the Anti-Zika Virus IgAM ELISA kit. Results revealed a sensitivity of 100% (31/31) and a specificity of 95% (38/40). In comparison, the single parameter Anti-Zika Virus IgM kit demonstrated a sensitivity of 29% (9/31) and a specificity of 100% (40/40). Thus, combined detection of both antibody classes rather than only IgM led to a threefold increase in the sensitivity for acute Zika virus infections without a significant loss of specificity.