Development of Zika NS1 ELISA methodology for seroprevalence detection in a cohort of Mexican patients in an endemic region

Background: Zika (ZIKV) is a mosquito-borne virus that has caused multiple outbreaks in Americas. The early and accurate diagnosis of ZIKV is the key to minimize the health burden imposed on the infected patients. Many commercial ZIKV diagnosis kit are available based on ZIKV envelope antigen with varying sensitivity and specificity. Objective: The aim of this study was to develop sensitive ELISA methodology based on recombinant ZIKV NS1 and NS1 β-ladder antigens for seroprevalence detection in a cohort of patients in an arbovirus endemic Mexican region in comparison to a commercial kit. Study design: We obtained serum samples from 60 patients presenting with febrile illness and from 10 healthy donors in Michoacán state in 2016–2017. These samples were screened for ZIKV by RT-PCR and used to develop NS1 based ELISA and compared to a commercial kit. Results: Our results indicate that both ZIKV sNS1 and β-ladder-based ELISA can reliably detect anti-ZIKV NS1 antibodies in infected patients, relevant for the serodiagnosis of ZIKV. Determination of antibody titers showed that it offered higher sensitivity than a commercially available ZIKV ELISA. Over 90% seropositivity against ZIKV for the febrile patients was detected in Lázaro Cárdenas which is an arbovirus endemic region while lower seropositivity was observed in the healthy volunteers in Morelia (non-endemic area). Conclusion: We conclude that our simple and sensitive in-house NS1 based ELISA used in this study has excellent sensitivity, is easy to use and can provide fast results suitable for larger population-based seroprevalence studies in the future.