Desenvolvimento de imunoensaio eletroquímico para detecção de anticorpos anti-Zika vírus visando o diagnóstico da doença

Abstract

Zika Virus (ZIKV) is a flavivirus transmitted by Aedes species. The disease may be asymptomatic or present clinical such as: conjunctivitis, fever, headache, and in severe cases development of fetal microcephaly and Guillain-Barré syndrome. The rapid spread of the virus and the difficulties of diagnosis require development of alternative methods for diagnosis with high specificity and sensibility. In this scenario, we proposed an electrochemical method for detection of Ab1ZIKV antibodies using magnetic beads modified with a recombinant non-structural protein (ΔNS1ZIKV) and anti-IgG antibodies labeled with horseradish peroxidase enzyme (HRP). The analytical method proposed involved the fabrication of microfluidic device and an immunoassay based in a sandwich type strategy. The device was built using low-cost materials, and the system’s layout comprised of an arrangement of 8-working electrodes, a pseudo-reference electrode, and a counter electrode. The electrochemical detection was performed based in the HRP electrocatalytic cycle by injecting a solution containing hydroquinone (redox mediator) and H2O2 as substrate. Cathodic peak current of HQ reduction was obtained as analytical signal and its intensity was proportional to the logarithm concentration of Ab1ZIKV. The immunoassay showed a linear response in the range of 0.01 to 9.8X10^5 pg mL-1 presented an equation of "Ip(µA) = 0.04 + 0.01 CAb1ZIKV" obtained by linear regression with a correlation coefficient of 0.981. The limit of detection and quantification obtained were of 0.48 pg mL-1 and 1.45 pg mL-1, respectively. The proposed immunoassay proved to be efficient for the detection of anti-ZIKV antibodies, presenting a low limit of detection, ensuring be a promise tool for diagnosis of the disease.