A highly specific and sensitive nanoimmunosensor for the diagnosis of neuromyelitis optica spectrum disorders

Publication year: 2019
Authors: Ariana de Souza Moraes 1,2,3, Doralina Guimarães Brum3,4, Jéssica Cristiane Magalhães Ierich 1,2,3, Akemi Martins Higa1,2,3, Amanda Stefanie Jabur Assis2,3, Celina Massumi Miyazaki2, Flávio Makoto Shimizu5, Luís Antonio Peroni 6, M. Teresa Machini7, Amilton Antunes Barreira8,9, Marystela Ferreira 2, Osvaldo N. Oliveira Jr.5 & Fabio Lima Leite2,3

1 Institute of Tropical Medicine of São Paulo, University of São Paulo, São Paulo, São Paulo, 05403000, Brazil.

2 Department of Physics, Chemistry and Mathematics, Federal University of São Carlos, Sorocaba, São Paulo,
18052780, Brazil.

3Nanoneurobiophysics research group (GNN), Federal University of São Carlos, Sorocaba,São Paulo, 18052780, Brazil.

4 Department of Neurology, Psychology and Psychiatry, São Paulo State University,Botucatu, São Paulo, 18618687, Brazil.

5 São Carlos Institute of Physics, University of São Paulo, São Carlos, SãoPaulo, 13560970, Brazil.

6 Rheabiotech Laboratory of Research and Development, Campinas, São Paulo, 13084791,Brazil.

7 Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, 05508000, Brazil.

8 Department of Neurosciences and Behavioural Sciences, Ribeirão Preto Medical School, University of São Paulo,
Ribeirão Preto, São Paulo, Brazil.

9 Amilton Antunes Barreira deceased

Published in: Scientific Reports
doi: doi.org/10.1038/s41598-019-52506-w

A precise diagnosis for neuromyelitis optica spectrum disorders (NMOSD) is crucial to improve patients’ prognostic, which requires highly specific and sensitive tests. The cell-based assay with a sensitivity of 76% and specificity of 100% is the most recommended test to detect anti-aquaporin-4 antibodies (AQP4-Ab). Here, we tested four AQP4 external loop peptides (AQP461–70, AQP4131–140, AQP4141–150, and AQP4201–210) with an atomic force microscopy nanoimmunosensor to develop a diagnostic assay. We obtained the highest reactivity with AQP461–70-nanoimunosensor. This assay was effective in detecting AQP4-Ab in sera of NMOSD patients with 100% specificity (95% CI 63.06–100), determined by the cut-off adhesion force value of 241.3 pN. NMOSD patients were successfully discriminated from a set of healthy volunteers, patients with multiple sclerosis, and AQP4-Ab-negative patients. AQP461–70 sensitivity was 81.25% (95% CI 56.50–99.43), slightly higher than with the CBA method. The results with the AQP461–70-nanoimmunosensor indicate that the differences between NMOSD seropositive and seronegative phenotypes are related to disease-specific epitopes. The absence of AQP4-Ab in sera of NMOSD AQP4-Ab-negative patients may be interpreted by assuming the existence of another potential AQP4 peptide sequence or non-AQP4 antigens as the antibody target.

MP-SPR keywords: AFM, antibody, Au sensor slide, biosensor development, neuromyelitis, PEG, peptide