Salivary Detection of Zika Virus Infection Using ATR-FTIR Spectroscopy Coupled with Machine Learning Algorithms and Univariate Analysis: A Proof-of-Concept Animal Study

Abstract

Zika virus (ZIKV) diagnosis is currently performed through an invasive, painful, and costly procedure using molecular biology. Consequently, the search for a non-invasive, more cost-effective, reagent-free, and sustainable method for ZIKV diagnosis is of great relevance. It is critical to prepare a global strategy for the next ZIKV outbreak given its devastating consequences, particularly in pregnant women. Attenuated total reflection–Fourier transform infrared (ATR-FTIR) spectroscopy has been used to discriminate systemic diseases using saliva; however, the salivary diagnostic application in viral diseases is unknown. To test this hypothesis, we intradermally challenged interferon-gamma gene knockout C57/BL6 mice with ZIKV (50 µL,105 FFU, n = 7) or vehicle (50 µL, n = 8). Saliva samples were collected on day three (due to the peak of viremia) and the spleen was also harvested. Changes in the salivary spectral profile were analyzed by Student’s t test (p < 0.05), multivariate analysis, and the diagnostic capacity by ROC curve. ZIKV infection was confirmed by real-time PCR of the spleen sample. The infrared spectroscopy coupled with univariate analysis suggested the vibrational mode at 1547 cm−1 as a potential candidate to discriminate ZIKV and control salivary samples. Three PCs explained 93.2% of the cumulative variance in PCA analysis and the spectrochemical analysis with LDA achieved an accuracy of 93.3%, with a specificity of 87.5% and sensitivity of 100%. The PCA-SVM analysis showed 100% discrimination between both classes. Our results suggest that ATR-FTIR applied to saliva might have high accuracy in ZIKV diagnosis with potential as a non-invasive and cost-effective diagnostic tool.

Intranasal Immunization for Zika in a Pre-Clinical Model

“…In the Zika solution, one major peak of the FTIR spectra (black) can be observed at 1648 cm −1 . These observations are consistent with the reported literature, with peaks at 1550 cm −1 and 1630 cm −1 [ 23 , 37 ]. The poly (D, L-lactide-co-glycolide) grade 75:25 (PLGA) polymer (red) [ 24 ] showed, as expected, small but visible peaks at 2954 cm −1 , 2833 cm −1 , 1758 cm −1 , and 1093 cm −1 .…”

“…In the Zika solution FTIR spectra (black), one main peak is seen at 1648 cm −1 . These observations are consistent with the reported literature [ 23 ]. Small, but visible peaks at 2954 cm −1 , 2833 cm −1 , 1758 cm −1 , and 1093 cm −1 are representative of the poly (D, L-lactide-co-glycolide) grade 75:25 (PLGA) polymer [ 24 ].…”

“…The peak representing the Zika solution at 1648 cm −1 was notably decreased. In a recent study, researchers were interested in identifying an infrared profile to detect ZIKV signatures that are present in saliva that can be used for screening or for diagnostic purposes [ 23 ]. Since saliva can contain proteins, for instance mRNA, it can also contain the presence of ZIKV.…”