ATR-FTIR spectroscopy coupled with multivariate analysis techniques for the identification of DENV-3 in different concentrations in blood and serum: a new approach

In most cases of virus infections the viral load is directly related to the intensity of the disease. Nowadays, the main routine diagnoses for dengue fever are only qualitative, they only inform us if the patient has dengue fever or not. However, it is important to be aware of the patient's viral load so that proper care can be taken. In this study we used attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) coupled with multivariate analysis techniques to identify and discriminate dengue serotype 3 (DENV-3) diluted in different concentrations in serum and blood samples with the purpose of developing a simple, fast and non-destructive methodology for a quantitative analysis of the dengue virus. Techniques such as principal component analysis-linear discriminant analysis (PCA-LDA), successive projection algorithm - linear discriminant analysis (SPA-LDA) and genetic algorithm - linear discriminant analysis (GA-LDA) were applied in this classification problem. Forty samples (40 for serum and 40 for blood) were infected with DENV-3 at different concentrations (ten samples for each concentration) and analyzed by IR spectroscopy. The results showed that the models were successful in classifying the virus, the best results being for blood samples. The results of the multivariate classification were tested based on sensitivity, specificity, positive and negative predictive values, Youden's index and positive and negative likelihood ratios, suggesting that ATR-FTIR spectroscopy coupled with multivariate analysis algorithms is an effective tool in quantifying the dengue virus in providing rapid results, in addition to being non-destructive to the sample.