Creation of the MALDI-TOF MS Database for Identification of <i>Loa </i><i>loa</i> Microfilaria: Preliminary Study

Mass spectrometry (MS) is a powerful tool for identifying bacteria and fungi. Several attempts have been made to apply the technique in clinical parasitology but not in filarial identification. The study shows that MALDI-TOF-MS is a promising tool to identify Loa loa microfilaria of patients from an endemic country. Loa loa microfilariae were isolated and purified from blood via a Percoll gradient. The microfilaria was separated into different groups from 1 microfilaria to 500 microfilaria specimens. Four extraction procedures were subsequently tested to determine the most adaptable procedure for the quality protein for MALDI-TOF MS analysis. A reference database of spectra was constructed and tested on a panel of 80 isolates. A blind test of 80 spectra was performed against the created library. Results showed that the best protocol for protein extraction used an equal volume of 70% formic acid 100% acetonitrile. Good resolution spectra were obtained at 400 microfilariae. The approach correctly identified all the patients. Ten spectra that were used to build a MS. The LSV obtained after comparison of the spectra with the MSP showed a good technical reproducibility ranged from 1.86 to 2.9, with a mean of 2.398 ± 0.046 and a good biological reproducibility with a mean of 2.13 [1.17 - 2.55]. MALDI-TOF MS is a promising approach, providing rapid and accurate identification of L. loa microfilaria.