MALDI-TOF mass spectrometry for the identification of freshwater snails from Senegal, including intermediate hosts of schistosomes

Abstract

Freshwater snails of the genera Biomphalaria, Bulinus, and Oncomelania are intermediate hosts of schistosomes that cause human schistosomiasis, one of the most significant infectious neglected diseases in the world. Identification of freshwater snails is usually based on morphology and, potentially, DNA-based methods, but these have many drawbacks that hamper their use. MALDI-TOF MS has revolutionised clinical microbiology and has emerged in the medical entomology field. This study aims to evaluate MALDI-TOF MS profiling for the identification of both frozen and ethanol-stored snail species using protein extracts from different body parts. A total of 530 field specimens belonging to nine species (Biomphalaria pfeifferi, Bulinus forskalii, Bulinus senegalensis, Bulinus truncatus, Bulinus globosus, Bellamya unicolor, Cleopatra bulimoides, Lymnaea natalensis, Melanoides tuberculata) and 89 laboratory-reared specimens, including three species (Bi. pfeifferi, Bu. forskalii, Bu. truncatus) were used for this study. For frozen snails, the feet of 127 field and 74 laboratory-reared specimens were used to validate the optimised MALDI-TOF MS protocol. The spectral analysis yielded intra-species reproducibility and inter-species specificity which resulted in the correct identification of all the specimens in blind queries, with log-score values greater than 1.7. In a second step, we demonstrated that MALDI-TOF MS could also be used to identify ethanol-stored snails using proteins extracted from the foot using a specific database including a large number of ethanol preserved specimens. This study shows for the first time that MALDI-TOF MS is a reliable tool for the rapid identification of frozen and ethanol-stored freshwater snails without any malacological expertise.

MALDI-TOF : A new tool for the identification of Schistosoma cercariae and detection of hybrids

“…Hamlili et al [29], have demonstrated that MALDI-TOF is a reliable tool for the rapid identification of frozen and ethanol-stored freshwater snails, permitting to distinguish intermediate hosts and non-intermediate hosts without any malacological expertise. In the present study, we confirm the usefulness of MALDI-TOF for malacological surveys in Schistosoma -endemic areas, enabling the rapid and reliable identification of emitted cercariae at species level and detection of hybrids.…”

“…One of the limitations of MALDI-TOF is its inability to detect cercariae directly from snail’s tissues, making it impossible to identify pre- or non-patent infection [29]. However, the majority of pre-patent snails never realised their cercariae [53].…”

“…One of the limitations of MALDI-TOF is its inability to detect cercariae directly from snail's tissues, making it impossible to identify pre-or non-patent infection [29].…”

Molecular and MALDI-TOF MS identification of swallow bugs Cimex hirundinis (Heteroptera: Cimicidae) and endosymbionts in France

“…MALDI-TOF MS has increasingly been used in the clinical microbiology field for rapid and reliable microorganism classification, and its advantages are currently driving its application in routine microbiological laboratories [ 26 ]. More recently, this proteomic tool has also proven its effectiveness in malacology [ 40 ]. Several entomological researchers have reported the usefulness of MALDI-TOF MS as a time-saving, effective and less laborious approach for the identification of various arthropods (ticks, fleas, mosquitoes, bed bugs, biting midges, triatomines), targeting different body parts used for protein extraction that generate specific spectra for each species [ 25 , 41 – 45 ].…”

Identification of Bulinus forskalii as a potential intermediate host of Schistosoma hæmatobium in Senegal

“…The feet of the snails were used for MALDI-TOF MS identification as described by Hamlili et al . (2021) [21]. Each specimens’ MALDI-TOF MS spectra were then compared to the in-house snails reference spectra database (available at https://doi.org/10.35088/f605-3922)[21] using the MALDI-Biotyper v3.0 software (Bruker Daltonics).…”