Electron Microscopy and Molecular Phylogenetic Characterization of the Allergenic Dust Mite Species Suidasia pontifica (Acari: Suidasiidae)

The clinical significance of house dust mites (HDMs) as sources of allergens for medical diagnostics, allergen-specific immunotherapy, and allergology research is dependent on accurate morphological and molecular data analysis for species identification and characterization. Here, we report the species identification and allergenicity of a tropical HDM, Suidasia pontifica ( Sp ), via morphological-molecular characterization tandem and IgE ELISA, respectively. Electron microscopy of monocultures of HDM samples collected from Laguna, Philippines, revealed five different traits related to chaetotaxy and body anatomy, such as the presence of scapular setae, cuticle patterns, vertical setae, ω ¹ setae, and anal suckers, suggesting that the sample identity is Sp . In addition, PCR amplification from the HDM monoculture genomic DNA and bidirectional sequencing of the 18S and COI gene markers were performed, which were subjected to sequence assembly, consensus acquisition, sequence alignment, and phylogenetic inference. The COI gene showed an exact match and phylogenetic attachment of the sample assembly to Sp , confirming the species-level identification, corroborated with morphological data. Furthermore, 18S gene character analysis was able to prove phylogenetic demarcation of the Sp 18S gene from the sister species S. nesbitti and other allergenic sarcoptiforman species. Our molecular phylogenetic analysis, which is strongly supported by electron microscopy data, indicates the identity of our monocultures as Sp . Interestingly, the Sp allergenicity profile of allergic patients and controls (n = 200) suggests 47% IgE-binding reactivity, confirming its allergenicity and clinical importance among atopic patients. This study emphasizes the resolving power of the morphological-molecular phylogenetic approach and IgE-reactivity to objectively verify Sp species identity and allergenicity for downstream immunological studies.