# Utility of the Ribosomal Gene 18S rRNA in the Classification of the Main House Dust Mites Involved in Hypersensitivity

## TL;DR

This study explores using the 18S rRNA gene to accurately identify house dust mite species that cause allergies, improving diagnosis.

## Contribution

The study introduces a new method using 18S rRNA gene sequencing and PCR to distinguish between key allergenic mite species.

## Key findings

- The 18S rRNA gene sequences of five mite species were successfully aligned to identify conserved and divergent regions.
- Designed oligonucleotides amplified specific 18S rRNA fragments for each species using real-time PCR.
- PCR results showed distinct amplification sizes and melting points for each species, enabling accurate identification.

## Abstract

Between 1% and 2% of the world’s population is sensitised to mites. Aetiological diagnosis is key to the management of allergic patients. However, methods based solely on morphological criteria are ambiguous in many cases. Polymerase chain reaction of ribosomal genes represents a valuable complementary approach. The 5 most representative species (Dermatophagoides pteronyssinus, Dermatophagoides farinae, Tyrophagus putrescentiae, Blomia tropicalis and Lepidoglyphus destructor) were selected as sources of allergens. They were first identified morphologically and the 18S rRNA gene sequences were obtained from the GenBank database. Alignment of the nucleotide sequences of the 18S rRNA ribosomal gene enabled the identification of the conserved and divergent regions in all of them. The alignment allowed the design of a pair of oligonucleotides in conserved regions of the gene, to amplify the sequence of interest in each of the species. We performed genomic DNA extraction, quantification and purity. PCR, using oligonucleotides designed to amplify the 18S sequence fragment of interest, showed the exact size for each species. Amplification, efficiency curves and melting points resulting from the amplification of the 18S amplicon of the five species were obtained. The oligonucleotides designed for real-time PCR studies, allow species identification by amplifying the specific fragment of each species using real-time PCR.