De novo Genome and Transcriptome Analysis Reveal Novel Allergens in Periplaneta americana (American Cockroach)

Periplaneta americana, also known as the American cockroach, plays a critical role in causing the allergic diseases including asthma, allergic rhinitis and eczema. Previous studies have only identified a limited number of allergens in the American cockroach. We aim at constructing high-quality genome and transcriptome of the American cockroach to facilitate the discovery of novel allergen groups as well as members of known groups. DNA and RNA of an adult female American cockroach from Bangkok, Thailand were extracted and sequenced using Illumina and Nanopore platforms. WHO/IUIS allergen nomenclature database was used to assist putative allergen discovery. Novel allergen groups were further identified and characterized by clustering detected allergens based on their primary amino-acid sequences and secondary structures. We assembled a high-quality American cockroach genome of 3.4 giga base-pairs in size, which shared 92.0% similarity with the previously published Shanghai strain. We also obtained a transcriptome with 97.2% BUSCO completeness. Analysis of the genome and transcriptome predicted 83,985 open reading frames, among which total 113 were mapped to the allergen database, including 78 putative allergens that had not been characterized as American cockroach allergen before. These novel candidates were originated from 17 protein families such as tropomyosin, heat-shock proteins and alpha-tubulin, and could be categorized into 3 known and 14 novel allergen groups in the American cockroach. Here, we provided well-assembled genome and transcriptome of the American cockroach, which served as powerful tools for expanding the allergen spectrum. We expected our results could contribute to the development of diagnostic targets and immunotherapeutic vaccines.