Expression profiles of an inactive aspartic protease (Bla g 2 allergen) in different life stages and body tissues of the German cockroach (Blattella germanica L.)

The German cockroach, Blattella germanica, is a source of multiple human allergens known as Bla g proteins, belonging to various protein families. One of the most abundant Bla g allergens is the inactive aspartic protease Bla g 2. Previous research shows that this protein is detectable in high quantities in the tergal glands of adult male German cockroaches. Although Bla g 2 protein expression has been quantified in various cockroach body parts, studies that link expression in various life stages and body tissues with mRNA abundance profiles have not been conducted. Therefore the goal of this study was to measure the relative abundances of Bla g 2 protein and mRNA in different tissues (head, gut, wings, male tergal glands, female and nymphal tergites, female oothecae, and carcasses) and life stages (nymphs, virgin males, virgin females, and gravid females) using immuno-blotting and quantitative PCR. We detected the Bla g 2 protein in every tissue, including the male tergal glands. Between different life stages, protein expression was relatively high in adult males and their tergal glands, particularly in comparison to nymphs and virgin females. As with the protein expression profiles, Bla g 2 mRNA transcript levels were relatively high in male tergal glands and adult males. Overall, this study provides new information on relatively high expression of the Bla g 2 allergen in adult males and their tergal glands and lays the foundation for future studies that aim to determine the function of this protein in German cockroach biology and development.