J. Chad Gore

Expression, production and excretion of Bla g 1, a major human allergen, in relation to food intake in the German cockroach, Blattella germanica

Abstract.  The German cockroach, Blattella germanica (Linnaeus) (Dictyoptera: Blattellidae), produces several potent human allergens, one of which, Blattella germanica allergen 1 (Bla g 1), is produced in the midgut and excreted in faeces. We tested with descriptive and experimental approaches the hypothesis that Bla g 1 production is related to food intake in adult males and females of the German cockroach. Bla g 1 mRNA expression in the female midgut (assayed by real time quantitative polymerase chain reaction), her Bla g 1 content (assayed by enzyme‐linked immunosorbent assay), and the females faeces production and its Bla g 1 content tracked a cyclic pattern in relation to the gonadotrophic cycle. All four measures rose as food intake increased, declined before oviposition in relation to diminishing food intake, and remained low while the female carried an egg case for 20 days. After her first clutch of embryos hatched, the female resumed feeding, and faeces and Bla g 1 production increased concomitantly. Both Bla g 1 mRNA expression and Bla g 1 protein levels remained low in experimentally starved females. However, when starved females were allowed to feed, Bla g 1 production elevated and the gonadotrophic cycle resumed. Bla g 1 mRNA expression also increased six‐fold in response to feeding compared to starved females. By contrast, there were no apparent cycles in the pattern of Bla g 1 production in males, reflecting their low and non‐cyclic food intake. Our results therefore demonstrate that Bla g 1 production in B. germanica is modulated in relation to food intake.

Gene Expression and Tissue Distribution of the Major Human Allergen Bla g 1 in the German Cockroach, Blattella germanica L. (Dictyoptera: Blattellidae)

Abstract Exposure and sensitization to cockroach allergens is an importantrisk factor for allergic disease in humans. Despite a recent burgeoningof clinical and socioeconomic studies regarding environmentalpervasiveness and human exposure to cockroach allergens, little isknown about the basic biology of these proteins. The purpose of thisstudy was to ascertain gene expression patterns and the tissuedistribution of Blattella germanica allergen 1 (Bla g1), a perennial indoor environmental allergen, thought to be involvedin digestion in cockroaches. We also investigated the relativepotential contribution of different life stages of the German cockroachto environmental Bla g 1. Enzyme-linked immunosorbent assay was used toquantify the Bla g 1 contents of feces and various anatomical tissues,and Northern blot analysis was used to elucidate tissue-specificexpression of Bla g 1. Results showed that the Bla g 1 protein is mostprevalent in the midgut, and the Bla g 1 gene is exclusively expressedby midgut cells. Although Bla g 1 is produced by both sexes and alllife stages of the German cockroach, adult females produce and excretesignificantly more Bla g 1 in their feces than males or nymphs, evenwhen corrected for body mass or mass of voided feces. Our results showthat the concentration of Bla g 1 in feces of adult females is 6- to 7-and 30-fold higher than in adult males and nymphs, respectively,probably because females process more food than other life stages ofthe German cockroach.

German cockroach allergen levels in North Carolina schools: comparison of integrated pest management and conventional cockroach control.

ABSTRACT Cockroach suppression is fundamental to cockroach allergen mitigation in infested homes. The effects of various cockroach control strategies on cockroach populations and allergen concentration have not been examined in schools. This study was conducted to compare the effectiveness of integrated pest management (IPM) and conventional pest control in controlling German cockroach (Blattella germanica L.) infestations and concentrations of the cockroach allergen Bla g 1 in public school buildings. Two school districts included six schools that used conventional pest control and one district included seven schools that used IPM to control pests. Cockroach traps were deployed to assess the level of infestation, settled dust samples were collected in food service areas, classrooms, and other school areas, and the Bla g 1 allergen was quantified by ELISA. Both cockroach counts and Bla g 1 concentrations were dependent on the pest control approach, with highly significant differences between IPM-treated schools and conventionally treated schools in both the cockroach mean trap counts (0 versus 82.6 ± 17.3 cockroaches/trap/wk, respectively) and in the amount of Bla g 1 in dust samples (2.8 ± 0.3 versus 30.6 ± 3.4 U/g dust). Cockroaches and Bla g 1 were primarily associated with food preparation and food service areas and much less with classrooms and offices. Our data extend recent findings from studies in homes, showing that cockroach allergens can be reduced by cockroach elimination alone or by integrating several tactics including education, cleaning, and pest control. IPM is not only effective at controlling cockroaches but also can lead to long-term reductions in cockroach allergen concentrations, resulting in a healthier environment for students and school personnel.