Insect glutathioneS-transferases (GSTs) play important roles in insecticide/drug resistance and stress response. Medically, GSTs of house dust mites (Dermatophagoides pteronyssinusandBlomia tropicalis) and German cockroach (Blattella germanica) are human allergens. In this study, classes, isoforms and B-cell and allergenic epitopes of GST of American cockroach,Periplaneta americana, the predominant species in the tropics and subtropics were investigated for the first time. Enzymatically active native and recombinantP.americana-GSTs bound to IgE in sera of allP.americanaallergic patients that were tested. By gel-based proteomics and multiple sequence alignments, the native GST comprises three isoforms of delta and sigma classes. All isoforms interacted with serum IgE of the cockroach allergic subjects. Molecularly, the protein contains six B-cell epitopes; two epitopes located at β1-α1 and β4-α3 regions bound to patients’ serum IgE, indicating that they are allergenic.P.americanaare ubiquitous and their GST can sensitize humans to allergic diseases; thus, the protein should be included in the allergen array for component resolved diagnosis (CRD) of allergic patients, either by skin prick test or specific IgE determination. The GST is suitable also as a target of environmental allergen detection and quantification for intervention of cockroach sensitization and allergic morbidity.

The rat lungworm Angiostrongylus malaysiensis is a metastrongyloid nematode parasite. It has been reported in Malaysia, Thailand, Laos, Myanmar, Indonesia and Japan. In this study, A. malaysiensis adult worms recovered from the lungs of wild rats in different geographical regions/provinces in Thailand were used to determine their haplotype by means of the mitochondrial partial cytochrome c oxidase subunit I (COI) gene sequence. The results revealed high COI haplotype diversity of A. malaysiensis from Thailand. The geographical isolates of A. malaysiensis from Thailand and other countries formed a monophyletic clade distinct from the closely related A. cantonensis. In the present study, five new haplotypes were identified in addition to the four haplotypes reported in the literature. Phylogenetic analysis revealed that four of these five new haplotypes – one from Mae Hong Song (northern region), two from Tak (western region) and one from Phang Nga (southern region) – formed a distinct clade with those from Phatthalung (southern region) and Malaysia. The haplotype from Malaysia was identical to that of Phatthalung (haplotype AM1). In general, the COI sequences did not differentiate unambiguously the various geographical isolates of A. malaysiensis. This study has confirmed the presence of high COI genetic diversity in various geographical isolates of A. malaysiensis. The COI gene sequence will be suitable for studying genetic diversity, population structure and phylogeography.

Allergic rhinitis (AR) is an IgE-mediated inflammation of the nasal membranes, which is naturally triggered by aeroallergens. House dust mites (HDM) are the most common inhalant allergens. Interleukin-18 (IL-18) has been established as an essential cytokine that can activate the generation of IgE. This randomized controlled study aimed to identify the possible relationship of the genetic variations in the IL-18 gene with AR in mite-sensitive Thai patients. Study subjects consisted of 150 AR patients and 50 normal participants. Genomic DNA of 30 randomized AR patients and 30 randomized controls were screened by sequencing for the selection of candidate single nucleotide polymorphisms (SNPs), and further analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay for all subjects. The following five SNPs were detected in the IL-18 gene: -656 G/T, -607 C/A, and -137 G/C in promoter 1 and -920 C/T and -373 C/G in promoter 2. The results showed that -656 G/T and -607 C/A SNPs were significantly correlated with IgE levels specific to Dermatophagoides pteronyssinus (Der p) allergen (P = 0.045 and P = 0.045, respectively), and significant differences were observed in the genotype distribution of AR patients when compared with controls [P = 0.044 and P = 0.044, respectively; odds ratios (ORs): 1.941 (95%CI, 1.014-3.715) and 1.941 (95%CI, 1.014-3.715), respectively]. Our findings indicate that the IL-18 alleles, -656T (rs1946519) and -607A (rs1946518), might be associated with the higher production of Der p allergen-specific IgE in mite-sensitive AR patients.