Graduate student University of Illinois Chicago, College of Medicine Rockford Rockford, Illinois, United States
In this study, we identified and characterized a pan allergen, a homologous molecule that is present in multiple nematode parasites with significant IgE reactivity. The molecule, WbNPA, was first identified from the human parasite, Wuchereria bancrofti by screening a phage displayed cDNA expression library of the microfilaria larval stages of the parasite with human monoclonal IgE antibodies prepared from individuals showing clinical symptoms of Tropical Pulmonary Eosinophilia (TPE), a hypersensitivity allergic reaction seen in subjects with W. bancrofti Infection. After five rounds of biopanning, 13 clones were picked and sent out for sequencing. Our results showed that the sequences belonged to a gene (Bm2855) that was not annotated previously. A phylogenetic tree analysis showed that Bm2855 is highly conserved among nematode parasites and showed over 95% similarity in several nematodes with no homology to the human. Therefore, we named this gene as Nematode Pan Allergen (NPA, accession # ON023112). Subsequent analysis showed that the NPA gene is highly expressed in the microfilaria stage and adult female stages of W. bancrofti compared to all other lifecycle stages. Similarly, sera samples from TPE, and microfilaremic subjects had high levels of antibodies against NPA compared to chronic pathology (CP), and endemic normal (EN) control subjects. Further characterization studies showed that WbNPA is a histamine releasing factor and can induce inflammatory cytokines from alveolar macrophages. Thus, we report here a novel pan allergen that is present in several nematode parasites, and can induce allergic inflammation.
