Burkholderia pseudomallei lectins: occurrence and expression

Lectins, also known as sugar binding proteins, play an essential role in the initiation of bacterial infections and biofilm production. To date, several lectins of Gram-negative bacteria such as Pseudomonas aeruginosa, Burkholderia cenocepacia, Ralstonia solanacearum and Chromobacterium violaceum have been identified. There are no published reports on the presence of lectins in Burkholderia pseudomallei, the causative agent of melioidosis. The aim of this study was to identify possible lectin genes of B. pseudomallei and generate recombinant proteins for assessment of hemagglutinating activity. Seven hypothetical lectins of B. pseudomallei were retrieved from the UniProt database. Four lectin domains, i.e., ricin B, C-type, H-type and Bulb-type lectins were identified. In silico analysis using a ligand binding site prediction server (3DLigandSite) predicted the presence of Nacetylglucosamine and calcium binding sites in two C-type lectins. Four recombinant proteins with the molecular weights of 11.7, 30.2, 36.2 and 46.4 kDa were expressed from the cloned genes; however none of them expressed any hemagglutinating activity. Further characterization of B. pseudomallei lectins may be able to provide insights into bacterial-host interaction that are required to initiate infections.

Immunoblot analysis of IgE and IgG antibodies to honey bee venom: cross sectional and sequential studies in bee sensitive subjects.

To investigate the specific IgE and IgG immune response to honey bee venom (bv), we performed immunoblot analysis of sera from 47 bee sensitive subjects and followed the response during and after venom immunotherapy in 15 of these subjects. Fifteen venom proteins varying in molecular size from 20 to 105 kDa were identified as being antigenic and consisted of a high molecular weight (HMW) group (5 to 105 kDa, containing the previously identified allergens B and C) and a low molecular weight group (LMW) containing hyaluronidase and phospholipase A. In general for a given individual the anti-venom IgE and IgG response was qualitatively similar although some variation between individuals was apparent. Reactivity with hyaluronidase and phospholipase A appeared only in those subjects showing reactivity with HMW components. During immunotherapy specific anti-venom IgG and IgE responses tended to be linked. Increased responses being seen against all components in 4 of 12 subjects, reductions in 3 and unchanged responses in the remainder. Following immunotherapy (mean 4.0 years), spontaneous reduction of IgE and IgG was seen in 5 of 5 subjects. Loss of reactivity with the LMW components was prominent in these sera.