Immune responses of selected phagotopes from monoclonal antibodies of Burkholderia pseudomallei.

Random peptide libraries displayed by bacteriophage T7 and M13 were employed to identify mimotopes from 4 monoclonal antibodies (MAbs) specific to Burkholderia pseudomallei. Insert DNA sequences of bound phages selected from four rounds of panning with each MAb revealed peptide sequences corresponding to B. pseudomallei K96243 hypothetical protein BPSL2046, hypothetical protein BpseP_02000035, B. pseudomallei K96243 hypothetical protein BPSS0784, B. pseudomallei 1710b hypothetical protein BURPS1710b_1104, and B. cenocepacia H12424 TonB-dependent siderophore receptor, all located at the outer membrane. The immune responses from all selected phagotopes were significantly higher than that of lipopolysaccharide. The study demonstrates the feasibility of identifying mimotopes through screening of phage-displayed random peptide libraries with B. pseudomallei MAbs.

The diagnosis of human opisthorchiasis.

Opisthorchiasis viverrini is a liver fluke infection causing a serious public health problem in Thailand, Lao PDR, Cambodia, and South Vietnam because it acts as a strong promoter of cholangiocarcinoma. The diagnosis of human opisthorchiasis is based on four approaches: clinical manifestations, parasitological, molecular biological, and immunological methods. These methods have advantages and disadvantages. Clinical manifestations of the patients are practically indistinguishable from those of other liver diseases. The features of the O. viverrini eggs are, by light microscopy, difficult to differentiate from those of other minute intestinal flukes' eggs. Polymerase chain reaction (PCR) is very complicated, needs special and expensive apparatus, and is time-consuming; it is, however, highly sensitive and specific. Immunological testing is the method of choice: the techniques are applicable to both routine laboratory work and field or epidemiological studies. Of these tests, enzyme-linked immunosorbent assay (ELISA) and immunoelectrotransfer blot assay are often used for the detection of O. viverrini-specific antigens (coproantigens) and antibodies (IgM, IgG, IgA, or IgE). Monoclonal antibodies are prepared to detect coproantigens, while the crude somatic and excretory-secretory antigens from the adult worms, metacercariae, eggs, and snail intermediate hosts are prepared in order to detect antibodies in sera. To eliminate the cross reactions between parasites, the appropriate amount, type, and efficacy of antigens or antibodies preparation should be considered. In this paper, the advantages and disadvantages of the four diagnostic methods are discussed.