Synthetic peptides as an antigenic base in an ELISA for laboratory diagnosis of schistosomiasis mansoni.

A pool of five synthetic peptides was used as an antigenic base in an ELISA (ELISA-Pp) for laboratory diagnosis of Schistosoma mansoni. Serum samples were obtained from individuals with acute (n=23) and chronic (n=30) schistosomiasis, with other parasitoses (n=39) or without parasitic infections (n=100). ELISA-Pp was compared with other immunoenzymatic methods for detection of IgM (IgM-ELISA) or IgG (IgG-ELISA) as well as an immunofluorescence test for detection of IgM antibodies (IgM-IFT). The sensitivity and specificity of ELISA-Pp was 86.8% and 94.2% when tested on the schistosomiasis group and the non-schistosomiasis group, respectively. Comparison of ELISA-Pp with other serological methods resulted in kappa concordance indices varying from 0.59 to 0.75. Evaluation of anti-peptide IgG antibodies showed higher levels in patients with acute compared with chronic schistosomiasis (P=0.001). ELISA-Pp showed satisfactory sensitivity and high specificity and may constitute a potentially useful method for laboratory diagnosis of schistosomiasis mansoni.

Application of synthetic peptides in development of a serologic method for laboratory diagnosis of schistosomiasis mansoni

The immunoreactivity of seven peptides synthesized from Schistosoma mansoni proteins, was evaluated by dot-blot and ELISA assays using two different sensitization methodologies. The best results were obtained on wells of the Costar 3590 microplates coated with peptides P1, P2, P3, P6, and P7 using conventional methodology. The signals increased considerably (p < 0.0003) on wells sensitized with P1 to P6 using alternative methodology. In contrast, the well coated with peptide P7 presented lower signal when compared with conventional methodology (p = 0.0019). These results, establish the basis for the application of synthetic peptides for laboratory diagnosis of schistosomiasis mansoni.

Application of synthetic peptides in development of a serologic method for laboratory diagnosis of schistosomiasis mansoni.

The immunoreactivity of seven peptides synthesized from Schistosoma mansoni proteins, was evaluated by dot-blot and ELISA assays using two different sensitization methodologies. The best results were obtained on wells of the Costar 3590 microplates coated with peptides P1, P2, P3, P6, and P7 using conventional methodology. The signals increased considerably (p < 0.0003) on wells sensitized with P1 to P6 using alternative methodology. In contrast, the well coated with peptide P7 presented lower signal when compared with conventional methodology (p = 0.0019). These results, establish the basis for the application of synthetic peptides for laboratory diagnosis of schistosomiasis mansoni.

Novel multiple 5'-amino-modified primer for DNA microarrays.

For DNA microarray analysis, total RNA is reverse-transcribed, labeled by incorporating fluorescent dye into the cDNA, and used to hybridize microarray. This protocol requires a minimum of 20 microg of total RNA. To overcome the sample limitation, an RNA amplification technique has been developed. Although it needs less RNA, this amplification technique is relatively expensive, time consuming, and, unfortunately, has been found to introduce bias. In this study, we designed a novel 5'-amino-modified primer and used it for priming cDNA synthesis. The novel primer has a special structure that contains four Uni-Link molecules with two nucleotide (thymine) residues inserted between them as spacers. This novel primer is used in the reverse-transcription reaction for cDNA synthesis. Using the novel 5'-modified primer combined with indirect labeling method, cDNA probes can be prepared with much less total RNA (5 microg or less) without amplification producing optimal results after hybridization of arrays. This primer can also be used to label nucleotides for other purposes.

Amino Acid Composition of Proteins Extracted from Endemic Goiter Glands.

Proteins were isolated and characterized in thyroid tissue of six patients from Brazil with endemic goiter. Biochemical studies of these thyroidal proteins included gel filtration, electrophoresis, and amino acid analysis. In addition to thyroglobulin, two of the most abundant proteins found in all goiters studied had molecular weights of 68 and 14 kDa. One protein was identified as albumin based on its immunoreactivity with antibodies to serum albumin. The other protein was identified as a hemoglobin subunit using reverse-phase high-performance liquid chromatography (H PLC). Identification was confirmed by partial N-terminal amino acid sequencing that showed several nonconservative differences in thyroid albumin when compared to human serum albumin (HSA). Biochemical findings were correlated with iodine and hormone contents in serum and thyroglobulin from these patients. Based on these findings, we suggest that hemoglobin and albumin are taken up from the blood by the hyperplastic thyroid tissue. Albumin would be processed by the thyroid follicular cell, becoming iodinated and released into the circulation.