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R E Blanton

Publications and source records attributed to R E Blanton.

25 records · Page 2Linked to original sources
PubMed1995

Preferential recognition by human IgE and IgG4 of a species-specific Schistosoma haematobium serine protease inhibitor.

IgE induction in schistosomiasis is an important human response to infection, yet few specific parasite allergens have been characterized. One allergen of Schistosoma haematobium was found to be a species-specific surface antigen and a member of the serine protease inhibitor gene family (SH serpin). The purified recombinant SH serpin protein was used to characterize human isotypic responses to this antigen. Quantitative ELISA based on the recombinant antigen revealed marked IgG4 and IgE responses and a high degree of species specificity (IgG = 96%, IgG4 = 66%, and IgE = 95%) in sera from S. haematobium-infected persons. In contrast, ELISA based on soluble adult worm or egg antigens could not discriminate between species. There was no correlation between serpin-specific IgE and IgG4 levels in 41 infected persons. Further, serpin-induced antibody production in vitro indicated that IgE and IgG4 responses are not coordinately regulated.

Adolescent↗
PubMed1994

Characterization of a native and recombinant Schistosoma haematobium serine protease inhibitor gene product.

Immunologic screening of a Schistosoma haematobium cDNA library with species-specific human antisera identified a clone whose predicted amino acid sequence encodes a member of the serine protease inhibitor (serpin) gene family. This cDNA consists of 1397 bp with a single open reading frame that can encode a 409-amino acid protein of 46,261 Da. The native antigen is a 54-58-kDa glycoprotein and is located on the surface of adult worms. Sequence comparison with other serpins predicts the amino acid Phe at the putative reactive center of the protein. Phenylalanine is also found at the corresponding site of a vaccinia serpin that may contribute to the hemorrhagic phenotype of some strains of cowpox virus. Though the human parasites S. haematobium and Schistosoma mansoni demonstrate a close antigenic relationship, the S. haematobium serpin gene product demonstrates marked species-specific immunogenicity. By Northern blot hybridization, however, both species express a 1700-nucleotide mRNA that hybridizes with the S. haematobium serpin cDNA. The intensity of cross hybridization for the S. mansoni mRNA is 10-fold lower than that for S. haematobium. Southern blots of genomic DNA and gene titration experiments indicate that the S. haematobium gene is present in approximately 4-5 copies per haploid genome.

Amino Acid Sequence↗
PubMed1992

Developmental regulation of protein synthesis in schistosomes.

Soon after infecting a mammalian host, cercariae of Schistosoma mansoni rapidly undergo a series of morphologic and biochemical adaptations associated with transformation to their next developmental stage, the schistosomulum. Few of these changes are associated with alterations in gene expression except for an apparent increase in protein synthesis. By pulse-labeling, we demonstrate that there is a gradual rise in methionine incorporation after transformation, and that the rise is not due to increasing amino acid uptake or increasing protein stability. This pattern of protein synthesis did not result from a general increase in transcription of mRNA. There was likewise no evidence of a rise in the availability of selected rate limiting components of the translational machinery such as rRNA or elongation factor 1 alpha as a mechanism for increasing levels of translation. Transcription of HSP 70 appears to be induced in both cercariae and schistosomula, though translation of this message was not detected. A comparison between the level of in vivo synthesis of proteins and the level of their corresponding mRNAs suggests that following transformation of cercariae to schistosomula the translation of most mRNAs is blocked and that this block is gradually reversed during the first 24 h.

Animals↗
PubMed1991

Ultrastructural localization of a protective 68,000 molecular weight antigen in Schistosoma mansoni.

Vaccination with SMW 68, an Mr 68,000 glycoprotein of Schistosoma mansoni, induces significant protection in mice against challenge schistosome infection. This resistance occurs without the use of adjuvants and without sensitizing animals to granuloma formation. Likewise, passive transfer of monoclonal antibody (MAb) 31-3B6 against SMW 68 confers partial protection against challenge infection. As a first step in understanding how the immune response to this molecule leads to resistance, SMW 68 was localized in three developmental stages of the parasite by immunoelectron microscopy using MAb 31-3B6 and polyclonal antisera raised against purified SMW 68. In cercariae and schistosomula, MAb 31-3B6 bound electron-dense granules within the head gland and similar granules in the preacetabular glands. In adult worms, SMW 68 or related antigens were found to be widely distributed in tissues. Binding of specific antisera was most pronounced in the gut and tegument of male worms, but less so in subtegumental muscles. We conclude that SMW 68 is presented to the immune system in various ways during parasite development. The protective protein or epitope is excreted, and presented on the surface and in the cytoplasm at various stages of the life cycle. The relationship of the location of this protein to its role in protective immunity is discussed.

Animals↗