Characterization of Sm13, a tegumental antigen of Schistosoma mansoni

Abstract

Sm13, a 13-kDa Schistosoma mansoni tegumental antigen, is one of the principal polypeptides recognized by antibodies from mice protectively vaccinated with adult-worm tegumental membranes. To obtain the complete gene encoding Sm13 we subcloned and sequenced a cDNA and a fragment of a genomic clone. The collated sequence contains 1,088 nucleotides and represents the full-length open reading frame of the gene, encoding a protein of 104 amino acids with a calculated molecular mass of 11,923 Da, compatible with the native protein identified in the tegumental membranes. The sequence derived from genomic DNA contains a 45-nucleotide intron. The analysis of the predicted protein suggests the presence of both N- and C-terminal hydrophobic membrane-spanning segments, and the coding region contains no homology in the currently available data bases. Additionally, the coding region is preceded by putative CCAAT and TATA boxes that may be involved in the control of expression. Western-blot analysis and indirect immunofluorescence resulted in the identification of a 13-kDa protein (Sm13) in the tegument of adult worms. The present study reveals that Sm13 behaves as an integral membrane protein upon partitioning in Triton X-1 14 and that it is present in worms of 3 weeks or older but not in schistosomula or miracidia. Moreover, it is also specifically recognized by sera from some schistosomiasis patients in enzyme-linked immunosorbent assay and Western-blot analysis, suggesting that it is immunogenic in human schistosomiasis.

Cloning and characterization of SmZF1, a gene encoding a Schistosoma mansoni zinc finger protein

“…This cDNA was amplified and cloned into pBlueScript KS + , and DNA sequencing revealed that the 603 bp cDNA shared no significant homology to the A157 clone (GenBank U67153) of the Sm13 gene (Abath et al 2000). Instead, it encoded a 88 amino acid protein which contained three zinc finger motifs, although lacking its N-terminal region.…”

Immunoblot analysis of membrane antigens of Schistosoma mansoni, Schistosoma intercalatum, and Schistosoma haematobium against Schistosoma-infected patient sera

“…1b, c). We do not know if the 13-kDa antigen that was detected may be the putative tegumental Sm13 protein (Abath et al 2000) which has a Sh13-kDa ortholog predominantly recognized by IgG3 antibodies from people exposed to S. haematobium parasites (Mutapi et al 2006) (Figs. 2a, b).…”

Scanning electron microscopy of the human low-density lipoprotein interaction with the tegument of Schistosoma mansoni

“…However, the possibility of LDL internalization in S. mansoni through LDL receptors in a way similar or not to human receptors cannot be excluded, as seen by Dinguirard and Yoshino (2006) who found LDL internalization through endocytosis in the larval stage of S. mansoni. Therefore, the characterization of tegument proteins is relevant to the improvement of the functional understanding of this structure and the identification of molecules that may act as targets for protective immune responses or may be useful in diagnosis (Abath et al 2000;Cesari et al 2010).…”