Molecular cloning and expression of SmIrV1, a Schistosoma mansoni antigen with similarity to calnexin, calreticulin, and OvRal1.
Protective immunity against schistosomiasis induced by vaccination of mice with irradiated cercaria can be passively transferred to uninfected mice with sera or IgG. Antigens that are uniquely or more strongly recognized by such protective sera compared with sera from infected unprotected mice have been identified previously. Two genes, SmIrV1 and SmIrV5, were selected from an adult worm cDNA library by screening with antibodies raised against these candidate vaccine proteins. Active immunization with the SmIrV5 protein induces high levels of protection in mice. We report here the molecular cloning and sequencing of SmIrV1 which contains a deduced amino acid sequence of 582 residues with similarity to three proteins: calnexin, calreticulin, and OvRal1, a surface antigen of the filarial nematode Onchocerca volvulus. SmIrV1 can be divided into three regions: a neutral N-terminal region with a putative signal sequence, followed by a proline- and tryptophan-rich P region in which two sets of sequences are repeated four times and a C-terminal region which is highly acidic with an isoelectric point of 4.7. We expressed the P and C regions of SmIrV1 and showed that this polypeptide reacts with sera of immunized as well as chronically infected mice.
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Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
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D000595:Amino Acid Sequence; D000818:Animals; D000947:Antigens, Helminth / Q000235:genetics*; D015152:Blotting, Northern; D002135:Calcium-Binding Proteins / Q000235:genetics*; D037281:Calnexin; D037282:Calreticulin; D003001:Cloning, Molecular / Q000379:methods; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D005260:Female; D015870:Gene Expression; D015723:Gene Library; D015801:Helminth Proteins / Q000235:genetics* / Q000302:isolation & purification; D051379:Mice; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification; D012091:Repetitive Sequences, Nucleic Acid; D015183:Restriction Mapping; D012550:Schistosoma mansoni / Q000235:genetics / Q000276:immunology*; D017386:Sequence Homology, Amino Acid
D000947:Antigens, Helminth; D002135:Calcium-Binding Proteins; D037282:Calreticulin; D015801:Helminth Proteins; C080575:RAL-1 protein, Onchocerca volvulus; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; C080574:SmIrV1 protein, Schistosoma mansoni; D037281:Calnexin; D004247:DNA