Cloning of a Schistosoma japonicum gene encoding a major immunogen recognized by hyperinfected rabbits

A library of randomly sheared Schistosoma japonicum genomic DNA fragments was constructed in the bacteriophage expression vector lambda gt11. A portion of the library was screened with sera collected from rabbits 8 weeks after they were infected with 1000 cercariae. Four clones whose recombinant gene products react with the rabbit sera were purified to homogeneity. Clone SjIR-12A was chosen for detailed study because of its very intense reaction with the rabbit sera. SjIR-12A was found to encode part of a 70 kDa protein (Sj70) that is present in both soluble egg antigen (SEA) and soluble worm antigen preparations (SWAP). Western blot analysis suggests that Sj70 is the only SWAP component that is strongly immunoreactive with the rabbit sera. Rabbit antibodies that react with the SjIR-12A fusion protein were immunoaffinity purified and used to localize immunoreactive product to the nervous tissue of male and female adult worms, the dorsal and lateral tegument of male adult worms, and in eggs to the miracidial tegument and the area between the eggshell and miracidium. Southern hybridization analysis suggests there are approximately four copies of the Sj70 gene per haploid genome.     

Identification of phage display peptides with affinity for the tegument of Schistosoma japonicum schistosomula

Peptides, bound to the tegument of live Schistosoma japonicum schistosomula, were differentially screened by phage display in vitro using three rounds of reverse absorption and bio-panning. Three M13 phage peptides were isolated and identified by determination of their recovery rate, immunohistochemical localization, immunoblot analysis, and their anti-schistosomal effects in vivo and in vitro. Of the three, M13 phage peptide ZL4 (MppZL4, YSGLQDSSLRLR, 1.4kDa, pI 8.8) bound to the tegument of mechanically transformed schistosomula and to other developmental stages of S. japonicum from the mammalian host. By contrast, MppZL4 did not bind to the surface of cercariae. To further examine its binding properties, MppZL4 was conjugated to Rhodamine B (RhB-YSGLQDSSLRLR, RhB-ZL4) and a peptide control (RhB-AIPYFSGILQWR, RhB-12P) was similarly synthesized. The binding capacities of RhB-ZL4 to the surface membrane of S. japonicum schistosomula in vitro and of S. japonicum adult worms in vivo were examined and revealed specificity for binding. When examined for anti-parasite activity, both MppZL4 and RhB-ZL4 exhibited a potent schistosomicidal effect in vitro. Further MppZL4 also affected the growth and development of schistosomula in vivo. These findings extend previous studies showing that phage display techniques can recover polypeptides that bind specifically to living schistosomes and, moreover, that these bound peptides have the potential to inhibit key physiological processes in these parasites. Our findings suggest further that ectogenic polypeptides, which can bind to the tegument of S. japonicum, might be adapted as vectors to deliver experimental probes and/or pharmacologically relevant compounds to the schistosome tegument, including drugs and immunological mediators.     

The different infectivity of Trichinella spiralis and Trichinella nativa in rat does not solely localize to enteral or parenteral phase

The histopathological changes of 14-day-old Schistosoma japonicum induced by a smaller single dose of mefloquine have been studied. Twenty-three mice infected with 60-80 S. japonicum cercariae for 14 days were treated orally with mefloquine at a single dose of 200 mg/kg (free base), and groups of three mice were killed at various intervals posttreatment. The liver of each mouse was removed, fixed and processed routinely, and examined by light microscopy. Eight hours posttreatment, 38.2% and 39.8% of schistosomulum sections were classified as degenerated and dead, respectively. The degenerated schistosomula revealed in high dilatation of gut with disruption of gut mucosa, swelling of the worm body accompanied by looseness or extensive lysis of parenchymal tissues, and focal swelling or peeling of tegument, while dead worms showed that their damaged tegument adhered to the vessel and inflammatory cell attached on and penetrated into the worm body. Twenty-four hours to 3 days posttreatment, the degenerated schistosomulum sections decreased from 28.1% to 8.2%, while the sections of dead schistosomula increased from 60.0% to 74.8%. At these time periods, the damage intensity of degenerated schistosomula aggravated, while dead schistosomula showed disintegration of internal structures infiltrated by eosinophil-predominant inflammatory cells to form the dead worm abscess. Seven days to 14 days posttreatment, no normal schistosomulum section was observed, and the percentages of degenerated and dead worms further decreased from 3.4% to 3.0% and 34.4% to 12.6%, respectively. Meanwhile, 62.2% to 84.4% of dead worms developed to dead worm granulomas and part of them situated in early stage. Twenty-eight days posttreatment, only dead worm granulomas were observed in the liver sections and part of them developed to late stage. The results indicate that a smaller single mefloquine dose 200 mg/kg exhibits a potential and fast killing effect against S. japonicum juvenile and induces severe histopathological lesions.     

Sj-UV-致弱尾蚴单链抗体库的构建及筛选

目的构建和鉴定日本血吸虫（Schistosoma japonicum,Sj）紫外线（UV）-照射致弱尾蚴单链抗体（single chain Fv,ScFv）表达文库,并以此作为高通量的库源筛选出针对有潜在保护力的Sj尾蚴66-68 kDa抗原（Schistosoma japonicum cercariae antigen 66-68kDa,SCA66-68kDa）的单链抗体。方法选择最佳紫外灯照射条件,构建UV-致弱尾蚴小鼠模型,通过其血清被动转移实验证实其是否具有抗血吸虫攻击感染的保护效果;随后提取该小鼠脾脏mRNA,利用噬菌体展示技术构建UV-照射致弱尾蚴单链抗体库,并从库容量、多样性等方面进行鉴定;运用直接菌落挖集法以SjSCA66-68kDa筛选该抗体库,获得阳性克隆进行蛋白表达,再与SCA进行反应,验证其与SjSCA66-68kDa反应的特异性。结果构建UV-致弱尾蚴动物模型中的血清转移至小鼠体内得到42.5%的减虫率,显著高于日本血吸虫感染血清转移组的减虫率（28.0%）;日本血吸虫UV-致弱尾蚴单链抗体库的库容量测定为1.9×108,重组率为100%;运用抗原直接菌落挖集法筛选共获得6个SCA66-68kDa阳性克隆,经SDS-PAGE、Western-blot分析结果显示可溶性ScFv获得了正确表达,且与相应抗原SjSCA66-68kDa特异性结合,证实成功获得了特异性抗SjSCA66-68kDa单链抗体。结论成功构建了高效日本血吸虫UV-致弱尾蚴单链抗体库,从该库筛选共获得6个阳性克隆,均能诱导表达SjSCA66-68kDa特异性可溶性单链抗体。     

Effectiveness of synthetic trioxolane OZ78 against Schistosoma japonicum in mice and rabbits

Antischistosomal activities of a synthetic peroxide OZ78 (an ozonide carboxylic acid) against Schistosoma japonicum have been studied in mice and rabbits. Among 132 mice used, 30 of them were infected with 80-100 S. japonicum cercariae for collection of juvenile and adult schistosomes applied in in vitro tests. The remaining 102 mice were infected with 40 schistosome cercariae used for experimental treatment. Other 13 rabbits infected each with 200 schistosome cercariae were treated orally with OZ78 42 days post-infection. Most treated mice and rabbits were sacrificed 4 weeks post-treatment to collect residual schistosomes for evaluation of the drug efficacy. OZ78 and its sodium salt (OZ78-Na salt) 10-60 μg/mL alone exhibited no in vitro effect against day 14, day 21 schistosomula, and day 35 adult schistosomes. But OZ78 and OZ78-Na salt 10 and 20 μg/mL together with hemin 80 μg/mL showed decrease in worm motor activity and severe damage to the worm tegument and intestine, and all worms died within 3 days post-incubation. After infected mice were treated orally with OZ78 at a single dose of 400 mg/kg for 1 day, 34.9% of the worms shifted to the liver. Three and 7 days post-treatment, 100% of the worms were recovered from the liver. Fourteen days post-treatment, 92.3% of the worms still remained in the liver and 7.7% of the worms returned back to the mesenteric veins. Male and female worms shifted to the liver revealed in apparent shrinkage, degeneration of worm body, depigmentation in gut, and disappearance of ova in the uterus of some female worms. Meanwhile, dead worm and dead worm fragments were found in the liver tissues. In mice infected with various stages of schistosomes and treated orally with single OZ78 400 mg/kg, moderate or potential effect of the drug against day 0 (3-h-old worm), day 7, day 14, and day 21 juvenile worms and day 28, day 35 as well as day 42 adult worms were observed, the differences of total or female worm burdens between each treated group and control group were statistically significant (P?相似文献   

2-Cys peroxiredoxins from Schistosoma japonicum: the expression profile and localization in the life cycle

Peroxiredoxin (Prx) is known to be an antioxidant protein that protects the organisms against various oxidative stresses and functions as a signal transductor. Here, we determined the full-length cDNA sequences of three types of Prx from an Asian blood fluke, Schistosoma japonicum: Prx-1, Prx-2 and Prx-3. According to the deduced amino acid sequences, only Prx-3 had a mitochondria-targeting sequence. Using RT-PCR, it was shown that these Prx genes were constitutively expressed in the eggs, cercariae and adult worms of the schistosome. Western blot analysis using antisera specific for each Prx revealed that all the three Prx proteins existed in these developmental stages. By immunolocalization analysis, Prx-1 existed on the surface of a miracidium and in the space between a miracidium and an eggshell. Furthermore, Prx-1 was deposited in the host tissues around the eggs. In adult worms, Prx-1 was not only expressed in the tegument, but also contained in their excretory/secretory products. The surface of the 7 day-schistosomula was stained with anti-Prx-1 antiserum. On the other hand, Prx-2 only existed inside the miracidia in eggs. In addition, Prx-2 was mainly detected in the sub-tegumental tissues, parenchyma, vitelline gland and gut epithelium of the adult worms, but was not detected in the tegument of adults and schistosomula. Taken together with previous reports by other investigators, these data suggest that Prx-1 acts to protect the parasite against the ROS produced by host immune cells, and that Prx-2 plays important roles in intracellular redox signaling and/or in the reduction of ROS generated through the hemoglobinolytic process in the digestive tract.     

Comparison of the cloned genes of the 26- and 28-kilodalton glutathione S-transferases of Schistosoma japonicum and Schistosoma mansoni.

Both Schistosoma japonicum and S. mansoni contain 28- and 26-kDa glutathione S-transferases (GSTs). Despite their immunological cross-reactivity using rabbit antisera, the S. japonicum 28-kDa GST (Sj28) is weakly immunogenic relative to the S. mansoni protein (Sm28) in mouse immunization experiments using GSTs purified from adult worms. The difference in immunogenicity is also observed during schistosome infection in mice. Using surface-labeled living S. japonicum worms, evidence was obtained for a surface location of Sj28 comparable to that reported for the S. mansoni molecule. The nucleotide and deduced amino acid sequences of cDNA clones corresponding to Sj28 and Sm28 were compared. Despite obvious homology (77% identity), differences were found in regions known to contain T epitopes in the S. mansoni protein which may be an explanation for the striking differences in immunogenicity in regard to antibody production in mice. The 26-kDa GSTs of these two parasites (Sj26 and Sm26) are also closely related on the basis of nucleotide and deduced amino acid sequences, there being 82% identity in the putative coding regions. When the amino acid sequences of Sj28 and Sm28 were compared with those of Sj26 and Sm26, the overall sequence identity was approximately 20%. However, a relatively conserved region was identified in otherwise structurally different molecules which may participate in common properties of these enzymes.     

Identification by monoclonal antibody of a major (28 kDa) surface membrane antigen of Schistosoma mansoni

Monoclonal antibody M.1 was generated from mice immunized with membrane enriched extracts of mechanically transformed schistosomula. M.1 bound to the surface membranes of cercariae and young (0-24 h post-transformation) schistosomula but did not bind to older schistosomula or cultured worms. M.1 immunoprecipitated an antigen of approximate molecular weight 27-28 kDa from schistosomula. Experiments using metabolic labeling showed that the antigen was actively synthesized by developing schistosomula. Further M.1 immunoprecipitated a similar 27-28 kDa antigen from membrane-enriched extracts of miracidia, lung and adult worms as well as from schistosomula.     

高效天然分子疫苗免疫猪血清筛选尾蚴抗原的结果分析

采用日本血吸虫天然分子(Schistosoma japonicum immature egg ws-vaccine,SjiEw)免疫猪血清识别日本血吸虫可溶性尾蚴抗原(Soluble cercariae antigen,SCA),以筛选新的具有保护性免疫潜在价值的抗原分子。按常规方法制备日本血吸虫尾蚴抗原。家猪随机分组并分次免疫日本血吸虫天然分子疫苗,制备SjiEw疫苗免疫猪血清,通过蛋白免疫印迹技术分析其与SCA的免疫反应性。结果显示SDS-PAGE中SCA有16条主带。SjiEw疫苗免疫猪血清共筛选6种具免疫学活性的抗原分子,分子量分别为:50、56、66、68、70、85kDa。这些抗原分子的获得为以后的天然分子编码基因工程疫苗的制备奠定基础。     

Further study on mefloquine concerning several aspects in experimental treatment of mice and hamsters infected with <Emphasis Type="Italic">Schistosoma japonicum</Emphasis>

Mefloquine, an antimalarial drug, has been found to be effective against various stages of schistosomes in vivo. The purpose of the study is to explore the in vitro effect of mefloquine against adult and juvenile Schistosoma japonicum and to compare its efficacy with praziquantel. Three-hour-old schistosomula were prepared by penetrating the mouse skin with schistosome cercariae, while schistosomes 7-, 14-, and 35-day-old were collected from mice infected with S. japonicum cercariae for 7, 14, and 35 days by perfusion. Schistosomes were placed to each of 24 wells of a Falcon plate and maintained in Hanks’ balanced salt solution–20% calf serum. Besides observation on the direct in vitro effect of mefloquine and praziquantel, adult worms exposed to mefloquine and praziquantel for 1 and 4 h were transferred to the medium without the drugs and incubated continuously for another 72 h. The reversible effect of mefloquine and praziquantel was assessed by the recovery of the worm motor activity and parasite survival. The minimal effective concentration of mefloquine against adult schistosomes in vitro was 10 μg/mL, which revealed that the worm motor activity was first stimulated, then decreased significantly, followed by bleb formation, focal swelling and elongation of the worm body, cessation of gut peristalsis, and death of 56.3% (18/32) worms within 24–72 h. Similar appearance was seen in the adult worms exposed to higher mefloquine concentration of 20 and 30 μg/mL, but all worms died within 4–24 h. The adult schistosomes exposed to praziquantel 1–30 μg/mL showed fast spasmodic contraction of the worm body, followed by bleb formation along the tegument, feeble movement of oral sucker, and death of a part of males and females 72 h after incubation. When male and female schistosomes exposed to mefloquine 10 and 20 μg/mL for 1 and 4 h were transferred to the medium without the drug, no apparent recovery of worm motor activity and survival was seen. In case of worms exposed to praziquantel at the same concentration for 1 and 4 h before replacement of drug-free medium, a well recovery of worm motor activity, looseness of worm body, and reduction or disappearance of blebs along the tegument were observed. Mefloquine also exhibited in vitro effect against 3-h-old and 7- and 14-day-old schistosomula which was similar to that seen in adult worms, but all or parts of worms showed decrease in motor activity or even death (3-h-old and 7-day-old schistosomula) at a lower mefloquine concentration of 5 μg/mL. In 14 day-old schistosomula exposed to praziquantel 1–30 μg/mL, spasmodic contraction and significant decrease in motor activity of the worm body with movement of oral and ventral suckers were observed, but no death of worm was seen during a 3-day incubation period. The results indicate that in vitro mefloquine exhibits a direct killing effect against adult and juvenile S. japonicum which is different from that of praziquantel. Meanwhile, the juvenile schistosomes are more susceptible to mefloquine than the adult ones. Furthermore, the in vitro effect of mefloquine against adult schistosomes is irreversible, while that of praziquantel is reversible.     

Partial characterization and kinetics of expression of Sm15, aSchistosoma mansoni tegumental antigen

Differential antibody screening of an adultSchistosoma mansoni cDNA expression library constructed in lambda gt11 identified a partial cDNA clone, A70. This cDNA encodes a fusion protein recognized by antibodies raised against highly irradiated schistosomula and adult worm tegumental membranes but not by anti-egg antibodies. Anti-tegumental membrane antisera affinity-purified on the A70 cDNA fusion protein were used for Western blotting analysis and indirect immunofluorescence, resulting in the identification of a 15-kDa protein (Sm15) in the tegument of adult worms. This is one of the principal tegumental antigens recognized by antibodies from mice protectively vaccinated with adult worm tegumental membranes. Sm15 is much smaller than the protein encoded by its gene, suggesting that it results from a highly processed precursor. It was found that Sm15 behaves as an integral membrane protein upon partitioning in Triton X-114 and that it is present in worms of 2 weeks or older but not in schistosomula or miracidia. The affinity-purified antibodies also revealed the presence of a 23-kDa antigen in whole-worm homogenates that is apparently coexpressed with Sm15. The 23-kDa antigen was not found associated with membranes and is probably a soluble protein. A further series of Western blots were undertaken using antibodies affinity-purified from serum raised against schistosomula. In this case, the 23- and 15-kDa products were not recognized, but rather soluble proteins ranging from 45- to 150-kDa were detected in almost all larval stages investigated. The results suggest that the precursor is differentially processed during maturation.     

日本血吸虫完整成虫盐水浸液抗原的化学及免疫学特性

本文报告日本血吸虫完整成虫盐水浸液抗原(ASE)的化学、免疫化学及免疫学性质。实验结果表明ASE中含有蛋白质、糖和类似核酸的物质。它与成虫抗原有相同的抗原成分与虫卵抗原也有共同的决定簇。PAGE结果显示ASE与新鲜成虫经Triton处理后的可溶性部份比较类似.以抗ASE与成虫冰冻切片进行IFA试验的结果证明ASE主要定位于虫的表膜,可以认为ASE主要含有成虫的表膜抗原。本实验中无论用ASE免疫家兔或用抗ASE-γ-G被动免疫小鼠都未能诱导动物产生对攻击感染的抵抗力;但抗ASE在有补体的参与下可在体外促使白细胞粘附在童虫的表面,产生对童虫的攻击作用。     

A cDNA clone encoding part of the major 25000-dalton surface membrane antigen of adultSchistosoma mansoni

Immunoscreening of an adultSchistosoma mansoni cDNA expression library, using antibodies raised against purified adult worm tegumental surface membranes, identified a recombinant clone containing a 141-bp insert. Antibodies raised against the recombinant antigen bound specifically to the tegument of adult worms and immunoprecipitated the major 25000-dalton surface membrane antigen as well as a 22000-dalton nascent polypeptide generated by cell-free translation of adultS. mansoni mRNA. The mature 25000-dalton antigen was found to be precipitated by antibodies from infected mice, rats and humans.Abbreviations IPTG isopropylthio-beta-galactoside - SDS sodium dodecyl sulphate - PAGE polyacrylamide gel electrophoresis - PMSF phenylmethylsulphonyl fluoride - FTTC fluorescein isothiocyanate - VMS serum from mice vaccinated with highly irradiated cercariae - CMS serum from chronically infected mice - Ram rabbit anti-membrane serum - IRS infected rat serum     

Identification of a multispecific lipoprotein receptor in adult Schistosoma japonicum by ligand blotting analyses

A 43-kDa putative lipoprotein receptor (Sj43) of adult Schistosoma japonicum worms has been identified using ligand blotting techniques. Single and two dimensional electrophoretic analyses showed that Sj43 consisted of a single acidic polypeptide with multiple lipoprotein specificity. The molecule bound 125I-labelled low-density (apo-B), very low-density or high-density (apo-A and/or apo-C) lipoproteins from different mammalian hosts that are permissive to S. japonicum infection, but did not bind mouse apo-A containing lipoprotein. The binding of 125I-labelled lipoprotein to Sj43 could be inhibited by unlabelled human LDL, EDTA or Suramin, or by chemical modification of lipoprotein lysine or arginine residues. Sj43 was localised at the parasite's tegument and gut lining.     

Expression in Escherichia coli of two Schistosoma mansoni genes that encode major antigens recognized by immune mice

Two clones which contain genes encoding Schistosoma mansoni proteins recognized by immune mouse sera were chosen from cDNA lambda gt11 expression vector library by preselecting clones from the library with rabbit antisera against adult worm phosphate-buffered saline (PBS)-soluble antigens. One clone, MAC 182, codes for part of a Mr 70 000 protein; the other clone, MAC 184, codes for a Mr 27 000 protein. The insert sizes of MAC 182 and MAC 184 are 400 bp and 800 bp, respectively. Both clones express S. mansoni beta-galactosidase fusion proteins as products of the construct. Antibodies from either chronically infected mice or mice vaccinated with irradiated cercariae recognize the MAC 182 fusion protein (MAC 182fp) but not the MAC 184 fusion protein (MAC 184fp). Rabbit antibodies prepared against MAC 182fp immunoprecipitate a Mr 70 000 in vitro translation product from adult mRNA and react in Western blot with a corresponding Mr 70 000 protein present in eggs, cercariae and adult worms but absent in schistosomula. Although the MAC 184fp is not recognized directly by chronic infection or vaccinated mouse antibodies, antisera prepared against the purified fusion protein immunoprecipitate a Mr 27 000 in vitro translation product which also reacts with mouse chronic infection sera. The same Mr 27 000 protein appears to be present in eggs, cercariae, schistosomula and adults as determined by Western blots with rabbit antisera against the MAC 184fp. These results suggest that the S. mansoni polypeptide encoded by the MAC 184 gene, when expressed within a fusion protein, fails to present epitopes normally recognized during natural infection. We propose that these epitopes are conformationally determined and are destroyed when the MAC 184 protein is expressed within beta-galactosidase. This abrogation of conformational epitopes may explain the failure of antibodies from chronically infected or vaccinated mice and rabbits to effectively recognize gene products of certain lambda gt11-fusion protein clones.     

Further characterisation of the Schistosoma japonicum protein Sj23, a target antigen of an immunodiagnostic monoclonal antibody.

Sj23, the 23-kDa target antigen in Schistosoma japonicum adult worms of the hybridoma monoclonal antibody (mAb) I-134, has been identified and cloned from cDNA libraries, mAb I-134 has been successfully used in immunodiagnostic assays to detect S. japonicum infection in Philippine patients. Sequence analysis has shown that Sj23 is the homologue, with 84% amino acid identity, of Sm23, a 23-kDa molecule from S. mansoni worms previously described from our laboratory. The domain structures of Sj23 and Sm23 are strikingly similar to the human membrane proteins ME491, CD37, CD53 and TAPA-1, which may suggest a functional role for the schistosome molecules in cellular proliferation.     

日本血吸虫24-26KD和90KD蛋白质“靶抗原”的抗原性

作者从日本血吸虫成虫抽提出两种国际公认在诱导保护性免疫力中起重要作用的24-26KD和90KD蛋白质“靶抗原”,用以免疫小鼠.结果表明上述两种“靶抗原”具有明显的抗原性.表现在(1)上述“靶抗原”免疫后可刺激宿主血清IgM升高,特别是IgG中的IgG1明显升高;(2)免疫鼠血清中的抗体能在成虫的表皮和实质层定位;(3)以ELISA和IFA检测免疫血清中的抗体水平时,均表现特异性抗体滴度明显增高(ELISA:90KD 1:5/20,24-26KD/:640;IFA:90KD1:80～1:2560,24-26KD1:40～1:160);(4)免疫血清中均存在着针对上述两种“靶抗原”的特异性抗体,免疫印渍试验结果进一步表明上述“靶抗原”免疫鼠血清中抗体均能特异地分别识别日本血吸虫抗原中分子量90KD和24-26KD的抗原决定簇。     

Characterization of a stage-specific Mr16000 schistosomular surface glycoprotein antigen of Schistosoma mansoni.

A 16 kDa Schistosoma mansoni schistosomular surface antigen (Sm16) was originally described as the target of a passively protective mAb (B3A). It appeared on the schistosomular surface after transformation of cercariae and was uniquely recognised by sera from animals exposed to attenuated cercariae. In this work sequential extractions of schistosomula with Triton X-114 and sodium dodecyl sulphate showed Sm16 to be an integral membrane structure which did not appear to be glycosylphosphatidylinositol-anchored as judged by experiments using phosphatidyl inositol-specific phospholipase C. The antigen was strongly reactive in Western blotting with rabbit irradiated vaccine sera. Sm16 was demonstrated in the hepatopancreas of S. mansoni-infected snails and was equally abundant in cercariae and mechanically- transformed schistosomula but was undetected in liver stage worms or eggs. Immunoelectron microscopy showed Sm16 to be localised, in cercariae, to what are believed to be subtegumental cell bodies packed with membraneous vesicles. Treatment with proteases and with sodium metaperiodate showed Sm16 to be a glycoprotein of which the epitope recognised by B3A was periodate sensitive. Two-dimensional electrophoresis gave a PI of 6. Neither the size or the recognition by B3A was affected by treatment with N-glycosidase F, endoglycosidase F or endo-alpha-N-acetylgalactosaminidase. Western blotting using a wide range of biotinylated lectins showed recognition only by peanut agglutinin and Ricinus communis agglutinin II (ricin). It is concluded that Sm16 has antigenic surface-exposed O-linked complex oligosaccharides which lack mannose/glucose, GlcNAc, L-fucose and sialic acid but contain terminal Gal beta (1-3) GalNAc and/or galactose.     

Surface proteins of Schistosoma mansoni and their expression during morphogenesis

Surface components of Schistosoma mansoni have been identified by lactoperoxidase-catalyzed iodination. Cercariae have a simple labeling pattern in comparison to schis- tosomula. Transformation of cercariae to schistosomula results in the loss of a low molecular weight material which may be the glycocalyx, and the appearance of many more labeled proteins. Mechanical conversion of cercariae to schistosomula requires subsequent incubation at 37 °C for more than 1 h to give the full surface-labeling pattern of schistosomula. The majority of proteins found on schistosomula appear to be present throughout the remaining part of the developmental cycle, although adult male worms had only low levels of these antigens, and female worms had virtually no detectable surface antigens. The low level of expression of schistosome antigen could be caused by adsorbed host antigen, although no evidence for adsorbed host protein was found, or by a reduced level of antigens present on the worm surface. The low level of schistosome antigen could have a role in the resistance of adult worms to the host's immune response.