Mass Spectrometry Identifies Taenia solium Proteins in Sera of Patients With and Without Parenchymal Neurocysticercosis

Neurocysticercosis (NCC), a major cause of global acquired epilepsy, results from Taenia solium larval brain infection. T. solium adult worms release large numbers of infective eggs into the environment contributing to high levels of exposure in endemic areas. This study identifies T. solium proteins in the sera of individuals with and without NCC using mass spectrometry to examine exposure in endemic regions. Forty-seven patients (18-51 years), 24 parenchymal NCC (pNCC), 8 epilepsy of unknown aetiology, 7 glioma, 8 brain tuberculoma, and 7 healthy volunteers were studied. Trypsin digested sera were subject to liquid chromatography-tandem mass spectrometry and spectra of 375-1700 m/z matched against T. solium WormBase ParaSite database with MaxQuant software to identify T. solium proteins. Three hundred and nineteen T. solium proteins were identified in 87.5% of pNCC and 56.6% of non-NCC subjects. Three hundred and four proteins were exclusive to pNCC sera, seven to non-NCC sera and eight in both. Ten percent, exhibiting immune-modulatory properties, originated from the oncosphere and cyst vesicular fluid. In conclusion, in endemic regions, T. solium proteins are detected in sera of individuals with and without pNCC. The immunomodulatory nature of these proteins may influence susceptibility and course of infection.

Advances in Serological Diagnosis of Taenia solium Neurocysticercosis in Korea

Cysticercosis, a parasitic disease caused by Taenia solium metacestode (TsM), has a major global public health impact in terms of disability-adjusted life years. The parasite preferentially infects subcutaneous tissue, but may invade the central nervous system, resulting in neurocysticercosis (NC). NC is an important neglected tropical disease and an emerging disease in industrialized countries due to immigration from endemic areas. The prevalence of taeniasis in Korea declined from 0.3%–12.7% during the 1970s to below 0.02% since the 2000s. A survey conducted from 1993 to 2006 revealed that the percentage of tested samples with high levels of specific anti-TsM antibody declined from 8.3% to 2.2%, suggesting the continuing occurrence of NC in Korea. Modern imaging modalities have substantially improved the diagnostic accuracy of NC, and recent advances in the molecular biochemical characterization of the TsM cyst fluid proteome also significantly strengthened NC serodiagnosis. Two glycoproteins of 150 and 120 kDa that induce strong antibody responses against sera from patients with active-stage NC have been elucidated. The 150 kDa protein showed hydrophobic-ligand binding activities and might be critically involved in the acquisition of host-derived lipid molecules. Fasciclin and endophilin B1, both of which play roles in the homeostatic functions of TsM, showed fairly high antibody responses against calcified NC cases. NC is now controllable and manageable. Further studies should focus on controlling late-onset intractable seizures and serological diagnosis of NC patients infected with few worms. This article briefly overviews diagnostic approaches and discusses current issues relating to NC serodiagnosis.

Fasciclin-calcareous corpuscle binary complex mediated protein-protein interactions in Taenia solium metacestode

Background

Neurocysticercosis (NC) caused by Taenia solium metacestode (TsM) is a serious neurological disease of global concern. Diverse bioactive molecules involved in the long-term survival of TsM might contribute to disease progression. Fasciclin (Fas) is an extracellular protein that mediates adhesion, migration and differentiation of cells by interacting with other molecules. We hypothesized that TsMFas might bind to calcareous corpuscle (CC) through its adhesive property and participate in crucial protein-protein interactions, thus contributing to the creation of a symbiotic interactome network.

Methods

Two paralogous TsMFas (TsMFas1 and TsMFas2) were isolated, and their molecular properties were characterized. The co-localization pattern of TsMFas1 and TsMFas2 with CC was determined. CC-TsMFas binary complex was generated by incubating CC with recombinant proteins (rTsMFas1 and 2). In vitro binding assay of CC-rTsMFas1 or CC-rTsMFas2 binary complex with TsM cellular proteins extracted from scolex and neck was conducted. Their binding partners were identified through proteomic analysis. Integrated protein-protein interaction networks were established.

Results

TsMFas1 (6072 bp long) was composed of 15 exons (841 amino acid polypeptide) interrupted by 14 introns. TsMFas2 (5201 bp long) comprised of 11 exons (597 amino acids) and 10 intervening introns. These proteins displayed 22% amino acid sequence identity to each other, but tightly conserved Fas-related domains. Several isoforms of Fas1 and Fas2 proteins might have been expressed through post-translational modifications. They showed adhesion activity with other cells. TsMFas proteins were largely distributed in parenchymal regions of the scolex and bladder wall. These molecules were co-localized with CC, a unique organelle found in platyhelminths. Subsequent proteome analysis of CC-Fas binary complex mediated protein-protein interactions revealed seven protein ligands in the TsM cellular proteins. Their functions were mainly segregated into carbohydrate metabolism (enolase, phosphoenolpyruvate carboxykinase, phosphoglycerate kinase and glyceraldehyde 3-phosphate dehydrogenase) and cytoskeleton/cellular motility (actin, paramyosin and innexin nuc-9). Those proteins had direct (physical) and/or indirect (functional) relationships along with their biochemical properties and biological roles.

Conclusion

Protein repertoires strongly suggest that TsMFas and CC may symbiotically mediate protein-protein interactions during biological processes to maintain efficacious homeostatic functions and ensure the prolonged survival of TsM in the host.

Electronic supplementary material

The online version of this article (10.1186/s13071-017-2359-2) contains supplementary material, which is available to authorized users.

Spatiotemporal Expression Patterns and Antibody Reactivity of Taeniidae Endophilin B1

Larval Taeniidae, such as metacestodes of Taenia solium, Echinococcus granulosus, and Echinococcus multilocularis, produce chronic and fatal helminthic diseases. Proper identification of these zoonotic cestodiases is often challenging and is hampered in some clinical settings. Endophilin B1 plays critical roles in the maintenance of membrane contours and endocytosis. We isolated proteins homologous to endophilin B1 from T. solium, Taenia saginata, and Taenia asiatica The three Taeniidae endophilin B1 proteins shared 92.9 to 96.6% sequence identity. They harbored a Bin1/amphiphysin/Rvs (BAR) domain and residues for a dimeric interface but lacked a SRC homology 3 (SH3) domain. Endophilin B1 showed a unique immunological profile and was abundantly expressed in the tegumental syncytium of Taeniidae metacestodes and adults. Bacterially expressed recombinant T. solium endophilin B1 (rTsMEndoB1) demonstrated a sensitivity of 79.7% (345/433 cases) for serodiagnosis of larval Taeniidae infections. The protein showed strong immune recognition patterns against sera from patients with chronic neurocysticercosis, cystic echinococcosis, or advanced-stage alveolar echinococcosis. Adult Taeniidae infections exhibited moderate degrees of positive antibody responses (65.7% [23/35 samples]). rTsMEndoB1 showed some cross-reactivity with sera from patients infected with Diphyllobothriidae (23.6% [25/106 samples]) but not with sera from patients with other parasitic diseases or normal controls. The specificity was 91.7% (256/301 samples). The positive and negative predictive values were 93.6% and 73.4%, respectively. Our results demonstrate that Taeniidae endophilin B1 may be involved in the control of membrane dynamics, thus contributing to shaping and maintaining the tegumental curvature. rTsMEndoB1 may be useful for large-scale screening, as well as for individual diagnosis and follow-up surveillance of Taeniidae infections.

Taenia solium metacestode fasciclin-like protein is reactive with sera of chronic neurocysticercosis

OBJECTIVES

Neurocysticercosis (NC), an infection of the central nervous system with Taenia solium metacestodes (TsM), invokes a formidable neurological disease. A bundle of antigens is applicable for serodiagnosis of active cases, while they demonstrate fairly low reactivity against sera of chronic NC. Identification of sensitive biomarkers for chronic NC is critical for appropriate management of patients.

METHODS

Proteome analysis revealed several isoforms of 65- and 83-kDa TsM fasciclin-like proteins (TsMFas) to be highly reactive with sera of chronic NC. A cDNA encoding one of the 83-kDa TsMFas (TsMFas1) was isolated from a cDNA library. We expressed a recombinant protein (rTsMFas1) and evaluated its diagnostic potential employing sera from chronic NC (n = 80), tissue-invasive cestodiases (n = 169) and trematodiases (n = 80) and those of normal controls (n = 50).

RESULTS

Secretory TsMFas1 was composed of 766 amino acid polypeptide and harboured fasciclin and fasciclin-superfamily domains. The protein was constitutively expressed in metacestode and adult stages, with preferential locality in the scolex. Bacterially expressed rTsMFas1 exhibited 78.8% sensitivity (63/80 cases) and 93% specificity (278/299 samples) in diagnosing chronic NC. Some cross-reactivity was observed with sera of cystic echinococcosis (10/56, 17.8%) and sparganosis (4/50, 8%). Positive and negative predictive values were 75% and 95.5%, respectively.

CONCLUSION

TsM fasciclin-like protein may be useful for differential diagnosis of chronic NC in clinical settings, especially where both NC and other infectious cerebral granulomatoses are prevalent.

Characterization of hydrophobic-ligand-binding proteins of Taenia solium that are expressed specifically in the adult stage

Taenia solium, a causative agent of taeniasis and cysticercosis, has evolved a repertoire of lipid uptake mechanisms. Proteome analysis of T. solium excretory-secretory products (TsESP) identified 10 kDa proteins displaying significant sequence identity with cestode hydrophobic-ligand-binding-proteins (HLBPs). Two distinct 362- and 352-bp-long cDNAs encoding 264- and 258-bp-long open reading frames (87 and 85 amino acid polypeptides) were isolated by mining the T. solium expressed sequence tags and a cDNA library screening (TsHLBP1 and TsHLBP2; 94% sequence identity). They clustered into the same clade with those found in Moniezia expansa and Hymenolepis diminuta. Genomic structure analysis revealed that these genes might have originated from a common ancestor. Both the crude TsESP and bacterially expressed recombinant proteins exhibited binding activity toward 1-anilinonaphthalene-8-sulfonic acid (1,8-ANS), which was competitively inhibited by oleic acid. The proteins also bound to cis-parinaric acid (cPnA) and 16-(9-anthroyloxy) palmitic acid (16-AP), but showed no binding activity against 11-[(5-dimethylaminonaphthalene-1-sulfonyl) amino] undecanoic acid (DAUDA) and dansyl-DL-α-aminocaprylic acid (DACA). Unsaturated fatty acids (FAs) showed greater affinity than saturated FAs. The proteins were specifically expressed in adult worms throughout the strobila. The TsHLBPs might be involved in uptake and/or sequestration of hydrophobic molecules provided by their hosts, thus contributing to host-parasite interface interrelationships.

Spinal cysticercosis mimicking a tumor in a pediatric patient

Parasitic infections of the central nervous system (CNS) occur mostly in underdeveloped regions of the world. Neurocysticercosis (NC) occurs when the larval form of the T. solium tapeworm invades the CNS. Spinal cysticercosis is an extremely rare type of NC and occurs when the cyst occupies the subarachnoid space of the spinal column. Previous cases have been successfully treated through both surgical and medical means. The current case describes the symptoms, diagnosis, and treatment of a patient with this extremely uncommon manifestation of neurocysticercosis.

Paralogous proteins comprising the 150 kDa hydrophobic-ligand-binding-protein complex of the Taenia solium metacestode have evolved non-overlapped binding affinities toward fatty acid analogs

We previously identified a hydrophobic-ligand-binding protein (HLBP) of the Taenia solium metacestode (TsM), which might be involved in the uptake of fatty acids (FAs) from host environments. The TsM 150kDa HLBP was a hetero-oligomeric complex composed of multiple 7kDa (RS1) and 10kDa (CyDA, b1 and m13h) subunits, and displayed a wide spectrum of binding affinities toward various FA analogs. In this study, we analysed biochemical properties and phylogenetic relationships of the individual subunits. Despite the low sequence identity (average 26.5%), these subunit proteins conserved an α-helix-rich structural domain and the first introns inserted in each of the respective chromosomal genes were found to be orthologous to one another, suggesting their common evolutionary origin. The recombinant RS1 protein bound strongly to all of the FA analogs examined including 11-[(5-dimethylaminonaphthalene-1-sulfonyl)amino]undecanoic acid (DAUDA), but not to 16-(9-anthroyloxy)palmitic acid (16-AP). The interactive binding between RS1 and FA analogs was specifically interfered with by the addition of non-fluorescent FA molecules or antibodies specific to the 150kDa protein. Conversely, the 10kDa members reacted only with the palmitic acid-derived 16-AP, whose interactive force was strengthened by the presence of other FA molecules. The use of mutagenic RS1 proteins demonstrated that a structural/electrostatic integrity around the second α-helix, rather than the conventional Trp residue, was the major factor governing the hydrophobic interaction. The 7 and 10kDa proteins exhibited distinctive immunoreactive patterns against sera from neurocysticercosis patients. These collective data suggest that the paralogous protein family have gained diverse functions during their evolution, to ensure the maintenance of metabolic homeostasis and survival of TsMs in hostile host environments.