Immunoblot analysis of a 10 kDa antigen in cyst fluid of Taenia solium metacestodes

High prevalence of neurocysticercosis among patients with epilepsy in a tertiary care hospital of Assam, India

Background:

Neurocysticercosis (NCC) is a parasitic disease of the central nervous system, which is caused by the metacestode of the pork tapeworm, Taenia solium. The present unicentric, hospital-based, cross-sectional study was undertaken to assess the contribution of NCC as a cause of active epilepsy among patients attending a tertiary health care center in Assam, India.

Materials and Methods:

Over a period of 2 years, 152 active epilepsy patients were investigated based on clinical, epidemiological, neuroimaging (contrast-enhanced computerized tomography), and immunological techniques to establish the diagnosis of NCC. A precoded questionnaire was administered to patients and/or guardians to collect detailed medical history.

Results:

Ninety-three cases (61.2%) fulfilled either definitive or probable diagnostic criteria for NCC. Anti-cysticercus immunoglobulin G antibodies were detected by ELISA and enzyme electro-immune transfer blot in 69 (45.4%) active epilepsy patients. Seroprevalence was higher in males, 46.6% (54/116); than in females, 41.7% (15/36), and increased significantly with age; peaking in the 20–39 years age group (36/76; χ² = 5.64; P = 0.02). Among the seropositive cases, 54 (78.3%) were diagnosed with NCC. A significantly higher number of seropositive individuals were diagnosed with NCC in the 20–39 years age group as compared to the 40 years and above age group (χ² = 6.28; P = 0.01). The association between seropositivity for NCC, and the number of lesions in the brain was statistically significant (χ² = −8.33; P = 0.003).

Conclusions:

This study indicates that NCC is a major cause of active epilepsy in Assam. A high prevalence of pediatric NCC is also a major concern.

Neurocysticercosis in patients with active epilepsy in the tea garden community of Assam, Northeast India

Neurocysticercosis is a significant cause of epilepsy in the tropics. The present cross-sectional survey was conducted in the socioeconomically backward tea garden community of Assam to gauge the prevalence of neurocysticercosis in patients with active epilepsy and to determine the associated risk factors. In a door to door survey, a total of 1028 individuals from every fifth household of the study Teagarden were enrolled to identify self-reported seizure cases, followed by a neurological examination to confirm the diagnosis of active epilepsy. Patients with active epilepsy underwent clinical, epidemiological, neuroimaging (contrast-enhanced computerized tomography) and immunological evaluations to establish the diagnosis of neurocysticercosis. Clinically confirmed 53 (5.16%) active epilepsy were identified; 45 agreed to further assessment for neurocysticercosis and 19 (42.2%) cases fulfilled either definitive or probable diagnostic criteria for neurocysticercosis. Patients with epilepsy due to neurocysticercosis were more likely to suffer from taeniasis (20.0% vs 0.0%), rear pigs (57.9% vs 15.4%) or have pigs in their neighbourhood (78.9% vs 53.8%) relative to epileptic patients without neurocysticercosis. Rearing pigs (aOR 14.35, 95% CI: 3.98–51.75) or having pigs in the neighbourhood (aOR 12.34, 95% CI: 2.53–60.31) were independent risk factors of neurocysticercosis. In this community, the prevalence of taeniasis (adult worm infection) was 6.6% based on microscopy. The study reports a high prevalence of active epilepsy in the tea garden community of Assam and neurocysticercosis as its primary cause. The high prevalence of taeniasis is also a significant concern.

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.

Co-occurrence of swine cysticercosis due to Taenia solium and Taenia hydatigena in ethnic minority villages at the Thai-Myanmar border

As part of the international joint projects working towards the control of taeniosis/cysticercosis in Asia Pacific, epidemiological studies on Taenia solium cysticercosis have been carried out in high-incidence populations, such as minority groups in Thailand. To assess the epidemiology of cysticercotic infections in pigs in the hill-tribe minority villages (Karen) in Tak province, Thailand, we conducted serological screening and necropsies. The patterns of antibody response to T. solium antigens were then investigated using immunoblot assays. Of the 188 pig serum samples tested for antibody responses to partially purified low-molecular-weight antigens of T. solium cyst fluid, positive responses were detected in 37 samples (19.7%). Based on these results, 16 pigs (10 seropositive and 6 seronegative) were necropsied for investigation of cysticerci and intestinal parasites. All seropositive pigs were coinfected with both T. solium and Taenia hydatigena cysticerci, except one, which was infected with T. hydatigena alone. Three of the six seronegative pigs were confirmed to be infected with T. hydatigena. Pigs infected with T. solium showed much stronger antibody responses than those infected with T. hydatigena. Our results demonstrate the co-occurrence of two swine cysticercoses due to T. solium and T. hydatigena in the studied areas. This study also reveals the importance of direct confirmation of the presence of cysticerci by necropsy after serological screening. In addition to the prevalence of swine cysticercosis in these endemic areas, our findings also reveal potential implications for the development of serological diagnostic assays for swine cysticercosis.

Taenia solium metacestode preparation in rural areas of sub-Saharan Africa: a source for diagnosis and research on cysticercosis

BACKGROUND

Taenia solium metacestodes/cysts obtained from pig carcasses constitute a primary source for diagnostic tools used for the detection of human cysticercosis. Data on T. solium cyst preparation in Africa is still scarce but required to establish independent reference laboratories.

OBJECTIVES

The aim of the present study is a) to present the likely yield of T. solium cyst material by the use of two different preparation methods in the field and b) to investigate its suitability for immunodiagnosis of human cysticercosis.

METHODS

In Zambia, Uganda and Tanzania 670 pigs were screened for T. solium infection. Cysts were prepared by 'shaking method' and 'washing method'. Generated crude antigens were applied in a standard western blot assay.

RESULTS

46 out of 670 pigs (6.9%) were found positive for T. solium (Zambia: 12/367, 3.3%; Uganda: 11/217, 5.1%; Tanzania 23/86, 26.7%). Mean values of 77.7 ml whole cysts, 61.8 ml scolices/membranes and 10.9 ml cyst fluid were obtained per pig. Suitability of collected material for the use as crude antigen and molecular diagnostic techniques was demonstrated.

CONCLUSION

This study clearly shows that T. solium cyst preparation in African settings by simple field methods constitutes an effective way to obtain high quality material as source for diagnostic tools and research purposes.

Comparative profile of circulating antigenic peptides in CSF, serum & urine from patients with neurocysticercosis diagnosed by immunoblotting

Traditionally serum and/or CSF specimens have been used for detection of either specific antibodies or antigens as a supportive diagnosis of NCC. However, in recent days, much interest has been shown employing noninvasive specimens such as urine. In our study, we identified and compared a profile of circulating antigenic peptides of parasite origin in three different body fluids (CSF, serum and urine) obtained from confirmed NCC cases and control subjects. The circulating antigenic peptides were resolved by SDS-PAGE and subjected to immunoblotting. For confirmation of their origin as parasite somatic or excretory secretory (ES) material, immunoreactivity was tested employing affinity purified polyclonal Taenia solium metacestode anti-somatic or ES antibodies, respectively. Only lower molecular weight antigenic peptides were found circulating in urine in contrast to serum and CSF specimens. Few somatic peptides were identified to be 100% specific for NCC (19·5 kDa in all three specimens; 131, 70 kDa in CSF and serum only; 128 kDa in CSF only). Similarly, the specific ES peptides detected were 32 kDa (in all three specimens), 16·5 kDa (in serum and CSF only), and 15 kDa (urine only). A test format detecting either one or more of these specific peptides would enhance the sensitivity in diagnosis of NCC.

Cysticercus cellulosae antigens in the serodiagnosis of neurocysticercosis

Neurocysticercosis (NCC) is difficult to diagnose clinically because of its varied clinical presentation. However, an accurate diagnosis is possible only after suspicion on epidemiological grounds, proper interpretation of the clinical data, analysis of the findings on imaging studies, and specific immunological tests on the serum and cerebrospinal fluid (CSF). The diagnosis of NCC by any single parameter thus continues to remain difficult. In the past, detection of NCC was based on autopsy studies and histological confirmation. In recent times, the advent of imaging methods such as computed tomography and magnetic resonance imaging have provided excellent non-invasive tools for easy detection of NCC. Nevertheless, an imaging technique of the brain, although useful, is not considered as a gold standard for the diagnosis of NCC. Serological tests are being increasingly used in adjunct with imaging techniques, to aid the diagnosis of NCC. Immunodiagnostic techniques include detection methods for specific antibodies and for circulating parasite antigens in the serum and CSF. Currently, many of the immunodiagnostic tests, including the enzyme-linked immunosorbent assay and enzyme immunotransfer blot, use purified native antigens for the immunodiagnosis of NCC. Nevertheless, the main problem with the use of native cysticercal antigens is that the native proteins often show cross reactions with sera from humans infected with other parasites. The preparation of native antigens also demand a constant supply of parasitic material from the intermediate host pig. In order to overcome the problems in using native antigens, the recombinant antigens or synthetic peptides, which can be produced under stable conditions, are being evaluated for the serodiagnosis of NCC.

Immunological and molecular diagnosis of cysticercosis

Cysticercosis, the infection with the larval stage of Taenia solium, is a cause of neurological symptoms including seizures, affecting the quality of life of patients and their families. Diagnosis focuses on brain imaging and serological tests are mostly used as confirmatory tools. Most cases, however, occur in poor endemic areas, where both kinds of diagnostic tools are poorly available. Development of point of care diagnostic tests is one of the most important priorities for cysticercosis researches today. The ideal point of care test would require detection of viable cysticercosis and hopefully identify cases with severe or progressive forms of neurocysticercosis, leading to referral of the patient for specialized medical attention. This manuscript describes the evolution of the serological diagnosis of cysticercosis over time, and the characteristics of the most common currently available tools, their advantages and disadvantages, and their potential use in future diagnostic tests.

Immunodiagnosis of CNS parasitic infections

The nature of many parasitic infections of the central nervous system (CNS) requires immunodiagnosis to confirm presumptive diagnoses. The CNS is the primary site of parasite infection for some parasitic organisms and for others, neurological infection occurs only in immunocompromised hosts. Still other parasites cause ectopic infections of the CNS and occur very rarely. This review concentrates on laboratory diagnosis of diseases that are caused by parasites with a primary predilection for the CNS. Emphasis is placed on laboratory diagnostic methods that are used and suitable for clinical diagnosis, rather than a comprehensive review of all the experimental methods that have been reported in the literature. Immunodiagnosis is not appropriate for the diagnosis of all parasitic infections of the CNS; in those cases, alternative diagnostic methods are presented, but not discussed in detail. In some instances potential new antigens or methods are presented, particularly if adoption of these methods is expected in the near future.

2D-PAGE analysis of Taenia solium metacestode 10-30 kDa antigens for the serodiagnosis of neurocysticercosis in children

Neurocysticercosis (NCC) caused by T. solium metacestode is an increasingly important health issue in Indian children. The sensitivity and specificity of available serological techniques were low in case of single cysticercus granuloma cases which is a more common feature in Indian patients who are children. Serum samples were collected from 13 clinically and radiologically suggestive NCC children and seropositive by ELISA, 25 clinically and radiologically suggestive NCC children and seronegative by ELISA and 25 control subjects. The 10-30 kDa antigens of T. solium metacestode were subjected to 2-dimensional gel electrophoresis (2D-PAGE) followed by enzyme-linked immunoelectrotransfer blot (EITB) assay to detect antibody in serum. Analysis of 10-30 kDa antigenic fraction 2D-PAGE map showed 31 proteins between 10 and ≤28 kDa and innumerable proteins between >28 and 30 kDa with the Isoelectric point of 3-10. All the 13 (100%) NCC seropositive and 15 (60%) out of 25 NCC seronegative samples were reactive with 2D fraction antigens. In the control group, none of the serum was reactive except 2 hydatid samples (92% specificity). The sensitivity and specificity of 2D-PAGE EITB assay were significantly higher than the ELISA which is the routine diagnostic method used in the endemic countries for the serodiagnosis of neurocysticercosis.

Serodiagnostic reliability of single-step enriched low-molecular weight proteins of Taenia solium metacestode of American and Asian isolates

The low-molecular weight proteins (LMWPs) of Taenia solium metacestode (TsM) constituted pertinent serodiagnostic antigens for cysticercosis. We established a novel single-step purification of the LMWPs from TsM cyst fluid (CF). When the CF was precipitated with trichloroacetic acid/acetone mixture at the final concentrations of 5 and 50%, most LMWPs (ranging 7-38kDa) remained in the supernatant fraction. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblot analyses revealed that the LMWPs consisted mainly with the previously reported subunit proteins of the 120- and 150-kDa antigen complexes. Serum samples from neurocysticercosis (NC) and other helminthic infections, as well as those from healthy controls were tested by both immunoblotting and micro-ELISA. In 135 cases of active stage NC patients, 132 cases (97.7%) showed positive reactions. Serum samples from other helminthic diseases (n=125) and healthy controls (n=100) exhibited no positive reactions except for cystic echinococcosis, of which 12% (3/25 cases) exhibited low levels of cross-reactivity. The LMWPs from different geographical regions (Korea and Mexico) showed diagnostic sensitivity and specificity of 97.7% and 98.7% against active stage NC. Our single-step separation method for the LMWPs provided excellent performance with easy applicability and high reproducibility, which has a great benefit for preparation of potent antigen in endemic areas.

A recombinant chimeric antigen toward a standardized serodiagnosis of Taenia solium neurocysticercosis

Neurocysticercosis (NC) invokes formidable neurological problems worldwide. Previous proteomic analyses revealed most of the low-molecular-weight proteins might derive from two macromolecules of 120 kDa (consisting of 14-38 kDa subunits) and 150 kDa (7-15 kDa subunits) of Taenia solium metacestode (TsM) cyst fluid (CF). We characterized serological properties of these two proteins and established an immunopotent chimera. The 120 and 150 kDa proteins harbored 54-81 and 94-98% of the antibody-binding activity of the crude CF with minimal antigenic cross-reactivity to each other. The expression and immune recognition of the 150 kDa subunits were relatively constant, regardless of the different geographical origins of the CF collected, while those of the 120 kDa subunits varied by their origins (Asia vs. America). We cloned four representative proteins (one from the 120 kDa and three from the 150 kDa) that showed different epitope specificities, generated a chimera, and demonstrated that this regimen may bolster serodiagnostic reliability. Overall sensitivity and specificity, against sera from active-/mixed-stage NC and those from other infections, and healthy-controls, were determined to be 97.5% (156/160 samples) and 97.8% (265/271 cases). Patient sera from adult taeniases, sparganosis, and fascioliasis showed weak cross-reactions. Micro-ELISA showed similar results. This chimera may prove useful in the construction of standardized platform for NC serodiagnosis.

Application of Toxocara canis excretory-secretory antigens and IgG subclass antibodies (IgG1-4) in serodiagnostic assays of human toxocariasis

A major problem in the serodiagnosis of human toxocariasis in tropical countries is cross-reaction with antibodies to other helminthic diseases and a lack of sensitivity. The majority of tests currently available use total IgG and, in this study, the use of peroxidase-conjugated anti-human IgG subclass antibodies (IgG1-4) was compared with total IgG for the diagnosis of human toxocariasis by using Toxocara excretory-secretory (TES) antigens in an enzyme-linked immunosorbent assay (ELISA) format. All four IgG subclass antibodies gave approximately 10-fold increases in optical density (OD) values for 50 toxocariasis patients compared to 29 healthy normals; this was significantly greater than the approximate doubling of OD values seen in the total IgG-ELISA format. IgG2 gave by far the greatest sensitivity (values: IgG, 50%; IgG1, 60%; IgG2, 98%; IgG3, 78%; IgG4, 64%). Significant cross-reactivity using all IgG subclasses in the TES ELISA was seen with 141 serum samples from patients with 10 other helminthic infections. However, IgG3 gave the best specificity (values: IgG, 73%; IgG1, 76%; IgG2, 71%; IgG3, 81%; IgG4, 71%). Thus, of the IgG subclass antibodies, IgG2 appeared best and employing this subclass can improve the serodiagnosis of human toxocariasis since it recognises carbohydrate epitopes of TES antigens.

The immune response in Taenia solium cysticercosis: protection and injury

This article reviews current knowledge on the innate and acquired immune responses in human Taenia solium neurocysticercosis, highlighting the conditions that appear to be favourable for the survival or destruction of the parasite and for the benefit or injury to its host.

Isolation of a 14 kDa antigen from Taenia solium cyst fluid by HPLC and its evaluation in enzyme linked immunosorbent assay for diagnosis of porcine cysticercosis

A fraction with a major band of 14kDa was obtained from crude cyst fluid of Taenia solium cysticerci by 2-step chromatography. A first fraction isolated by gel filtration (Sephacryl S-300 high resolution) was purified using an anion exchange column (Mono Q HR 5/5) on high performance liquid chromatography. Evaluation of the analytic sensitivity of this fraction (F3) was carried out in an antibody enzyme linked immunosorbent assay (Ab-ELISA-F3) using serum samples from pigs experimentally infected with different doses of T. solium eggs. The cross-reactivity of F3 was evaluated with serum samples from pigs that were naturally or experimentally infected with Taenia hydatigena, Taenia saginata asiatica, Fasciola hepatica, Trichinella spiralis, Metastrongylus apri, Trypanosoma congolense and Sarcoptes scabiei, and with serum samples of rabbits hyper-immunised with metacestode cyst fluid of T. hydatigena and T. solium. Antibody titres of lightly or heavily infected pigs differed in their kinetics. However, the increase in F3-specific antibodies could not be related to the infection level. Analysis of the specificity of the F3 showed that serum samples of pigs infected with other parasites did not recognise this antigen. Cross-reaction with T. hydatigena occurred in ELISA using cyst fluid as antigen, but the F3 antigen fraction was not recognized by rabbit hyper-immune serum samples to T. hydatigena. Evaluation of the diagnostic sensitivity and specificity of the Ab-ELISA-F3 was done by a non-parametric receiver operating characteristic (ROC) analysis using 66 serum samples from Zambian village pigs. The total number of cysticerci of these pigs was determined by dissection (28 pigs harboured T. solium cysticerci and 38 were negative at dissection). In addition, 58 serum samples from Cameroonian pigs (28 pigs from cysticercosis-free farms and 30 pigs with cysticerci at tongue inspection) were used in a separate ROC analysis. The results from the ROC analysis yielded a low diagnostic value (area under ROC curve=0.48) with the sera from the Zambian pigs while a relatively high diagnostic value was obtained with the sera from Cameroonian pigs (area under ROC curve=0.78). The main factor contributing to a low diagnostic value based on the Zambian serum samples seemed to be the false-positive reactions that were likely caused by the occurrence of transient antibodies in the non-infected animals.

Molecular cloning and characterisation of Ts8B1, Ts8B2 and Ts8B3, three new members of the Taenia solium metacestode 8kDa diagnostic antigen family

Antibody screening of a lambdaZAP-XR Taenia solium metacestode cDNA library yielded a clone (Ts8B1), with an insert of 345 bp, and an open reading frame of 258 bp, that coded for a protein with 85 amino acid residues. Alignment of the predicted amino acid sequence with sequences from SWISSPROT revealed an 88% identity with TcA5.5, a 10 kDa immunodiagnostic antigen of T. crassiceps, 75% identity with CyDA a T. solium metacestode antigen, 40-50% identity with several variants of the 8 kDa subunit of antigen B of Echinococcus spp. and with members of the T. solium metacestode 8 kDa antigen family. Two other Ts8B1 related molecules, Ts8B2 and Ts8B3, were identified in the metacestode cDNA library by PCR, coding for 85 and 66 amino acid polypeptides, respectively. Both Ts8B1 and Ts8B2 were characterized as E/S antigens through their subcellular localisation in the secretory membrane system when expressed in NRK cells. The three cDNA inserts were expressed, purified and probed in enzyme-linked immunosorbent assays (ELISA) with sera and cerebro-spinal fluid from patients with confirmed neurocysticercosis, and with sera from pigs infected with T. solium. The most promising antigen, Ts8B2, performed with a sensitivity of 96.8% and specificity of 93.1% in the detection of active NCC when using serum samples in the assay and performed similarly in the porcine system. The implications of these findings are discussed.

Feasibility of baculovirus-expressed recombinant 10-kDa antigen in the serodiagnosis of Taenia solium neurocysticercosis

Bacterially expressed recombinant 10-kDa protein of Taenia solium metacestode (TsM) was previously found to be reliable in the diagnosis of active stage neurocysticercosis (NCC) by immunoblotting but not by ELISA. In this study, we evaluated the diagnostic feasibility of detecting eukaryote-expressed recombinant 10-kDa protein of TsM by ELISA (rTsM10-ELISA) in the serum and cerebrospinal fluid (CSF) from NCC patients. In 45 cases of active NCC, 91.1 and 97.8% cases showed positive reactions for serum and CSF by rTsM10-ELISA. ELISA employing the crude cyst fluid antigen (CF-ELISA) also revealed a similar result. Negligible cross-reactions were observed in serum samples from control subjects and from subjects with other helminthic diseases by rTsM10-ELISA (5/139 cases, 3.6%). By contrast, CF-ELISA demonstrated a high degree of cross-reactivity (24/139, 17.3%) especially from those patients with alveolar and cystic echinococcoses. The overall sensitivity and specificity of rTsM10-ELISA were 94.3 and 96.4%; and those of CF-ELISA were 95.7 and 84.5%, for serum and CSF, respectively. Antibody responses to rTsM10 were detected as early as 3 months after experimental infection of T. solium eggs in pigs. Our results show that ELISA with rTsM10 could be highly applicable in the serodiagnosis of NCC from early stage of infection.

Diagnostic values of IgG4 in human gnathostomiasis

The diagnostic values of immunoglobulin G subclass antibodies from patients with gnathostomiasis were assessed by immunoblot technique. Antigen was prepared from crude extracts of Gnathostoma spinigerum advanced third-stage larvae obtained from naturally infected eels. The sera were obtained from 14 parasite-confirmed gnathostomiasis cases, 63 patients with other helminthic infections and 13 healthy controls. Nine prominent IgG4 reactive bands appeared with molecular weights of 94, 51, 47, 43, 38, 24, 21, 20 and 15 kDa. The diagnostic sensitivity of each of the nine reactive bands ranged from 100% to 64.3% in 14 parasite-confirmed gnathostomiasis cases. All (100%) confirmed cases recognized the 21 kDa antigenic band, but not other helminthic infections or parasite-free control. Recognition of 21 kDa antigen in G. spinigerum advanced third-stage larvae crude extracts is the most specific diagnostic marker for human gnathostomiasis, with 100% sensitivity and specificity. The 20 and 24 kDa protein bands were additional diagnostic bands for confirming diagnosis of infection where the 21 kDa band was faint. No specific binding of IgG1, IgG2, or IgG3 antibodies was observed in any sera from confirmed gnathostomiasis cases.

Proteomic analysis of a 120 kDa protein complex in cyst fluid of Taenia solium metacestode and preliminary evaluation of its value for the serodiagnosis of neurocysticercosis

Cyst fluid (CF) of Taenia solium metacestode (TsM) is an important source of serodiagnostic antigens. We have investigated the molecular characteristics of the 120 kDa protein complex in TsM CF purified by fast performance liquid chromatography. The structure of the purified protein was characterized by a variety of proteomic analyses. The protein was found to consist of 2 major components of 42-46 and 22-28 kDa, and shared 3 subunits of 14, 16 and 18 kDa. The 42-46 kDa component was determined to contain 3 additional subunits of 22, 28 and 38 kDa. These 6 subunits were shown to originate from either the 14 or 18 kDa precursor. We assessed the antibody reactivity of the native protein, its individual subunits and the recombinant 14 and 18 kDa proteins, and found that the 120 kDa protein, particularly 14 and 18 kDa subunits revealed high reliability for differentiation of active and mixed stage NC from chronic NC. The subunits of the 120 kDa protein complex identified herein represent some of the low-molecular weight glycoproteins which have been described in several previous studies. Recognizing and understanding the structural and immunological relationship of these proteins will facilitate the development of new serodiagnostic assays.

Immunoblot findings of calcareous corpuscles binding proteins in cyst fluid of Taenia solium metacestodes

After collecting calcareous corpuscles from plerocercoid of Spirometra mansoni (sparganum), we evaluated the antigenic values of calcareous corpuscles binding proteins obtained from the cyst fluid of Taenia solium metacestodes. Immunoblot analysis revealed that cysticercosis patient sera strongly recognized 10 and 95 kDa calcareous corpuscles binding proteins. This result demonstrated that calcareous corpuscles are bound with major secretory antigenic proteins, which is possibly involved in the secretory pathways of the 10 and 95 kDa proteins presenting in the cyst fluid of T. solium metacestodes.

Immunolocalization of the 150 kDa protein in cyst fluid of Taenia solium metacestodes

The 150 kDa protein of cyst fluid (CF) of Taenia solium metacestodes was purified by ammonium sulfate fractionation and Superose 6 HR gel filtration chromatography. The purified protein consisted of three subunits (15, 10 and 7 kDa proteins), which were analyzed with the use of a 7.5-15% gradient sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Immunofluorescence study was carried out by using immunize specific polyclonal antibody. Positive reactions were noticed at bladder walls, calcareous corpuscles, granules of cyst fluid and some host tissue surrounding the bladder wall of the metacestodes. These results suggest that the 150 kDa protein was secreted into host tissues, inducing immune responses in the host, and it may play important roles in the cellular physiology of the parasites.

Cysticercosis/Taeniasis in Asia and the Pacific

Three taeniid tapeworms infect humans in Asia and the Pacific: Taenia solim, Taenia saginata, and Taenia asiatica. Although there is continuing debate about the definition of a new species, phylogenetic analyses of these parasites have provided multiple lines of evidence that T. asiatica is an independent species and the sister species of T. saginata. Here we review briefly the morphology, pathology, molecular biology, distribution and control options of taeniasis/cysticercosis in Asia and the Pacific and comment on the potential role which dogs may play in the transmission of T. solium. Special attention is focused on Indonesia: taeniasis caused by T. asiatica in North Sumatra, taeniasis/cysticercosis of T. solium and taeniasis of T. saginata in Bali, and taeniasis/cysticercosis of T. solium in Papua (formerly Irian Jaya). Issues relating to the spread of taeniasis/cysticercosis caused by T. solium in Papua New Guinea are highlighted, since serological evidence suggests that cysticercosis occurs among the local residents. The use of modern techniques for detection of taeniasis in humans and cysticercosis in humans, pigs and dogs, with the possible adoption of new control measures will provide a better understanding of the epidemiology of taeniasis/cysticercosis in Asia and the Pacific and lead to improved control of zoonotic and simultaneously meat-borne disease transmission.

Taenia solium: identification of specific antibody binding regions of metacestode 10-kDa protein

Taenia solium neurocysticercosis (NCC) represents one of the major public health problems associated with several neurological manifestations worldwide. We previously identified a recombinant 10-kDa protein of T. solium metacestode (CyDA) specific to active NCC. Immunoblottings with sera from active NCC patients and from animals experimentally infected with larval T. solium (pig), T. saginata (pig), T. asiatica (pig), and T. crassiceps (mouse) strongly recognized CyDA, while sera from patients infected only with adult worms did not. Mapping of antigenic sites using deletion mutants revealed that amino acids (aa) residues 30-34, Asn-Met-Thr-Val-Met (NMTVM), reacted only with sera from active stage T. solium cysticercosis cases. Recognition of CyDA aa 30-34 resided almost exclusively in the IgG4 isotype. Competitive immunoprecipitation with synthetic peptides confirmed the specificity of anti-sera for this penta-peptide. These results demonstrated that aa residues NMTVM in CyDA comprise the core sequence for an active stage NCC-related antigenic determinant. ligand binding protein, HLBP; Cyst fluid, CF; Pooled serum of 10 active NCC patients, serum-pool.

Use of Taenia crassiceps cysticercus antigen preparations for detection of antibodies in cerebrospinal fluid samples from patients with neurocysticercosis (Taenia solium)

Antigen extracts obtained from the vesicular fluid of Taenia crassiceps cysticerci and from fractions purified by affinity chromatography with the lectin concanavalin A and the glycoprotein antigen separated by electrophoresis were used for the detection of Taenia solium anticysticercus antibodies. The sensitivity and specificity obtained for all antigens were 100% in enzyme-linked immunosorbent assay with good reproducibility. Using immunoblotting of the three antigens, low-molecular-mass peptides (18 and 14 kDa) were characterized only in cerebrospinal fluid samples from patients with neurocysticercosis. The results confirm that antigen fractions purified from T. crassiceps cisticerci are important sources of specific peptides and proved to be efficient in detecting anti-T. solium antibodies.

Cysticercus antigens in cerebrospinal fluid samples from patients with neurocysticercosis

Antigens were detected in cerebrospinal fluid (CSF) samples from patients with neurocysticercosis (NC) by enzyme-linked immunosorbent assay (ELISA) using polyclonal sera of rabbit anti-Taenia solium cysticerci (anti-Tso) and anti- Taenia crassiceps cysticerci vesicular fluid (anti-Tcra or anti-Tcra <30 kDa). A group of NC patients (n = 174) were studied (NC), including 40 patients in different phases of the disease. ELISAs carried out with the anti-Tso, anti-Tcra, and anti-Tcra <30 kDa showed sensitivities of 81.2, 90, and 95.8% and specificities of 82, 98, and 100%, respectively. The 14- and 18-kDa low-molecular-weight peptides were only detected in CSF samples from patients with NC by immunoblotting with anti-Tso and anti-Tcra sera. Because of the importance of the diagnosis and prognosis of cysticercosis, the detection of antigens may contribute as an additional marker to the study and clarification of the parasite-host relationship.

IgG antibody responses in early experimental sparganosis and IgG subclass responses in human sparganosis

Antigenic components in the crude extracts of Spirometra mansoni plerocercoid were analyzed in early experimental infections and in IgG subclass observed in clinical sparganosis. By IgG immunoblot, sera obtained serially from experimental mice, fed 5 spargana each, were reacted with the crude extracts. Protein bands at 36-26 kDa and 103 kDa showed positive reactions since two weeks after infection. In a differential immunoblot, in which a monospecific antibody against sparganum chymase at 36 kDa was pre-treated, the reactions at 36-26 kDa disappeared, indicating that the sparganum chymase and its degradation products invoked IgG antibody reactions. When 69 patients sera of human sparganosis were examined for their IgG subclass responses, IgG4 levels showed the highest reaction which was followed by IgG1. The IgG4 antibody also reacted mainly with 36-31 kDa protease. These results indicate that 36 kDa chymase of S. mansoni plerocercoid is the main antigenic component inducing IgG antibody response in early stage of experimental sparganosis and for specific IgG subclass reactions in human sparganosis.

The 10 kDa protein of Taenia solium metacestodes shows genus specific antigenicity

Genus specific antigenicity of the 10 kDa protein in cyst fluid (CF) of Taenia solium metacestodes was demonstrated by comparative immunoblot analysis. When CFs from taeniid metacestodes of T. saginata, T. solium, T. taeniaeformis and T. crassiceps were probed with specific monoclonal antibody (mAb) raised against 150 kDa protein of T. solium metacestodes, specific antibody reactions were observed in 7 and 10 kDa proteins of T. solium and in 7/8 kDa of T. saginata, T. taeniaeformis and T. crassiceps. The mAb did not react with any protein in hydatid fluid of Echinococcus granulosus and E. multilocularis. This result revealed that the 10 kDa peptide of T. solium metacestodes and its equivalent proteins of different Taenia metacestodes are genus specific antigens that are shared among different Taenia species.

Persisting antibody reaction in paragonimiasis after praziquantel treatment is elicited mainly by egg antigens

Antibody responses in serum and cerebrospinal fluid (CSF) samples from patients with active and chronic paragonimiasis and in sera from patients on whom follow-up studies were done after praziquantel treatment were analyzed using antigens of Paragonimus westermani prepared from eggs, metacercariae, juveniles of 4- and 7-week old, adult worms and recombinant protein of 28 kDa cruzipain-like cysteine protease (rPw28CCP). The patient sera/CSFs of active and chronic paragonimiasis revealed strong antibody reactions against the crude extracts of 4- and 7-week old juveniles as well as against those from egg and adult. rPw28CCP also showed specific reaction to the sera with active paragonimiasis. After the treatment, levels of specific antibodies in the sera gradually decreased to negative range in most patients. In some cases with persisting high antibody levels, however, the reactions at 27 kDa egg protein were sustained throughout the observation period of 34 months. The reactions at 35 and 32 kDa in adult extract and rPw28CCP disappeared rapidly after the treatment. Persistent antibody reactions even after successful treatment are provoked by continuous antigenic challenge from eggs which were not resolved by treatment.

Usefulness of IgG4 subclass antibodies for diagnosis of human clonorchiasis

The present study analyzed serum IgG subclass antibody reaction to major antigenic bands of Clonorchis sinensis to investigate improvement of its serodiagnosis. Of the four subclass antibodies, IgG1 and IgG2 antibodies were produced but not specific, IgG3 antibody was least produced, and IgG4 antibody was prominent and specific. The serum IgG antibody reaction to any of 43-50, 34-37, 26-28, and 8 kDa bands was found in 65.5% of 168 egg positive cases while IgG4 antibody reaction was found in 22.0% of them. The positive rates of IgG and IgG4 antibodies were directly correlated with the intensity of infection. All of the sera from heavily infected cases over EPG 5,000 showed positive reaction for specific IgG and IgG4 antibodies. The specific serum IgG4 antibody disappeared within 6 months after treatment. The bands of 35 kDa and 67 kDa cross-reacted with IgG antibodies but not with IgG4 antibodies in sera of other trematode infections. The present findings suggest that serum IgG4 antibody reaction to 8 kDa band is specific but not sensitive. Any method to increase its sensitivity is required for improved serodiagnosis.