Excretory/secretory antigens (ES) from in-vitro cultures of Taenia crassiceps cysticerci, and use of an anti-ES monoclonal antibody for antigen detection in samples of cerebrospinal fluid from patients with neurocysticercosis

Serological and molecular detection of neurocysticercosis among epileptic patients in Nagpur, Maharashtra state (India)

Neurocysticercosis (NCC), one of the most important neuroparasitic diseases in humans, is caused by Cysticercus cellulosae, the metacestode stage of digenetic zoonotic cestode Taenia solium. The present study aims at the detection of anti-cysticercus antibodies in the sera of epileptic patients (n=26) visiting a tertiary care hospital in Nagpur, Maharashtra state, India, by an in-house developed indirect IgG-ELISA and enzyme-linked immunoelectro transfer blot (EITB) assay using different antigens (namely, Whole Cyst Antigen (WCA), Cystic Fluid Antigen (CFA), Scolex Antigen (SA), Excretory-Secretory Antigen (ESA) and Membrane-Body Antigen (MBA)) prepared from T. solium metacestodes to find out the status of NCC. An attempt has also been made for molecular detection of NCC from blood samples of those patients by Polymerase Chain Reaction (PCR) assay targeted at large subunit rRNA gene of T. solium. The IgG ELISA level of anti-cysticercus antibodies against WCA, CFA, SA, ESA and MBA antigens were as follows: 19.23 %, 23.07 %, 38.46 %, 30.76 % and 15.38 %. The seroreactivity to CFA, SA and ESA was found in equal proportions in patients with ring-enhancing lesions. In the EITB assay, the lower and medium molecular weight protein bands of SA and ESA were immunodominant compared to the higher WCA and CFA peptides. PCR positivity could be observed in 34.6 % (9/26) of the patients under study. It is the first report of detecting NCC among epileptic patients of the Nagpur region of Maharashtra state in India using serological and molecular tools.

Elucidating the influence of praziquantel nanosuspensions on the in vivo metabolism of Taenia crassiceps cysticerci

The aim of this work was to develop nanosuspensions of praziquantel (PZQ) and to evaluate their influence on the energetic metabolism of cysticerci inoculated in BALB/c mice. We analyzed metabolic alterations of glycolytic pathways and the tricarboxylic acid cycle in the parasite. The nanosuspensions were prepared by precipitation and polyvinyl alcohol (PVA), poloxamer 188 (P188) and poloxamer 407 (P407) were used as stabilizers. Nanosuspension prepared with PVA had a particle size of 100nm, while P188- and P407-based nanosuspensions had particle sizes of 74nm and 285nm, respectively. The zeta potential was -8.1, -8.6, and -13.2 for the formulations stabilized with PVA, P188 and P407, respectively. Treatments of T. crassiceps cysticerci-infected mice resulted in an increase in glycolysis organic acids, and enhanced the partial reversion of the tricarboxylic acid cycle, the urea cycle and the production of ketonic bodies in the parasites when compared to the groups treated with conventional PZQ. These data suggest that PZQ nanosuspensions greatly modified the energetic metabolism of cysticerci in vivo. Moreover, the remarkable metabolic alterations produced by the stabilizers indicate that further studies on nanoformulations are required to find potentially suitable nanomedicines.

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.

Antiparasitic antibodies occur with similar frequency in patients with clinically established multiple sclerosis with or without oligoclonal bands in the cerebrospinal fluid

The "hygiene hypothesis" postulates an inverse relationship between the prevalence of parasitic infections and the frequency of multiple sclerosis (MS). Objective: It was to study whether antibodies against parasites could be demonstrated more frequently in blood serum from MS patients with oligoclonal bands (OCB) than from MS patients without OCB. Methods: We studied serum samples from 164 patients who had previously been analyzed to investigate OCB. Parasitic antibodies were studied through unidimensional electrophoresis of proteins on polyacrylamide gel against Taenia antigens, searching for antiparasitic specific low molecular weight antibodies and also for antiparasitic nonspecific high molecular weight antibodies. Results: Two of the 103 patients with no evidence of OCB had antibodies of low molecular weight and 59 of them had antibodies of high molecular weight. Of the 61 patients with evidence of OCB, one showed antibodies of low molecular weight and 16 showed antibodies of high molecular weight. Conclusion: Antiparasitic antibodies are detected with similar frequency in MS patients with OCB and in MS patients without OCB.

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.

Development of the S3Pvac vaccine against murine Taenia crassiceps cysticercosis: a historical review

Our work of the last 25 yr was concerned with the development of a vaccine aimed to prevent porcine Taenia solium cysticercosis and was based on cross-reacting Taenia crassiceps antigens that had proved protective against experimental intraperitoneal murine T. crassiceps cysticercosis (EIMTcC). In recent times the efficacy of the vaccine has been considered in need of confirmation, and the use of EIMTcC has been questioned as a valid tool in screening for vaccine candidates among the many antigens possibly involved. A review of our work divided in 2 parts is presented at this point, the first dealing with EIMTcC and the second with porcine T. solium cysticercosis (presented in this issue). Herein, we revise our results using EIMTcC as a measure of the protective capacity of T. crassiceps complex antigen mixtures, of purified native antigens, and of S3Pvac anti-cysticercosis vaccine composed by 3 protective peptides: GK-1, KETc1, and KETc12 either synthetic or recombinantly expressed and collectively or separately, by diverse delivery systems when administered at different doses and by different routes. Statistical analyses of the data lead confidently to the strong inference that S3Pvac is indeed an effective vaccine against EIMTcC via specific and non-specific mechanisms of protection.

Fatty acids oxidation and alternative energy sources detected in Taenia crassiceps cysticerci after host treatment with antihelminthic drugs

Human cysticercosis caused by Taenia crassiceps is rare however it is considered of zoonotic risk. The treatment of the infected patients was successful when using albendazole or praziquantel. The active forms of albendazole inhibit the glucose uptake and the active forms of praziquantel alter glycogen levels and nutrients absorption. The aim of this study was to analyze the production of organic acids that indicate the oxidation of fatty acids and the use of alternative energy sources from T. crassiceps cysticerci removed from the peritoneal cavity of mice treated with low dosages of albendazole (5.75 and 11.5mg/kg) or praziquantel (3.83 and 7.67 mg/kg). The beta-hydroxibutyrate production was higher by the larval stage cysticerci in all treated groups and the propionate production was higher in final stage cysticerci treated with 11.5mg/kg of albendazole when compared to the control group. The larval stages of cysticerci from the groups treated with 5.75 mg/kg of albendazole and 3.83 mg/kg of praziquantel produced more urea than the initial and final stages which indicate amino acids breakdown. We conclude that it was possible to detect the fatty acid oxidation and amino acids breakdown which indicate the use of alternative energy production sources as the used dosages only cause a partial blockage of the glucose uptake and leads to metabolic alterations in the cysticerci. The metabolic behavior observed after host treatment was different from former descriptions of the in vitro one which indicates great host-parasite interaction.

Taenia crassiceps: host treatment alters glycolisis and tricarboxilic acid cycle in cysticerci

Human cysticercosis by Taenia crassiceps is rare although it is considered of zoonotic risk, especially to immunocompromised individuals. Albendazole and praziquantel are widely used and effective in its treatment. Their active forms inhibit the glucose uptake by the parasite and induce muscle contractions that alter its glycogen levels interfering in the energetic metabolism of the parasite and leading to its death. The aim of this study was to evaluate alterations in glycolysis, the tricarboxylic acid cycle and glucose concentrations caused by low dosage treatments of the hosts with albendazole and praziquantel. Therefore, T. crassiceps intraperitoneally infected mice were treated by gavage feeding with 5.75 or 11.5 mg/kg of albendazole and 3.83 or 7.67 mg/kg of praziquantel. The treated mice were euthanized after 24 h and the cysticerci collected were morphologically classified into initial, larval or final phases. Concentrations of the organic acid produced and glucose were evaluated to detect alterations into the glycolysis and the tricarboxylic acid cycle pathways through chromatography and spectrophotometry. The low dosage treatment caused a partial blockage of the glucose uptake by the cysticerci in spite of the non significant difference between its concentrations. An activation of the tricarboxylic acid cycle was noted in the cysticerci that received the treatment due to an increase in the production of citrate, malate and α-ketoglutarate and the consumption of oxaloacetate, succinate and fumarate. The detection of α-ketoglutarate indicates that the cysticerci which were exposed to the drugs after host treatment present different metabolic pathways than the ones previously described after in vitro treatment.

Seroepidemiological study of human cysticercosis with blood samples collected on filter paper, in Lages, State of Santa Catarina, Brazil, 2004-2005

INTRODUCTION

Human serofrequency of antibodies against Taenia solium antigens was determined and risk factors for cysticercosis transmission were identified.

METHODS

Individuals (n=878) from periurban and rural locations of Lages, SC, were interviewed to gather demographic, sanitary and health information. Interviews and blood sample collections by finger prick on Whatman filter paper were performed from August 2004 to May 2005. Observation determined that 850 samples were suitable for analysis and were tested by ELISA using vesicular fluid of Taenia crassiceps heterologous antigen. To ensure the reliability of the results, 77 samples of the dried blood were matched with sera. The reactive samples were submitted to a serum confirmatory immunoblot (IB) test using purified Taenia crassiceps glycoproteins.

RESULTS

The ELISA results for the dried blood and serum samples were statistically consistent. ELISA was positive in 186 (21.9%) out of 850 individuals. A group of 213 individuals were asked to collect vein blood for IB (186 with positive result in ELISA and 27 with inappropriate whole blood samples) and 130 attended the request. The IB was positive in 29 (3.4%) out of 850 individuals. A significant correlation (p = 0.0364) was determined among individuals who tested positive in the IB assay who practiced both pig rearing and kitchen gardening.

CONCLUSIONS

ELISA with dried blood eluted from filter paper was suitable for cysticercosis population surveys. In Lages, human infection was associated with pig rearing and kitchen gardening. The prevalence index was compatible with other Latin American endemic areas.

Immune response to different fractions of Taenia solium cyst fluid antigens in patients with neurocysticercosis

The immunopathogenesis of neurocysticercosis (NCC) largely remains unknown. We analyzed the immune response to different fractions of Taenia solium cyst fluid antigens in patients with NCC. Lymphocytes were separated from 48 patients with NCC-related active epilepsy and 30 healthy controls. T. solium (isolated from pig muscles) antigens (crude lysate, CL; cyst wall, CW and cyst fluid, CF) at 20 μg/well concentrations were used to stimulate the cells in a lymphocyte transformation test (LTT). Only CF antigen stimulated cell proliferation significantly greater than control (p<0.001), hence cyst fluid antigens were further studied. The CF antigens were electro-blotted on nitrocellulose membrane (NC), cut at 0.5 cm distance and particulate antigens were prepared. A total of 12 fractions, designated F1 to F12 according to molecular weight were tested in-vitro for LTT. After 72 h of stimulation by the different fractions, Th1 (IL-1β, TNF-α, IL-2) and Th2 (IL-4, IL-10) cytokine responses were determined in culture supernatants by ELISA. Low molecular weight fractions F1 through F4 (Mol. wt.<25 kDa) were found to be potent inducers of cytokines. Fractions F1, F3 and F4 induced the production of Th1 (IL-1β, TNF-α, IL-2), whereas F2 induced the production of Th2 (IL-4 and IL-10) cytokine. The study shows that the low molecular weight fractions of CF antigens are immuno-dominant. Most of these fractions (F1, F3, F4) induce strong Th1 immune response except F2 which induces Th2 response. Further studies are needed to identify the different antigens present in these fractions to determine the molecules responsible for the immune response.

Antibody specific to 43kDa excretory-secretory antigenic peptide of Taenia solium metacestode as a potential diagnostic marker in human neurocysticercosis

Recent studies suggest excretory-secretory (ES) antigen specific antibody detection tests to be of promising utility in laboratory diagnosis of many parasitic diseases in human including neurocysticercosis (NCC). The objective of the present study was to characterize the ES antigens collected from in vitro culture of Taenia solium metacestode larvae, and to identify specific ES peptides as diagnostic markers. Three ES peptides viz., 67kDa, 43kDa and 32kDa, were found to be diagnostic for NCC based on high sensitivity and specificity of their reactivity to either serum or cerebrospinal fluid (CSF) specimens. More remarkably, the 43kDa ES peptide was found reactive with CSF and serum specimens from confirmed NCC patients with absolute specificity and a high sensitivity (88.23% in serum and 89.28% in CSF). This peptide was also detected by sera and CSF from clinically suspected NCC patients but with a decreased sensitivity correlating with the decreasing order of the certainty of diagnosis as per a criteria proposed earlier. The 43kDa ES peptide is suggested to be an important peptide of diagnostic utility in NCC.

Immunochemical and biological characterization of monoclonal antibodies against BaP1, a metalloproteinase from Bothrops asper snake venom

BaP1 is a P-I class of Snake Venom Metalloproteinase (SVMP) relevant in the local tissue damage associated with envenomations by Bothrops asper, a medically-important species in Central America and parts of South America. Six monoclonal antibodies (MoAb) against BaP1 (MABaP1) were produced and characterized regarding their isotype, dissociation constant (K(d)), specificity and ability to neutralize BaP1-induced hemorrhagic and proteolytic activity. Two MABaP1 are IgM, three are IgG1 and one is IgG2b. The K(d)s of IgG MoAbs were in the nM range. All IgG MoAbs recognized conformational epitopes of BaP1 and B. asper venom components but failed to recognize venoms from 27 species of Viperidae, Colubridae and Elapidae families. Clone 7 cross-reacted with three P-I SVMPs tested (moojeni protease, insularinase and neuwiedase). BaP1-induced hemorrhage was totally neutralized by clones 3, 6 and 8 but not by clone 7. Inhibition of BaP1 enzymatic activity on a synthetic substrate by MABaP1 was totally achieved by clones 3 and 6, and partially by clone 8, but not by clone 7. In conclusion, these neutralizing MoAbs against BaP1 may become important tools to understand structure-function relationships of BaP1 and the role of P-I class SVMP in snakebite envenomation.

Taenia crassiceps cysticerci: Characterization of the 14-kDa glycoprotein with homologies to antigens from Taenia solium cysticerci

Glycoproteins from the total vesicular fluid of Taenia crassiceps (VF-Tc) were prepared using three different purification methods, consisting of ConA-lectin affinity chromatography (ConA-Tc), preparative electrophoresis (SDS-PAGE) (14 gp-Tc), and monoclonal antibody immunoaffinity chromatography (18/14-Tc). The complex composition represented by the VF-Tc and ConA-Tc antigens revealed peptides ranging from 101- to 14-kDa and from 92- to 12-kDa, respectively. Immunoblotting using lectins confirmed glucose/mannose (glc/man) residues in the 18- and 14-kDa peptides, which are considered specific and immunodominant for the diagnosis of cysticercosis, and indicated that these fractions are glycoproteins. Serum antibodies from a patient with neurocysticercosis that reacted to the 14 gp band from T. crassiceps (Tc) were eluted from immunoblotting membranes and showed reactivity to 14 gp from Taenia solium. In order to determine the similar peptide sequence, the N-terminal amino acid was determined and analyzed with sequences available in public databases. This sequence revealed partial homology between T. crassiceps and T. solium peptides. In addition, mass spectrometry along with theoretical M(r) and pI of the 14 gp-Tc point suggested a close relationship to some peptides of a 150-kDa protein complex of the T. solium previously described. The identification of these common immunogenic sites will contribute to future efforts to develop recombinant antigens and synthetic peptides for immunological assays.

Evaluation of an IgG-ELISA strategy using Taenia solium metacestode somatic and excretory-secretory antigens for diagnosis of neurocysticercosis revealing biological stage of the larvae

Diagnosis of neurocysticercosis (NCC) is complicated because of the variability in clinical presentations and course of the disease where viability of parasite is a major determinant. The present study describes evaluation of ELISAs using Taenia solium metacestode somatic and excretory-secretory (ES) antigens for detection of anti-T. solium metacestode IgG antibodies in serum and cerebrospinal fluid (CSF). And results of the ELISAs in cases with a definitive diagnosis of NCC are correlated with the biological stages of the parasite such as live vesicular or degenerated stage. The sensitivity of the IgG-ELISA using ES antigen is observed to be much higher in serum (88.2%) than in CSF (64.28%) although it is only marginally higher in serum (76.4%) than in CSF (75%) when somatic antigen is used in the ELISA. Whereas, the specificities of the ELISA using either somatic or ES antigen for detection of IgG antibodies in serum (97.97%; 96.96%) and CSF (96.42%; 97.61%) are comparable. A strong association is observed between live stage of the parasite and detection of antibodies in sera and CSF from more number of NCC patients by ELISA using ES antigens. Similarly, detection of antibodies by ELISA using somatic antigens could be associated with the dead or degenerated stage of the parasite in brain. The IgG-ELISA strategy developed in the present study opens up an avenue for diagnosis of NCC in hospitals or in population prevalence studies. The use of crude extracts of ES proteins might improve the serodiagnosis of the cases of NCC carrying live vesicular stage of the parasite larvae.

Neurocysticercosis immunodiagnosis using Taenia solium cysticerci crude soluble extract, excretory secretory and lower molecular mass antigens in serum and urine samples of Indian children

Neurocysticercosis (NCC), the most common neurological disorder of parasite etiology, results from lodgement of Taenia solium cysticerci in the central nervous system and is now increasingly being recognized in children. The confirmed diagnosis is based collectively on radiological findings and serodiagnostic techniques. The serodiagnostic techniques have variable sensitivity and specificity depending upon the technique, antigens used, location and number of cysts. Crude soluble extract (CSE), excretory secretory (ES) and lower molecular mass (LMM) (10-30 kDa) antigenic fraction of T. solium cysticerci were evaluated for antibody detection in serum and urine samples by ELISA. Serum and urine samples were collected each from 125 clinically suspected and radiologically proven NCC (111 with single Computed Tomography (CT) lesions and 14 with multiple CT lesions) and 125 control subjects (60 with neurological disorders other than NCC, 40 with other parasitic diseases and 25 apparently healthy subjects). The sensitivity of the ELISA with the use of CSE, ES and LMM antigenic fractions was 38.4%, 63.2% and 30.4% with serum (cut off dilution 400), 46.4%, 44% and 47.2% with neat urine and the specificity was 88%, 76.8% and 85.6% with serum (cut off dilution 400), 66.4%, 65.2% and 58.4% with neat urine samples, respectively. The study suggests that detection of antibody to ES antigen in serum samples may serve useful purpose for the serodiagnosis of human NCC.

Collagen binding is a key factor for the hemorrhagic activity of snake venom metalloproteinases

Snake venom metalloproteinases (SVMPs) are multifunctional enzymes involved in several symptoms following snakebite, such as severe local hemorrhage. Multidomain P-III SVMPs are strongly hemorrhagic, whereas single domain P-I SVMPs are not. This indicates that disintegrin-like and cysteine-rich domains allocate motifs that enable catalytic degradation of ECM components leading to disruption of capillary vessels. Interestingly, some P-III SVMPs are completely devoid of hemorrhagic activity despite their highly conserved disintegrin-like and cysteine-rich domains. This observation was approached in the present study by comparing the effects of jararhagin, a hemorrhagic P-III SVMP, and berythractivase, a pro-coagulant and non-hemorrhagic P-III SVMP. Both toxins inhibited collagen-induced platelet aggregation, but only jararhagin was able to bind to collagen I with high affinity. The monoclonal antibody MAJar 3, that neutralizes the hemorrhagic effect of Bothrops venoms and jararhagin binding to collagen, did not react with berythractivase. The three-dimensional structures of jararhagin and berythractivase were compared to explain the differential binding to collagen and MAJar 3. Thereby, we pinpointed a motif within the Da disintegrin subdomain located opposite to the catalytic domain. Jararhagin binds to both collagen I and IV in a triple helix-dependent manner and inhibited in vitro fibrillogenesis. The jararhagin-collagen complex retained the catalytic activity of the toxin as observed by hydrolysis of fibrin. Thus, we suggest that binding of hemorrhagic SVMPs to collagens I and IV occurs through a motif located in the Da subdomain. This allows accumulation of toxin molecules at the site of injection, close to capillary vessels, where their catalytic activity leads to a local hemorrhage. Toxins devoid of this motif would be more available for vascular internalization leading to systemic pro-coagulant effects. This reveals a novel function of the disintegrin domain in hemorrhage formation.

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.

Cysticercosis immunodiagnosis using 18- and 14-kilodalton proteins from Taenia crassiceps cysticercus antigens obtained by immunoaffinity chromatography

Monoclonal antibodies (MAb) against Taenia crassiceps and Taenia solium cysticerci were produced and showed cross-reactivity with a 14-kDa protein from T. solium and with 18- and 14-kDa proteins from T. crassiceps. These MAbs and antibodies from cerebrospinal fluid (CSF) as well as serum samples from patients with neurocysticercosis (NC) reacted with 18- and 14-kDa T. crassiceps proteins purified by immunoaffinity chromatography using a Sepharose column coupled with MAbs (anti-excretory/secretory or anti-vesicular fluid antigens). Immunoaffinity-purified 18- and 14-kDa proteins were used in the design of a diagnostic enzyme-linked immunosorbent assay (ELISA) to detect antibodies in 23 CSF and 20 serum samples from patients with NC, showing 100% sensitivity. The test specificity was determined using 42 noninflammatory CSF samples and 70 inflammatory CSF samples from patients with other neurological disorders (OND), showing 100% and 99.1% (confidence interval, 97.3% to 100%) specificity, respectively. A false-positive CSF sample result in the OND group was from a human immunodeficiency virus-positive patient with meningoencephalitis. By using serum samples from 194 healthy individuals, the specificity was 100%. Analysis of an additional 16 serum samples from individuals with other parasitic diseases (13 with intestinal parasitosis and 3 with schistosomiasis) showed negative results. Three (10%) serum samples from patients with hydatidosis were positive in our ELISA and in ELISA with T. solium cysticerci antigens. Two of them were also positive by immunoblotting. The use of 18- and 14-kDa T. crassiceps immunoaffinity-purified proteins for detection of anti-cysticercus antibodies in CSF and/or serum samples using an ELISA system showed a good performance and high specificity for serum samples, dispensing with the use of confirmatory tests, such as immunoblotting, for checking specificity.

Helminth antigens (Taenia solium, Taenia crassiceps, Toxocara canis, Schistosoma mansoni and Echinococcus granulosus) and cross-reactivities in human infections and immunized animals

Helminth antigens were investigated in the search for accessible heterologous antigens capable to discriminate different helminthiases, by the enzyme linked immunosorbent assay (ELISA) and the immunoblot assay (IB). Antigens used were: Taenia solium cysticercus total saline (Tso); Taenia crassiceps cysticercus vesicular fluid (Tcra-VF); T. crassiceps cysticercus glycoproteins (Tcra-GP and Tcra-(18-14)-GP); Toxocara canis larva excretory-secretory (TES); Schistosoma mansoni adult total saline (Sm) and Echinococcus granulosus hydatid fluid (Eg). The assayed sera were from patients with: cysticercosis (n = 18); toxocariasis (n = 40); schistosomiasis (n = 19) and hydatidosis (n = 50) with proven clinical and laboratory diagnosis, and sera from rabbits immunized with Tso, Tcra-VF, TES and Eg. Cross-reactivity occurred mostly between infections caused by Taenia and Echinococcus or in immunized rabbits, by ELISA. Moreover, the cross-reactivity among helminthiases was found with the use of antigens belonging to phylogenetically related parasite species, Eg, Tso and Tcra-VF, by sharing same antigenic components. Lower cross-reactivities were obtained by IB technique, when only peptides were considered as antigens, and the use of T. crassiceps purified glycoproteins demonstrated high sensitivity and specificity in the diagnosis of human cysticercosis, similarly to that using homologous antigen (Tso) by the same technique.

Snake venom metalloproteinases: structure/function relationships studies using monoclonal antibodies

Snake Venom Metalloproteinases (SVMPs) are synthesized as zymogens and undergo proteolytic processing resulting in a variety of multifunctional proteins. Jararhagin is a P-III SVMP, isolated from the venom of Bothrops jararaca, comprising metalloproteinase, disintegrin-like and cysteine-rich domains. The catalytic domain is responsible for the hemorrhagic activity. The disintegrin-like/cysteine-rich domains block alpha2beta1 integrin binding to collagen and apparently enhance the hemorrhagic activity of SVMPs. The relevance of disintegrin-like domain is described in this paper using a series of mouse anti-jararhagin monoclonal antibodies (MAJar 1-7). MAJar 3 was the only antibody able to completely neutralize jararhagin hemorrhagic activity. Neutralization of catalytic activity was partial by incubation with MAJar 1. MAJars 1 and 3 efficiently neutralized jararhagin binding to collagen with IC50 of 330 and 8.4 nM, respectively. MAJars 1 and 3 recognized the C-terminal portion of the disintegrin domain, which is apparently in conformational proximity with the catalytic domain according to additivity tests. These data suggest that disintegrin-like domain epitopes are in close contact with catalytic site or functionally modulate the expression of hemorrhagic activity in SVMPs.

Phylogenetic conservation of a snake venom metalloproteinase epitope recognized by a monoclonal antibody that neutralizes hemorrhagic activity

Snake venom metalloproteinases (SVMPs) are present in large quantities in venoms of viper snakes and also in some elapids. Jararhagin is a representative of a P-III multidomain hemorrhagic SVMP present in Bothrops jararaca venom. It is comprised of a catalytic, a disintegrin-like and a cysteine-rich domain. Seven anti-jararhagin monoclonal antibodies (MAJar 1-7) were produced, of which six reacted with the disintegrin domain. MAJar 3 recognized an epitope present at the C-terminal part of the disintegrin-like domain, and neutralized jararhagin-induced hemorrhage. In this study, we evaluated the reactivity of these monoclonal antibodies with venoms from 27 species of snakes belonging to different families. MAJar 3 recognized most of the hemorrhagic venoms. By ELISA, MAJar 3 reacted strongly with venoms from Viperidae family and weakly with Colubridae and Elapidae venoms. This recognition pattern was due to bands between 50 and 80 kDa, corresponding to P-III SVMPs. This antibody preferentially neutralized the hemorrhage induced by venoms of Bothrops snakes. This fact suggests that the epitope recognized by MAJar 3 is present in other metalloproteinases throughout snake phylogeny. However, slight structural differences in the epitope may result in insufficient affinity for neutralization of biological activities.