Immunoelectrophoretic analysis of major component proteins in cystic fluid of Taenia solium metacestodes

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.

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

The diagnostic value of a 10 kDa subunit of 150 kDa protein in cyst fluid (CF) of Taenia solium metacestodes was evaluated. Immunoblot analysis revealed that most sera from patients with neurocysticercosis recognized the 10 kDa subunit strongly (209/217 cases, 84.6%), while a few sera from individuals with other parasitic diseases including alveolar echinococcosis (AE, 2/20, 10%) and cystic echinococcosis (CE, 2/25, 8%) showed faint reactions. Sera of cases with other parasitic diseases, especially AE and CE, exhibited cross reactions against other bands in CF. Both differential immunoblot and immunoprecipitation analyses showed that the 10 kDa subunit was the most specific to cysticercosis and highly antigenic, whereas other components at 20-40, 64, 95 and 106 kDa in CF were cross-reactive. IgG subclass ELISA and immunoblot demonstrated that both IgG4 and IgG1 reactions were predominant in neurocysticercosis and recognized the 10 kDa.

Immunoglobulin G (IgG) subclass and IgE responses in human paragonimiases caused by three different species

In 40 cases of human paragonimiases caused by Paragonimus westermani (20 cases), P. miyazakii (10 cases), and P. skrjabini (10 cases), responses of serum immunoglobulin G (IgG), IgG subclasses, and IgE were analyzed by immunoblotting with crude antigens prepared from egg, 4-week-old juvenile, and adult forms of P. westermani. The 32- and 35-kDa proteins in the adult extracts showed specific reactions regardless of the causative species (39 of 40 cases; 98%). Sera of patients infected with P. westermani and P. miyazakii reacted strongly with the 28-, 46-, and 94-kDa proteins of egg extracts, while those from patients infected with P. skrjabini reacted faintly. No sera from patients with other trematodiases (0 of 15 cases), cestodiases (0 of 20 cases), or lung cancer (0 of 5 cases) or from healthy controls (0 of 10 individuals) showed positive reactions. Analysis by IgG subclass revealed that IgG4 (33 of 40 cases; 83%) and IgG1 (29 of 40 cases; 73%) antibodies in the patient sera recognized the 32- and 35-kDa proteins predominantly. IgG3 reaction was found in 50% (10 of 20 cases) and 30% (3 of 10 cases) of the sera of patients infected with P. westermani and P. miyazakii, respectively. In an IgE immunoblot, 83% (33 of 40 cases) of the sera from paragonimiasis patients reacted with the 32- and 35-kDa proteins while no sera from patients with heterologous diseases and healthy controls showed a positive reaction. Both 32- and 35-kDa proteins in adult extracts of P. westermani were highly reliable for serodiagnosis of human paragonimiases.

Measurement of 150 kDa protein of Taenia solium metacestodes by antibody-sandwich ELISA in cerebrospinal fluid of neurocysticercosis patients

An antigenic protein in cystic fluid of Taenia solium metacestodes (CF) of 150 kDa was measured by antibody-sandwich ELISA in serum and cerebrospinal fluid (CSF) of neurocysticercosis patients. Capture antibodies were rabbit antisera against CF (RACF) and a monoclonal antibody (MAb) against 150 kDa protein in CF. Lower limit of antibody-sandwich ELISA was 8 ng/ml of the protein. Except CF, no tested helminths extracts reacted. Levels of the protein in 351 sera from 255 patients (55 surgery confirmed and 202 antibody and CT/MRI confirmed) were below sensitivity of the assay. Of 276 CSF from 212 patients, 31 samples (11.2%) showed positive findings. This assay, therefore, was not sensitive enough to be a diagnostic. Instead, the 150 kDa protein appeared in CSF in such situations as in 2 days after praziquantel treatment, or as in a patient infected with a racemose cysticercus with degenerated cyst wall. Of cases whose follow-up CSF were assayed, 2 cases showed that the protein appeared intermittently. These results suggest strongly that appearance of free 150 kDa protein is associated with cyst wall rupture. In CSF which contained the 150 kDa protein over 61 ng/ml, the protein was recognized in SDS-PAGE before and after immunoprecipitation.