Lymphatic filariasis is a mosquito-borne parasitic disease responsible for morbidity and disability that affects 1.2 billion people worldwide, mainly the poor communities. Currently, filarial antigen testing is the method of choice for the detection of bancroftian filariasis, and to date, there are two commonly used tests. In the present study, a recently reported recombinant monoclonal antibody (5B) specific to BmSXP filarial antigen was used in developing an ELISA for the detection of circulating filarial antigen in sera of patients with bancroftian filariasis. The performance of the ELISA was evaluated using 124 serum samples. The ELISA was positive with all sera from microfilaremic bancroftian filariasis patients (n = 34). It also showed 100% diagnostic specificity when tested with sera from 50 healthy individuals and 40 patients with other parasitic diseases. The developed assay using the novel 5B recombinant monoclonal antibody could potentially be a promising alternative antigen detection test for bancroftian filariasis.
Cystic echinococcosis (CE) is a neglected zoonotic disease with a worldwide distribution and is a major public health problem in some areas. Diagnosis of CE is mainly based on clinical symptoms, imaging and serological testing, however, improvement in serodiagnosis is still needed. This study was aimed at detecting circulating Echinococcus antigen in CE patients using a lateral flow dipstick (LFD) assay. Three types of hydatid antigens i.e. hydatid cyst fluid (HCF), native antigen B (nAgB) and recombinant antigen B (rAgB) were prepared and polyclonal rabbit antiserum was raised against each antigen. Purified IgG fractions were prepared and a portion was conjugated to gold nanoparticles. After a series of optimizations, a final antigen detection LFD assay was developed using a combination of anti-nAgB-IgG and gold-conjugated anti-HCF-IgG. Evaluation of the assay showed that 27 out of 35 (77%) serum samples from CE patients gave positive results. Meanwhile, the test showed a diagnostic specificity of 82% when tested with sera from 38 healthy individuals and 13 patients with other parasitic diseases. In conclusion, the antigen detection LFD assay seemed to be useful for diagnosis of CE and possibly for post-treatment follow-up, and merit further evaluation studies. We foresee that it may improve serodiagnosis of CE when used in tandem with an antibody detection test.
Currently, the laboratory diagnosis of toxocariasis, caused by Toxocara canis or T. cati, mainly relies on serological tests. Unfortunately, however, the specificities of most of the commercial tests that are available for the serodiagnosis of this disease are not very high and this may cause problems, especially in tropical countries where co-infections with other helminths are common. In an effort to develop a serological assay with improved specificity for the detection of Toxocara infection, an IgG(4)-ELISA based on a recombinant version (rTES-30USM) of the 30-kDa Toxocara excretory-secretory antigen (TES-30) has recently been developed. To produce the antigen, the TES-30 gene was cloned via assembly PCR, subcloned into a His-tagged prokaryotic expression vector, and purified by affinity chromatography using Ni(2+)-nitrilotriacetic-acid (Ni-NTA) resin. The performance of the ELISA based on the recombinant antigen was then compared with that of commercial kit, based on an IgG-ELISA, for the serodiagnosis of toxocariasis (Toxocara IgG-ELISA; Cypress Diagnostics, Langdorp, Belgium). Both assays were used to test 338 serum samples, including 26 samples from probable cases of toxocariasis. Assuming that all the probable cases were true cases, the assay based on rTES-30USM demonstrated a sensitivity of 92.3% (24/26) and a specificity of 89.6% (103/115) whereas the commercial kit exhibited a sensitivity of 100% (26/26) but a specificity of only 55.7% (64/115). The high sensitivity and specificity exhibited by the new IgG(4)-ELISA should make the assay a good choice for use in tropical countries and any other area where potentially cross-reactive helminthic infections are common.