A rapid latex agglutination test for the detection of anti-cysticercus antibodies in cerebrospinal fluid (CSF)

Conventional rapid latex agglutination in estimation of von Willebrand factor: method revisited and potential clinical applications

Measurement of von Willebrand factor antigen (VWF : Ag) levels is usually performed in a specialised laboratory which limits its application in routine clinical practice. So far, no commercial rapid test kit is available for VWF : Ag estimation. This paper discusses the technical aspect of latex agglutination method which was established to suit the purpose of estimating von Willebrand factor (VWF) levels in the plasma sample. The latex agglutination test can be performed qualitatively and semiquantitatively. Reproducibility, stability, linearity, limit of detection, interference, and method comparison studies were conducted to evaluate the performance of this test. Semiquantitative latex agglutination test was strongly correlated with the reference immunoturbidimetric assay (Spearman's rho = 0.946, P < 0.001, n = 132). A substantial agreement (κ = 0.77) was found between qualitative latex agglutination test and the reference assay. Using the scoring system for the rapid latex test, no agglutination is with 0% VWF : Ag (control negative), 1+ reaction is equivalent to <20% VWF : Ag, and 4+ reaction indicates >150% VWF : Ag (when comparing with immunoturbidimetric assay). The findings from evaluation studies suggest that latex agglutination method is suitable to be used as a rapid test kit for the estimation of VWF : Ag levels in various clinical conditions associated with high levels and low levels of VWF : Ag.

A rapid slide agglutination test for the diagnosis of neurocysticercosis in the rural health set up

Background:

Simple and rapid latex-based diagnostic tests have been used for detecting specific antigens or antibodies in several diseases.

Aims:

The aim of the present study was to standardize and evaluate the latex agglutination test (LAT) for the detection of Taenia solium metacestode antigen in the cerebrospinal fluid (CSF) and serum for the diagnosis of neurocysticercosis (NCC).

Settings and Design:

The study was conducted at Department of Microbiology, Jawaharlal Institute of Post graduate medical education and research after obtaining informed consent from the study subjects.

Materials and Methods:

In the present study, CSF and serum samples were collected from clinically suspected NCC, CT/MRI proven cases of NCC, non-cysticercal central nervous system infection control and from healthy control subjects. CSF was not collected from healthy controls. Polyclonal antisera raised in rabbits against porcine T. solium metacestode complete homogenate antigen, was used in the LAT to detect the antigen in the specimens.

Statistical Analysis Used:

The statistical analysis was carried out using Epi Info. The sensitivity, specificity, positive predictive value, and negative predictive value of the LAT were calculated.

Results:

The LAT exhibited sensitivity of 64.7% and specificity of 85.7% with CSF samples and sensitivity of 52.08% and specificity of 96% with serum samples.

Conclusions:

Results of the present study shows that the LAT can be employed as a moderately sensitive and specific test for the detection of T. solium metacestode antigen in the CSF and serum specimens for the diagnosis of NCC in poorly equipped laboratories.

Detection of C-reactive protein in evanescent wave field using microparticle-tracking velocimetry

A new technique is developed to measure the nanoparticles' brownian motions by employing microparticle-tracking velocimetry (micro-PTV) in evanescent wave field, which can provide high signal-to-noise ratio images for analyzing nanoparticles' movements. This method enables real-time detection of C-reactive proteins (CRPs) during the rapid interaction between CRPs and anti-CRP-coated nanobeads as CRP concentrations are related to the nanobeads' brownian velocity in the equilibrium state. The smallest observable nanobeads with 185 nm were utilized in this experiment to detect CRP concentrations as low as 0.1 microg/mL even in a high-viscosity solution. Further, the dissociation constant, K(D), can be evaluated based on the experimental results.

Immunodiagnostic tools for human and porcine cysticercosis

The development of improved immunodiagnostic tools has contributed to our knowledge on the importance of taeniosis/cysticercosis by enabling sero-epidemiological surveys and community-based studies to be carried out. Immunodiagnostic techniques include detection methods for specific antibodies and for circulating parasite antigen in serum or cerebrospinal fluid. The antigens used in immunoblot and enzyme-linked immunosorbent assay (ELISA) for antibody detection have evolved from crude extracts to highly purified specific fractions and recombinant antigens of the glycoprotein family, increasing both the sensitivity and the specificity of the tests. The application of ELISA for the detection of circulating parasite antigens may present some diagnostic advantages since it demonstrates not only exposure but also active infections. Until now only a few of the current techniques have been standardised and fully validated, making comparisons between studies difficult. The lack of a gold standard is a serious drawback. In surveys on cysticercosis, antibody detection systems have been useful in identifying the risk factors associated with transmission of Taenia solium; a high seroprevalence in a community indicates a "hot spot" where preventive and control measures should be applied. In contrast, the potential use of immunodiagnostic tools to identify cases of neurocysticercosis (NCC) in man is subject to debate. The correlation between a positive serology and neurological symptoms and/or lesions indicative for NCC on neuro-imaging techniques is poor to fair in most studies. This may be explained by the unpredictable clinical outcome of the infection and the variable immunological response of the human host to infection. A major problem is that in many developing countries, neuro-imaging methods are inaccessible and/or too expensive for the rural population at risk. Under these conditions, serology may provide the only tool for diagnosis of the infection.