Comparison of dot-ELISA and standard ELISA for detection of Neisseria meningitidis outer membrane complex–specific antibodies

Abstract

Dot-ELISA using the outer membrane complex antigens of Neisseria meningitidis as a target was standardized for rapid detection of meningococcal-specific antibodies in human serum. We investigated the level of meningococcal-specific IgG, IgA, and IgM in serum using dot-ELISA with outer membrane antigens prepared from Neisseria meningitidis serotype B:4.19:P1.15,3,7,9 (a strain isolated from a Brazilian epidemic). The dot-ELISA is based on the same principles as the standard ELISA and is useful for detection of anti-N. meningitidis B antibodies in serum of patients with meningococcal infections. For the assay, outer membrane complexes (OMCs) were absorbed by nitrocellulose membrane and blocked with a 5% skim milk solution. Serum samples were drawn upon hospital admission and during convalescence from patients with meningococcal septicemia, and single samples were drawn from uninfected controls. We retrospectively examined a total of 57 serum samples: 35 from patients infected with N. meningitidis B, 12 from patients infected with Haemophilus influenzae b, and 10 from health individuals. When performed at room temperature, dot-ELISA took approximately four hours to perform, and the optimum antigen concentration was 0.42 microg per dot. The specificity of IgG, IgM, and IgA demonstrates that dot-ELISA using OMCs from N. meningitidis B as a target is suitable for serologic verification of clinically suspected meningococcal disease in patients and for titer determination of antibodies produced during different phases of natural infection. Furthermore, the sensitivity of dot-ELISA was comparable to that of standard ELISA. Overall, dot-ELISA is simple to perform, rapid, and low cost. Further validation of the test as a screening tool is required.

Attractive and healthy-looking male faces do not show higher immunoreactivity

“…Then secondary antibodies are added, which are specially labelled and bind to the primary antibodies with the antigen. A chromogenic substrate, which is added last, causes a colour response that is measured by spectrophotometer 62 . Sufficient response is at least 1:4 titres (the dilution of the serum where antibodies still react with the antigens) and ideally even higher 63 .…”

A dot-ELISA using a partially purified cathepsin-L-like protein fraction fromTaenia soliumcysticerci, for the diagnosis of human neurocysticercosis

“…Unfortunately, EITB and standard ELISA require sophisticated equipment and trained personnel and are too complex to be used routinely under field conditions in developing countries. The simpler dot-ELISA, which have already been used to diagnose bacterial meningitis (Belo et al ., 2010), avian influenza virus infection (Chen et al ., 2008), toxocariasis (Roldán et al ., 2009), cystic echinococcosis (Swarna and Parija, 2008), fascioliasis (Shaheen et al ., 1989) and leishmaniasis (Pappas et al ., 1983), may offer an efficient immunodiagnostic method for NCC in resource-poor areas (Xu et al ., 1989). Such assays are relatively rapid and easy to perform, generally use components that are inexpensive and/or easily manufactured, and only require small amounts of antigen (Kondo et al ., 2007; Belo et al ., 2010).…”