Serological tests can be used to screen for or diagnose viral, fungal and parasitic infectious diseases, and assess the subject's immune status which is of particular importance to pregnant women and the immunodeficient patient.
A range of techniques is used to detect antigen-antibody binding. Most involve immunoenzymatic methods such as ELISA but we also use particle agglutination, haemagglutination, complement fixation, direct and indirect immunofluorescence, Western blotting and immunoelectrophoresis. Automated microplate ELISA instruments (open machines with microplate distributors and handlers) afford maximum security with results linked to bar codes on both sample tubes and reagents, and which are processed through a centralised computer system.
The various techniques used, enable us to both quantify humoral responses and characterise the isotype of the antibody in question (IgG, IgA or IgM) when necessary. These methods can be applied to antibodies against viruses (HIV, HCV, EBV), bacteria (Lyme disease, pertussis, etc.), parasites (both local—echinococcus infection and toxocariasis—and tropical—amoebiasis and schistosomiasis) and fungi (notably Candida albicans and Aspergillus fumigatus). For example, for the diagnosis of aspergillosis, immuno-electrophoresis yields a catalase arc which indicates active disease.