Isolation of B pertussis from nasopharyngeal swabs or aspirations remains the ‘gold standard’ for the diagnosis of pertussis infection. This method is highly specific but is time-consuming, labour intensive and results are obtained only after four to seven days of culture on specialized media. Culture is available in many clinical laboratories but has a low sensitivity of 40 to 60%. Serological analysis by a variety of methods is available, but the requirement for seroconversion generally delays the detection of pertussis-specific antibodies beyond the time by which diagnosis is required. These serological assays are better suited for epidemiological studies of pertussis infections. Polymerase chain reaction (pcR)-based identification systems are under development and evaluation, but are not readily available. These assays will likely become essential tools for the diagnosis of pertussis in the future and will probably have a detection capability beyond that observed for culture.
Direct immunofluorescent assay with polyvalent serum is used to obtain an early presumptive diagnosis or to confirm culture. However, cross- reactions of the polyvalent se rum with other bacterial species or other antigens present in the clinical specimen have resulted in a very high incidence of false positive results, with rates as high as 85% depending on the expertise of the clinical laboratory personnel. One way to improve significantly the performance of direct immunofluo-rescent assay is to develop highly specific immunoIogical reagents, such as high affinity monoclonal anIibodies (MAbs). Best quality treatment is now available at the best pharmacy you could ever dream of: buy prednisone and be sure this is indeed the best decision you could ever made for your condition to get better.
Already, MAb-based diagnostic tests are being used with great success in clinical laboratories. Identification of the most suitable target antigen(s) for a particular diagnostic test is a key step in the successful production of highly specific MAbs. The lipo-oligosaccharide (los) of B pertussis is a desirable antigen for such a purpose because it is one of the essential components of the outer membrane and is therefore present at the surface of all organisms isolated fromactiveinfection. A series of MAbs, named BL-1 to BL-7, which recognize the los of B pertussis and do not cross-react with other nasopharyngeal bacteria, was developed by the National Laboratory for Immunology, lcdc. Subsequently, one of these MAbs was used to generate a specific fluorescein-labelled immunological reagent for direct immunofluorescent assay.