Infect. investigations (1, 3, 6, 9, 24, 27, 28). The measurement of immunoglobulin G (IgG) antibodies to pertussis toxin (PT) are particularly important because all acellular pertussis vaccines consist of inactivated PT and because the quantitation of IgG anti-PT antibodies has been found to become the most useful assay for serodiagnosis (2, 10, 13, 15, 19, 23). As a result, numerous laboratories have developed IgG anti-PT enzyme-linked immunosorbent assays (ELISAs) (7, 9, 10, 17, 20, 21). Despite their importance, ideal standardization of these assays has not been achieved. This study was designed to obtain data to advance these attempts. An international meeting was held in 2007 to discuss the current status of harmonization of pertussis immunoassays and to prioritize the activities required to reach this goal (25). Among the priorities were the development of research materials and evaluation of criteria for acceptance of these reagents. The use of a common research serum was regarded as a high priority, and the recent approval of a World Health Corporation (WHO) international research pertussis antiserum was a major step forward in the harmonization attempts (30). The antigens utilized for covering in immunoassays were identified DM1-Sme as essential reagents, and one exceptional query for the IgG anti-PT assay was whether the source of the PT would influence results. In previously carried out collaborative studies (13, 14, 17, 25, 29), each participating laboratory used their personal in-house methods and reagents. These studies suggested that the source of PT covering antigen did not have a major influence within the results. However, none of the studies was designed to allow the posting of PT antigens among the laboratories and to evaluate the effect of the source of the PT antigen within the assay results. To address these outstanding questions, four different sources of PT antigens were compared in four different laboratories with prior encounter in carrying out IgG anti-PT ELISAs. This design allowed both an intra- and interlaboratory assessment. Except for the PT covering antigen and the necessity for each laboratory to calibrate their assay to the WHO International Standard (Is definitely) or the U.S. Research Pertussis Antiserum (human being), lot 3 (CBER3; Center for Biologics Study and Review, U.S. Federal government Drug Administration, Rockville, MD) and statement results in international units (IU), all four laboratories adopted their own founded procedures and used in-house certified reagents. The panel of sera for assay standardization included subjects with different age groups and vaccination status. (Part of this research was offered in the 9th International Bordetella Symposium, Baltimore, MD, 30 September to 3 October 2010. ) MATERIALS AND METHODS Study coordination. Four laboratories participated in the study: the Centers for Disease Control and Prevention (CDC), Vanderbilt University or college Medical Center (VU), Sanofi Pasteur (SP), and GlaxoSmithKline Biologicals (GSK). Laboratories were randomly designated A to D to ensure anonymity of results. A fifth laboratory, Harbor-UCLA Medical Center (UCLA), offered serum samples but did not perform assays. The CDC coordinated screening in the DM1-Sme four laboratories and distributed the antigens and panels of sera. Antigens. Two of the PT antigen preparations Rabbit Polyclonal to RBM34 were provided by study participants (SP and GSK), and two preparations were obtained from commercial sources, List Biological Laboratories Inc. (List) (Campbell, CA) and Protein Express, Inc. (PE) (Cincinnati, OH). All antigen preparations, randomly assigned here as antigens 1 to 4, met in-house requirements for purity and storage (Table 1). The antigens were handled per the manufacturer specifications. Purified PT antigens from List, PE, GSK, and SP were DM1-Sme available in the following concentrations: 200 g/ml, 200 g/ml, 95.5 g/ml, and 392 g/ml, respectively. Table 1 Properties of pertussis toxin antigens from your four sources(16). Precision actions how far a set DM1-Sme of observations deviates from a right line and is quantified using Pearson’s and measurements between 0.90 and 0.98, 0.93 and 0.99, 0.92 and 0.98, and 0.93 and 0.99 for PT antigens 1 to 4, respectively (Table 3). Similarly, pairs of antigens displayed a high degree of concordance for each laboratory with ideals ranged from 0.99, 0.99 to 1 1.00, 1.00, and 0.97 to 1 1.00, for labs A to D, respectively (Table 4). Open in a separate windowpane Fig 1 Scatter plots illustrating the assessment of pairs of laboratories for pertussis toxin antigen 1 (PT1). The DM1-Sme ideals.