However, the number of reported cases has fluctuated, with a peak incidence of 8.72 per 100,000 persons when 25,616 cases occurred in 2005, according to the CDC (24). A nasopharyngeal swab culture is considered the gold standard for the diagnosis of pertussis contamination; however, many factors affect culture results, such as specimen transport and swab material (14). only 61 to 68% of IgG positives confirmed by immunoblotting. The two immunoblots correlated well with each other, with 91.7% Rabbit monoclonal to IgG (H+L)(HRPO) and 94.3% agreement for IgG and IgA, respectively. When the FHA band was used with the PT band as the criterion for positivity, significant differences existed in specificity compared to the ELISA (IgG, 84.1% versus 33.3%; IgA, 82.4% versus 71.0%). Calcium-Sensing Receptor Antagonists I When the positive IgA immunoblots (evidence of natural recent infection) were compared to the positive PT-100 IgG immunoblots (evidence of recent contamination or vaccination), the PT-100 blot showed a 71% sensitivity in detecting natural recent infection. immunoblots, alone or in combination with ELISAs, can aid in the diagnosis of infection. INTRODUCTION is usually a slow-growing Gram-negative coccobacillus, the causative agent of pertussis (whooping cough) and a highly transmittable respiratory contamination of the tracheal epithelial cilia (6, 13, 20). Symptoms in unvaccinated persons include fits of coughing, inspiratory whoop, and posttussive vomiting; however, individuals with partial immunity have milder, cold-like symptoms and a chronic cough (5, 13, 19, 20). After the introduction of the pertussis vaccine in the 1940s, the number of cases reached a low in the United States in the late 1970s and early 1980s, with a reported 0.5 to 1 1.0 cases per 100,000 persons (20). However, the number of reported cases has fluctuated, with a peak incidence of 8.72 per 100,000 persons when 25,616 cases occurred in 2005, according to the CDC (24). A nasopharyngeal swab culture is considered the gold standard for the diagnosis of pertussis contamination; however, many factors affect culture results, such as specimen transport and swab material (14). Numerous studies, however, have established that there is an increase in anti-pertussis toxin (PT) and anti-filamentous hemagglutinin (FHA) serum antibodies during contamination and that the measurement of these antibodies could assist in the laboratory confirmation of pertussis (7, 10C12). Since PT is usually produced only by contamination (18, 20). Anti-FHA antibodies are less specific than PT antibodies and may be produced following infection with species, such as and (7, 16, 18). Adenylate cyclase toxin (ACT) antibodies have also been proposed to be a sensitive marker for sp. Calcium-Sensing Receptor Antagonists I infection (27). The detection of IgA antibodies against PT and FHA suggests natural contamination not immunization, since IgA is usually rarely if at all detected following immunization (17, 21). However, the detection of IgG to PT and FHA is usually more sensitive than that of IgA, since not all individuals mount a detectable IgA response following contamination (22). An IgM response is only rarely and inconsistently seen following exposure or immunization (25). Additionally, since both PT and FHA are included in the acellular pertussis vaccines, antibodies to these antigens often persist following vaccination, hindering serodiagnosis in vaccinated individuals. Therefore, standardization of the diagnostic threshold would be important for the detection of active contamination. The World Health Organization (WHO) accepts significant increases in IgG or IgA antibodies to PT or FHA as an indication of pertussis, even though other species produce FHA (14, 20). The WHO human pertussis antiserum reference reagent became available in January 2009, and an international collaborative study established that 1 ELISA unit (EU) of IgG anti-PT is approximately equal to 1 international unit (IU) of IgG anti-PT (28). The criteria, however, for defining the diagnostic threshold have not been established by international and national health organizations. Baughman et al. used mixture modeling of data from a population of more than 6,000 U.S. residents of ages 6 to 49 years Calcium-Sensing Receptor Antagonists I to establish an anti-PT IgG level of >94 EU/ml as the diagnostic cutoff for recent infection, with a lower value of >49 EU/ml as an intermediate cutoff (3, 4). Other diagnostic thresholds have been developed by others, including the Massachusetts State Laboratory, which uses a cutoff value of 200 EU/ml, and the Netherlands, which uses a value of 125 EU/ml (9, 18). Multiple indirect methods for serological detection of antibodies to have been manufactured, the most common being ELISA (13C15, 23). Immunoblot assays may prove to be a useful tool for distinguishing between infections and infections from other species (25). In this study we analyzed the results for 250 patient samples submitted for IgG, IgA, and IgM antibody testing using two commercially available immunoblot assays that use different combinations of PT, FHA, and ACT antigens. The goal of this study was to assess the utility of immunoblot assays for anti-antibody testing using the ELISA method as the.
