Protective activities of the filamentous hemagglutinin (FHA) and the lymphocytosis-promoting factor (LPF) of Bordetella pertussis were compared by active and passive protection tests with intracerebral or respiratory challenge in mice. Mice immunized twice by intraperitoneal injection of 8 micrograms of FHA or glutaraldehyde-inactivated LPF were protected after aerosol challenge. One intraperitoneal injection of inactivated LPF also protected mice from intracerebral challenge; the dose protecting 50% of the mice was 8.5 micrograms. However, one intraperitoneal injection of 48 micrograms of FHA or two weekly intraperitoneal injections of 20 micrograms did not protect mice from death after intracerebral challenge. Injection of affinity-purified antibody to LPF from mouse hybridomas or from goats gave a dose-dependent protection against aerosol challenge. The smallest dose giving protection was 80-90 micrograms. Polyclonal or monoclonal antibody to FHA at doses of 1,440 micrograms or 360 micrograms, respectively, gave very little protection from disease after respiratory challenge. These data indicate that active immunization of mice followed by respiratory challenge with B. pertussis is a useful model to identify protective antigens.
The role of the filamentous hemagglutinin (FHA) and the lymphocytosis-promoting factor hemagglutinin (LPF) in pertussis pathogenesis and immunity is the subject of active investigation. To be certain of their role as protective antigens, the hemagglutinins must be pure and free of each other. This report describes procedures to separate and purify FHA and LPF from the culture supernatant of stationary cultures of Bordetella pertussis Tohama, using hydroxylapatite, haptoglobin-Sepharose, and Sepharose CL-6B filtration chromatography. Purified FHA contained less than 0.002% active LPF assayed by histamine-sensitizing activity, and both hemagglutinins contained less than 0.01% of each other based on antigenic activity measured by an enzyme-linked immunosorbent assay, using affinity chromatography-purified antibody to each hemagglutinin. LPF and FHA were also shown to be antigenically distinct by immunodiffusion and were judged to be highly purified proteins by polyacrylamide gel electrophoresis. In addition, the purification procedures yielded milligram amounts of each hemagglutinin with very good recovery of starting activities.
During an outbreak of pertussis in residents and staff of a facility for the developmentally disabled, 149 persons had laboratory evidence of Bordetella pertussis infection; 130 (87%) reported respiratory illness. Infection rates (IR) in affected wards ranged from 6% to 91%. Most residents were adolescents and adults and had received a full course of diphtheria-tetanus toxoids-pertussis (DTP) vaccine; IRs increased with increasing time after the last DTP dose in fully vaccinated residents. The IR was lower in residents on wards where erythromycin treatment/prophylaxis was started two or fewer weeks after the onset of illness in the first case on the ward (IR, 16%), compared with four or more weeks after onset (IR, 75%; P less than 10(-6)). Respiratory symptoms were milder in ill residents treated within seven days of onset of illness. Although B. pertussis transmission was substantial, erythromycin treatment of patients and prophylaxis of exposed persons was effective in decreasing transmission and disease severity. Carbamazepine toxicity occurred in seven (19%) of 37 residents when carbamazepine was administered with erythromycin.
During a pertussis outbreak in a facility for the developmentally disabled, culture- or direct fluorescent-antibody-confirmed cases were identified in 24 residents and 17 staff members; 38 (93%) were culture positive for Bordetella pertussis. An enzyme-linked immunosorbent assay (ELISA) was used to detect serum IgG and IgA to the filamentous hemagglutinin and lymphocytosis-promoting factor of B. pertussis. Using criteria from ELISA values, we identified an additional 83 residents and 28 staff members as seropositive. Among seropositive persons, antibody levels were elevated by the time of onset of respiratory symptoms and, in three of the four assays, remained elevated for 14 mo. In 44 seropositive persons tested within two weeks of onset of symptoms, 80% were culture positive, compared with 33% of 15 tested two to four weeks after onset (P = .003) and none of 15 tested more than four weeks after onset. The most specific (94%) clinical case definition identified only 41% of seropositive persons. Thus, ELISAs are important tools for individual diagnosis and epidemiological studies of pertussis.
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