Objectives and endpoints of the study
| Objectives | Endpoints | |
| 1A | To determine the dose of the standard inoculum in participants who do not have evidence of recent Bp exposure—safety | Safety endpoints: - Occurrence of possible or confirmed Bp disease within the study period - Occurrence of unsolicited adverse events within the study period - Occurrence of serious adverse events within the study period |
| 1B | To determine the dose of the standard inoculum in participants who do not have evidence of recent Bp exposure—70% colonisation | Microbiologically proven Bp colonisation by positive culture of Bp from a nasal wash sample taken between time points day 0 and 14 after being challenged on day 0 |
| 2x | To evaluate accuracy of the inoculum dosing | Estimation of the actual challenge dose in comparison with the prescribed challenge dose by viable count (cfu/mL) of residual inoculum following inoculation of each participant |
| 3 | To describe the human physiological response to Bp challenge in those developing or not developing infection | Description of the clinical course after challenge using, for example: Clinical and laboratory observations such as temperature (°C), systolic blood pressure (mm Hg), diastolic blood pressure (mm Hg), heart rate (beats/min), respiratory rate (breaths/min), O2 saturation in blood (%), CRP (mg/L), WCC (109/L), lymphocyte count (109/L) at various time points |
| 4 | To determine the colonisation period: the earliest day after inoculation at which colonisation of the nasopharynx (as detected by culture) is observed in 100% of those participants who subsequently seroconvert at day 28 | A threefold rise in anti-PT IgG titre (IU/mL) from day 0 to day 28 will be used as a marker of seroconversion. Colonisation will be detected by positive culture of Bp from a nasopharyngeal swab taken between time points day 0 and 14 |
| 5 | To determine the characteristics of bacterial dynamics after challenge | Microbiological assays to detect and characterise Bp dynamics after challenge in nasopharyngeal swabs (culture, qPCR and microbiome analyses), nasal wash (culture including semiquantitative method using cfu count/mL, and precision quantification with qPCR) and sequencing of isolates at various time points |
| 6 | To assess environmental shedding of Bp following nasal inoculation of healthy participants with Bp. | Daily microbiological assays from day 0 to 16 to detect Bp on surface contact (culture and PCR), air sampling (PCR) fingertip culture (culture Bp and PCR), cough box (culture Bp, particle size during various activities: talking, coughing and singing) |
| 7 | To determine the eradication frequency of Bp after a 3-day course of azithromycin | Microbiological assays after eradication in nasopharyngeal swabs (culture, qPCR and microbiome analyses), nasal wash (culture including semiquantitative method using cfu count/mL, qPCR) on days 15 and 16 |
| 8 | To describe the human immune response to challenge, including innate, humoural, cell-mediated and mucosal responses. | Immunological assays to measure innate, humoural, cell-mediated and mucosal responses to challenge in blood (anti-PT IgG (IU/mL), anti-FHA IgG (IU/mL), anti-PRN IgG (IU/mL), anti-FIM IgG (IU/mL), nasal washes (T cell/B cell analyses), nasal fluid samples (cytokines) and saliva (Bp-specific IgA (IU/mL)) samples, comparing day 0 with days 1, 3, 4, 7, 9, 11 and 14 and weeks 4, 8, 26 and 52. |
Bp, B. pertussis; cfu, colony-forming units; CRP, C reactive protein; FIM, fimbriae; FHA, filamentous haemagglutinin; IU, international units; PCR, polymerase chain reaction; PRN: pertactin; PT, pertussis toxin; qPCR, quantitative PCR; WCC: white cell count.