Protocol for a controlled human infection with genetically modifiedNeisseria lactamicaexpressing the meningococcal vaccine antigen NadA: a potent new technique for experimental medicine

Abstract

IntroductionNeisseria lactamicais a commensal organism found in the human nasopharynx and is closely related to the pathogenN. meningitidis(meningococcus). Carriage ofN. lactamicais associated with reduced meningococcal carriage and disease. We summarise an ethically approved protocol for an experimental human challenge study using a genetically modified strain ofN. lactamicathat expresses the meningococcal antigen NadA. We aim to develop a model to study the role of specific bacterial antigens in nasopharyngeal carriage and immunity, to evaluate vaccines for their efficacy in preventing colonisation and to provide a proof of principle for the development of bacterial medicines.Methods and analysisHealthy adult volunteers aged 18–45 years will receive an intranasal inoculation of either the NadA containing strain ofN. lactamicaor a genetically modified, but wild-type equivalent control strain. These challenge volunteers will be admitted for 4.5 days observation following inoculation and will then be discharged with strict infection control rules. Bedroom contacts of the challenge volunteers will also be enrolled as contact volunteers. Safety, colonisation, shedding, transmission and immunogenicity will be assessed over 90 days after which carriage will be terminated with antibiotic eradication therapy.Ethics and disseminationThis study has been approved by the Department for Environment, Food and Rural Affairs and South Central Oxford A Research Ethics Committee (reference: 18/SC/0133). Findings will be published in peer-reviewed open-access journals as soon as possible.Trial registration numberNCT03630250; Pre-results.