Interaction of Bordetella pertussis with human nasal epithelium

Summary Bordetella pertussis (Bp), a gram-negative bacterium is the causative agent of whooping cough or pertussis, an acute disease primarily in infants and young children. Despite high vaccination coverage, pertussis is resurging in many countries including the USA. Bp infection in vaccinated individuals cause mild symptoms or are asymptomatic. This results in severe underreporting of global pertussis incidence. Current acellular pertussis vaccines (aPV) elicit suboptimal and short-lived immunity and fail to prevent the colonization of the nasal cavity. These infected individuals serve as a reservoir for bacterial transmission. Since Bp is restricted to humans as hosts and has no environmental or animal reservoir, it is critical to utilize model systems that resemble the environment of the human respiratory tract. Traditionally, the focus of Bp research has been on studying its interactions and pathogenesis in the context of lower respiratory tract and by utilizing animal models. The mechanisms utilized by Bp to survive and establish persistent infection in the human nasal cavity are poorly understood. We hypothesize that attachment to nasal epithelium followed by biofilm formation are key determinants of long-term infection of Bp in the human nasopharynx. In this proposal, we will use primary well- differentiated human nasal epithelial cultures (HNEC) grown at the air-liquid interface. These primary HNECs produce mucus, are ciliated and mimic the human nasal environment. In Specific Aim 1, we will determine (i) how Bp attaches, establishes colonizes and forms biofilms on HNEC; (ii) the role of known virulence factors in facilitating HNEC infection and (iii) how Bp infection alters the cellular and morphological characteristics of HNEC. Infection often elicits a dynamic cascade of events resulting in the adaptation of both the host and the pathogen. The crosstalk between Bp and the nasal cells following infection is yet to be investigated. We hypothesize that infection of nasal cavity by Bp triggers transcriptional changes in both the bacterial and host cells resulting in shaping of the infection process. In Specific Aim 2, we will use high throughput dual RNA sequencing technology to analyze the changes in the transcriptome of both Bp and HNEC. With the proposed research, we will gain an advanced understanding of host-pathogen interactions and identify the dynamic changes occurring in both the host and bacterial transcriptome during infection.