Abstract
ABSTRACTBordetella pertussis is the causative agent of whooping cough, a respiratory disease still considered as a major public health threat and for which recent re-emergence has been observed. Constant reshuffling of Bordetella pertussis genome organization was observed during evolution. These rearrangements are essentially mediated by Insertion Sequences (IS), a mobile genetic elements present in more than 230 copies in the genome, which are supposed to be one of the driving forces enabling the pathogen to escape from vaccine-induced immunity.Here we use high-throughput sequencing approaches (RNA-seq and differential RNA-seq), to decipher Bordetella pertussis transcriptome characteristics and to evaluate the impact of IS elements on transcriptome architecture. Transcriptional organization was determined by identification of transcription start sites and revealed also a large variety of non-coding RNAs including sRNAs, leaderless mRNAs or long 3′ and 5′UTR including seven riboswitches. Unusual topological organizations, such as overlapping 5′- or 3′-extremities between oppositely orientated mRNA were also unveiled. The pivotal role of IS elements in the transcriptome architecture and their effect on the transcription of neighboring genes was examined. This effect is mediated by the introduction of IS harbored promoters or by emergence of hybrid promoters. This study revealed that in addition to their impact on genome rearrangements, most of the IS also impact on the expression of their flanking genes. Furthermore, the transcripts produced by IS are strain-specific due to the strain to strain variation in IS copy number and genomic context.
Highlights
Bordetella pertussis, the main causative agent of whooping cough, is a strictly human pathogen, responsible world-wide for an estimated 24.1 million pertussis cases, associated with 160,700 pertussis-linked death in 2014 [1]
To characterize the primary transcriptome of Bordetella pertussis we used high through-put sequencing (HTS) of strand-specific cDNA obtained from transcripts of the Tohama I derivative BPSM, grown in standard conditions at the exponential growth phase [33]
We combined two independent sequencing approaches to maximize information about the transcriptome architecture, a classical RNA-sequencing method (RNA-seq) on a library of strand-orientated cDNA prepared from total RNA depleted for rRNA and differential RNA-seq method detecting the transcriptional start sites (TSS) by using terminator 5 0-phosphatedependent Exonuclease (TEX)-treated and -untreated RNA samples
Summary
Bordetella pertussis, the main causative agent of whooping cough, is a strictly human pathogen, responsible world-wide for an estimated 24.1 million pertussis cases, associated with 160,700 pertussis-linked death in 2014 [1]. Vaccination programs, first introduced in the 1950’s, have resulted in a drastic decrease of pertussis incidence [3]. Despite a high global vaccination coverage, in many countries a re-emergence of the disease has been observed over the past 10 years, which qualifies whooping cough today as the most prevalent vaccine-preventable childhood disease [4,5,6]. Many B. pertussis strains lacking pertactin, one of the major vaccine components of acellular vaccines, have been isolated in countries where acellular vaccines are used [12,13,14,15]. The lack of pertactin production in these strains is due to various mechanisms, including frame-shift mutations, deletions, insertions and inversions, suggesting vaccine-induced pressure
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
