Evolution of bordetella pertussis genome may play a role in the increased rate of whooping cough cases in the United States

Author

Kevin Loftus, James Madison UniversityFollow

Creative Commons License

This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Date of Graduation

Summer 2018

Document Type

Thesis

Degree Name

Bachelor of Science (BS)

Department

Department of Integrated Science and Technology

Advisor(s)

Louise Temple

Amanda Biesecker

Steven Cresawn

Abstract

Bordetella pertussis is the bacterium responsible for pertussis, a disease commonly referred to as whooping cough. Recently, pertussis has made a resurgence in the U.S. despite high-vaccination coverage. Possible causes of the increased number of pertussis cases include genetic evolution of B. pertussis, increased awareness of the disease, better laboratory diagnostics, and the switch from a whole-cellular (wP) vaccine to an acellular vaccine (aP) in the 1990s. Fortunately, just as B. pertussis is evolving, so is the arsenal of technologies used to understand and combat this pathogenic bacterium. Whole genome sequencing is one technology that helps researchers better understand the evolution B. pertussis. This project included the isolation of genomic DNA and sequencing of two novel B. pertussis strains isolated from patients in Virginia. This project also utilized bioinformatics to analyze data obtained from genomes of twelve previously sequenced B. pertussis isolates. Specifically, the genomes were analyzed and compared to each other and to vaccine reference strains. PubMLST, a database hosted by the University of Oxford, was used to perform multi-locus sequence typing (MLST) and to determine alleles of genes that encode for pertussis toxin subunit 1 (ptxA), the pertussis toxin promotor (ptxP, pertactin (prn), and fimbriae serotype 3 (fim3), which are common components in acellular pertussis vaccines. Protein variants were then determined by comparing the protein sequences of PtxA, Prn, and Fim3 to known references using NCBI BLAST. Data gathered from PubMLST and protein alignments support other studies that indicate B. pertussis may be evolving to evade pertussis vaccines. Notably, all of the 14 strains analyzed in this paper carry a ptxP3 allele whereas vaccine reference strains such as Tohama 1 and C393 carry a ptxP1 allele. The other genes analyzed, ptxA, prn, and fim3, also showed divergence from the allele types of Tohama 1 and C393. This project builds on information gathered from previous studies and contributes to the growing knowledge of the evolution of the B. pertussis genome as related to whooping cough.

Recommended Citation

Loftus, Kevin, "Evolution of bordetella pertussis genome may play a role in the increased rate of whooping cough cases in the United States" (2018). Senior Honors Projects, 2010-2019. 522.
https://commons.lib.jmu.edu/honors201019/522