Dissertation
Genomic and proteomic differences among strains of Anaplasma marginale differing in transmission efficiency phenotype
Washington State University
Doctor of Philosophy (PhD), Washington State University
08/2010
DOI:
https://doi.org/10.7273/000006056
Abstract
The causative agent of bovine anaplasmosis, Anaplasma marginale, is the most prevalent tick-borne infection of cattle world-wide. A. marginale infects erythrocytes, and is transmitted via the feeding of ixodid ticks. Ticks acquire the bacteria in the blood meal, where A. marginale can colonize the tick midgut epithelial cells and replicate. The bacteria disseminate through the tick host and infect the tick salivary glands. If the tick feeds on a new host, the bacteria are transmitted through the saliva and begin infecting mammalian erythrocytes. Two strains of Anaplasma marginale, the highly virulent St. Maries strain and the less virulent Israel vaccine strain (Anaplasma marginale ss centrale) differ greatly in transmission efficiency phenotype. Transmission efficiency may be linked to replication in the tick salivary glands, since the St. Maries strain was shown to replicate to numbers 10-fold greater as compared to the Israel vaccine strain. Recent completion of the genome sequences for both strains has allowed us to use comparative genomics to identity strain-specific genes potentially responsible for observed differences in transmission efficiency. We identified 58 strain-specific genes, which we tested for transcription in mammalian blood and tick salivary glands. None were found to be upregulated in the tick salivary glands. However, twenty of the St. Maries strain-specific genes and 16 of those in the Israel strain were transcribed in the tick salivary gland at the time of transmission. If strain-specific genes play a role in transmission efficiency, they likely have a secondary role while the organism resides in the mammalian host, such as virulence. Due to milder symptoms associated with the Israel vaccine strain, it has been used as a live vaccine for over a century to prevent severe symptoms that occur from infection with more virulent strains. We used an immunoproteomic approach to identify shared antigens between these two strains and found sixteen St. Maries strain proteins that were recognized by serum from animals inoculated with the vaccine strain. Strain-specific genes and shared antigens identified in this study provide targets for developing a vaccine that either blocks transmission or induces protection against disease severity.
Metrics
4 File views/ downloads
15 Record Views
Details
- Title
- Genomic and proteomic differences among strains of Anaplasma marginale differing in transmission efficiency phenotype
- Creators
- Joseph Agnes
- Contributors
- Guy Hughes Palmer (Chair)Kelly A. Brayton (Committee Member) - Washington State University, Department of Veterinary Microbiology and PathologyAudrey O. T. Lau (Committee Member)Glen A Scoles (Committee Member) - Washington State University, Department of Veterinary Microbiology and Pathology
- Awarding Institution
- Washington State University
- Academic Unit
- College of Veterinary Medicine
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 55
- Identifiers
- 99901055028801842
- Language
- English
- Resource Type
- Dissertation