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The highest priority: what microbial genomes are telling us about immunity.
1Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99164-7040, USA. gpalmer@vetmed.wsu.edu
Veterinary Immunology and Immunopathology
|February 28, 2002
Summary
Small bacterial pathogens, like Rickettsia prowazekki, have reduced genomes due to evolution. They prioritize immune evasion by maintaining surface molecule genes for survival and vaccine development.
Area of Science:
- Microbial genomics
- Pathogen evolution
- Immunology
Background:
- Small genome bacterial pathogens (< or = 1/3 size of Escherichia coli) include chlamydiae, rickettsiae, ehrlichiae, mycoplasmas, and spirochetes.
- Their small genome size is attributed to reductive evolution, involving gene loss and deletion.
- Rickettsia prowazekki's 1.1 Mb genome has 24% non-coding DNA, unlike E. coli's 10% in a 4.4 Mb genome.
Purpose of the Study:
- To understand the essential functions retained by small genome pathogens.
- To investigate the evolutionary strategies employed by these pathogens for survival.
- To identify potential targets for vaccine development.
Main Methods:
- Comparative genomics of small genome bacterial pathogens.
- Analysis of genome size and non-coding DNA content.
- Identification of gene families and their functional significance.
Main Results:
- Small genome pathogens prioritize functions essential for host survival and propagation.
- Genetic deletion primarily affects metabolic functions and redundant pathways.
- A high percentage of retained genes are dedicated to polymorphic surface molecules.
Conclusions:
- Immune evasion is a primary strategy for obligate microbial pathogens.
- Polymorphic surface molecules are crucial for evading host immune responses.
- These surface molecules represent promising targets for developing protective vaccines.