Table of Contents
International Journal of Evolutionary Biology
Volume 2012, Article ID 457264, 16 pages
Review Article

Comparative Pathogenomics of Bacteria Causing Infectious Diseases in Fish

Microbiology Laboratory, Fishery Quality Control Center, Ministry of Agriculture and Fisheries Wealth, P.O. Box 427, 100 Muscat, Oman

Received 6 February 2012; Accepted 20 March 2012

Academic Editor: Shinji Kondo

Copyright © 2012 Ponnerassery S. Sudheesh et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Fish living in the wild as well as reared in the aquaculture facilities are susceptible to infectious diseases caused by a phylogenetically diverse collection of bacterial pathogens. Control and treatment options using vaccines and drugs are either inadequate, inefficient, or impracticable. The classical approach in studying fish bacterial pathogens has been looking at individual or few virulence factors. Recently, genome sequencing of a number of bacterial fish pathogens has tremendously increased our understanding of the biology, host adaptation, and virulence factors of these important pathogens. This paper attempts to compile the scattered literature on genome sequence information of fish pathogenic bacteria published and available to date. The genome sequencing has uncovered several complex adaptive evolutionary strategies mediated by horizontal gene transfer, insertion sequence elements, mutations and prophage sequences operating in fish pathogens, and how their genomes evolved from generalist environmental strains to highly virulent obligatory pathogens. In addition, the comparative genomics has allowed the identification of unique pathogen-specific gene clusters. The paper focuses on the comparative analysis of the virulogenomes of important fish bacterial pathogens, and the genes involved in their evolutionary adaptation to different ecological niches. The paper also proposes some new directions on finding novel vaccine and chemotherapeutic targets in the genomes of bacterial pathogens of fish.