Molecular mechanisms of pathogenicity: how do pathogenic microorganisms develop cross-kingdom host jumps?

Authors


  • Editor: Ramón Díaz Orejas

Correspondence: Bart P.H.J. Thomma, Laboratory of Phytopathology, Wageningen University, Binnenhaven 5, 6709 PD Wageningen, The Netherlands. Tel.: +0031 317 484536; fax: +0031 317 483412; e-mail: bart.thomma@wur.nl

Abstract

It is common knowledge that pathogenic viruses can change hosts, with avian influenza, the HIV, and the causal agent of variant Creutzfeldt–Jacob encephalitis as well-known examples. Less well known, however, is that host jumps also occur with more complex pathogenic microorganisms such as bacteria and fungi. In extreme cases, these host jumps even cross kingdom of life barriers. A number of requirements need to be met to enable a microorganism to cross such kingdom barriers. Potential cross-kingdom pathogenic microorganisms must be able to come into close and frequent contact with potential hosts, and must be able to overcome or evade host defences. Reproduction on, in, or near the new host will ensure the transmission or release of successful genotypes. An unexpectedly high number of cross-kingdom host shifts of bacterial and fungal pathogens are described in the literature. Interestingly, the molecular mechanisms underlying these shifts show commonalities. The evolution of pathogenicity towards novel hosts may be based on traits that were originally developed to ensure survival in the microorganism's original habitat, including former hosts.

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