"Pathogenicity Islands"
Ecological Aspect

Bacterial Pathogenicity


The first attempt to consider bacterial pathogenicity as a peculiar biological phenomenon had been made in the Russian academic issue “Biomolecular Bases of Bacterial Pathogenicity” in the end of 1970s by Dr. Yu. Ezepchuk (2). The principle point of analysis was the poly-functional character of pathogenicity phenomenon. It was demonstrated that some biological functions realized by a pathogen through bio-molecules production, lie in the basis of pathogenicity phenomenon. The biological active molecules named “Pathogenicity Factors” (PF) are grouped in accordance with their functional features.

The epithet “Pathogenicity Island” (PAI) appeared in the 1980s in a special publication related to genetic study of bacterial pathogenesis. The concept of PAI was founded by Dr. Jorg Hacker and coauthors who investigated genetic basis of virulence of UPEC strains (6). It was shown that PAI are mobile elements of bacterial genome carrying the genes that code the pathogenicity determinant production. The elements play a pivotal role in virulent function of bacterial pathogens of humans, animals and plants. PAI apparently have been acquired during the speciation of pathogens from their nonpathogenic ancestors. The acquisition of PAI demonstrates the appearance of the new biological function that causes the interaction of a pathogen with eukaryotic host cells and the effect in a new ecological niche.

There are three approaches in consideration of pathogenicity phenomenon: biological, medical and applied aspects.

Biology of pathogenicity based on the study of evolution, speciation of pathogens, ecology, genetic determination and encoding of biosynthesis of macromolecules possessing the function of pathogenicity factors (PF). The mechanism of interactions of PF and the host target-cells is also important part in the biological process of pathogenicity.

The medical aspect of bacterial pathogenicity indicates a realization of pathogenic potency in the host organism. It is a problem of infectious disease, diagnostic, prophylactic and treatment of illness induced by the pathogen.

In the applied area, the knowledge of PF, their structure and functions may have important practical implication such as providing delivery systems for vaccination, tools for cell biology, and tools for the development of new strategies for therapy of bacterial infections.

Yurii V. Ezepchuk, Ph.D.
Professor of Biochemistry
Denver, Colorado, U.S.A.

E-mail: ezepchuk@usa.net