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Mycoplasma genetic variation and its implication for pathogenesis
1Institute of Bacteriology and Animal Hygiene, University of Veterinary Medicine, Vienna, Austria.
Abstract:
Several pathogenic mycoplasma species are known etiologic agents of diseases in man and animals, which typically involve the respiratory tract, urogenital tract and joints and often show chronicity. Although the basis for this chronicity is not well understood, it is apparent that several species of pathogenic mycoplasmas are endowed with a sophisticated genetic machinery for altering their surface attributes. This surface phenotypic variation is thought to play a key role in the establishment and persistence of mycoplasma infections by enabling evasion of host defences and by ensuring adaptation to the rapidly changing microenvironmental conditions encountered in the host. The variability of mycoplasma surface characteristics results both from reversible ON- and OFF-switching of distinct membrane surface proteins (phase variation), from structural changes of these proteins (size variation) and from changes in their surface presentation (epitope masking and demasking). The majority of these surface proteins that are subject to variation are encoded by multiple variant single-copy genes and are lipid-modified proteins which represent the major coat proteins and surface antigens of several pathogenic mycoplasmas. Variable surface lipoproteins play an important role in the pathogenesis of a mycoplasma infection by providing escape from immune response, and probably by influencing both colonization of and translocation across the mucosal barrier. In this minireview, recent developments regarding the genetic mechanisms and the functional significance of surface lipoprotein variation in the pathogenesis of mycoplasma infections are summarized.
Insights
Pathogenic mycoplasmas evade host defenses through sophisticated genetic mechanisms that alter their surface proteins. This surface variation is crucial for establishing and persisting infections in hosts.
Area of Science:
- Microbiology
- Immunology
- Molecular Biology
Background:
- Pathogenic mycoplasma species cause chronic diseases in humans and animals, often affecting the respiratory tract, urogenital tract, and joints.
- The basis for mycoplasma infection chronicity is not fully understood, but surface attribute alteration is implicated.
Purpose of the Study:
- To summarize recent developments in the genetic mechanisms and functional significance of surface lipoprotein variation in mycoplasma pathogenesis.
- To highlight the role of surface phenotypic variation in mycoplasma infections.
Main Methods:
- Review of recent literature on mycoplasma surface variation.
- Analysis of genetic mechanisms driving surface protein changes (phase variation, size variation, epitope masking/demasking).
Main Results:
- Mycoplasmas possess genetic machinery for altering surface attributes, including reversible ON/OFF switching (phase variation), size variation, and epitope masking/demasking.
- Variable surface lipoproteins, encoded by multiple variant single-copy genes, are major coat proteins and surface antigens.
- Surface variation aids mycoplasmas in evading host immune responses and adapting to changing microenvironments.
Conclusions:
- Surface lipoprotein variation is a key strategy for pathogenic mycoplasmas to establish and persist infections.
- This variation facilitates immune evasion and influences colonization and translocation across mucosal barriers.
- Understanding these mechanisms is vital for developing effective treatments against mycoplasma infections.