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Adherence of mycoplasmas to cells and inert surfaces: phenomena, experimental models and possible mechanisms
Abstract:
Mycoplasmas are typical surface parasites colonizing the mucous membranes of animals and man. Efficient adherence mechanisms are therefore a prerequisite for survival and, in some species, for pathogenicity. The lack of a rigid cell wall enables the mycoplasmas, in contrast to bacterial mechanisms, to actively rearrange their surface structure in a vertical or horizontal direction. The energy requirement for attachment of M. pneumoniae in inert surfaces strongly suggests such a mechanism, although no supporting morphological data are yet available. There seem to exist different kinds of adherence mechanisms depending on the species of mycoplasma and the host involved. The receptors of sheep erythrocytes for M. pneumoniae, M. gallisepticum and M. dispar are neuraminidase-sensitive, whereas those for M. hominis and M. salivarium are not, but are protease-sensitive. On the other hand the receptors of rabbit red blood cells for M. pneumoniae and M. dispar are neuraminidase-resistant. The binding sites on the mycoplasma surface too differ in some properties. Data on M. pneumoniae suggest a protein as major constituent of the binding mechanism. The results of all studies are to some extent also dependent on the method used to examine adherence. Most work was done with either hemagglutination and hemadsorption or with attachment to cells and organ cultures. A special experimental system is provided by the adherence of some species to glass or plastic surfaces. On this model the role of energy metabolism could be studied in more detail. Further strategy of research must include biochemical methods as well as morphological and immunological approaches.
Insights
Mycoplasmas, lacking cell walls, use adaptable surface mechanisms for adherence to host cells. Different mycoplasma species and host receptors exhibit varied binding properties, influencing survival and pathogenicity.
Area of Science:
- Microbiology
- Cell Biology
- Parasitology
Background:
- Mycoplasmas are surface parasites of mucous membranes in animals and humans.
- Efficient adherence is crucial for mycoplasma survival and pathogenicity.
- Unlike bacteria, mycoplasmas can actively rearrange surface structures due to their lack of a rigid cell wall.
Purpose of the Study:
- To investigate the diverse adherence mechanisms of mycoplasmas.
- To understand the role of host receptors and mycoplasma binding sites in attachment.
- To explore the energy requirements and surface dynamics involved in mycoplasma adhesion.
Main Methods:
- Hemagglutination and hemadsorption assays.
- Attachment studies using cell and organ cultures.
- Adherence experiments on inert surfaces (glass/plastic) to study energy metabolism.
Main Results:
- Mycoplasma adherence mechanisms vary by species and host.
- Receptor sensitivity to neuraminidase and protease differs among host cells and mycoplasma species.
- M. pneumoniae attachment to inert surfaces suggests an energy-dependent mechanism, potentially involving surface protein components.
Conclusions:
- Mycoplasma adherence is a complex process involving species-specific interactions with host receptors.
- The ability to modify surface structures is key to mycoplasma adhesion.
- Future research should integrate biochemical, morphological, and immunological methods to fully elucidate these mechanisms.