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Characterization and taxonomic status of tick spiroplasmas: a review
Abstract:
Three serologically distinct groups of spiroplasmas have been recovered from ticks. Spiroplasma mirum strains (from rabbit ticks, Haemaphysalis leporispalustris) and Y32 group (VI) spiroplasmas (from Ixodes pacificus) are the only spiroplasmas to have a clear association with these arthropods. Group (VI) spiroplasmas are distinguished by an unusual nonhelical morphology and their capacity to hemadsorb guinea pig erythrocytes. S. mirum strains are unique in their ability to induce cataracts or lethal brain infections in a number of young vertebrates and in their virulence for the chick embryo. The 277F spiroplasma, while initially recovered from a pool of rabbit ticks (H. leporispalustris), is related by certain serological and genetic properties to spiroplasmas in the S. citri complex (serogroup I). These relationships suggest that the 277F spiroplasma may not be a natural inhabitant of the rabbit tick.
Insights
Three distinct spiroplasma groups were found in ticks. Spiroplasma mirum and Group VI spiroplasmas show clear tick associations, while the 277F spiroplasma may not be a natural tick inhabitant.
Area of Science:
- Microbiology
- Arthropod-borne pathogens
Background:
- Spiroplasmas are tick-associated bacteria with diverse characteristics.
- Previous studies identified distinct serological groups of spiroplasmas in ticks.
Purpose of the Study:
- To characterize and differentiate tick-borne spiroplasma groups.
- To investigate the taxonomic and ecological relationships of spiroplasmas recovered from ticks.
Main Methods:
- Serological analysis to distinguish spiroplasma groups.
- Morphological characterization, including hemadsorption assays.
- Genetic analysis to assess relationships with known spiroplasma complexes.
Main Results:
- Three serologically distinct spiroplasma groups were identified in ticks.
- Group VI spiroplasmas exhibit unique nonhelical morphology and hemadsorb guinea pig erythrocytes.
- Spiroplasma mirum strains demonstrate virulence in vertebrates and chick embryos.
- The 277F spiroplasma shows serological and genetic links to the Spiroplasma citri complex, suggesting it may not be endemic to rabbit ticks.
Conclusions:
- Spiroplasma mirum and Group VI spiroplasmas are significantly associated with specific tick species.
- The 277F spiroplasma's relationship to the S. citri complex warrants further investigation into its ecological role.
- Tick-borne spiroplasmas represent a diverse group with varied pathogenic potentials and host associations.