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PubMed2026

Friends or foes: Unraveling the tsetse fly-Spiroplasma symbiosis.

Tsetse flies (Glossina spp.) transmit African trypanosomes, the causative agents of human African and African animal trypanosomiases (HAT and AAT, respectively). These neglected tropical diseases impose significant public health and economic burdens across sub-Saharan Africa. Trypanosome transmission by tsetse flies is influenced by multiple factors, including host genetic background, ecological factors, and interactions with heritable microbial endosymbionts. Spiroplasma glossinidia has recently emerged as an important modulator of tsetse reproductive fitness and vector competence, making it a potential target for symbiont-based vector control strategies. In this review, we summarize the current knowledge of the tsetse-Spiroplasma symbiosis. We detail Spiroplasma's spatial and temporal infection dynamics in laboratory-reared and natural populations. Additionally, we highlight key aspects of the bacterium's genomics, phylogenetics, and physiological interactions with its tsetse host, including influences on host gene expression reproductive physiology, and vector competence. Finally, we discuss how the tsetse-Spiroplasma symbiosis could be harnessed to develop innovative, biological-based vector control and trypanosome transmission-blocking strategies, and we identify critical gaps that must be addressed to translate these findings into effective disease control interventions.

Animals↗
PubMed2025

Comparative genomics and transcriptomics of the Spiroplasma glossinidia strain sGff reveal insights into host interaction and trypanosome resistance in Glossina fuscipes fuscipes.

Tsetse (Glossina spp.) are vectors of African trypanosomes, the causative agents of Human and African Animal trypanosomiases, diseases that remain significant medical and socioeconomic challenges in sub-Saharan Africa. In addition to trypanosomes, tsetse harbor both obligate and facultative symbiotic bacteria that can influence vector competence and reproductive biology. One such facultative symbiont, Spiroplasma glossinidia, infects several tsetse species within the Palpalis subgroup. In Glossina fuscipes fuscipes (Gff), the Spiroplasma glossinidia strain sGff induces a trypanosome-refractory phenotype and negatively impacts reproductive fitness by reducing female fecundity. However, the mechanisms behind these Spiroplasma-derived phenotypes remain poorly understood. Here, we report successful in vitro cultivation of sGff and present complete genomes from three sources: in vitro cultured sGff and sGff isolated from both laboratory-maintained and wild-caught (Uganda) Gff flies. Comparative genomic analyses revealed a high degree of similarity in gene content and synteny among these sGff samples, confirming that they represent isolates of the same strain. Phylogenomic analyses placed sGff within the Spiroplasma poulsonii clade. The sGff genome is highly dynamic, containing numerous mobile genetic elements. Additionally, in silico annotations indicate that sGff relies on its host for both lipids and carbohydrates and produces several toxins, all of which could be implicated in the observed trypanosome refractory phenotype. Finally, comparative transcriptomic analysis of sGff from host hemolymph versus in vitro culture provided insights into potential factors relevant to host-symbiont interactions. Our findings provide a foundation for understanding the nutritional dialogue between sGff and its host and identify symbiotic products that may contribute to trypanosome resistance. Furthermore, the establishment of an in vitro culture system for sGff represents a significant resource for future functional studies with potential implications for vector control.

Glossina fuscipes fuscipes↗
PubMed1985

[Spiroplasmas and hematophagous arthropods; prospects in tropical pathology].

Spiroplasmas are original wall-free prokaryotes which exhibit motility and a helical shape although lacking any cell wall or motile apparatus. They are known by phytopathologists because some of them are responsible for severe arthropod-borne plant diseases, such as Spiroplasma citri, the etiologic agent of "citrus stubborn disease". Other spiroplasmas are pathogenic for a number of insects: drosophila, bees and beetles. More recently spiroplasmas were also isolated from ticks, mosquitoes, horse-flies and deer-flies opening a new chapter in medical pathology. These agents are of possible great significance in Tropical Medicine.

Animals↗
PubMed1986

[Sensitivity to various antibiotics of spiroplasmas isolated from mosquitoes in France].

Spiroplasmas are helical mycoplasmas that play a significant role in plant diseases. They are also found in arthropods that are likely to bite humans, such as ticks and mosquitoes. These arthropods can act as vectors and therefore may be of epidemiologic significance. Furthermore, mainly on the grounds of morphologic evidence, spiroplasmas have been incriminated in the genesis of human Creutzfeld-Jacob disease. We recovered six strains of Spiroplasma sp. from 1927 female mosquitoes. In vitro susceptibility of each strain to the following antibiotics was studied: tetracycline, oxytetracycline, doxycycline, erythromycin, chloramphenicol, rifampin, kanamycin, gentamicin and pefloxacin. Minimal inhibitory concentrations (MICs) were determined by dilution in liquid SP4 medium using microtiter plates. Plates were incubated for 24 to 48 hours at 30 degrees C. The inoculum contained approximately 5 X 10(5) CFU/ml. Each of the six strains was found to be highly susceptible to tetracycline, oxytetracycline, doxycycline, erythromycin, chloramphenicol and pefloxacin (MICs less than or equal to 0.16 microgram/ml, 0.63 microgram/ml, 0.08 microgram/ml, 0.16 microgram/ml and 0.32 microgram/ml respectively). On the opposite, the strains exhibited resistance to rifampin and variable degrees of susceptibility to kanamycin (12.5 micrograms/ml less than MIC less than 50 micrograms/ml) and gentamicin (3.12 micrograms/ml less than MIC less than 50 micrograms/ml). From our results, spiroplasmas seem to have more or less the same susceptibility to antibiotics as mycoplasmas.

Animals↗
PubMedDate not supplied

Spiroplasmas in leafhoppers: a review.

This review describes the pathway a plant pathogenic mycoplasma or spiroplasma takes in its passage through a leafhopper vector. Reference is made to several strains of spiroplasma and acholeplasma, but, in particular, data are presented for Spiroplasma citri and the corn stunt spiroplasma. Acquisition of the organisms is discussed, together with the different methods of infection (feeding on plants and through membranes or following injection) and the effect they have on the inoculum dose. The dose, together with the environmental conditions, are also factors which effect multiplication in both whole insects and salivary glands. Titers reached by the organisms in the insect are given. Pathogenic effects on the insects are discussed. The analogy is given of the insect acting as a chemostat with poor nutrition or high temperature adversely affecting the balance. Feeding behavior and the number of organisms ejected are two factors affecting transmission.

Animals↗
PubMed1984

Diversity of spiroplasma host-parasite relationships.

Studies of many new mollicutes isolates from insects collected over the last 2 years have suggested a tentative grouping of host-parasite relationships. Those that have been partially studied to date include: 1) temporary gut infection or gut contamination in which the spiroplasmas may survive gut passage with little or no multiplication and with very limited persistence; 2) permanent gut infection in which the host gut is the year-round reservoir; 3) gut infection with hemolymph invasion in which spiroplasmas occur commonly in insect guts but with ability to invade the hemolymph of certain species to which they are pathogenic; and 4) hemolymph infection with noncultivable spiroplasmas in which spiroplasmas occurring in hemolymph or other host tissues are noncultivable.

Animals↗
PubMed1984

Occurrence and frequency of subgroup I-6 spiroplasma in arthropods associated with old fields in Maryland and Virginia.

The Subgroup I-6 spiroplasma, "Maryland Flower Spiroplasma," originally discovered on fall flowers and subsequently recovered from a syrphid fly and a beetle triungulin, was isolated from two new fall flower hosts and from the guts of nine nectar-imbibing insect species. These data, together with lack of recovery of I-6 spiroplasma from foliage-feeding, plant-sucking, or flightless flower-associated insects, suggest that I-6 spiroplasma may infect and be disseminated by nectar- or pollen-foraging insects, and that the dynamics of maintenance will prove to be complex.

Animals↗
PubMed1984

Arginine aminopeptidase activity of phytopathogenic spiroplasmas.

The arginine aminopeptidase activity of arginine-utilizing phytopathogenic spiroplasmas was investigated with arginine beta-naphthylamide substrate using the fluorometric method. Hydrolysis of this substrate was demonstrated with broth cultures, washed concentrated whole cells, and cell-free extracts of corn stunt spiroplasma (CSS) and Spiroplasma citri. Growing CSS and S. citri in the presence of 47 mM arginine resulted in a reduction in aminopeptidase activity, indicating that synthesis of the enzyme might be subject to control by catabolic repression. Results of these experiments suggest a possible biochemical basis for pathogenicity of phytopathogenic spiroplasmas in vivo.

Aminopeptidases↗
PubMed1984

Characterization of spiroplasma virus group 4 (SV4).

Spiroplasma virus Group 4 was propagated, purified and characterized. The isometric capsid is made from one major protein of 60,000 Da and contains a circular single-stranded DNA molecule of 1.7 X 10(6) Da. The host-range of SV4 is limited to Subgroup I-2 spiroplasmas. The virions are released from the infected cells by a lytic process. Transfection of spiroplasmas of Subgroup I-2 by the viral DNA was demonstrated. A high efficiency of transfection was routinely obtained in the presence of polyethyleneglycol. These experiments indicate that spiroplasmas can absorb viral DNA, opening the way for cloning.

Bacteriophages↗
PubMedDate not supplied

Serological classification of spiroplasmas: current status.

Data concerning serological classification of spiroplasmas are in good agreement, but slightly different numerical designations have been given to existing groups. It is proposed that a standardized system be adopted based on information developed mainly by the IRPCM working team on spiroplasmas. The type species (Spiroplasma citri) should be redefined to include only the agent of citrus stubborn disease (subgroup I-1). Six other subgroups, including three proposed by Bové et al. in this volume (I-5, I-6, and I-7), are members of the Group I complex. Because subgroups I-1, I-2, and I-3 (1) show significant reciprocal differences in DNA-DNA homology and two-dimensional electrophoretic protein profiles, (2) occupy exclusive habitats, (3) are each associated with important diseases, and (4) consist of clusters of very similar or identical strains, it is suggested that Latin binomials could be assigned to subgroups I-2 and I-3. It is proposed that those criteria could serve as general guidelines for consideration of subgroups for species status in the class Mollicutes. The I-4 subgroup is assigned an uncertain status, pending comparisons with the LB-12 (I-5), M55 (I-6), and N525 (I-7) subgroups. To previously described serogroups we add the CN-5 Cotinus beetle spiroplasma (IX), the AES-1 mosquito strain (X), and the MQ-4 Monobia strain (XI).

DNA, Bacterial↗
PubMed1995

Resistance of Spiroplasma citri Lines to the Virus SVTS2 Is Associated with Integration of Viral DNA Sequences into Host Chromosomal and Extrachromosomal DNA.

Spiroplasmavirus SVTS2, isolated from Spiroplasma melliferum TS2, produces plaques when inoculated onto lawns of Spiroplasma citri M200H, a derivative of the type strain Maroc R8A2. S. citri strains MR2 and MR3, originally selected as colonies growing within plaques on a lawn of M200H inoculated with SVTS2, were resistant to SVTS2. Genomic DNA fingerprints and electrophoretic protein profiles of M200H, MR2, and MR3 were similar, but three proteins present in M200H were missing or significantly reduced in both resistant lines. None of these three polypeptides reacted with antiserum against S. citri membrane proteins, indicating that they probably are not surface-located virus receptors. Electroporation with SVTS2 DNA produced 1.5 x 10(sup5) transfectants per (mu)g of DNA in M200H but none in MR2 or MR3, suggesting that resistance may result from inhibition of viral replication. The digestion patterns of the extrachromosomal double-stranded (ds) DNA of these lines were similar. Three TaqI fragments of MR2 extrachromosomal DNA that were not present in M200H extrachromosomal DNA hybridized strongly to an SVTS2 probe, and two of these fragments plus an additional one hybridized with the MR3 extrachromosomal DNA, indicating that a fragment of SVTS2 DNA was present in the extrachromosomal ds DNA of MR2 and MR3 but not of M200H. When the restricted genomes of all three lines were probed with SVTS2 DNA, strong hybridization to two EcoRI fragments of chromosomal MR2 and MR3 DNA but not M200H DNA indicated that SVTS2 DNA had integrated into the genomes of MR2 and MR3 but not of M200H. When MR3 extrachromosomal ds DNA containing a 2.1-kb SVTS2 DNA fragment was transfected into M200H, the transformed spiroplasmas were resistant to SVTS2. These results suggest that SVTS2 DNA fragments, possibly integrated into the chromosomal or extrachromosomal DNA of a previously susceptible spiroplasma, may function as viral incompatibility elements, providing resistance to superinfection by SVTS2.

Journal Article↗
PubMed1994

Characterization of a cryptic extrachromosomal element isolated from the mollicute Spiroplasma taiwanense.

Characterization of an extrachromosomal element from an organism in the genus Spiroplasma is likely to be an essential step in the development of cloning vectors which replicate in these organisms. A restriction map for an 11-kb element, designated pCT-1, isolated from Spiroplasma taiwanese strain CT-1 (ATCC 43302) has been constructed using the restriction enzymes Bg/II, EcoRI, HincII, HindIII, HpaI, PstI, and XbaI. This element is distinct from any previously characterized spiroplasma virus or plasmid. pCT-1 has been cloned into the Escherichia coli vector pBR322 as a step in the development of a biphasic shuttle vector system.

Animals↗
PubMed2006

Spiroplasma infection causes either early or late male killing in Drosophila, depending on maternal host age.

Symbiont-induced male-killing phenotypes have been found in a variety of insects. Conventionally, these phenotypes have been divided into two categories according to the timing of action: early male killing at embryonic stages and late male killing at late larval stages. In Drosophila species, endosymbiotic bacteria of the genus Spiroplasma have been known to cause early male killing. Here, we report that a spiroplasma strain normally causing early male killing also induces late male killing depending on the maternal host age: male-specific mortality of larvae and pupae was more frequently observed in the offspring of young females. As the lowest spiroplasma density and occasional male production were also associated with newly emerged females, we proposed the density-dependent hypothesis for the expression of early and late male-killing phenotypes. Our finding suggested that (1) early and late male-killing phenotypes can be caused by the same symbiont and probably by the same mechanism; (2) late male killing may occur as an attenuated expression of early male killing; (3) expression of early and late male-killing phenotypes may be dependent on the symbiont density, and thus, could potentially be affected by the host immunity and regulation; and (4) early male killing and late male killing could be alternative strategies adopted by microbial reproductive manipulators.

Aggression↗
PubMed1994

Production and characterization of a polyclonal antiserum against Spiroplasma mirum (ATCC 29335).

Spiroplasma mirum (ATCC 29335), an American tick isolate, was cultivated and its purity was controlled using electron microscopy and Tricine-SDS-PAGE. In the SDS-PAGE analysis, the protein pattern of the antigen used revealed a polypeptide profile (35 bands) with an approximate molecular weight of 161 kDa to 10.5 kDa. This strain was used to immunize two rabbits. The produced antisera did not cross-react with Mycoplasma pneumoniae, Salmonella minnesota, Borrelia burgdorferi, Treponema pallidum but did still react in Western blot analysis with Spiroplasma mirum at a dilution of 1:128.000. This specific and sensitive antiserum was used to examine 72 midgut smears of Berlin ticks (lxodes ricinus) individually by direct immunofluorescence. In 26 samples, we could demonstrate fluorescent structures, but we were not able to culture spiroplasmas from these samples.

Animals↗
PubMed2000

Common elements of spiroplasma plectroviruses revealed by nucleotide sequence of SVTS2.

DNA of SpV1-like spiroplasma plectroviruses (rods with single-stranded circular DNA) is scattered in the genome of the phytopathogen Spiroplasma citri and has significant consequences for evolution of the S. citri genome. We determined the complete nucleotide sequence of SVTS2, a SpV1-like virus of S. melliferum, a honeybee pathogen, to ascertain, by comparison with S. citri SpV1 viruses (GenBank U28974 and X51344), the defining features of this important group. The 6,824 nt DNA contains nine ORFs homologous to ORFs of S. citri SpV1 viruses and five ORFs unique to SVTS2. The predicted amino acid sequences of the homologous ORFs were 17-38% identical to those of their S. citri counterparts. The SVTS2 predicted ORF 1 product (Mr 47,031) was considerably smaller than those of known S. citri SpV1 viruses. Also, in contrast to those viruses, SVTS2 lacked an ORF with recognizable similarity to a transposase. ORF 2 of all three viruses had a homologue among the products of genes of MVL-1, a virus of Acholeplasma laidlawii, another plectrovirus. The results suggest that, at most, only slightly more than half of SpV1 genomes consists of genes shared by all spiroplasma viruses of the group.

Amino Acid Sequence↗
PubMed2003

Motility modes of Spiroplasma melliferum BC3: a helical, wall-less bacterium driven by a linear motor.

Spiroplasma are members of the Mollicutes (Mycoplasma, Acholeplasma and Spiroplasma) - the simplest, minimal, free-living and self-replicating forms of life. The mollicutes are unique among bacteria in completely lacking cell walls and flagella and in having an internal, contractile cytoskeleton, which also functions as a linear motor. Spiroplasma are helical, chemotactic and viscotactic active swimmers. The Spiroplasmal cytoskeleton is a flat ribbon composed of seven pairs of fibrils. The ribbon is attached to the inner side of the cell membrane along its innermost (shortest) helical line. The cell's geometry and dynamic helical parameters, and consequently motility, can be controlled by changing differentially and in a co-ordinated manner, the length of the fibrils. We identified several consistent modes of cell movements and motility originating, most likely, as a result of co-operative or local molecular switching of fibrils: (i). regular extension and contraction within the limits of helical symmetry (this mode also includes straightening, beyond what is allowed by helical symmetry, and reversible change of helical sense); (ii). spontaneous and random change of helical sense originating at random sites along the cell (these changes propagate along the cell in either direction and hand switching is completed within approximately 0.08 second); (iii). forming a deformation on one of the helical turns and propagating it along the cell (these helical deformations may travel along the cell at a speed of up to approximately 40 microm s-1); (iv). random bending, flexing and twitching (equivalent to tumbling). In standard medium (viscosity = 1.147 centipoise) the cells run at approximately 1.5 microm s-1, have a Reynolds number of approximately 3.5 x 10-6 and consume approximately 30 ATP molecules s-1. Running velocity, duration, persistence and efficiency increase with viscosity upon adding ficoll, dextran and methylcellulose to standard media. Relative force measurements using optical tweezers confirm these findings.

Culture Media↗
PubMed1991

Spiroplasma (Mollicutes: Spiroplasmataceae) pathogenic for Aedes aegypti and Anopheles stephensi (Diptera: Culicidae).

Intrathoracic inoculation with the mosquito spiroplasma, Spiroplasma taïwanense Abalain-Colloc et al., was found to reduce significantly the survival of adult male and female Aedes aegypti (L.) and Anopheles stephensi Liston. This spiroplasma also reduced significantly the flight capacity of adult female Ae. aegypti 5-8 d after inoculation and adult female An. stephensi 4 d after inoculation. Adult female An. stephensi were incapable of flight 5 d after inoculation. As such, S. taïwanense joins Bacillus thuringiensis and B. sphaericus as bacteria known to be pathogenic for mosquito vectors.

Aedes↗
PubMed1997

Three spiroplasmas isolated from Haematopota sp. (Diptera:Tabanidae) in France.

On August 1991, three spiroplasmas (Tab 2A, Tab 2B and Tab 4C) were isolated from Haematopota sp. flies collected from Indre-et-Loire, France. Isolations were made at 28 degrees C in MD1 medium from ground individual flies, but not from external washings. All isolates adapted well to SP4 medium at 30 and 37 degrees C and were triple cloned before serological identification. Using the cross deformation test, the 3 isolates were compared with 42 known spiroplasmas isolated from diseased plants, flowers, various insects and ticks belonging to 25 serological groups. Each isolate cross-reacted with others and exhibited weak 1-way reactions with TABS-2 or PLHS-1, two spiroplasmas isolated in the United States from respectively Tabanus abactor Philip and Panorpa helena L, a scorpion-fly. These results suggest that Tab 2A, Tab 2B and Tab 4C together with TABS-2 and PLHS-1 may represent, members of a new serological supergroup.

Animals↗