Transmission of Members of the “Candidatus Midichloriaceae” Family to Vertebrates and Possible Involvement in Disease Pathogenesis

Castelli, Michele; McCarthy, Una; Petroni, Giulio; Bazzocchi, Chiara

doi:10.1007/978-3-319-46859-4_14

Cited by 4 publications

(2 citation statements)

References 28 publications

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“…Alternatively, it is possible that ticks could transmit this endosymbiont to humans and consequently to other ticks, completing a tick-to-human-to tick transmission route, similar to that described for tick-borne pathogens. Indeed, this endosymbiont has been detected in the blood of humans and mammals bitten by ticks [54].…”

Section: Candidatus Midichloria Mitochondriimentioning

confidence: 99%

Rickettsial Agents Associated with Ectoparasites in Attica, Greece

et al. 2022

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The bacteria of the families Rickettsiaceae and Anaplasmataceae, harbored by arthropod vectors, may cause disease in animals and humans. The aim of this study was to screen ectoparasites collected from cats and dogs in Attica, Greece for the bacteria of the Rickettsiales group, by molecular methods. The ectoparasites examined were Ctenocephalides felis fleas and Rhipicephalus sanguineus s.l., Rhipicephalus sp., and Ixodes sp. ticks. Rickettsia felis was detected in 4.8% of C. felis fleas, and Rickettsia conorii was detected in 7.3% of R. sanguineus s.l. ticks. Ehrlichia canis was found in one R. sanguineus s.l. tick, and Wolbachia pipientis was detected in the majority of fleas. Another endosymbiont, Cancidatus Midichloria mitochondrii (Cancidatus Midichloriaceae), was detected in one Ixodes sp.. This is the first report of R. conorii and E. canis in R. sanguineus s.l. ticks in this study area. Given the fact that Greece is considered endemic for spotted fever group rickettsioses, further investigation of these rickettsial pathogens’ distribution in their vectors and hosts could enhance our knowledge of their epidemiology, in order to assess their potential implications for public health in this metropolitan area.

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Section: Candidatus Midichloria Mitochondriimentioning

confidence: 99%

Rickettsial Agents Associated with Ectoparasites in Attica, Greece

et al. 2022

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“…Although two members of Candidatus Midichloriaceae (Candidatus Midichloria mitochondrii and Candidatus Lariskella arthropodarum) have been found in symbionts with ticks and in human blood, there is still insufficient evidence to suggest its pathogenicity towards humans. 2,3 Therefore, Candidatus Midichloriaceae is often excluded from discussions on Rickettsial disease.…”

Section: Introductionmentioning

confidence: 99%

Role of Rickettsial Outer Membrane Protein A in the Pathogenesis of Rickettsial Diseases

Harun,

Yuhana,

Chua

et al. 2024

J. Pure Appl. Microbiol.

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Diseases caused by Rickettsiales are often overlooked, although they pose important public health concerns. The Rickettsiales family comprises a broad range of intracellular bacteria with distinct evolutionary adaptations, making the development of treatment measures to combat infections, such as vaccines or antibiotics, a challenge. Interestingly, the outer membrane protein A (OmpA) was found to exist in the cell surface of most human pathogenic bacteria in the order Rickettsiales. However, knowledge about OmpA in each species and strain is scattered and ambiguous. In this study, we systematically compiled the existing information on OmpA and its relationship with human pathogenic rickettsiae to serve as a reference for future research. A comprehensive literature search was conducted using specific keywords across five databases. According to the literature, OmpA of spotted fever group rickettsia plays a crucial role as an adhesin and invasin that directly interacts with the surface of mammalian host cells to mediate bacterial localization in host cells. The presence of a premature stop codon in the amino acid sequence resulted in the secretion of non-functional OmpA, which is one of the main reasons for rickettsial strains or species to become avirulent. Similarly, OmpA also functions as an important adhesin in the Anaplasma family when it interacts with the sLex and sLex-like glycan of myeloid and endothelial cells, respectively. However, the OmpA of Anaplasma must be co-functional with the other two adhesins to promote bacterial internalization. Interestingly, certain sites in the amino acid residues of Ehrlichia and Orientia OmpA are predicted to be homologous to the binding domain region of Anaplasma OmpA. It is therefore suggested that OmpA is an important adhesin for bacteria to bind to their specific mammalian host cells.

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Two intracellular and cell type-specific bacterial symbionts in the placozoan Trichoplax H2

et al. 2019

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Placozoa is an enigmatic phylum of simple, microscopic, marine metazoans1,2. Although intracellular bacteria have been found in all members of this phylum, almost nothing is known about their identity, location and interactions with their host3–6. We used metagenomic and metatranscriptomic sequencing of single host individuals, plus metaproteomic and imaging analyses, to show that the placozoan Trichoplax sp. H2 lives in symbiosis with two intracellular bacteria. One symbiont forms an undescribed genus in the Midichloriaceae (Rickettsiales)7,8 and has a genomic repertoire similar to that of rickettsial parasites9,10, but does not seem to express key genes for energy parasitism. Correlative image analyses and three-dimensional electron tomography revealed that this symbiont resides in the rough endoplasmic reticulum of its host’s internal fibre cells. The second symbiont belongs to the Margulisbacteria, a phylum without cultured representatives and not known to form intracellular associations11–13. This symbiont lives in the ventral epithelial cells of Trichoplax, probably metabolizes algal lipids digested by its host and has the capacity to supplement the placozoan’s nutrition. Our study shows that one of the simplest animals has evolved highly specific and intimate associations with symbiotic, intracellular bacteria and highlights that symbioses can provide access to otherwise elusive microbial dark matter.

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Transmission of Members of the “Candidatus Midichloriaceae” Family to Vertebrates and Possible Involvement in Disease Pathogenesis

Cited by 4 publications

References 28 publications

Rickettsial Agents Associated with Ectoparasites in Attica, Greece

Rickettsial Agents Associated with Ectoparasites in Attica, Greece

Role of Rickettsial Outer Membrane Protein A in the Pathogenesis of Rickettsial Diseases

Two intracellular and cell type-specific bacterial symbionts in the placozoan Trichoplax H2

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