"''Candidatus'' Cardinium" is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

Gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall ...

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has c ...

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

that reside within cells of some

arthropods Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...

and

nematodes The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-parasitic nematodes also known as eelworms. They are a diverse animal phylum inhabiting a broa ...

. Although they have not yet been isolated in pure culture (hence the designation ''

Candidatus In prokaryote nomenclature, ''Candidatus'' (Latin for candidate of Roman office) is used to name prokaryotic phyla that are well characterized but yet-uncultured. Contemporary sequencing approaches, such as 16S sequencing or metagenomics, provide m ...

''), they are known to negatively influence reproduction in their hosts in order to further their own proliferation. This leads to their classification as a

reproductive parasite The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction. Many non-living substances such as fluids, hormones, and pheromones are als ...

. One of the only other examples of this type of parasitism is the genus ''

Wolbachia ''Wolbachia'' is a genus of intracellular bacteria that infects mainly arthropod species, including a high proportion of insects, and also some nematodes. It is one of the most common parasitic microbes, and is possibly the most common reproduct ...

'', which also infects arthropods. These two genera can also co-infect the same animal, as in some

. "''Candidatus'' Cardinium" bacteria use many of the same methods to interfere with host reproduction as ''

,'' including inducing

cytoplasmic incompatibility Cytoplasmic incompatibility (CI) is a phenomenon that results in sperm and eggs being unable to form viable offspring. The effect arises from changes in the gamete cells caused by intracellular parasites like ''Wolbachia'', which infect a wide range ...

and distorting the sex ratio in the host population to favor females. The mechanisms by which "''Candidatus'' Cardinium" induces these conditions in hosts are thought to be different from the mechanisms used by ''

''. "''Candidatus'' Cardinium" bacteria are maternally inherited; infections are maintained through generations through the egg cells (termed

vertical transmission Vertical transmission of symbionts is the transfer of a microbial symbiont from the parent directly to the offspring. Many metazoan species carry symbiotic bacteria which play a mutualistic, commensal, or parasitic role. A symbiont is acquire ...

). It is estimated that 6–10% of all arthropods are infected with "''Candidatus'' Cardinium" bacteria. "''Candidatus'' Cardinium" were first discovered in 1996 in the cells of deer ticks, although attempts to culture them independently of host cells were unsuccessful.

References

{{Taxonbar, from=Q85750631 Sphingobacteriia Candidatus taxa