Novel Clade of Rickettsia spp. from Leeches

Abstract

Intracellular rickettsia-like structures were found in the tissues of a glossiphoniid leech, Torix tagoi, by transmission electron microscopy. Diagnostic PCR analysis using specific primers suggested that of the nine glossiphoniid species examined, two species, T. tagoi and Hemicrepsis marginata, harbored bacteria of the genus Rickettsia. A 1.5-kb eubacterial 16S rRNA gene segment obtained from each of these species was amplified by PCR, cloned, and sequenced. Phylogenetic analysis of the 16S rRNA gene demonstrated that the Rickettsia species found in the leeches constituted a novel clade that is distinct from the clade of arthropod-associated Rickettsia species. In natural populations, 97.7% (43 of 44) of T. tagoi leeches and 100% (9 of 9) of H. marginata leeches carried Rickettsia, suggesting that infection with Rickettsia is prevalent in these leeches. This is the first report of Rickettsia found in annelids.

Nuclearia pattersoni sp. n. (Filosea), a new species of amphizoic amoeba isolated from gills of roach (Rutilus rutilus), and its rickettsial endosymbiont

“…suggests that the primary host of an ancestor of this endosymbiont might have been a leech from which the ancestral rickettsia was transmitted by bloodsucking to fish and then through the process of phagocytosis became endosymbiont of amoeba. This indirectly supports the hypothesis that the role of leeches in the aquatic ecosystems is analogous to the bloodsucking arthropods in the terrestrial ecosystems (Kikuchi et al 2002).…”

Rickettsia Symbiont in the Pea Aphid Acyrthosiphon pisum : Novel Cellular Tropism, Effect on Host Fitness, and Interaction with the Essential Symbiont Buchnera

“…Some facultative insect endosymbionts, such as ␥-proteobacterial secondary symbionts in aphids, are housed in different types of specialized cells called secondary mycetocytes and sheath cells (4,14,16,22,40). On the other hand, no such specific cellular localization has been reported for facultative symbionts that are widely found across diverse insect taxa, such as Wolbachia, Spiroplasma, and Rickettsia (8,11,15,20,21,23), although concentrated distributions in ovary and germ plasm were recognized in some cases (8,18,20).…”

“…In these cases, the Rickettsia bacterium is inherited by ovarial transmission through host generations with a high fidelity, is detected in host populations at a considerable frequency, and can be regarded as a facultative endosymbiotic associate (9,44). Thus far, such Rickettsia symbionts have been identified from a wide variety of invertebrates such as ladybird beetles (19,43,46), an aphid (6), a leafhopper (10), a bruchid beetle (13), ticks (2,30), leeches (21), and others.…”

“…Although some Rickettsia species occasionally infect vertebrates with pathology, and a few species are obligatorily associated with vertebrates, it is believed that the primary hosts of most Rickettsia species are arthropods and other invertebrates (9,21,44). In these cases, the Rickettsia bacterium is inherited by ovarial transmission through host generations with a high fidelity, is detected in host populations at a considerable frequency, and can be regarded as a facultative endosymbiotic associate (9,44).…”

New Gammaproteobacteria Associated with Blood-Feeding Leeches and a Broad Phylogenetic Analysis of Leech Endosymbionts

“…Kikuchi et al (17) described a Rickettsia sp. found in various tissues of two species of Japanese glossiphoniid leeches.…”