Transmission rates of the bacterial endosymbiont, Neorickettsia risticii, during the asexual reproduction phase of its digenean host, Plagiorchis elegans, within naturally infected lymnaeid snails

Greiman, Stephen E.; Tkach, Vasyl V.; Vaughan, Jefferson A.

doi:10.1186/1756-3305-6-303

Cited by 29 publications

(37 citation statements)

References 35 publications

(29 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…DNA sequence analysis demonstrated that the Neorickettsia isolates used in this study were identical to the genotype reported from P. elegans by Greiman et al (11,12). This genotype shows 1.8% sequence dif- ference in the 16S gene compared to the typical N. risticii (Illinois strain) and may represent a new species of Neorickettsia (12).…”

Section: Resultssupporting

confidence: 48%

“…A consistent source of Neorickettsia-infected digeneans was needed in order to perform these studies. Because the prevalence of Neorickettsia infection within natural populations of digeneans is generally low (3 to 23%) (11,12), we established and maintained in our laboratory the life cycle of a digenean, P. elegans. This species is common in eastern North Dakota, is naturally infected with Neorickettsia, and is amenable to laboratory culture.…”

Section: Methodsmentioning

confidence: 99%

“…and their digenean hosts. Greiman et al (11) studied the vertical transmission of Neorickettsia sp. during asexual reproduction of Plagiorchis elegans and found that the prevalence of Neorickettsia infection among cercariae shed by infected snails never reached 100%, despite the fact that all of the progenitor stages (i.e., the sporocysts) within infected snails were infected.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Germs within Worms: Localization of Neorickettsia sp. within Life Cycle Stages of the Digenean Plagiorchis elegans

Greiman

Rikihisa

Cain

et al. 2016

Appl Environ Microbiol

View full text Add to dashboard Cite

Neorickettsia spp. are bacterial endosymbionts of parasitic flukes (Digenea) that also have the potential to infect and cause disease (e.g., Sennetsu fever) in the vertebrate hosts of the fluke. One of the largest gaps in our knowledge of Neorickettsia biology is the very limited information available regarding the localization of the bacterial endosymbiont within its digenean host. In this study, we used indirect immunofluorescence microscopy to visualize Neorickettsia sp. within several life cycle stages of the digenean Plagiorchis elegans. Individual sporocysts, cercariae, metacercariae, and adults of P. elegans naturally infected with Neorickettsia sp. were obtained from our laboratory-maintained life cycle, embedded, sectioned, and prepared for indirect immunofluorescence microscopy using anti-Neorickettsia risticii horse serum as the primary antibody. Neorickettsia sp. was found within the tegument of sporocysts, throughout cercarial embryos (germ balls) and fully formed cercariae (within the sporocysts), throughout metacercariae, and within the tegument, parenchyma, vitellaria, uteri, testes, cirrus sacs, and eggs of adults. Interestingly, Neorickettsia sp. was not found within the ovarian tissue. This suggests that vertical transmission of Neorickettsia within adult digeneans occurs via the incorporation of infected vitelline cells into the egg rather than direct infection of the ooplasm of the oocyte, as has been described for other bacterial endosymbionts of invertebrates (e.g., Rickettsia and Wolbachia). Bacteria in the genus Neorickettsia (order Rickettsiales, family Anaplasmataceae) are intracellular endosymbionts of digeneans. Digeneans are a diverse group of metazoan endoparasitic flatworms, with Ͼ18,000 nominal species (1). Digeneans have complex life cycles involving several stages that require two to four hosts for completion. Adult digeneans produce eggs containing a miracidium stage that penetrates the body of the first intermediate host (always a mollusk). The miracidium develops into a mother sporocyst, which produces daughter sporocysts, or rediae, by asexual reproduction, depending on the group of digeneans. Daughter sporocysts/rediae produce numerous free-living cercariae, which usually (with some exceptions) need to penetrate a second intermediate (usually an arthropod or a vertebrate) host to become metacercariae. When an infected intermediate host is eaten by a suitable definitive host, the metacercariae develop into hermaphroditic adult digeneans, which then reproduce sexually.Neorickettsiae are maintained throughout the digenean life cycle by vertical transmission. In some cases, neorickettsiae may be transmitted horizontally by digeneans to their vertebrate definitive hosts, where the bacteria can infect leukocytes and cause debilitating disease in horses, dogs, black bears, and humans (2).The localization of Neorickettsia in the vertebrate definitive host tissue is well known. A number of studies (3-8) have used techniques, such as in situ hybridization, immunofluorescence microsc...

show abstract

Section: Resultssupporting

confidence: 48%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Germs within Worms: Localization of Neorickettsia sp. within Life Cycle Stages of the Digenean Plagiorchis elegans

Greiman

Rikihisa

Cain

et al. 2016

Appl Environ Microbiol

View full text Add to dashboard Cite

show abstract

“…of trematodes, and Myotis yumanensis bats and tree swallows (Hirundo rustica and Tachycineta bicolor) were also reported to be infected with N. risticii (10). In addition, N. risticii DNA fragments have been detected in various other digenean trematodes having life cycles typical of freshwater/terrestrial ecosystems (11,12). However, due to limited molecular analysis, the relatedness of these Neorickettsia organisms to N. risticii strains infecting horses, and whether they can infect horses and cause PHF, is unknown.…”

mentioning

confidence: 98%

An Ecotype of Neorickettsia risticii Causing Potomac Horse Fever in Canada

Xiong

Bekebrede

Sharma

et al. 2016

Appl Environ Microbiol

View full text Add to dashboard Cite

Neorickettsia (formerly Ehrlichia) risticii is an obligatory intracellular bacterium of digenetic trematodes. When a horse accidentally ingests aquatic insects containing encysted trematodes infected with N. risticii, the bacterium is transmitted from trematodes to horse cells and causes an acute and often fatal disease called Potomac horse fever (PHF). Since the discovery of N. risticii in the United States in 1984, using immunofluorescence and PCR assays, PHF has been increasingly recognized throughout North America and South America. However, so far, there exist only a few stable N. risticii culture isolates, all of which are from horses within the United States, and the strain diversity and environmental spreading and distribution of pathogenic N. risticii strains remain poorly understood. This paper reports the isolation of N. risticii from the blood of a horse with acute PHF in Ontario, Canada. Intracellular N. risticii colonies were detected in P388D 1 cells after 47 days of culturing and 8 days after the addition of rapamycin. Molecular phylogenetic analysis based on amino acid sequences of major surface proteins P51 and Ssa1 showed that this isolate is distinct from any previously sequenced strains but closely related to midwestern U.S. strains. This is the first Canadian strain cultured, and a new method was developed to reactivate dormant N. risticii to improve culture isolation. IMPORTANCENeorickettsia risticii is an environmental bacterium that lives inside flukes that are parasitic to aquatic snails, insects, and bats. When a horse accidentally ingests insects harboring flukes infected with N. risticii, the bacterium is transmitted to the horse and causes an acute and often fatal disease called Potomac horse fever. Although the disease has been increasingly recognized throughout North and South America, N. risticii has not been cultured outside the United States. This paper reports the first Canadian strain cultured and a new method to effectively culture isolate N. risticii from the horse blood sample. Molecular analysis showed that the genotype of this Canadian strain is distinct from previously sequenced strains but closely related to midwestern U.S. strains. Culture isolation of N. risticii strains would confirm the geographic presence of pathogenic N. risticii, help elucidate N. risticii strain diversity and environmental spreading and distribution, and improve diagnosis and development of vaccines for this dreadful disease.

show abstract

“…The absence of the bacterium in these helminths may be related to agent specificity for its hosts, and also to transmission capacity for subsequent generations, when infected (Greiman et al, 2013).…”

Section: (C) (A) (B)mentioning

confidence: 99%

Molecular investigation of Neorickettsia risticii in trematodes and snails in a region with serological evidence of this agent in horses, state of Rio de Janeiro

Costa

Vitari

Silva

et al. 2016

Arq. Bras. Med. Vet. Zootec.

View full text Add to dashboard Cite

In Brazil, some studies have indicated that Neorickettsia risticii circulates in horses, but it is unclear which are the possible intermediate vectors of this bacterium in the country. The aim of this study was to use molecular techniques in order to analyze the presence of N. risticii in snails and larval stages of trematodes in farms in a region with a history of seroreactive horses towards this bacterium, in Rio de Janeiro, Brazil. Convenience sampling was used in the studied region. The collected snails were exposed to incandescent light (60W) for 2-4 hours in order to investigate trematodes in larval forms. Deoxyribonucleic acid (DNA) was extracted from snail tissue and trematode. Real-time PCR (qPCR) technique was used to investigate the presence of a 16S rRNA gene fragment of N. risticii. Snail specimens (n=410) were collected from 11 horse-breeding farms, and the following species were identified: Melanoides tuberculata, Pomacea sp., Biomphalaria tenagophila, Physa acuta, Drepanotrema anatinum and Biomphalaria straminea. Only 3.17% (n=13/410) of the collected snails were infected by trematodes. The cercariae obtained from these snails were classified as Megalourous cercariae, Pleurolophocercus cercariae and Furcocercous cercariae. There was no amplification of the target DNA of N. risticii in the snail and trematode samples tested by qPCR. Based on these data, the transmission of N. risticii by trematodes using these snail species in this region does not appear to occur or occurs at very low rates. Thus, further studies are needed in order to clarify which species of invertebrate hosts are infected by this bacterium and potentially participate in the transmission chain of equine neorickettsiosis in the state of Rio de Janeiro, Brazil.

show abstract

Transmission rates of the bacterial endosymbiont, Neorickettsia risticii, during the asexual reproduction phase of its digenean host, Plagiorchis elegans, within naturally infected lymnaeid snails

Cited by 29 publications

References 35 publications

Germs within Worms: Localization of Neorickettsia sp. within Life Cycle Stages of the Digenean Plagiorchis elegans

Germs within Worms: Localization of Neorickettsia sp. within Life Cycle Stages of the Digenean Plagiorchis elegans

An Ecotype of Neorickettsia risticii Causing Potomac Horse Fever in Canada

Molecular investigation of Neorickettsia risticii in trematodes and snails in a region with serological evidence of this agent in horses, state of Rio de Janeiro

Contact Info

Product

Resources

About