The role of cofeeding arthropods in the transmission of Rickettsia felis

Fongsaran, Chanida; Jirakanwisal, Krit; Tongluan, Natthida; Latour, Allison; Healy, Sean P.; Christofferson, Rebecca C.; Macaluso, Kevin R.

doi:10.1371/journal.pntd.0010576

Cited by 7 publications

(7 citation statements)

References 47 publications

(77 reference statements)

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“…felis sca1 :: tn mutant in the salivary glands of exposed fleas, warranted further investigation into its ability to be transmitted by fleas while feeding on a murine host. Subsequently, a cofeeding bioassay was employed as a means of tracking transmission to proximal feeding arthropods in the presence of a vertebrate host [ 10 , 36 ]. Donor (infected) fleas were allowed to feed with recipient (naïve) fleas for 3 days.…”

Section: Resultsmentioning

confidence: 99%

“…Due to the inefficiency to induce R. felis systemic infection in mouse models, cofeeding bioassays were used to assess transmission of rickettsiae between vectors. While deposition of infectious salivary secretions into the skin of vertebrate hosts does not guarantee transmission of the agent that progresses to a systemic infection, detection of rickettsiae in the host skin at the arthropod feeding site is associated with transmission to proximal feeding arthropods [10,36]. Indeed, R. felis sca1::tn can be inoculated into murine skin and acquired by cofeeding, naïve fleas.…”

Section: Plos Pathogensmentioning

confidence: 99%

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Transposon mutagenesis of Rickettsia felis sca1 confers a distinct phenotype during flea infection

et al. 2022

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Since its recognition in 1994 as the causative agent of human flea-borne spotted fever, Rickettsia felis, has been detected worldwide in over 40 different arthropod species. The cat flea, Ctenocephalides felis, is a well-described biological vector of R. felis. Unique to insect-borne rickettsiae, R. felis can employ multiple routes of infection including inoculation via salivary secretions and potentially infectious flea feces into the skin of vertebrate hosts. Yet, little is known of the molecular interactions governing flea infection and subsequent transmission of R. felis. While the obligate intracellular nature of rickettsiae has hampered the function of large-scale mutagenesis strategies, studies have shown the efficiency of mariner-based transposon systems in Rickettsiales. Thus, this study aimed to assess R. felis genetic mutants in a flea transmission model to elucidate genes involved in vector infection. A Himar1 transposase was used to generate R. felis transformants, in which subsequent genome sequencing revealed a transposon insertion near the 3’ end of sca1. Alterations in sca1 expression resulted in unique infection phenotypes. While the R. felis sca1::tn mutant portrayed enhanced growth kinetics compared to R. felis wild-type during in vitro culture, rickettsial loads were significantly reduced during flea infection. As a consequence of decreased rickettsial loads within infected donor fleas, R. felis sca1::tn exhibited limited transmission potential. Thus, the use of a biologically relevant model provides evidence of a defective phenotype associated with R. felis sca1::tn during flea infection.

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Section: Resultsmentioning

confidence: 99%

Section: Plos Pathogensmentioning

confidence: 99%

Transposon mutagenesis of Rickettsia felis sca1 confers a distinct phenotype during flea infection

et al. 2022

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“…Even though R. bellii is a tick-borne Rickettsia , and the primary arthropod host for R. felis is the cat flea, these two Rickettsia have a larger potential host pool than the other species in this study. R. bellii has been identified in more than 25 species of hard and soft ticks [ 39 ], while R. felis has been found in, and can persist in hard ticks, fleas, lice, and mosquitos [ 40 , 41 ]. Their large and partially convergent effector repertoires may be an important factor in this broad arthropod host range.…”

Section: Resultsmentioning

confidence: 99%

Analysis of the Type 4 Effectome across the Genus Rickettsia

Aspinwall

Brayton

2022

IJMS

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Rickettsia are obligate intracellular bacteria primarily carried by arthropod hosts. The genus Rickettsia contains several vertebrate pathogens vectored by hematophagous arthropods. Despite the potential for disease, our understanding of Rickettsias are limited by the difficulties associated with growing and manipulating obligate intracellular bacteria. To aid with this, our lab conducted an analysis of eight genomes and three plasmids from across the genus Rickettsia. Using OPT4e, a learning algorithm-based program designed to identify effector proteins secreted by the type 4 secretion system, we generated a putative effectome for the genus. We then consolidated effectors into homolog sets to identify effectors unique to Rickettsia with different life strategies or evolutionary histories. We also compared predicted effectors to non-effectors for differences in G+C content and gene splitting. Based on this analysis, we predicted 1571 effectors across the genus, resulting in 604 homolog sets. Each species had unique homolog sets, while 42 were present in all eight species analyzed. Effectors were flagged in association with pathogenic, tick and flea-borne Rickettsia. Predicted effectors also varied in G+C content and frequency of gene splitting as compared to non-effectors. Species effector repertoires show signs of expansion, degradation, and horizontal acquisition associated with lifestyle and lineage.

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Section: Discussionmentioning

confidence: 99%

“…This phenomenon, which has also been described for Rickettsia spp. in other arthropods [50], might lead to the detection of Orientia in mite species that do not serve as natural vector/reservoir. For O. tsutsugamushi, this has also been proven in animal experiments as well as suggested in field studies from Thailand [51,52].…”

Section: Discussionmentioning

confidence: 99%

Eco-epidemiology of rodent-associated trombiculid mites and infection with Orientia spp. in Southern Chile

et al. 2023

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Background Scrub typhus is a potentially severe infection caused by bacteria of the genus Orientia, endemic in Asia-Pacific and recently discovered in southern Chile. The presented study aimed to determine the prevalence and species richness of rodent-associated trombiculid mites and their infection with Orientia spp. in different areas of two regions in southern Chile. Methodology/Principal findings During summer 2020, trombiculid mites were collected from rodents captured in three areas in southern Chile known to be endemic for scrub typhus (Cochamó and Chiloé Island in the Los Lagos Region and Tortel in the Aysén Region). A total of 132 rodents belonging to five species were captured using Sherman-like traps; 89.4% were infested with trombiculids. Mite specimens were morphologically identified and subsequently tested by Orientia-specific qPCR. Six mite species were identified. Among chigger-infested rodents, 33.9% carried Orientia-positive mites; this rate was higher in Tortel (63.8%) than in Cochamó (45.0%) and Chiloé Island (2.0%). The analysis of individual mites (n = 901) revealed that 31.2% of Herpetacarus antarctica samples (n = 202) were positive for Orientia DNA; the prevalence was 7.0% in Paratrombicula neuquenensis (n = 213), 6.9% in Herpetacarus eloisae (n = 144), 3.6% in Argentinacarus expansus (n = 55), and 0% in Paratrombicula goffi (n = 110) and Quadraseta chiloensis (n = 177). The southernmost site (Tortel) showed the highest rates of trombiculid infestation, trombiculid load, and Orientia infection in the captured rodents. Conclusions/Significance Our study provides new insights into the trombiculid fauna and prevalence of Orientia in mites collected from wild rodents in southern Chile. Orientia DNA was detected in four of the six mite species. Rates of infestation, mite loads, and Orientia prevalences differed geographically and were highest in the Aysén Region. Our data improve our knowledge on possible vectors of scrub typhus and their distribution in Chile.

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The role of cofeeding arthropods in the transmission of Rickettsia felis

Cited by 7 publications

References 47 publications

Transposon mutagenesis of Rickettsia felis sca1 confers a distinct phenotype during flea infection

Transposon mutagenesis of Rickettsia felis sca1 confers a distinct phenotype during flea infection

Analysis of the Type 4 Effectome across the Genus Rickettsia

Eco-epidemiology of rodent-associated trombiculid mites and infection with Orientia spp. in Southern Chile

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