Diversity of Rickettsia in Ticks Collected in Abruzzi and Molise Regions (Central Italy)

Rickettsiae have worldwide occurrence and rickettsiosis are widely recognized as emerging infections in several parts of the world. For decades, it was thought that a single pathogenic tick-borne spotted fever group (SFG), Rickettsia, occurred in each continent. Nowadays, thanks to molecular biology, new species of Rickettsia responsible for disease in humans are continuously identified worldwide. In a framework of diagnostic activities of the Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise “G. Gaporale” and considering some reports of suspected human clinical cases of rickettsiosis, a survey on ticks collected form animals and humans was carried out with the aim to identify the Rickettsia species circulating in Abruzzi and Molise regions. A total of 603 ticks, previously identified at species level by morphology, pooled into 178 tick samples, were tested by pan-Rickettsia RealTime PCR. DNA from specimens positive for Rickettsia spp. was then sequenced in order to identify the Rickettsia species involved. The highest infection rate was detected in Dermacentor marginatus followed by Ixodes ricinus. The selected targets for this purpose were OmpA and gltA. Rickettsia slovaca, Rickettsia monacensis, Rickettsia massiliae, Rickettsia conorii, Rickettsia aeschlimannii, Rickettsia helvetica, Rickettsia raoultii, and Rickettsia felis – like organisms were identified in this study. These are the first data available in the literature for the circulation of SFG Rickettsia species in the selected geographical area. Results made evidence of high rate of infection in ticks. All Rickettsia species detected have been previously involved in human infection. The diversity of Rickettsia detected, and tick species collected reflects the biodiversity in term of wildlife and environment of the area. An association between Rickettsia species, ticks, and the relationships with vertebrate host species are discussed. Due to the peculiar eco-biology of each Rickettsia species, the use of diagnostic tools able to identify Rickettsia at the species level is thus recommended in order to assess the risk for humans and to elucidate more precise etiological diagnosis in clinical cases.

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Significant Growth by Rickettsia Species within Human Macrophage-Like Cells Is a Phenotype Correlated with the Ability to Cause Disease in Mammals

Pathogens ◽

10.3390/pathogens10020228 ◽

2021 ◽

Vol 10 (2) ◽

pp. 228

Author(s):

M. Nathan Kristof ◽

Paige E. Allen ◽

Lane D. Yutzy ◽

Brandon Thibodaux ◽

Christopher D. Paddock ◽

...

Keyword(s):

Endothelial Cells ◽

Spotted Fever ◽

Growth Characteristic ◽

Human Macrophage ◽

Rickettsia Conorii ◽

Spotted Fever Group ◽

Rocky Mountain Spotted Fever ◽

Phagocytic Cells ◽

Pathogenic Potential ◽

Rickettsia Species

Rickettsia are significant sources of tick-borne diseases in humans worldwide. In North America, two species in the spotted fever group of Rickettsia have been conclusively associated with disease of humans: Rickettsia rickettsii, the causative agent of Rocky Mountain spotted fever, and Rickettsia parkeri, the cause of R. parkeri rickettsiosis. Previous work in our lab demonstrated non-endothelial parasitism by another pathogenic SFG Rickettsia species, Rickettsia conorii, within THP-1-derived macrophages, and we have hypothesized that this growth characteristic may be an underappreciated aspect of rickettsial pathogenesis in mammalian hosts. In this work, we demonstrated that multiple other recognized human pathogenic species of Rickettsia, including R. rickettsii, R. parkeri, Rickettsia africae, and Rickettsiaakari can grow within target endothelial cells as well as within PMA-differentiated THP-1 cells. In contrast, Rickettsia bellii, a Rickettsia species not associated with disease of humans, and R. rickettsii strain Iowa, an avirulent derivative of pathogenic R. rickettsii, could invade both cell types but proliferate only within endothelial cells. Further analysis revealed that similar to previous studies on R. conorii, other recognized pathogenic Rickettsia species could grow within the cytosol of THP-1-derived macrophages and avoided localization with two different markers of lysosomal compartments; LAMP-2 and cathepsin D. R. bellii, on the other hand, demonstrated significant co-localization with lysosomal compartments. Collectively, these findings suggest that the ability of pathogenic rickettsial species to establish a niche within macrophage-like cells could be an important factor in their ability to cause disease in mammals. These findings also suggest that analysis of growth within mammalian phagocytic cells may be useful to predict the pathogenic potential of newly isolated and identified Rickettsia species.

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Taxonomic Relationships among Spotted Fever Group Rickettsiae as Revealed by Antigenic Analysis with Monoclonal Antibodies

Journal of Clinical Microbiology ◽

10.1128/jcm.36.4.887-896.1998 ◽

1998 ◽

Vol 36 (4) ◽

pp. 887-896 ◽

Cited By ~ 18

Author(s):

Wenbin Xu ◽

Didier Raoult

Keyword(s):

Monoclonal Antibodies ◽

Phylogenetic Analyses ◽

Spotted Fever ◽

Rickettsia Conorii ◽

Spotted Fever Group ◽

Antigenic Analysis ◽

Taxonomic Relationships ◽

Rickettsia Africae ◽

Rickettsia Slovaca ◽

Rickettsia Sibirica

The spotted fever group (SFG) is made up of more than 20 different rickettsial species and strains. Study of the taxonomic relationships among the group has been attempted by phenotypic, genotypic, and phylogenetic analyses. In this study, we determined taxonomic relationships among the SFG rickettsiae by comparative analysis of immunogenic epitopes reactive against a panel of monoclonal antibodies. A total of 98 monoclonal antibodies, which were directed against epitopes on the major immunodominant proteins or on the lipopolysaccharide-like antigens of strains of Rickettsia africae, Rickettsia conorii, Rickettsia massiliae, Rickettsia akari, Rickettsia sibirica, and Rickettsia slovaca, were used in the study. The distribution and expression of the epitopes among 29 SFG rickettsiae and Rickettsia bellii were assessed by determination of reaction titers in a microimmunofluorescence assay. The results were scored as numerical taxonomic data, and cluster analysis was used to construct a dendrogram. The architecture of this dendrogram was consistent with previous taxonomic studies, and the implications of this and other findings are discussed.

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Development of a Multiplex Loop-Mediated Isothermal Amplification (LAMP) Method for Simultaneous Detection of Spotted Fever Group Rickettsiae and Malaria Parasites by Dipstick DNA Chromatography

Diagnostics ◽

10.3390/diagnostics10110897 ◽

2020 ◽

Vol 10 (11) ◽

pp. 897

Author(s):

Lavel Chinyama Moonga ◽

Kyoko Hayashida ◽

Naoko Kawai ◽

Ryo Nakao ◽

Chihiro Sugimoto ◽

...

Keyword(s):

Detection System ◽

Spotted Fever ◽

Simultaneous Detection ◽

Febrile Illness ◽

Isothermal Amplification ◽

Lamp Method ◽

Spotted Fever Group ◽

Loop Mediated Isothermal Amplification ◽

Rickettsia Monacensis ◽

Sfg Rickettsia

Spotted fever group (SFG) rickettsiae causes febrile illness in humans worldwide. Since SFG rickettsiosis’s clinical presentation is nonspecific, it is frequently misdiagnosed as other febrile diseases, especially malaria, and complicates proper treatment. Aiming at rapid, simple, and simultaneous detection of SFG Rickettsia spp. and Plasmodium spp., we developed a novel multiple pathogen detection system by combining a loop-mediated isothermal amplification (LAMP) method and dipstick DNA chromatography technology. Two primer sets detecting SFG Rickettsia spp. and Plasmodium spp. were mixed, and amplified products were visualized by hybridizing to dipstick DNA chromatography. The multiplex LAMP with dipstick DNA chromatography distinguished amplified Rickettsia and Plasmodium targeted genes simultaneously. The determined sensitivity using synthetic nucleotides was 1000 copies per reaction for mixed Rickettsia and Plasmodium genes. When genomic DNA from in vitro cultured organisms was used, the sensitivity was 100 and 10 genome equivalents per reaction for Rickettsia monacensis and Plasmodium falciparum, respectively. Although further improvement will be required for more sensitive detection, our developed simultaneous diagnosis technique will contribute to the differential diagnosis of undifferentiated febrile illness caused by either SFG Rickettsia spp. or Plasmodium spp. in resource-limited endemic areas. Importantly, this scheme is potentially versatile for the simultaneous detection of diverse infectious diseases.

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The Rickettsia conorii Autotransporter Protein Sca1 Promotes Adherence to Nonphagocytic Mammalian Cells

Infection and Immunity ◽

10.1128/iai.01165-09 ◽

2010 ◽

Vol 78 (5) ◽

pp. 1895-1904 ◽

Cited By ~ 53

Author(s):

Sean P. Riley ◽

Kenneth C. Goh ◽

Timothy M. Hermanas ◽

Marissa M. Cardwell ◽

Yvonne G. Y. Chan ◽

...

Keyword(s):

Mammalian Cells ◽

Spotted Fever ◽

Expression System ◽

Host Cells ◽

Rickettsia Conorii ◽

Spotted Fever Group ◽

Gram Negative Bacteria ◽

Heterologous Expression System ◽

Cell Association ◽

Sfg Rickettsia

ABSTRACT The pathogenesis of spotted fever group (SFG) Rickettsia species, including R. conorii and R. rickettsii, is acutely dependent on adherence to and invasion of host cells, including cells of the mammalian endothelial system. Bioinformatic analyses of several rickettsia genomes revealed the presence of a cohort of genes designated sca genes that are predicted to encode proteins with homology to autotransporter proteins of Gram-negative bacteria. Previous work demonstrated that three members of this family, rOmpA (Sca0), Sca2, and rOmpB (Sca5) are involved in the interaction with mammalian cells; however, very little was known about the function of other conserved rickettsial Sca proteins. Here we demonstrate that sca1, a gene present in nearly all SFG rickettsia genomes, is actively transcribed and expressed in R. conorii cells. Alignment of Sca1 sequences from geographically diverse SFG Rickettsia species showed that there are high degrees of sequence identity and conservation of these sequences, suggesting that Sca1 may have a conserved function. Using a heterologous expression system, we demonstrated that production of R. conorii Sca1 in the Escherichia coli outer membrane is sufficient to mediate attachment to but not invasion of a panel of cultured mammalian epithelial and endothelial cells. Furthermore, preincubation of a recombinant Sca1 peptide with host cells blocked R. conorii cell association. Together, these results demonstrate that attachment to mammalian cells can be uncoupled from the entry process and that Sca1 is involved in the adherence of R. conorii to host cells.

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One Health Approach to Rickettsiosis: A Five-Year Study on Spotted Fever Group Rickettsiae in Ticks Collected from Humans, Animals and Environment

Microorganisms ◽

10.3390/microorganisms10010035 ◽

2021 ◽

Vol 10 (1) ◽

pp. 35

Author(s):

Ilaria Pascucci ◽

Elisa Antognini ◽

Cristina Canonico ◽

Marco Giuseppe Montalbano ◽

Alessandro Necci ◽

...

Keyword(s):

Spotted Fever ◽

Rhipicephalus Sanguineus ◽

Geographic Area ◽

Molecular Diagnostic ◽

Spotted Fever Group ◽

Rickettsia Species ◽

Glta Gene ◽

Starting Point ◽

Pcr Products ◽

Sfg Rickettsia

The spotted fever group of Rickettsiae is a heterogeneous group of Rickettsiae transmitted by ticks, causing similar diseases in humans (spotted fever). Until recently, it was supposed that a single pathogenic tick-borne SFG Rickettsia circulated in each different geographic area and that R. conorii subsp. conorii was the SFG Rickettsiae circulating in Italy, but in the last decade, thanks to molecular diagnostic, several different Rickettsia species, previously not considered pathogenic for decades, have been isolated from ticks and definitively associated to human disease, also in Italy. The present survey was carried out with the aim of investigating the presence of different SFG Rickettsia species in a geographic area where no information was available. Ticks collected from animals submitted to necropsy, removed from humans in local hospitals and collected from the environment were identified and tested by PCR for Rickettsia spp. based on the gltA gene, and positive PCR products were sequenced. A total of 3286 ticks were collected. Fifteen tick species were recognized, the most represented (79.52%) species in the collection was Ixodes ricinus, followed by Rhipicephalus sanguineus (9.13%). The overall prevalence of Rickettsia infection was 7.58%. Eight species of Rickettsia were identified, the most frequent was R. monacensis (56%), followed by R. helvetica (25.50%). Noteworthy, is the detection in the present study of Rrhipicephali, detected only twice in Italy. These are the first data available on SFG Rickettsiae circulation in the study area and they can be considered as starting point to assess the possible risk for humans.

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New Spotted Fever Group Rickettsia Isolate, Identified by Sequence Analysis of Conserved Genomic Regions

Pathogens ◽

10.3390/pathogens9010011 ◽

2019 ◽

Vol 9 (1) ◽

pp. 11

Author(s):

Dar Klein ◽

Adi Beth-Din ◽

Regev Cohen ◽

Shirley Lazar ◽

Itai Glinert ◽

...

Keyword(s):

Current Knowledge ◽

Spotted Fever ◽

Diagnostic Procedures ◽

Clinical Samples ◽

Severe Illness ◽

Rickettsia Conorii ◽

Spotted Fever Group ◽

Rickettsia Species ◽

Questing Ticks ◽

Absolute Identity

The clinical features of spotted fever group (SFG) Rickettsia induced disease range from a mild to severe illness. The clinical complexity is even greater due to the fact that the disease can be caused by different species with varying degrees of virulence. Current knowledge asserts that the Israeli SFG (ISF) strain Rickettsia conorii israelensis is the only human pathogenic SFG member in Israel. Current diagnostic procedures distinguish between SFG and the typhus group rickettsiosis, assuming all SFG-positive clinical samples positive for ISF. Molecular studies on questing ticks over the past decade have uncovered the existence of other SFG strains besides ISF in Israel and the region. This study describes the first documented analysis of SFG-positive samples from Israeli patients with the goal of distinguishing between ISF and non-ISF SFG strains. We managed to identify a new Rickettsia isolate from three independent clinical samples in Israel which was shown to be an as-yet unknown SFG member, showing no absolute identity with any known Rickettsia species present in the NCBI database.

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RETROSPECTIVE SEROLOGICAL DIAGNOSTICS OF SPOTTED FEVER GROUP RIKKETSIOSES IN HIGH RISK AREAS OF RICKETTSIA CONORII SUBSP. CASPIA INFECTION

Russian Clinical Laboratory Diagnostics ◽

10.18821/0869-2084-2019-64-6-354-359 ◽

2019 ◽

Vol 64 (6) ◽

pp. 354-359 ◽

Cited By ~ 1

Author(s):

T. A. Chekanova ◽

S. Zh. Netalieva ◽

S. N. Shpynov ◽

M. A. Babaeva ◽

A. V. Kostarnoy

Keyword(s):

High Risk ◽

Spotted Fever ◽

Activity Period ◽

Rickettsia Conorii ◽

Spotted Fever Group ◽

Adenovirus Infection ◽

Risk Areas ◽

Acute Respiratory Viral Infection ◽

Serological Diagnostics ◽

Sfg Rickettsia

723 blood sera from 537 patients of Regional Infectious Clinical Hospital, Astrakhan were obtained during high activity period of Rhipicephalus ticks (May-September 2015) and retrospectively studied for IgG/IgM to antigen of spotted fever group (SFG) Rickettsia. IgG and/or IgM to Rickettsia conorii were detected in 145 sera from 130 patients, and antibodies to R. sibirica (group-specific) were detected in 143 sera from 145. Antibodies to R. conorii were detected for 71,4% patients with Astrakhan spotted fever (ASF), for 28,4% patients with acute respiratory viral infection, for 19,1% patients with infection of unspecified etiology and for 40% patients having symptoms of a adenovirus infection. Acute rickettsiosis, provably ASF, is serologically validated for 71 patients. Dynamic of IgM/IgG to R. conorii in sera of patients having different preliminary diagnoses is discussed. IgM to R. conorii in sera of patients having adenovirus infection symptoms were detected at a later time as compared with others. For regions of high risk of R. conorii subsp. caspia infection the differentiation of diagnostic and anamnestic specific antibodies is very important. The absence of serological and molecular biological markers in third of patients with ASF symptoms is necessary to study. Preparations and algorithms for diagnosis of SFG rickettsioses are needed to improve.

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Identification and Characterization of “Candidatus Rickettsia Thierseensis”, a Novel Spotted Fever Group Rickettsia Species Detected in Austria

Microorganisms ◽

10.3390/microorganisms8111670 ◽

2020 ◽

Vol 8 (11) ◽

pp. 1670

Author(s):

Anna-Margarita Schötta ◽

Michiel Wijnveld ◽

Dieter Höss ◽

Gerold Stanek ◽

Hannes Stockinger ◽

...

Keyword(s):

Sequence Similarity ◽

Spotted Fever ◽

Intergenic Spacer ◽

Borrelia Burgdorferi Sensu Lato ◽

Species Discrimination ◽

Spotted Fever Group ◽

Pathogenic Potential ◽

Rickettsia Species ◽

Intergenic Spacer Region ◽

Sfg Rickettsia

Rickettsia spp. are the second most common pathogens detected in Ixodes ricinus ticks in Austria after Borrelia burgdorferi sensu lato. Species belonging to the spotted fever group (SFG) are the causative agents for tick-borne rickettsiosis across the world. So far, only four SFG Rickettsia spp. were detected in Austria, namely R. helvetica, R. raoultii, R. monacensis and R. slovaca. Here, we describe the identification of a new SFG Rickettsia species detected in an I. ricinus tick. Sequencing of various rickettsial genes revealed a nucleotide sequence similarity of 99.6%, 98.5%, 97.3% and 98.5% to the gltA, ompA, ompB, and sca4 genes, respectively, of known and validated species. Additionally, sequencing of the htrA gene and 23S-5S intergenic spacer region also only showed 99.6% and 99.2%, respectively, similarity to known species. Therefore, and in accordance with current criteria for Rickettsia species discrimination, we hereby describe a new species of the SFG with putative pathogenic potential. We propose the name “Candidatus Rickettsia thierseensis” based on the village Thiersee in the Austrian province of Tyrol, where the carrying tick was found.

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Evaluation of PCR-Based Assay for Diagnosis of Spotted Fever Group Rickettsiosis in Human Serum Samples

Clinical and Diagnostic Laboratory Immunology ◽

10.1128/cdli.12.6.759-763.2005 ◽

2005 ◽

Vol 12 (6) ◽

pp. 759-763 ◽

Cited By ~ 54

Author(s):

Yeon-Joo Choi ◽

Seung-Hyun Lee ◽

Kyung-Hee Park ◽

Young-Sang Koh ◽

Keun-Hwa Lee ◽

...

Keyword(s):

Spotted Fever ◽

Bacterial Species ◽

Immunoglobulin M ◽

Rickettsia Conorii ◽

Spotted Fever Group ◽

Sequencing Analysis ◽

Pcr Assay ◽

Serum Samples ◽

Dna Fragment ◽

Sfg Rickettsia

ABSTRACT A nested PCR assay was developed for the detection of spotted fever group (SFG) rickettsiae in serum samples. The assay was based on specific primers derived from the rickettsial outer membrane protein B gene (rompB) of Rickettsia conorii. An SFG rickettsia-specific signal is obtained from R. akari, R. japonica, R. sibirica, and R. conorii. Other bacterial species tested did not generate any signal, attesting to the specificity of the assay. As few as seven copies of the rompB gene of R. conorii could be detected in 200 μl of serum sample. The assay was evaluated with a panel of sera obtained from patients with acute-phase febrile disease tested by immunofluorescent antibody assay (IFA). The SFG rickettsia-specific DNA fragment was detected in 71 out of 100 sera, which were proven to have immunoglobulin M antibodies against SFG rickettsial antigen by IFA. The results were further confirmed by restriction fragment length polymorphism and sequencing analysis of the DNA fragments. The results indicated that this PCR assay is suitable for the diagnosis of spotted fever group rickettsiosis in Korea.

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Zoonotic Rickettsia Species in Small Ruminant Ticks From Tunisia

Frontiers in Veterinary Science ◽

10.3389/fvets.2021.676896 ◽

2021 ◽

Vol 8 ◽

Author(s):

Hanène Belkahia ◽

Rachid Selmi ◽

Sayed Zamiti ◽

Monia Daaloul-Jedidi ◽

Lilia Messadi ◽

...

Keyword(s):

Small Ruminant ◽

Citrate Synthase ◽

Spotted Fever ◽

Protein A ◽

Rhipicephalus Sanguineus ◽

Spotted Fever Group ◽

Rickettsia Species ◽

Rickettsia Monacensis ◽

Significant Public Health ◽

Pcr Targeting

Tick-borne rickettsioses present a significant public health threat among emerging tick-borne diseases. In Tunisia, little is known about tick-borne Rickettsia pathogens. Therefore, the aim of this study was to investigate the presence of Rickettsia species in small ruminant ticks from Tunisia. Adult ticks (n = 694) were collected from goats and sheep in northern Tunisia. Obtained ticks were identified as Rhipicephalus turanicus (n = 434) and Rhipicephalus sanguineus sensu lato (n = 260). Selected ticks (n = 666) were screened for the presence of Rickettsia spp. by PCR targeting a partial sequence of the ompB gene followed by sequence analysis. Rickettsial DNA was detected in 122 (18.3%) tested tick samples. The infection rates in Rh. turanicus and Rh. sanguineus s.l. ticks were 23.4 and 9.5%, respectively. The overall prevalence of rickettsial DNA was markedly higher in ticks collected from goats (23.2%) compared to those infesting sheep (7.9%). The detection of rickettsial DNA was significantly higher in ticks from the governorate of Beja (39.0%) than those from the governorate of Bizerte (13.9%). Two additional genes, the outer membrane protein A gene (ompA) and the citrate synthase gene (gltA), were also targeted for further characterization of the detected Rickettsia species. Genotyping and phylogenetic analysis based on partial sequences (n = 106) of the three different genes revealed that positive ticks are infected with different isolates of two Spotted Fever Group (SFG) Rickettsia, namely, Rickettsia massiliae and Rickettsia monacensis, closely related to those infecting camels and associated ticks from Tunisia, and humans and small ruminant ticks from neighboring countries like Italy, France, and Spain.

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