scholarly journals Wide Dispersal and Possible Multiple Origins of Low-Copy-Number Plasmids in Rickettsia Species Associated with Blood-Feeding Arthropods

2010 ◽  
Vol 76 (6) ◽  
pp. 1718-1731 ◽  
Author(s):  
Gerald D. Baldridge ◽  
Nicole Y. Burkhardt ◽  
Marcelo B. Labruna ◽  
Richard C. Pacheco ◽  
Christopher D. Paddock ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Ixodes Scapularis ◽  
Blood Feeding ◽  
Adaptive Traits ◽  
Phylogenetic Groups ◽  
Plasmid Copy ◽  
Rickettsia Species ◽  
Real Time Quantitative Pcr ◽  
Rickettsia Amblyommii ◽  
Obligate Intracellular Bacteria

ABSTRACT Plasmids are mobile genetic elements of bacteria that can impart important adaptive traits, such as increased virulence or antibiotic resistance. We report the existence of plasmids in Rickettsia (Rickettsiales; Rickettsiaceae) species, including Rickettsia akari, “Candidatus Rickettsia amblyommii,” R. bellii, R. rhipicephali, and REIS, the rickettsial endosymbiont of Ixodes scapularis. All of the rickettsiae were isolated from humans or North and South American ticks. R. parkeri isolates from both continents did not possess plasmids. We have now demonstrated plasmids in nearly all Rickettsia species that we have surveyed from three continents, which represent three of the four major proposed phylogenetic groups associated with blood-feeding arthropods. Gel-based evidence consistent with the existence of multiple plasmids in some species was confirmed by cloning plasmids with very different sequences from each of two “Ca. Rickettsia amblyommii” isolates. Phylogenetic analysis of rickettsial ParA plasmid partitioning proteins indicated multiple parA gene origins and plasmid incompatibility groups, consistent with possible multiple plasmid origins. Phylogenetic analysis of potentially host-adaptive rickettsial small heat shock proteins showed that hsp2 genes were plasmid specific and that hsp1 genes, found only on plasmids of “Ca. Rickettsia amblyommii,” R. felis, R. monacensis, and R. peacockii, were probably acquired independently of the hsp2 genes. Plasmid copy numbers in seven Rickettsia species ranged from 2.4 to 9.2 per chromosomal equivalent, as determined by real-time quantitative PCR. Plasmids may be of significance in rickettsial evolution and epidemiology by conferring genetic plasticity and host-adaptive traits via horizontal gene transfer that counteracts the reductive genome evolution typical of obligate intracellular bacteria.

scholarly journals Molecular detection of Rickettsia africae in Amblyomma ticks collected in cattle from Southern and Central Mozambique

2020 ◽  
Vol 14 (06) ◽  
pp. 614-622
Author(s):  
Vlademiro Magaia ◽  
Elisa Taviani ◽  
Nidia Cangi ◽  
Luis Neves
Keyword(s):  
Phylogenetic Analysis ◽  
Spotted Fever ◽  
Etiologic Agent ◽  
Spotted Fever Group ◽  
Rickettsia Species ◽  
Rickettsia Africae ◽  
African Tick Bite Fever ◽  
Obligate Intracellular Bacteria ◽  
Spotted Fever Group Rickettsia ◽  
Amblyomma Ticks

Introduction: Rickettsia are Gram-negative and obligate intracellular bacteria, which cause typhus and spotted fever-like diseases in humans. In Africa, Rickettsia africae of the Spotted Fever Group Rickettsia (SFGR) is the etiologic agent of the African Tick-Bite Fever. The disease is transmitted by ticks of the genus Amblyomma, which serve as vectors and reservoirs of Rickettsia. In this study, we aimed to detect Rickettsia species in ticks collected from cattle in south and central Mozambique. Methodology: DNA from 412 adult ticks and 22 pools of larvae were extracted and tested for the presence of Rickettsia genes gltA, ompA and ompB by PCR, followed by sequencing and phylogenetic analysis. Results: Our results showed that in adult ticks, 79.5% (n = 330), 66% (n = 274) and 67% (n = 275) samples were positive for gltA, ompA and ompB genes, respectively. Among the 22 pools of larvae analysed, 77.2% (n = 17) were positive for the three genes tested. The infection rates ranged from 43% to 100% for Rickettsia by gltA in all locations studied, with maximum values of 100% observed in the districts of Maputo province namely Changalane, Boane and Matutuine district. The phylogenetic analysis of amplified sequences revealed that samples under study grouped with R. africae for the 3 genes. Conclusion: The study showed that Spotted Fever Group Rickettsia represented by R. africae widely circulate in Amblyomma ticks collected in south and central regions of Mozambique.

scholarly journals Tick Ecdysteroid Hormone, Global Microbiota/Rickettsia Signaling in the Ovary versus Carcass during Vitellogenesis in Part-Fed (Virgin) American Dog Ticks, Dermacentor variabilis

2021 ◽  
Vol 9 (6) ◽  
pp. 1242
Author(s):  
Loganathan Ponnusamy ◽  
Haley Sutton ◽  
Robert D. Mitchell ◽  
Daniel E. Sonenshine ◽  
Charles S. Apperson ◽  
...  
Keyword(s):  
Hormonal Regulation ◽  
Natural Populations ◽  
Blood Feeding ◽  
Dermacentor Variabilis ◽  
Transovarial Transmission ◽  
Rickettsia Species ◽  
Adult Females ◽  
Dog Tick ◽  
Total Bacteria

The transovarial transmission of tick-borne bacterial pathogens is an important mechanism for their maintenance in natural populations and transmission, causing disease in humans and animals. The mechanism for this transmission and the possible role of tick hormones facilitating this process have never been studied. Injections of physiological levels of the tick hormone, 20-hydroxyecdysone (20E), into part-fed (virgin) adult females of the American dog tick, Dermacentor variabilis, attached to the host caused a reduction in density of Rickettsia montanensis in the carcass and an increase in the ovaries compared to buffer-injected controls. This injection initiates yolk protein synthesis and uptake by the eggs but has no effect on blood feeding. Francisella sp. and R. montanensis were the predominant bacteria based on the proportionality in the carcass and ovary. The total bacteria load increased in the carcass and ovaries, and bacteria in the genus Pseudomonas increased in the carcass after the 20E injection. The mechanism of how the Rickettsia species respond to changes in tick hormonal regulation needs further investigation. Multiple possible mechanisms for the proliferation of R. montanensis in the ovaries are proposed.

scholarly journals Genetic Diversity and Phylogenetic Analysis of Citrus tristeza virus Isolates from Turkey

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Gözde Erkiş-Güngör ◽  
Bayram Çevik
Keyword(s):  
Phylogenetic Analysis ◽  
Citrus Tristeza Virus ◽  
Molecular Characteristics ◽  
Cloning And Sequencing ◽  
Phylogenetic Groups ◽  
The 1960S ◽  
Tristeza Virus ◽  
Virus Isolates ◽  
Stem Pitting ◽  
Citrus Tristeza

The presence of Citrus tristeza virus (CTV) in Turkey has been known since the 1960s and the virus was detected in all citrus growing regions of the country. Even though serological and biological characteristics of CTV have been studied since the 1980s, molecular characteristics of CTV isolates have not been studied to date in Turkey. In this study, molecular characteristics of 15 CTV isolates collected from different citrus growing regions of Turkey were determined by amplification, cloning, and sequencing of their major coat protein (CP) genes. The sequence analysis showed that the CP genes were highly conserved among Turkish isolates. However, isolates from different regions showed more genetic variation than isolates from the same region. Turkish isolates were clustered into three phylogenetic groups showing no association with geographical origins, host, or symptoms induced in indicator plants. Phylogenetic analysis of Turkish isolates with isolates from different citrus growing regions of the world including well-characterized type isolates of previously established strain specific groups revealed that some Turkish isolates were closely related to severe quick decline or stem pitting isolates. The results demonstrated that although CTV isolates from Turkey are considered biologically mild, majority of them contain severe components potentially causing quick decline or stem pitting.

scholarly journals Ixodes scapularis Tick Saliva Proteins Sequentially Secreted Every 24 h during Blood Feeding

2016 ◽  
Vol 10 (1) ◽  
pp. e0004323 ◽  
Author(s):  
Tae Kwon Kim ◽  
Lucas Tirloni ◽  
Antônio F. M. Pinto ◽  
James Moresco ◽  
John R. Yates ◽  
...  
Keyword(s):  
Ixodes Scapularis ◽  
Blood Feeding ◽  
Tick Saliva

scholarly journals Blood Digestion by Trypsin-Like Serine Proteases in the Replete Lyme Disease Vector Tick, Ixodes scapularis

Insects ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 201
Author(s):  
Jeremiah Reyes ◽  
Cuauhtemoc Ayala-Chavez ◽  
Arvind Sharma ◽  
Michael Pham ◽  
Andrew B. Nuss ◽  
...  
Keyword(s):  
Lyme Disease ◽  
Blood Meal ◽  
Serine Proteases ◽  
Ixodes Scapularis ◽  
Life Stage ◽  
Blood Feeding ◽  
Eastern United States ◽  
Blood Digestion ◽  
Hemoglobin Degradation

Ixodes scapularis is the major vector of Lyme disease in the Eastern United States. Each active life stage (larva, nymph, and adult) takes a blood meal either for developing and molting to the next stage (larvae and nymphs) or for oviposition (adult females). This protein-rich blood meal is the only food taken by Ixodes ticks and therefore efficient blood digestion is critical for survival. Studies in partially engorged ticks have shown that the initial stages of digestion are carried out by cathepsin proteases within acidic digestive cells. In this study, we investigated the potential role of serine proteases in blood digestion in replete ticks. RNA interference was used for functional analysis and a trypsin-benzoyl-D, L-arginine 4-nitoanilide assay was used to measure active trypsin levels. Hemoglobinolytic activity was determined in vitro, with or without a serine protease inhibitor. Our data suggest that trypsin levels increase significantly after repletion. Knockdown of serine proteases negatively impacted blood feeding, survival, fecundity, levels of active trypsin in the midgut, and resulted in lower hemoglobin degradation. Incubation of midgut extract with a trypsin inhibitor resulted in 65% lower hemoglobin degradation. We provide evidence of the serine proteases as digestive enzymes in fully engorged, replete females. Understanding the digestive profile of trypsin during blood meal digestion in I. scapularis improves our understanding of the basic biology of ticks and may lead to new methods for tick control.

scholarly journals mcrA-Targeted Real-Time Quantitative PCR Method To Examine Methanogen Communities

2009 ◽  
Vol 75 (13) ◽  
pp. 4435-4442 ◽  
Author(s):  
Lisa M. Steinberg ◽  
John M. Regan
Keyword(s):  
Quantitative Pcr ◽  
Alternative Energy ◽  
Molecular Techniques ◽  
Pig Manure ◽  
Phylogenetic Groups ◽  
Anaerobic Digesters ◽  
Α Subunit ◽  
Real Time Quantitative Pcr ◽  
Three Samples ◽  
Culture Independent

ABSTRACT Methanogens are of great importance in carbon cycling and alternative energy production, but quantitation with culture-based methods is time-consuming and biased against methanogen groups that are difficult to cultivate in a laboratory. For these reasons, methanogens are typically studied through culture-independent molecular techniques. We developed a SYBR green I quantitative PCR (qPCR) assay to quantify total numbers of methyl coenzyme M reductase α-subunit (mcrA) genes. TaqMan probes were also designed to target nine different phylogenetic groups of methanogens in qPCR assays. Total mcrA and mcrA levels of different methanogen phylogenetic groups were determined from six samples: four samples from anaerobic digesters used to treat either primarily cow or pig manure and two aliquots from an acidic peat sample stored at 4°C or 20°C. Only members of the Methanosaetaceae, Methanosarcina, Methanobacteriaceae, and Methanocorpusculaceae and Fen cluster were detected in the environmental samples. The three samples obtained from cow manure digesters were dominated by members of the genus Methanosarcina, whereas the sample from the pig manure digester contained detectable levels of only members of the Methanobacteriaceae. The acidic peat samples were dominated by both Methanosarcina spp. and members of the Fen cluster. In two of the manure digester samples only one methanogen group was detected, but in both of the acidic peat samples and two of the manure digester samples, multiple methanogen groups were detected. The TaqMan qPCR assays were successfully able to determine the environmental abundance of different phylogenetic groups of methanogens, including several groups with few or no cultivated members.

Phylogenetic diversity of a microbialite reef in a cold alkaline freshwater lake

2014 ◽  
Vol 60 (6) ◽  
pp. 391-398 ◽  
Author(s):  
Olivia W. Chan ◽  
Donnabella C. Bugler-Lacap ◽  
Jennifer F. Biddle ◽  
Darlene S. Lim ◽  
Christopher P. McKay ◽  
...  
Keyword(s):  
British Columbia ◽  
Phylogenetic Analysis ◽  
Water Column ◽  
Quantitative Pcr ◽  
Phylogenetic Diversity ◽  
Rrna Genes ◽  
Archaeal Diversity ◽  
Bacterial Phylotypes ◽  
Real Time Quantitative Pcr ◽  
Culture Independent

A culture-independent multidomain survey of biodiversity in microbialite structures within the cold alkaline Pavilion Lake (British Columbia, Canada) revealed a largely homogenous community at depths from 10 to 30 m. Real-time quantitative PCR was used to demonstrate that bacteria comprised approximately 80%–95% of recoverable phylotypes. Archaeal phylotypes accounted for <5% of the community in microbialites exposed to the water column, while structures in sediment contact supported 4- to 5-fold higher archaeal abundance. Eukaryal phylotypes were rare and indicated common aquatic diatoms that were concluded not to be part of the microbialite community. Phylogenetic analysis of rRNA genes from clone libraries (N = 491) revealed that alphaproteobacterial phylotypes were most abundant. Cyanobacterial phylotypes were highly diverse but resolved into 4 dominant genera: Acaryochloris, Leptolyngbya, Microcoleus, and Pseudanabaena. Interestingly, microbialite cyanobacteria generally affiliated phylogenetically with aquatic and coral cyanobacterial groups rather than those from stromatolites. Other commonly encountered bacterial phylotypes were from members of the Acidobacteria, with relatively low abundance of the Betaproteobacteria, Chloroflexi, Nitrospirae, and Planctomycetes. Archaeal diversity (N = 53) was largely accounted for by Euryarchaeota, with most phylotypes affiliated with freshwater methanogenic taxa.

scholarly journals Phylogenetic Analysis Indicates That Evasin-Like Proteins of Ixodid Ticks Fall Into Three Distinct Classes

2021 ◽  
Vol 11 ◽  
Author(s):  
Shoumo Bhattacharya ◽  
Patricia Anne Nuttall
Keyword(s):  
Phylogenetic Analysis ◽  
Blood Feeding ◽  
Ixodid Ticks ◽  
Cysteine Residues ◽  
Tick Saliva ◽  
Class A ◽  
Leucocyte Migration ◽  
Biochemical Characterisation ◽  
Class B ◽  
Functional Classes

Chemokines are structurally related proteins that activate leucocyte migration in response to injury or infection. Tick saliva contains chemokine-binding proteins or evasins which likely neutralize host chemokine function and inflammation. Biochemical characterisation of 50 evasins from Ixodes, Amblyomma and Rhipicephalus shows that they fall into two functional classes, A and B, with exclusive binding to either CC- or CXC- chemokines, respectively. Class A evasins, EVA1 and EVA4 have a four-disulfide-bonded core, whereas the class B evasin EVA3 has a three-disulfide-bonded “knottin” structure. All 29 class B evasins have six cysteine residues conserved with EVA3, arrangement of which defines a Cys6-motif. Nineteen of 21 class A evasins have eight cysteine residues conserved with EVA1/EVA4, the arrangement of which defines a Cys8-motif. Two class A evasins from Ixodes (IRI01, IHO01) have less than eight cysteines. Many evasin-like proteins have been identified in tick salivary transcriptomes, but their phylogenetic relationship with respect to biochemically characterized evasins is not clear. Here, using BLAST searches of tick transcriptomes with biochemically characterized evasins, we identify 292 class A and 157 class B evasins and evasin-like proteins from Prostriate (Ixodes), and Metastriate (Amblyomma, Dermacentor, Hyalomma, Rhipicephalus) ticks. Phylogenetic analysis shows that class A evasins/evasin-like proteins segregate into two classes, A1 and A2. Class A1 members are exclusive to Metastriate ticks and typically have a Cys8-motif and include EVA1 and EVA4. Class A2 members are exclusive to Prostriate ticks, lack the Cys8-motif, and include IHO01 and IRI01. Class B evasins/evasin-like proteins are present in both Prostriate and Metastriate lineages, typically have a Cys6-motif, and include EVA3. Most evasins/evasin-like proteins in Metastriate ticks belong to class A1, whereas in Prostriate species they are predominantly class B. In keeping with this, the majority of biochemically characterized Metastriate evasins bind CC-chemokines, whereas the majority of Prostriate evasins bind CXC-chemokines. While the origin of the structurally dissimilar classes A1 and A2 is yet unresolved, these results suggest that class B evasin-like proteins arose before the divergence of Prostriate and Metastriate lineages and likely functioned to neutralize CXC-chemokines and support blood feeding.

scholarly journals Expansion of Tick-Borne Rickettsioses in the World

2020 ◽  
Vol 8 (12) ◽  
pp. 1906
Author(s):  
Mariusz Piotrowski ◽  
Anna Rymaszewska
Keyword(s):  
Spotted Fever ◽  
Rapid Evolution ◽  
Diagnostic Techniques ◽  
Molecular Diagnostic ◽  
Molecular Diagnostic Techniques ◽  
Spotted Fever Group ◽  
Rickettsia Species ◽  
The World ◽  
New Locations ◽  
Obligate Intracellular Bacteria

Tick-borne rickettsioses are caused by obligate intracellular bacteria belonging to the spotted fever group of the genus Rickettsia. These infections are among the oldest known diseases transmitted by vectors. In the last three decades there has been a rapid increase in the recognition of this disease complex. This unusual expansion of information was mainly caused by the development of molecular diagnostic techniques that have facilitated the identification of new and previously recognized rickettsiae. A lot of currently known bacteria of the genus Rickettsia have been considered nonpathogenic for years, and moreover, many new species have been identified with unknown pathogenicity. The genus Rickettsia is distributed all over the world. Many Rickettsia species are present on several continents. The geographical distribution of rickettsiae is related to their vectors. New cases of rickettsioses and new locations, where the presence of these bacteria is recognized, are still being identified. The variety and rapid evolution of the distribution and density of ticks and diseases which they transmit shows us the scale of the problem. This review article presents a comparison of the current understanding of the geographic distribution of pathogenic Rickettsia species to that of the beginning of the century.

scholarly journals Borrelia burgdorferi Population Kinetics and Selected Gene Expression at the Host-Vector Interface

2002 ◽  
Vol 70 (7) ◽  
pp. 3382-3388 ◽  
Author(s):  
Emir Hodzic ◽  
Sunlian Feng ◽  
Kimberly J. Freet ◽  
Dori L. Borjesson ◽  
Stephen W. Barthold
Keyword(s):  
Gene Expression ◽  
Population Dynamics ◽  
Borrelia Burgdorferi ◽  
Gene Transcription ◽  
Ixodes Scapularis ◽  
Rna Transcription ◽  
Population Kinetics ◽  
Real Time Quantitative Pcr ◽  
Attachment Sites ◽  
Tick Attachment

ABSTRACT By using real-time quantitative PCR, the population dynamics and gene transcription of Borrelia burgdorferi were examined in ticks and skin of mice during acquisition of the infection from mice by ticks and during transmission of the infection from ticks to mice. Population dynamics were determined by using a flaB DNA target. A quantitative analysis of flaB, ospA, ospC, dbpA, and arp transcription was also performed. The results revealed that both uninfected larval and nymphal Ixodes scapularis ticks acquired B. burgdorferi as early as 1 day after attachment and that the sizes of spirochete populations within ticks increased during feeding. In addition, all gene targets revealed that there was RNA transcription during feeding. Similar events occurred within infected nymphal ticks feeding on uninfected hosts. Transmission from infected nymphal ticks to mice could be detected within 1 day after attachment. Analysis of skin during the first 3 days after attachment of infected ticks revealed rising numbers of spirochetes but minimal gene transcription. In contrast, the skin of mice with established infections revealed static populations of spirochetes and active but stable transcription of flaB, ospC, dbpA, and arp. There were consistent reductions in the number of spirochetes in the skin at the tick attachment sites compared to the number of spirochetes in the skin at nontick sites, but there were no differences in gene expression between tick and nontick skin sites. Evidence of ospA transcription in skin could be found 1 day after tick attachment but not thereafter.

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