scholarly journals Differential Expression of Genes in Uninfected and Rickettsia-Infected Dermacentor variabilis Ticks as Assessed by Differential-Display PCR

2003 ◽  
Vol 71 (11) ◽  
pp. 6165-6170 ◽  
Author(s):  
Kevin R. Macaluso ◽  
Albert Mulenga ◽  
Jason A. Simser ◽  
Abdu F. Azad
Keyword(s):  
Differential Expression ◽  
Differential Display ◽  
Spotted Fever ◽  
Dermacentor Variabilis ◽  
Coated Vesicle ◽  
Spotted Fever Group ◽  
Differential Display Pcr ◽  
Reverse Transcription Pcr ◽  
Close Relationship ◽  
Farnesylated Protein

ABSTRACT Ticks serve as both the vector and the reservoir for members of the spotted fever group rickettsiae. The molecular interaction(s) that results from this close relationship is largely unknown. To identify genetic factors associated with the tick response to rickettsial infection, we utilized differential-display PCR. The majority of upregulation appeared in the infected tissue. We cloned and sequenced 54 differentially expressed transcripts and compared the sequences to those in the GenBank database. Nine of the 54 clones were assigned putative identities and included a clathrin-coated vesicle ATPase, peroxisomal farnesylated protein, Ena/vasodilator-stimulated phosphoprotein-like protein, α-catenin, tubulin α-chain, copper-transporting ATPase, salivary gland protein SGS-3 precursor, glycine-rich protein, and Dreg-2 protein. Confirmation of the rickettsial influence on the differential expression in the ovaries for a number of these clones was demonstrated by semiquantitative reverse transcription-PCR and Northern blot analyses, resulting in confirmation of six out of nine and three out of four assessed clones, respectively. Further characterization of the clones identified tissue-dependent expression in the midguts and salivary glands. The potential roles of these molecules in the maintenance and transmission of rickettsiae are discussed.

Collaborating With Community Scientists Across Arkansas to Update Tick Distributions and Pathogen Prevalence of Spotted Fever Group Rickettsia and Ehrlichia

2021 ◽  
Author(s):  
Ashley P G Dowling ◽  
Sean G Young ◽  
Kelly Loftin
Keyword(s):  
Tick Species ◽  
Spotted Fever ◽  
Dermacentor Variabilis ◽  
Amblyomma Americanum ◽  
Spotted Fever Group ◽  
Primary Role ◽  
Prevalence Rates ◽  
Spotted Fever Group Rickettsia ◽  
Community Science ◽  
Tick Distributions

Abstract Tick-borne diseases (TBD) in humans have dramatically increased over recent years and although the bulk of cases are attributable to Lyme Disease in the Northeastern US, TBDs like spotted fever rickettsiosis and ehrlichiosis heavily impact other parts of the country, namely the mid-south. Understanding tick and pathogen distributions and prevalence traditionally requires active surveillance, which quickly becomes logistically and financially unrealistic as the geographic area of focus increases. We report on a community science effort to survey ticks across Arkansas to obtain updated data on tick distributions and prevalence of human tick-borne disease-causing pathogens in the most commonly encountered ticks. During a 20-mo period, Arkansans submitted 9,002 ticks from 71 of the 75 counties in the state. Amblyomma americanum was the most common tick species received, accounting for 76% of total tick submissions. Nearly 6,000 samples were screened for spotted fever group Rickettsia (SFGR) and Ehrlichia, resulting in general prevalence rates of 37.4 and 5.1%, respectively. In addition, 145 ticks (2.5%) were infected with both SFGR and Ehrlichia. Arkansas Department of Health reported 2,281 spotted fever and 380 ehrlichiosis cases during the same period as our tick collections. Since known SFGR vectors Dermacentor variabilis and Amblyomma maculatum were not the most common ticks submitted, nor did they have the highest prevalence rates of SFGR, it appears that other tick species play the primary role in infecting humans with SFGR. Our investigation demonstrated the utility of community science to efficiently and economically survey ticks and identify vector-borne disease risk in Arkansas.

Rickettsial Diseases

2017 ◽  
Author(s):  
Lisa Sun ◽  
Michael V. Johnston
Keyword(s):  
Endothelial Cells ◽  
Q Fever ◽  
Spotted Fever ◽  
The United States ◽  
Dermacentor Variabilis ◽  
Farm Animals ◽  
Spotted Fever Group ◽  
Rocky Mountain Spotted Fever ◽  
The World ◽  
The Brain

Tick-borne rickettsioses are emerging as more important health problems throughout the world. The spotted fever group including Rickettsia rickettsia can cause encephalopathy, meningitis and brain damage by selectively targeting capillary endothelial cells in the brain, and stimulating inflammation, capillary leakage, hemorrhage, and intravascular coagulation. Rickettsia are are arthropod-borne gram-negative coccobacilli bacteria and are obligate intracellular organisms that do not survive in artificial medium. In North and South America, the most common rickettsial disorder is rocky mountain spotted fever (RMSF) transmitted by the dog tick Dermacentor variabilis or the wood tick Dermacentor andersoni. A characteristic “starry sky” pattern can be seen on MRI imaging of the brain in some patients with RMSF encephalopathy and is thought to reflect the organisms targeting of brain endothelial cells in capillaries the white matter. Early treatment with doxycycline is curative and reverses signs of encephalopathy if given within a few day of onset, but delayed treatment can be associated with permanent neurological disability. The typhus group of rickettsia bacteria include R. prowazekii, which causes epidemic typhus and R. typhi, which causes murine typhus (endemic) typhus in tropical and subtropical parts of the world. Flying squirrels and humans carry R prowazekii and rats are carry R. typhi. Q fever caused by the rickettsia organism Coxiella burnetti is transmitted from farm animals including sheep and is seen throughout the world including the United States.

scholarly journals Minimal Duration of Tick Attachment Sufficient for Transmission of Infectious Rickettsia rickettsii (Rickettsiales: Rickettsiaceae) by Its Primary Vector Dermacentor variabilis (Acari: Ixodidae): Duration of Rickettsial Reactivation in the Vector Revisited

2019 ◽  
Author(s):  
Michael L Levin ◽  
Shelby L Ford ◽  
Kris Hartzer ◽  
Lnna Krapiunaya ◽  
Hannah Stanley ◽  
...  
Keyword(s):  
Salivary Glands ◽  
Guinea Pigs ◽  
Pathogenic Bacteria ◽  
Spotted Fever ◽  
Dermacentor Variabilis ◽  
Control Group ◽  
Spotted Fever Group ◽  
Susceptible Host ◽  
Rickettsia Rickettsii ◽  
Tick Attachment

Abstract It has been reported that starving ticks do not transmit spotted fever group Rickettsia immediately upon attachment because pathogenic bacteria exist in a dormant, uninfectious state and require time for ‘reactivation’ before transmission to a susceptible host. To clarify the length of reactivation period, we exposed guinea pigs to bites of Rickettsia rickettsii-infected Dermacentor variabilis (Say) and allowed ticks to remain attached for predetermined time periods from 0 to 48 h. Following removal of attached ticks, salivary glands were immediately tested by PCR, while guinea pigs were observed for 10–12 d post-exposure. Guinea pigs in a control group were subcutaneously inoculated with salivary glands from unfed D. variabilis from the same cohort. In a parallel experiment, skin at the location of tick bite was also excised at the time of tick removal to ascertain dissemination of pathogen from the inoculation site. Animals in every exposure group developed clinical and pathological signs of infection. The severity of rickettsial infection in animals increased with the length of tick attachment, but even attachments for less than 8 h resulted in clinically identifiable infection in some guinea pigs. Guinea pigs inoculated with salivary glands from unfed ticks also became severely ill. Results of our study indicate that R. rickettsii residing in salivary glands of unfed questing ticks does not necessarily require a period of reactivation to precede the salivary transmission and ticks can transmit infectious Rickettsia virtually as soon as they attach to the host.

Spotted Fever Group Rickettsiae in Dermacentor variabilis from Cape Cod, Massachusetts

1980 ◽  
Vol 29 (4) ◽  
pp. 691-694 ◽  
Author(s):  
William C. Feng ◽  
Kamlesh Dang ◽  
Catherine Smith ◽  
Charles Spickert ◽  
Edward S. Murray ◽  
...  
Keyword(s):  
Spotted Fever ◽  
Dermacentor Variabilis ◽  
Cape Cod ◽  
Spotted Fever Group ◽  
Spotted Fever Group Rickettsiae

scholarly journals Exploring the niche of Rickettsia montanensis (Rickettsiales: Rickettsiaceae) infection of the American dog tick (Acari: Ixodidae), using multiple species distribution model approaches.

2020 ◽  
Author(s):  
Catherine Lippi ◽  
Holly D Gaff ◽  
Alexis L White ◽  
Heidi K St John ◽  
Allen L Richards ◽  
...  
Keyword(s):  
Species Distribution ◽  
Species Distribution Model ◽  
Health Planning ◽  
Spotted Fever ◽  
Dermacentor Variabilis ◽  
Distribution Model ◽  
Spotted Fever Group ◽  
Modeling Framework ◽  
American Dog Tick ◽  
Dog Tick

The American dog tick, Dermacentor variabilis (Say), is a vector for several human disease causing pathogens such as tularemia, Rocky Mountain spotted fever, and the understudied spotted fever group rickettsiae (SFGR) infection caused by Rickettsia montanensis. It is important for public health planning and intervention to understand the distribution of this tick and pathogen encounter risk. Risk is often described in terms of vector distribution, but greatest risk may be concentrated where more vectors are positive for a given pathogen. When assessing species distributions, the choice of modeling framework and spatial layers used to make predictions are important. We first updated the modeled distribution of D. variabilis and R. montanensis using MaxEnt, refining bioclimatic data inputs, and including soils variables. We then compared geospatial predictions from five species distribution modeling (SDM) frameworks. In contrast to previous work, we additionally assessed whether the R. montanensis positive D. variabilis distribution is nested within a larger overall D. variabilis distribution, representing a fitness cost hypothesis. We found that 1) adding soils layers improved the accuracy of the MaxEnt model; 2) the predicted "infected niche" was smaller than the overall predicted niche across all models; and 3) each model predicted different sizes of suitable niche, at different levels of probability. Importantly, the models were not directly comparable in output style, which could create confusion in interpretation when developing planning tools. The random forest (RF) model had the best measured validity and fit, suggesting it may be most appropriate to these data.

scholarly journals Identification of Host Proteins Involved in Rickettsial Invasion of Tick Cells

2014 ◽  
Vol 83 (3) ◽  
pp. 1048-1055 ◽  
Author(s):  
Natthida Petchampai ◽  
Piyanate Sunyakumthorn ◽  
Kaikhushroo H. Banajee ◽  
Victoria I. Verhoeve ◽  
Michael T. Kearney ◽  
...  
Keyword(s):  
Host Cell ◽  
Tyrosine Kinases ◽  
Molecular Mechanisms ◽  
Rho Gtpase ◽  
Spotted Fever ◽  
Dermacentor Variabilis ◽  
Host Cells ◽  
Spotted Fever Group ◽  
Bacterial Survival ◽  
Content Type

Tick-borne spotted fever group (SFG)Rickettsiaspecies are obligate intracellular bacteria capable of infecting both vertebrate and invertebrate host cells, an essential process for subsequent bacterial survival in distinct hosts. The host cell signaling molecules involved in the uptake ofRickettsiainto mammalian andDrosophilacells have been identified; however, invasion into tick cells is understudied. Considering the movement of SFGRickettsiabetween vertebrate and invertebrate hosts, the hypothesis is that conserved mechanisms are utilized for host cell invasion. The current study employed biochemical inhibition assays to determine the tick proteins involved inRickettsia montanensisinfection of tick-derived cells from a natural host,Dermacentor variabilis. The results revealed several tick proteins important for rickettsial invasion, including actin filaments, actin-related protein 2/3 complex, phosphatidylinositol-3′-kinase, protein tyrosine kinases (PTKs), Src family PTK, focal adhesion kinase, Rho GTPase Rac1, and neural Wiskott-Aldrich syndrome protein. Delineating the molecular mechanisms of rickettsial infection is critical to a thorough understanding of rickettsial transmission in tick populations and the ecology of tick-borne rickettsial diseases.

scholarly journals Molecular Detection of Spotted Fever Group Rickettsiae (Rickettsiales: Rickettsiaceae) in Dermacentor variabilis (Acari: Ixodidae) Collected Along the Platte River in South Central Nebraska

2019 ◽  
Vol 57 (2) ◽  
pp. 519-523
Author(s):  
Brandon E Luedtke ◽  
Julie J Shaffer ◽  
Estrella Monrroy ◽  
Corey W Willicott ◽  
Travis J Bourret
Keyword(s):  
Spotted Fever ◽  
Rocky Mountain ◽  
Dermacentor Variabilis ◽  
Amblyomma Americanum ◽  
Spotted Fever Group ◽  
Rocky Mountain Spotted Fever ◽  
Rickettsia Species ◽  
Platte River ◽  
Rickettsia Rickettsii ◽  
South Central

Abstract Dermacentor variabilis is the predominant tick species in Nebraska and is presumed to be the primary vector of Rickettsia rickettsii associated with cases of Rocky Mountain spotted fever (RMSF). Interestingly, RMSF cases in Nebraska have increased on a year-to-year basis, yet the prevalence of R. rickettsii in D. variabilis ticks has not been established for Nebraska. Here we sought to set a baseline for the prevalence of R. rickettsii and other spotted fever group (SFG) rickettsiae harbored by D. variabilis ticks. Over a 3-yr period, D. variabilis were collected along the Platte River in south central Nebraska. Individual tick DNA was analyzed using endpoint PCR to identify ticks carrying SFG rickettsiae. In total, 927 D. variabilis were analyzed by PCR and 38 (4.1%) ticks tested positive for SFG rickettsiae. Presumptive positives were sequenced to identify the Rickettsia species, of which 29 (76%) were R. montanensis, 5 (13%) were R. amblyommatis, 4 (11%) were R. bellii, and R. rickettsii was not detected. These data indicate that R. rickettsii is likely at a low prevalence in south central Nebraska and spillover of R. amblyommatis into D. variabilis is likely occurring due to the invasive lone star tick (Amblyomma americanum). In addition, our data suggest that R. montanensis and R. amblyommatis could be associated with the increase in SFG rickettsiae infections in Nebraska. This information will be of value to clinicians and the general public for evaluating diagnosis of disease- and risk-associated environmental exposure, respectively.

scholarly journals Exploring the Niche of Rickettsia montanensis (Rickettsiales: Rickettsiaceae) Infection of the American Dog Tick (Acari: Ixodidae), Using Multiple Species Distribution Model Approaches

2020 ◽  
Author(s):  
Catherine A Lippi ◽  
Holly D Gaff ◽  
Alexis L White ◽  
Heidi K St. John ◽  
Allen L Richards ◽  
...  
Keyword(s):  
Species Distribution ◽  
Species Distribution Model ◽  
Health Planning ◽  
Spotted Fever ◽  
Dermacentor Variabilis ◽  
Distribution Model ◽  
Spotted Fever Group ◽  
Modeling Framework ◽  
American Dog Tick ◽  
Dog Tick

Abstract The American dog tick, Dermacentor variabilis (Say) (Acari: Ixodidae), is a vector for several human disease-causing pathogens such as tularemia, Rocky Mountain spotted fever, and the understudied spotted fever group rickettsiae (SFGR) infection caused by Rickettsia montanensis. It is important for public health planning and intervention to understand the distribution of this tick and pathogen encounter risk. Risk is often described in terms of vector distribution, but greatest risk may be concentrated where more vectors are positive for a given pathogen. When assessing species distributions, the choice of modeling framework and spatial layers used to make predictions are important. We first updated the modeled distribution of D. variabilis and R. montanensis using maximum entropy (MaxEnt), refining bioclimatic data inputs, and including soil variables. We then compared geospatial predictions from five species distribution modeling frameworks. In contrast to previous work, we additionally assessed whether the R. montanensis positive D. variabilis distribution is nested within a larger overall D. variabilis distribution, representing a fitness cost hypothesis. We found that 1) adding soil layers improved the accuracy of the MaxEnt model; 2) the predicted ‘infected niche’ was smaller than the overall predicted niche across all models; and 3) each model predicted different sizes of suitable niche, at different levels of probability. Importantly, the models were not directly comparable in output style, which could create confusion in interpretation when developing planning tools. The random forest (RF) model had the best measured validity and fit, suggesting it may be most appropriate to these data.

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