scholarly journals Beyond the IFA: Revisiting the ELISA as a More Sensitive, Objective, and Quantitative Evaluation of Spotted Fever Group Rickettsia Exposure

Pathogens ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 88
Author(s):  
Navatha Alugubelly ◽  
John V. Stokes ◽  
Claire E. Cross ◽  
Anne-Marie L. Ross ◽  
Anna E. Crawford ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Signal To Noise Ratio ◽  
Spotted Fever ◽  
Clinical Signs ◽  
Enzyme Linked Immunosorbent Assay ◽  
Spotted Fever Group ◽  
Rickettsia Parkeri ◽  
Rickettsial Infections ◽  
Spotted Fever Group Rickettsia ◽  
Guinea Pig Model

Based on limited serological studies, at least 10% of the US population has been exposed to spotted fever group Rickettsia (SFGR) species. The immunofluorescence antibody assay (IFA) has been the gold standard for the serodiagnosis of rickettsial infections such as spotted fever rickettsiosis (SFR). However, the IFA is semi-quantitative and subjective, requiring a high level of expertise to interpret it correctly. Here, we developed an enzyme-linked immunosorbent assay (ELISA) for the serodiagnosis of Rickettsia parkeri infection in the guinea pig. Our ELISA is an objective, quantitative, and high-throughput assay that shows greater sensitivity and resolution in observed titers than the IFA. We methodically optimized relevant parameters in sequence for optimal signal-to-noise ratio and low coefficient of variation% values. We used a guinea pig model as it is a part of our overall research efforts to understand the immunological and clinical response to SFGR species after tick transmission. Guinea pigs are a useful model to study SFR and show clinical signs of SFR, such as fever and eschars. We anticipate that this assay will be easily adapted to other hosts, including humans and other SFGR species.

scholarly journals Targeted Knockout of the Rickettsia rickettsii OmpA Surface Antigen Does Not Diminish Virulence in a Mammalian Model System

mBio ◽  
2015 ◽  
Vol 6 (2) ◽  
Author(s):  
Nicholas F. Noriea ◽  
Tina R. Clark ◽  
Ted Hackstadt
Keyword(s):  
Guinea Pig ◽  
Stop Codon ◽  
Spotted Fever ◽  
Premature Stop Codon ◽  
Group Ii Intron ◽  
Pig Model ◽  
Spotted Fever Group ◽  
Wild Type ◽  
Group Ii ◽  
Guinea Pig Model

ABSTRACTStrains ofRickettsia rickettsii, the causative agent of Rocky Mountain spotted fever (RMSF), differ dramatically in virulence despite >99% genetic homology. Spotted fever group (SFG) rickettsiae produce two immunodominant outer membrane proteins, rickettsial OmpA (rOmpA) and rOmpB, which are conserved throughout the SFG and thought to be fundamental to pathogenesis. rOmpA is present in all virulent strains ofR. rickettsiibut is not produced in the only documented avirulent strain, Iowa, due to a premature stop codon. Here we report the creation of an isogenicompAmutant in the highly virulent strain Sheila Smith by insertion of intronic RNA to create a premature stop codon 312 bp downstream of the 6,747-bp open reading frame initiation site (int312). Targeted insertion was accomplished using an LtrA group II intron retrohoming system. Growth and entry rates of Sheila SmithompA::int312 in Vero cells remained comparable to those of the wild type. Virulence was assessed in a guinea pig model by challenge with 100 PFU of eitherompA::int312 Sheila Smith or the wild type, but no significant difference in either fever peak (40.5°C) or duration (8 days) were shown between the wild type and the knockout. The ability to disrupt genes in a site-specific manner using an LtrA group II intron system provides an important new tool for evaluation of potential virulence determinants in rickettsial disease research.IMPORTANCER. rickettsiirOmpA is an immunodominant outer membrane autotransporter conserved in the spotted fever group. Previous studies and genomic comparisons suggest that rOmpA is involved in adhesion and may be critical for virulence. Little information is available for rickettsial virulence factors in an isogenic background, as limited systems for targeted gene disruption are currently available. Here we describe the creation of an rOmpA knockout by insertion of a premature stop codon into the 5′ end of the open reading frame using a group II intron system. An isogenic rOmpA knockout mutation in the highly virulent Sheila Smith strain did not cause attenuation in a guinea pig model of infection, and no altered phenotype was observed in cell culture. We conclude that rOmpA is not critical for virulence in a guinea pig model but may play a role in survival or transmission from the tick vector.

scholarly journals A biosafety level-2 dose-dependent lethal mouse model of spotted fever rickettsiosis: Rickettsia parkeri Atlantic Rainforest-like isolate

2018 ◽  
Author(s):  
Andrés Felipe Londoño ◽  
Nicole L. Mendell ◽  
David H. Walker ◽  
Donald H. Bouyer ◽  
Keyword(s):  
Mouse Model ◽  
Post Infection ◽  
Spotted Fever ◽  
Spotted Fever Group ◽  
Rickettsia Parkeri ◽  
Spotted Fever Group Rickettsia ◽  
Dose Dependent ◽  
Level 2 ◽  
Biosafety Level ◽  
Biosafety Level 2

Background The species of the Rickettsia genus is separated into four groups: the ancestral group, typhus group, transitional group and spotted fever group. Rickettsia parkeri, a spotted fever group Rickettsia, has been reported across the American continents as infecting several tick species and is associated with a relatively mild human disease characterized by eschar formation at the tick feeding site, fever, myalgia and rash. Currently several mouse models that provide a good approach to study the acute lethal disease caused by Rickettsia, but these models can only be performed in an animal biosafety level 3 laboratory. We present an alternative mouse model for acute lethal rickettsial disease, using R. parkeri and C3H/HeN mice, with the advantage that this model can be studied in an animal biosafety level 2 laboratory. Principal findings In the C3H/HeN mouse model, we determined that infection with 1x106 and 1x107 viable R. parkeri Atlantic Rainforest-like isolate produced dose-dependent severity, whereas infection with 1x108 viable bacteria resulted in a lethal illness. The animals became moribund on day five or six post-infection. The lethal disease was characterized by ruffled fur, erythema, labored breathing, decreased activity, and hunched back, which began on day three post-infection (p.i.) and coincided with the peak bacterial loads. Significant splenomegaly (on days three and five p.i.), neutrophilia (on days three and five p.i.), and thrombocytopenia (on days one, three and five p.i.) were observed. Significance The greatest advantage of this inbred mouse model is the ability to investigate immunity and pathogenesis of rickettsiosis with all the tools available at biosafety level 2.

scholarly journals Seroprevalence of Rickettsia rickettsii and Rickettsia parkeri in dogs during a Brazilian Spotted Fever outbreak in the State of Rio de Janeiro

2018 ◽  
Vol 70 (3) ◽  
pp. 667-674 ◽  
Author(s):  
I.T. Poubel ◽  
N.C. Cunha ◽  
A.B.M. Fonseca ◽  
A. Pinter ◽  
A.H. Fonseca ◽  
...  
Keyword(s):  
Rio De Janeiro ◽  
Spotted Fever ◽  
Immunofluorescence Assay ◽  
Spotted Fever Group ◽  
Ambient Conditions ◽  
Rickettsia Parkeri ◽  
Rickettsia Rickettsii ◽  
Brazilian Spotted Fever ◽  
Spotted Fever Group Rickettsia ◽  
Janeiro State

ABSTRACT The present paper is the first to perform this evaluation in dogs from the cities of Natividade, Porciuncula and Varre-Sai. The aim of this study is to search for Spotted Fever Group Rickettsia in canine sera using indirect immunofluorescence assay and to identify the probable causative agent of sera reactions in animals. Of the 253 sampled canines, 67.59% (171/253) were seroreactive for Rickettsia rickettsii and 11.07% (28/253) for Rickettsia parkeri, both in dilution 1:64. Titration of tested sera against R. rickettsii antigens reached 1:131.072 and, for R. parkeri, 1:4.096. We conclude that dogs are important sentinels for R. rickettsii infection, and can be infected regardless of sex, age, the habit of visiting woodlands or being in direct contact with equines and capybaras. Serological diagnosis has highlighted many dogs infected by R. rickettsii, and ambient conditions, such as the presence of flowing water bodies, was important for the occurrence of Brazilian Spotted Fever in the northwestern of Rio de Janeiro State.

scholarly journals Isolation of Rickettsia parkeri and Identification of a Novel Spotted Fever Group Rickettsia sp. from Gulf Coast Ticks (Amblyomma maculatum) in the United States

2010 ◽  
Vol 76 (9) ◽  
pp. 2689-2696 ◽  
Author(s):  
Christopher D. Paddock ◽  
Pierre-Edouard Fournier ◽  
John W. Sumner ◽  
Jerome Goddard ◽  
Yasmin Elshenawy ◽  
...  
Keyword(s):  
United States ◽  
Gulf Coast ◽  
Spotted Fever ◽  
The United States ◽  
Spotted Fever Group ◽  
The Novel ◽  
Amblyomma Maculatum ◽  
Rickettsia Parkeri ◽  
Gulf Coast Ticks ◽  
Spotted Fever Group Rickettsia

ABSTRACT Until recently, Amblyomma maculatum (the Gulf Coast tick) had garnered little attention compared to other species of human-biting ticks in the United States. A. maculatum is now recognized as the principal vector of Rickettsia parkeri, a pathogenic spotted fever group rickettsia (SFGR) that causes an eschar-associated illness in humans that resembles Rocky Mountain spotted fever. A novel SFGR, distinct from other recognized Rickettsia spp., has also been detected recently in A. maculatum specimens collected in several regions of the southeastern United States. In this study, 198 questing adult Gulf Coast ticks were collected at 4 locations in Florida and Mississippi; 28% of these ticks were infected with R. parkeri, and 2% of these were infected with a novel SFGR. Seventeen isolates of R. parkeri from individual specimens of A. maculatum were cultivated in Vero E6 cells; however, all attempts to isolate the novel SFGR were unsuccessful. Partial genetic characterization of the novel SFGR revealed identity with several recently described, incompletely characterized, and noncultivated SFGR, including “Candidatus Rickettsia andeanae” and Rickettsia sp. Argentina detected in several species of Neotropical ticks from Argentina and Peru. These findings suggest that each of these “novel” rickettsiae represent the same species. This study considerably expanded the number of low-passage, A. maculatum-derived isolates of R. parkeri and characterized a second, sympatric Rickettsia sp. found in Gulf Coast ticks.

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.

scholarly journals Comparative growth of spotted fever group Rickettsia spp. strains in Vero cells

2016 ◽  
Vol 111 (8) ◽  
pp. 528-531
Author(s):  
Arannadia Barbosa Silva ◽  
Myrian Morato Duarte ◽  
Vinicius Figueiredo Vizzoni ◽  
Ana Íris de Lima Duré ◽  
Diego Montenegro Lopéz ◽  
...  
Keyword(s):  
Spotted Fever ◽  
Vero Cells ◽  
Spotted Fever Group ◽  
Spotted Fever Group Rickettsia

scholarly journals Rickettsia spp. in rodent-attached ticks and first evidence of Spotted fever Group Rickettsia species Candidatus Rickettsia uralica in Europe.

2020 ◽  
Author(s):  
Maria Vikentjeva ◽  
Julia Geller ◽  
Jaanus Remm ◽  
Irina Golovljova
Keyword(s):  
Spotted Fever ◽  
Ixodid Ticks ◽  
Distribution Area ◽  
Myodes Glareolus ◽  
Ixodes Persulcatus ◽  
Spotted Fever Group ◽  
Human Pathogens ◽  
Rickettsia Species ◽  
Questing Ticks ◽  
Spotted Fever Group Rickettsia

Abstract BACKGROUND Rickettsia spp. are human pathogens that cause a number of diseases and are transmitted by arthropods, including ixodid ticks. Estonia contributes a region, where the distribution area of two exophilic tick species of known medical importance, Ixodes persulcatus and I. ricinus, overlap. The presence of the nidicolous rodent-associated I. trianguliceps has recently been shown for Estonia. Although there is no Estonian data available on human disease caused by tick-borne Rickettsia spp., the presence of three Rickettsia species in non-nidicolous ticks, albiet at very dissimilar rates, was also previously reported. The aim of this studywas to screen, identify and characterize Rickettsia species in nidicolous and non-nidicolous ticks attached to rodents. RESULTS Nymphs and larvae of I. ricinus ( n = 1004), I . persulcatus ( n = 75) and I. trianguliceps ( n = 117) attached to rodents and shrews caught in different parts of Estonia were studied for the presence of Rickettsia spp. by nested PCR. Ticks were removed from 314 small animals of 5 species (bank voles Myodes glareolus , yellow necked mice Apodemus flavicollis , striped field mice A. agrarius, pine voles M. subterranius and common shrews S. araneus) . Rickettsial DNA was detected in 8,7% (103/1186) studied ticks. In addition to R. helvetica, previously found in questing ticks, this study reports the first identification of the recently described I. trianguliceps- associated Candidatus R. uralica in west of the Ural.

Sign in / Sign up

Export Citation Format

Share Document