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Prevalence of antibodies to Coxiella burnetti, Rickettsia conorii, and Rickettsia typhi in seven African countries.

The prevalences of antibodies reactive with Coxiella burnetti, Rickettsia conorii, and Rickettsia typhi were determined by indirect fluorescent antibody testing of sera from seven African countries. The seroprevalences of antibodies reactive with C. burnetti and R. conorii in countries from North Africa were similar to those reported from southern Europe. In countries of sub-Saharan Africa, the seroprevalence of antibodies reactive with C. burnetti varied greatly; the generally higher figures for West Africa, where stock breeding is prominent, suggested that domestic animals might be the main …

Some lessons from Rickettsia genomics.

Sequencing of the Rickettsia conorii genome and its comparison with its closest sequenced pathogenic relative, i.e., Rickettsia prowazekii, provided powerful insights into the evolution of these microbial pathogens. However, advances in our knowledge of rickettsial diseases are still hindered by the difficulty of working with strict intracellular bacteria and their hosts. Information gained from comparing the genomes of closely related organisms will shed new light on proteins susceptible to be targeted in specific diagnostic assays, by new antimicrobial drugs, and that could be employed in th…

[Pulmonary hypertension following Rickettsia infection?].

A latent or stable pulmonary hypertension was established in three patients with a Q-Fever-Infection confirmed as occupational disease. According to sparse informations in the literature the development of a pulmonary hypertension in the course of this disease is taken into account. The investigation programme regarding Q-Fever-Infections should be completed by measurement of pulmonary artery pressure.

Cryptic Genes for Interbacterial Antagonism Distinguish Rickettsia Species Infecting Blacklegged Ticks From Other Rickettsia Pathogens.

BACKGROUND: The genus Rickettsia (Alphaproteobacteria: Rickettsiales) encompasses numerous obligate intracellular species with predominantly ciliate and arthropod hosts. Notable species are pathogens transmitted to mammals by blood-feeding arthropods. Mammalian pathogenicity evolved from basal, non-pathogenic host-associations; however, some non-pathogens are closely related to pathogens. One such species, Rickettsia buchneri, is prevalent in the blacklegged tick, Ixodes scapularis. While I. scapularis transmits several pathogens to humans, it does not transmit Rickettsia pathogens. We hypothe…

Genomic Features of Rickettsia heilongjiangensis Revealed by Intraspecies Comparison and Detailed Comparison With Rickettsia japonica.

Rickettsia heilongjiangensis is the causative agent of Far-Eastern spotted fever (FESF). In Japan, a human case of FESF was identified in Sendai in Miyagi Prefecture in 2008, and R. heilongjiangensis bacteria were isolated from Haemaphysalis concinna ticks collected in the suspected geographical area of infection. Although the intraspecies genome diversity of Rickettsia has been poorly investigated, our recent analysis revealed extremely low genomic diversity of R. japonica, the agent of Japanese spotted fever, which is a close relative of R. heilongjiangensis. In this study, to investigate th…

Effects of Rickettsia amblyommatis Infection on the Vector Competence of Amblyomma americanum Ticks for Rickettsia rickettsii.

Although Dermacentor spp. ticks are considered the primary vectors of Rickettsia rickettsii in the United States, other North American tick species are also capable of transmitting the agent, including the lone star tick-Amblyomma americanum. The lone star tick is an aggressive human-biting tick abundant in the South, Central, and Mid-Atlantic United States, which has been shown to be a competent vector of R. rickettsii in laboratory studies. However in nature, A. americanum frequently carry Rickettsia amblyommatis-another member of the spotted fever group-with the prevalence of infection reac…

Новые Foci of Spoted Fever Group Rickettsiae, включая Rickettsia honei в Западной Австралии.

Мы описываем первый зарегистрированный случай рикетциоз группы пятнистой лихорадки в Западной Австралии и два случая вероятного Рикиттсии хони с новой географической точки зрения. Эти результаты свидетельствуют о необходимости повышения осведомленности о риксеттской инфекции среди местных врачей, а также тех, кто оказывает помощь посетителям этого региона, что имеет важное значение для отдыха на открытом воздухе.

Совпадение в аннотации оригинала
We describe the first reported case of spotted fever group rickettsiosis in Western Australia, and two cases of probable Rickettsia honei from a new geographic focus. These findings highlight the need to raise awareness of ricksettsial infection among local clinicians as well as those treating visitors to this region, important for outdoor recreation.

Роль T-лимфоцитов в производстве антител для антигенов Рикитцутсугамуши и других видов Рикиттси.

Требования в отношении лимфоцитов, зависящих от тимуса, для производства антител в Рикитсиа цуцугамуши, Рикитсиа акари, Рикиеттсии conorii и Рикиетсийском тифе были исследованы путем сопоставления производства антител в атимичном (nu/nu) или тиммуносном BALB/c мышах. Мыши Athymic BALB/c производили антитело после заражения с помощью R. akari, R. conorii и R. тифа, измеряемого с помощью непрямой флуоресцентной титрации антител или радиоиммуномассы. Производство антител в этих мышах было большим или большим, чем в мышах с тиммусулятором, и демонстрировало похожие кинетики. В отличие от этого, ан

Совпадение в аннотации оригинала
The requirement of thymus-dependent lymphocytes for antibody production to Rickettsia tsutsugamushi, Rickettsia akari, Rickettsia conorii, and Rickettsia typhi was investigated by comparing antibody production in athymic (nu/nu) or thymus-bearing BALB/c mice. Athymic BALB/c mice produced antibody after infection with R. akari, R. conorii, and R. typhi as mea…

Isolation of species-specific protein antigens of Rickettsia typhi and Rickettsia prowazekii for immunodiagnosis and immunoprophylaxis.

A simple procedure for the selective isolation of the protective species-specific protein antigens (SPAs) of Rickettsia typhi and Rickettsia prowazekii was developed to permit use of the SPAs in the immunodiagnosis and immunoprophylaxis of typhus infections. Although the SPAs were readily extracted from lysozyme- or detergent-treated rickettsiae, as measured by rocket immunoelectrophoresis, other polypeptides were also present, as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In contrast, both water and seven buffers, each at a 10 mM concentration and pH 7.6, were nearly …

Isolation and Characterization of Rickettsia finnyi, Novel Pathogenic Spotted Fever Group Rickettsia in Dogs, United States.

In 2020, a novel spotted fever group Rickettsia was described in 3 clinically ill dogs in the United States. Using naturally infected canine blood, the novel Rickettsia sp. was isolated in epithelial (Vero E6) and mononuclear (DH82 and 030D) cell lines. The sequenced whole genome revealed a 1.27 Mb circular chromosome with 96.87% identity to Rickettsia raoultii on the basis of average nucleotide identity analysis. A maximum-likelihood phylogeny tree placed the novel Rickettsia in its own branch within the spotted fever group. Immunofluorescence revealed single rods localized along the membrane…

Genetic characterization of Candidatus Rickettsia vini, a new rickettsia amplified in ticks from La Rioja, Spain.

A total of 222 ticks removed from birds in La Rioja (Spain) were screened for spotted fever group rickettsia species using ompA PCR assays. Rickettsia monacensis (n=1) and R. sibirica (n=1) were detected. Apart from that, 27 out of 29 Ixodes spp. DNA extracts that tested positive for ompA did not match with any validated spotted fever group rickettsia. Multilocus sequence typing for 16S rRNA, gltA, ompB, sca4, and 17-kDa antigen genes was performed, and R. heilongjiangensis was found to be the nearest validly published spotted fever group rickettsia. Based on genetic criteria agreed by experts…

Ixodes ricinus ticks are reservoir hosts for Rickettsia helvetica and potentially carry flea-borne Rickettsia species.

BACKGROUND: Hard ticks have been identified as important vectors of rickettsiae causing the spotted fever syndrome. Tick-borne rickettsiae are considered to be emerging, but only limited data are available about their presence in Western Europe, their natural life cycle and their reservoir hosts. Ixodes ricinus, the most prevalent tick species, were collected and tested from different vegetation types and from potential reservoir hosts. In one biotope area, the annual and seasonal variability of rickettsiae infections of the different tick stages were determined for 9 years. RESULTS: The DNA …

Evaluation of IgG antibody response against Rickettsia conorii and Rickettsia slovaca in patients with DEBONEL/TIBOLA.

The aim of the study was to determine the IgG antibody response to spotted fever group Rickettsia (SFGR) R. conorii and R. slovaca, and its specificity and sensitivity in patients with DEBONEL/TIBOLA. A prospective study of 31 patients with DEBONEL was carried out from January 2001 to May 2004. The SFGR serology testing (IgG IFA) for the diagnosis of DEBONEL/TIBOLA showed 61% sensitivity and 100% specificity. The R. slovaca antigen allowed the diagnoses in 18 of the 31 patients (58%), and 17 patients (55%) were diagnosed with this disease using R. conorii antigen. Therefore, using R. slovaca a…

Genomic identification of Rickettsia slovaca among spotted fever group rickettsia isolates from Dermacentor marginatus in Armenia.

Restriction fragment length polymorphism (RFLP) analysis of polymerase chain reaction (PCR) amplified genes was used for genomic identification of Armenian isolates of the Spotted fever group (SFG) rickettsiae with unclear taxonomic position. Analysis was performed by using one genus-specific primer pair derived from R. prowazekii citrate synthase gene and two species-specific primer pairs derived from R. rickettsii genes for 190 K and 120 K antigens following AluI, PstI and RsaI digestion of amplicons. All tested rickettsial SFG Armenian isolates from Dermacentor marginatus were identified as…

Rickettsia fournieri sp. nov., a novel spotted fever group rickettsia from Argas lagenoplastis ticks in Australia.

Strain AUS118T was isolated from an Argas lagenoplastis tick collected from the nest of a Petrochelidon ariel (fairy martin) in Australia in 2013. Microscopic observation of infected cell cultures indicated this strain had a morphology and intracellular location typical of Rickettsiaspecies. Phylogenetic analysis of this strain based firstly on multi-locus sequence analysis and subsequently on whole genome analysis demonstrated that AUS118T was most closely related to, but divergent from Rickettsia japonica and Rickettsia heilongjiangensis. We therefore propose the creation of a novel species,…

Experimental infection with Rickettsia rickettsii in an Amblyomma dubitatum tick colony, naturally infected by Rickettsia bellii.

Amblyomma dubitatum engorged females, naturally infected by Rickettsia bellii, were used to establish a laboratory colony. Larvae, nymphs, and adults were exposed to two strains of Rickettsia rickettsii by feeding on needle-inoculated guinea pigs, and thereafter reared on uninfected guinea pigs. After acquisition feeding, engorged larvae and nymphs molted to nymphs and adults, respectively, which were shown to be infected (confirming transstadial perpetuation), and were able to transmit both strains of R. rickettsii to uninfected animals, as demonstrated by clinical, serological, and molecular…