Project description:Comparison of gene expression between the virulent Rickettsia rickettsii R strain and avirulent Rickettsia rickettsii Iowa. Keywords: virulent vs avirulent
Project description:Rickettsia parkeri is an Amblyomma-associated, spotted fever group Rickettsia species that causes an eschar-associated, febrile illness in multiple countries throughout the Western Hemisphere. Many other rickettsial species of known or uncertain pathogenicity have been detected in Amblyomma spp. ticks in the Americas, including Rickettsia amblyommii, "Candidatus Rickettsia andeanae" and Rickettsia rickettsii. In this study, we utilized an immunoproteomic approach to compare antigenic profiles of low-passage isolates of R. parkeri and R. amblyommii with serum specimens from patients with PCR- and culture-confirmed infections with R. parkeri. Five immunoreactive proteins of R. amblyommii and nine immunoreactive proteins of R. parkeri were identified by matrix-assisted laser desorption ionization tandem time-of-flight mass spectrometry. Four of these, including the outer membrane protein (Omp) A, OmpB, translation initiation factor IF-2, and cell division protein FtsZ, were antigens common to both rickettsiae. Serum specimens from patients with R. parkeri rickettsiosis reacted specifically with cysteinyl-tRNA synthetase, DNA-directed RNA polymerase subunit alpha, putative sigma (54) modulation protein, chaperonin GroEL, and elongation factor Tu of R. parkeri which have been reported as virulence factors in other bacterial species. Unique antigens identified in this study may be useful for further development of the better serological assays for diagnosing infection caused by R. parkeri.
Project description:We constructed a small RNA cDNA library, using small RNA fraction with a length of 19-29 bases, and we performed deep sequencing of the cDNA library.
Project description:A flea-borne rickettsia, previously referred to as ELB, has been implicated as a cause of human illness. Using sequence data obtained from a fragment of the citrate synthase gene, we compared ELB, Rickettsia australis, R. rickettsii, and R. akari with the louse-borne R. prowazekii. We tallied 24 base pair differences between ELB and R. prowazekii and 25 between R. rickettsii and R. prowazekii; there were 30 base pair differences between R. australis and R. prowazekii and 29 between R. akari and R. prowazekii. We observed 32 differences between Rickettsia typhi and ELB. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot analyses of ELB, with typing sera against R. typhi indicate that ELB surface antigens are more closely related to the flea-borne R. typhi than to the mite-borne R. akari. On the basis of the results of citrate synthase gene sequence comparisons, as well as previous comparisons with 16S rRNA and 17-kDa-protein gene segments, we found that ELB is sufficiently genetically distinct from other rickettsiae to be designated a new species, Rickettsia felis.
Project description:PCR amplification indicated the minimum infection rate of Rickettsia spp. was 0.66% in Haemaphysalis longicornis ticks collected from Shandong Province, China. Phylogenetic analysis based on the rrs, gltA, ompA, and ompB genes indicated that the ticks carried R. japonica, Candidatus Rickettsia longicornii, and a novel Rickettsia species related to R. canadensis.
Project description:We found that 14.3% (15/105) of Amblyomma maculatum and 3.3% (10/299) of Dermacentor variabilis ticks collected at 3 high-use military training sites in west-central Kentucky and northern Tennessee, USA, were infected with Rickettsia parkeri and Rickettsia montanensis, respectively. These findings warrant regional increased public health awareness for rickettsial pathogens and disease.
Project description:Using PCR, we screened 411 ticks from four genera collected in Russia and Kazakhstan for the presence of rickettsiae and ehrlichiae. In Russia, we detected "Rickettsia heilongjiangensis," Rickettsia sp. strain RpA4, and Ehrlichia muris. In Kazakhstan, we detected Rickettsia sp. strain RpA4 and a rickettsia closely related to Rickettsia aeschlimannii. These agents should be considered in a differential diagnosis of tick-borne infections in these areas.
Project description:DNA of several spotted fever group rickettsiae was found in ticks in Israel. The findings include evidence for the existence of Rickettsia africae and Candidatus Rickettsia barbariae in ticks in Israel. The DNA of R. africae was detected in a Hyalomma detritum tick from a wild boar and DNA of C. Rickettsia barbariae was detected in Rhipicephalus turanicus and Rhipicephalus sanguineus collected from vegetation. The DNA of Rickettsia massiliae was found in Rh. sanguineus and Haemaphysalis erinacei, whereas DNA of Rickettsia sibirica mongolitimonae was detected in a Rhipicephalus (Boophilus) annulatus. Clinicians should be aware that diseases caused by a variety of rickettsiae previously thought to be present only in other countries outside of the Middle East may infect residents of Israel who have not necessarily traveled overseas. Furthermore, this study reveals again that the epidemiology of the spotted fever group rickettsiae may not only involve Rickettsia conorii but may include other rickettsiae.
Project description:Comparison of gene expression between the virulent Rickettsia rickettsii R strain and avirulent Rickettsia rickettsii Iowa. Keywords: virulent vs avirulent Virulent Rickettsia rickettsii R strain in triplicate was compared to avirulent Rickettsia rickettsii Iowa in triplicate
Project description:Three hundred and forty-four tick samples were collected from vegetation at Taksin Maharat National Park, Tak province, northwestern Thailand. They were morphologically identified and molecularly confirmed by 16S rRNA and COI genes as Dermacentor laothaiensis (n = 105), D. steini (n = 139), and D. auratus (n = 100). These ticks were examined for the spotted fever group rickettsiae (SFGRs) using PCR and DNA sequencing of six genes; 17-kDa, gltA, 16S rRNA, ompA, ompB, and sca4. Of these ticks, 6.10% (21/344) gave positive results for the presence of SFGRs. Phylogenetic analyses of the SFGRs clearly indicated that a novel genotype assigned as Candidatus Rickettsia takensis was detected in D. laothaiensis (19/105) and at lesser frequency in D. steini (1/139). Furthermore, Candidatus Rickettsia laoensis was also found at a low frequency in D. auratus (1/100), the first record in Thailand. Although, the pathogenicities of these SFGRs remain unknown, our findings suggest potential risks of SFGRs being transmitted via ticks near the border between Thailand and Myanmar, a gateway of daily migrations of local people and visitors both legal and illegal.