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Biomedical subjects

Sally J Cutler

Publications and source records attributed to Sally J Cutler.

7 recordsLinked to original sources

Q fever.

An outbreak of Q fever occurred in Scotland during this summer and was reported in news headlines. Despite these newsworthy headlines, Q fever remains poorly understood. The causative organism, Coxiella burnetii, has a worldwide distribution, with the notable exception of New Zealand. Even with its ubiquitous nature, Q fever is rarely reported. We explore some of the underlying reasons for this apparent under diagnosis together with some of the diagnostic challenges posed by this obligate intracellular pathogen. The host range for this microbe spans arthropods, through to birds and a diverse range of mammals including livestock, companion animals and man. In most, infection remains sub-clinical, however, in some, infection can cause severe and life-threatening complications. Furthermore, possible long-term persistence within those infected, may result in long-term sequelae disassociated from initial risk factors or acute clinical presentation. We review current thinking on C. burnetii, and identify some of our current knowledge gaps.

Adult↗

Identification and characterization of variable-number tandem-repeat markers for typing of Brucella spp.

Members of the genus Brucella infect many domesticated and wild animals and cause serious zoonotic infection in humans. The availability of discriminatory molecular typing tools to inform and assist conventional epidemiological approaches would be invaluable in controlling these infections, but efforts have been hampered by the genetic homogeneity of the genus. We report here on a molecular subtyping system based on 21 variable-number tandem-repeat (VNTR) loci consisting of 13 previously unreported loci and 8 loci previously reported elsewhere. This approach was applied to a collection of 121 Brucella isolates obtained worldwide and representing all six classically recognized Brucella species. The size of repeats selected for inclusion varied from 5 to 40 bp giving VNTR loci with a range of diversities. The number of alleles detected ranged from 2 to 21, and Simpson's diversity index values ranged from 0.31 to 0.92. This assay divides the 121 isolates into 119 genotypes, and clustering analysis results in groups that, with minor exceptions, correspond to conventional species designations. Reflecting this, the use of six loci in isolation was shown to be sufficient to determine species designation. On the basis of the more variable loci, the assay could also discriminate isolates originating from restricted geographical sources, indicating its potential as an epidemiological tool. Stability studies carried out in vivo and in vitro showed that VNTR profiles were sufficiently stable such that recovered strains could readily be identified as the input strain. The method described here shows great potential for further development and application to both epidemiological tracing of Brucella transmissions and in determining relationships between isolates worldwide.

Animals↗

Ornithodoros moubata, a soft tick vector for Rickettsia in east Africa?

Omithodoros moubata complex (Argasidae) ticks collected from human dwellings in central Tanzania were found to carry a novel rickettsial species that clustered among the spotted fever group. Although no evidence of human infection was evident, these ticks feed primarily on man, thus providing opportunity for zoonotic infection.

ATP Citrate (pro-S)-Lyase↗

Possibilities for relapsing fever reemergence.

Relapsing fever Borrelia infections have attracted little attention in recent years; however, where endemic, these infections still result in considerable illness and death. Despite the marked antimicrobial drug susceptibility of these organisms, therapy is often delayed through lack of clinical suspicion. With increasing travel, infections may be imported, through exotic relapsing fever infection or through resurgence of infected disease vectors. Although louseborne relapsing fever is now geographically limited, it was once of global importance. The possibility for reemergence was recently highlighted by the probable reemergence of louseborne relapsing fever in homeless persons from France. Host limitations enforced through louseborne transmission are less applicable for the tickborne forms of relapsing fever. Although the latter have reduced potential for epidemic spread, they have the ability to infect diverse hosts, thus establishing reservoirs of infection and presenting greater challenges for their control.

Animals↗

Use of amplified fragment length polymorphism to identify and type Brucella isolates of medical and veterinary interest.

Amplified fragment length polymorphism (AFLP) is a whole-genome fingerprinting method that relies on the selective PCR amplification of restriction fragments. The potential of this approach for the discrimination of Brucella isolates at the species and intraspecies level was assessed. A number of different combinations of restriction enzymes and selective primers were examined, and one, using EcoRI and MseI with additional selective TC bases on the MseI primer, was selected for full assessment against a panel of Brucella isolates. The technique could readily differentiate Brucella spp. from all Ochrobactrum spp. representing the group of organisms most closely related to Brucella spp. Application of AFLP highlighted the genetic homogeneity of Brucella. In spite of this determination of AFLP profiles of large numbers of isolates of human and animal origin, including Brucella abortus, B. melitensis, B. ovis, B. neotomae, marine mammal isolates (no species name), B. canis, and B. suis, confirmed that all but the latter two species could be separated into distinct clusters based on characteristic and conserved differences in profile. Only B. suis and B. canis isolates clustered together and could not be distinguished by this approach, adding to questions regarding the validity of species assignments in this group. Under the conditions examined in the present study only limited intraspecies genomic differences were detected, and thus this AFLP approach is likely to prove most useful for identification to the species level. However, combination of several of the useful restriction enzyme-primer combinations identified in the present study could substantially add to the discriminatory power of AFLP when applied to Brucella and enhance the value of this approach.

Animals↗

Generation of the Brucella melitensis ORFeome version 1.1.

The bacteria of the Brucella genus are responsible for a worldwide zoonosis called brucellosis. They belong to the alpha-proteobacteria group, as many other bacteria that live in close association with a eukaryotic host. Importantly, the Brucellae are mainly intracellular pathogens, and the molecular mechanisms of their virulence are still poorly understood. Using the complete genome sequence of Brucella melitensis, we generated a database of protein-coding open reading frames (ORFs) and constructed an ORFeome library of 3091 Gateway Entry clones, each containing a defined ORF. This first version of the Brucella ORFeome (v1.1) provides the coding sequences in a user-friendly format amenable to high-throughput functional genomic and proteomic experiments, as the ORFs are conveniently transferable from the Entry clones to various Expression vectors by recombinational cloning. The cloning of the Brucella ORFeome v1.1 should help to provide a better understanding of the molecular mechanisms of virulence, including the identification of bacterial protein-protein interactions, but also interactions between bacterial effectors and their host's targets.

Bacterial Proteins↗