Evolutional and geographical relationships of Bartonella grahamii isolates from wild rodents by multi-locus sequencing analysis.

To clarify the relationship between Bartonella grahamii strains and both the rodent host species and the geographic location of the rodent habitat, we have investigated 31 B. grahamii strains from ten rodent host species from Asia (Japan and China), North America (Canada and the USA), and Europe (Russia and the UK). On the basis of multi-locus sequencing analysis of 16S rRNA, ftsZ, gltA, groEL, ribC, and rpoB, the strains were classified into two large groups, an Asian group and an American/European group. In addition, the strains examined were clearly clustered according to the geographic locations where the rodents had been captured. In the phylogenetic analysis based on gltA, the Japanese strains were divided into two subgroups: one close to strains from China, and the other related to strains from Far Eastern Russia. Thus, these observations suggest that the B. grahamii strains distributed in Japanese rodents originated from two different geographic regions. In the American/European group, B. grahamii from the North American continent showed an ancestral lineage and strict host specificity; by contrast, European strains showed low host specificity. The phylogenetic analysis and host specificity of B. grahamii raise the possibility that B. grahamii strains originating in the North American continent were distributed to European countries by adapting to various rodent hosts.

Diversity of Bartonella genotypes in Richardson's ground squirrel populations.

The diversity and dynamics of Bartonella genotypes found in wild Richardson's ground squirrels (RGS), Spermophilus richardsonii were monitored at multiple sites in Saskatchewan, Canada from 2002 to 2004. Based on sequence analysis of a portion of the Bartonella citrate synthase (gltA) gene, four different genotypes were detected in 233 isolates from 176 animals. The majority (87%) of sequences were identified as genotype H, with genotypes I, J, and K accounting for 8%, 4%, and 1% of sequences, respectively. Only one animal was concurrently infected with multiple Bartonella genotypes. Of 23 animals sampled four times or more, 26% were never infected with Bartonella. Of 32 RGS infected with Bartonella at first capture and then sampled again the following month, 50% were infected with the same Bartonella genotype, 41% were no longer infected, and 9% were infected with a different Bartonella genotype in the subsequent sample. The diversity of Bartonella genotypes varied among sites. At one site almost all RGS were infected with genotype H in September, and up to 60% of the same population was infected with genotype I the following spring. We compare our results with previous studies of Bartonella infections in rodents and discuss possible explanations for the observed differences.

Bartonella seropositivity in children with Henoch-Schonlein purpura.

BACKGROUND: An association between Henoch-Schonlein purpura (HSP) and seropositivity for Bartonella henselae (BH) has been described. The objective of this study was to see if such an association exists in northern Alberta. METHODS: Immunofluorescent antibody testing utilizing an antigen prepared from B. henselae was undertaken on sera from six children with current HSP, 22 children with remote HSP, and 28 controls that were matched for age. Blood from the six children with current HSP was analysed by polymerase chain reaction (PCR) assay with primers derived from the citrate synthase (gltA) gene for the detection of Bartonella DNA. RESULTS: The seropositivity rate for BH was 61% in cases versus 21% in controls (p < 0.03). The PCR assay was negative in all six current cases. CONCLUSION: There is an increased seropositivity rate for BH in children with HSP. However, it is not clear if infection with B. henselae or a related Bartonella species can result in HSP, or if the increased seropositivity is from non-specific or cross-reacting antibodies.

Rodent-associated Bartonella in Saskatchewan, Canada.

Six species of wild rodents were sampled at 10 sites in 2002 and 2003 to determine the prevalence of Bartonella infections in rodent communities near Saskatoon, Saskatchewan, Canada. Isolates were characterized genotypically and compared with isolates found at other locations. Of 104 wild rodents examined, 57% were infected with Bartonella and prevalence within species varied from 49% for Richardson's ground squirrels (Spermophilus richardsonii) to 90% for Franklin's ground squirrels (S. franklinii). Infected rodents were found at all sites. Sequencing of a 379-bp portion of the citrate synthase gene was performed on 54 isolates and revealed 13 distinct genotypes, eight of which had not been described previously. The most common genotype detected in red-backed voles (Clethrionomys gapperi) was 99.1% similar to B. grahamii, a known human pathogen. Two of 10 Franklin's ground squirrels were concurrently infected with multiple Bartonella genotypes. All genotypes, with the exception of one detected in both Franklin's and thirteen-lined ground squirrels (S. tridecemlineatus), were found in only one host, and all genotypes from each species, with the exception of genotypes detected in red-backed voles, clustered together within the same relatedness group, suggesting that at least some Bartonella genotypes are specific to some rodent hosts.

Characterization and expression of the Neurospora crassa nmt-1 gene.

The Neurospora crassa homologue of the yeast no message in thiamine ( nmt-1) gene was characterized. The deduced 342-amino-acid gene product has more than 60% identity with other fungal homologues and 42% similarity to a putative bacterial permease. In addition to three introns disrupting the coding sequence, a differentially spliced intron in the 5' untranslated region was also detected. Unlike other fungi, the N. crassa nmt-1 gene is repressed only 6- to 8-fold by exogenous thiamine concentrations above 0.5 microM; and a high basal level of nmt-1 mRNA persists even at 5 microM thiamine. Immuno-blotting with purified antibodies detected two variants of NMT-1 which differ in size and charge. The more abundant 39-kDa form is more strongly repressed by thiamine than the 37-kDa protein. NMT-1 abundance modulates slowly in response to changes in the concentration of exogenous thiamine, suggesting that N. crassa maintains thiamine reserves in excess of immediate needs. Disruption of the nmt-1 gene demonstrated that it is essential for growth in the absence of exogenous thiamine. NMT-1-deficient strains had a growth rate and colony density which was about 70% of the wild type, despite supplementation with a wide range of exogenous thiamine. These results suggest that the nmt-1 gene plays some other role in addition to thiamine biosynthesis.

Coxiella burnetii seroprevalence of shepherds and their flocks in the lower Saint-Lawrence River region of Quebec, Canada.

OBJECTIVE: To determine the seroprevalence of Coxiella burnetii among the shepherds and their sheep in the lower Saint-Lawrence River region (LSLRR) of Quebec, Canada. DESIGN: A prospective human-animal comparative study was conducted with 81 shepherds from 46 farms and a control group matched for sex and age. All participants answered a standardized questionnaire to evaluate their risk factors for Q fever, including a specific section on the work practices of the shepherds. All human subjects had a blood sample taken for serology to phase I and phase II antigens of C burnetii performed by indirect immunofluorescence assay. At each participating farm, seven to nine sheep had blood samples taken for C burnetii serology to be assessed by the complement fixation test. RESULTS: The seroprevalence to C burnetii was higher in the group of shepherds (28.4%) than the control group (1.2%) (P<0.005). Among the group of shepherds, spending more than 5 h/week in the sheep barn (P=0.06) and buying and/or trading sheep within the past six months (P=0.004) were associated with positive C burnetii serology. A total of 137 of 334 sheep (41%) were seropositive for C burnetii. These positive sheep were distributed in 41 of the 46 flocks (89%). No correlation could be demonstrated between a serology for C burnetii in the herds and the shepherds. CONCLUSION: Q fever is highly prevalent in the LSLRR of Quebec, affecting 89% of the flocks and 28% of the shepherds. Shepherds in this region are at increased risk for C burnetii infection in comparison to the general population.