从黑龙江小兴安岭棕背和花鼠分离到莱姆病螺旋体

目的：为初步掌握黑龙江省小兴安岭林区动物莱姆病分布情况。方法：于1995年7月用鼠笼捕获野鼠30只，采用间接免疫荧光抗体法调查鼠血清抗莱姆病螺旋体抗体。用BSK培养基从鼠脏器分离病原。结果：阳性共8只，阳性率26.67％；其中优势种属野鼠阳性率达31．36％；从棕背和花鼠各分离出1株莱姆病螺旋体。新分离株的单克隆抗体反应与国内分离株SR1相同，与美国B(31)有区别，对H(6831)呈阴性反应。结论：鼠型啮齿动物可能是莱姆病螺旋体的动物宿主，属野鼠则是重要动物宿主。     

Dynamics of Puumala virus infection in bank voles in Ardennes department (France)

The hantaviruses (genus Hantavirus, family Bunyaviridae) include human pathogens and occur worldwide. In Western and Central Europe, the predominant serotype is Puumala (PUU) virus, which causes epidemic nephropathy. Voles are considered to be the main reservoir and the vector of PUU virus. A total of 719 rodents (mainly Clethrionomys glareolus, Apodemus sp.) trapped by capture-mark-recapture (CMR) in four sites in Ardennes department (France) between April 2004 and October 2005 were tested for the presence of PUU virus antibodies by enzyme-linked immunosorbent assay (ELISA). The predominant species, C. glareolus (86.5% [622 of 719]), also had the highest antibody prevalence (37.6% [291 of 773]). In C. glareolus, the antibody prevalence rate increased with age (weight) in site A, B and D, reaching more than 50% in the heaviest weight, and suggesting that horizontal infection may be important.     

Distribution of hantavirus foci in Belgium

During 1999 and 2000, we performed rodent captures on 15 sites all over Belgium to evaluate the presence of hantaviruses in local rodent populations. Viral antibody and RNA detection was performed by ELISA/focus reduction neutralisation test and RT-PCR, respectively. We found hantavirus-positive rodents on 13 out of 15 trapping sites and 3 rodent species were found positive for hantavirus infection. Apart from Puumala virus that was carried by Clethrionomys glareolus, 2 additional rodent species, Microtus arvalis and Apodemus sylvaticus, were found antibody- and/or RNA-positive.     

Demographic factors associated with hantavirus infection in bank voles (Clethrionomys glareolus)

The bank vole (Clethrionomys glareolus) is the natural reservoir of Puumala virus (PUUV), a species in the genus Hantavirus. PUUV is the etiologic agent of nephropathia epidemica, a mild form of hemorrhagic fever with renal syndrome. Factors that influence hantavirus transmission within host populations are not well understood. We evaluated a number of factors influencing on the association of increased PUUV infection in bank voles captured in a region in northern Sweden endemic for the virus. Logistic regression showed four factors that together correctly predicted 80% of the model outcome: age, body mass index, population phase during sampling (increase, peak, or decline/low), and gender. This analysis highlights the importance of population demography in the successful circulation of hantavirus. The chance of infection was greatest during the peak of the population cycle, implying that the likelihood of exposure to hantavirus increases with increasing population density.     

On the Utility of Heteroplasmy in Genotoxicity Studies: An Example from Chornobyl

We examine the utility of mtDNA heteroplasmy in assessing genetic damage due to environmental insult. Site heteroplasmy was quantified in a 400 bp portion of the cytochrome b gene in voles from a contaminated area near Chornobyl, Ukraine and from a relative control site by examining pregnant females and their embryos. A four hundred base pair segment was sequenced from approximately ten clones from each mother and embryo. Taq and/or cloning mutations were evaluated to estimate technical error. Although the rates of substitutions in clonal variants for experimentals, biological controls and technical controls were 1 in 1,840 bp, 1 in 2,280 bp, and 1 in 3,333 bp, respectively, we could not reject the null hypothesis that the variants were the result of a single, combined, mutation rate. However, multiple substitutions and transversions were restricted to clones from the Chornobyl samples. Bootstrap analyses indicate that these aspects of variation were significantly different from the controls. Examination of the mitochondrial genome by cloning individual molecules for site heteroplasmy to estimate effects of pollution on mutation rate in free-living organisms appears to warrant additional study.     

Detection of phylogenetically distinct Puumala-like viruses from red-grey vole Clethrionomys rufocanus in China

In order to investigate whether Puumala virus (PUUV) or PUUV-like virus is present in China, Clethrionomys rufocanus and C. rutilus were captured in the Jilin province during the spring and autumn of 2002-2003 for detection of PUUV viral RNA by RT-PCR and confirmation of PUUV-positive antigens by an immunofluorescence assay. PUUV-positive RNA was identified in six out of 121 C. rufocanus but not in any of the 41 C. rutilus. Complete S and partial M sequences (nt 1,316-1,598 and 2,687-3,089) were amplified by RT-PCR directly from some of the antigen positive lung tissues and subjected to nucleic acid sequencing. It was found that the Chinese PUUV-like viruses were related most closely with the PUUV strains with 77.7-81.7% identity at the nucleotide level and 91.7-97% identity at the amino acid level for S segment, and with 77-78.8% identity at the nucleotide level and 91.5-92.6% identity at the amino acid level for the partial M segment (nt 1,316-1,598). Genetic analysis indicated that the Chinese PUUV-like viruses shared the highest level of identity with the viruses which circulate in C. rufocanus in the Far East region of Russia with 85.1-87.4% identity at the nucleotide level and 95.9% identity at the amino acid level for the partial M segment (nt 2,687-3,089), respectively. Phylogenetic analysis revealed that the Chinese PUUV-like viruses are distinct from those identified from Japan, South Korea, Europe or Russia. These results indicate that PUUV-like virus is present in China in addition to Hantaan, Seoul and Dabieshan viruses.     

中国20个省、区、市动物莱姆病初步调查研究

目的：广泛调查我国动物莱姆病分布情况。方法：血清流行病学和病原学研究。结果：１９８７～１９９７年间，牛、羊、狗、野兔和８种野鼠有莱姆病的感染存在，其中牛、羊、狗和野鼠的感染率分别为１８．１８％～３２．６１％、１７．１２％～６１．２１％、３８．５％～６０．００％和４１．１８％～８６．０５％；从黑线姬鼠和白腹巨鼠的胎鼠分离到莱姆病螺旋体，证实莱姆病螺旋体可通过胎盘垂直传播。９种蜱的中肠携带莱姆病螺旋体，带菌率以全沟硬蜱、二棘血蜱和粒形硬蜱为高，分别为２０．００％～４５．００％、１６．００％～４０．００％和２４．００％。从华南兔、８种野鼠和８种蜱分离出１２８株莱姆病螺旋体。证实黑线姬鼠和棕背是中国莱姆病螺旋体的重要储存宿主；多种蜱的中肠内携带莱姆病螺旋体，我国北方林区莱姆病螺旋体的主要生物媒介是全沟硬蜱，南方林区二棘血蜱和粒形硬蜱是重要的生物媒介。结论：我国动物莱姆病广泛存在     

Marked species and age-dependent differences in cell proliferation and neurogenesis in the hippocampus of wild-living rodents

Variations in the extent of adult neurogenesis and natural and experimental factors controlling it have been described in laboratory animals. The wide range of variation seen even within a species, the mouse, raises the question as to which rates of neurogenesis can be expected in natural populations. Answering this question is important to evaluate the functional significance of adult neurogenesis under natural conditions and to define the factors controlling it. To address this issue, we investigated four species of wild-living rodents and outbred laboratory mice using markers for proliferating cells, Ki-67, and developing neurons, doublecortin and NeuroD. We found about four times as many Ki-67-positive cells per mm3 granule cell layer in two wood mouse species (Muridae; Apodemus spp.) than in bank and pine voles (Arvicolidae; Clethrionomys glareolus and Microtus subterraneus). Laboratory mice show proliferation rates between wood mice and voles. Markers for developing neurons, NeuroD and doublecortin, reflect the findings of proliferation activity. Hippocampal cell proliferation decreases dramatically with age in wild-living species. The onset of the downregulation varies among species. It occurs late in the life span of the yellow-necked wood mouse. In aged animals, the number of proliferating cells per mm3 granule cell layer is reduced to 19% of the adult value. Downregulation occurs early in pine voles, in which cell proliferation in adult animals is reduced to 33% of juvenile values. Proliferation and age-dependent changes along the deep border of the alveus and angular bundle follow those of the dentate gyrus. We conclude that cell proliferation and neurogenesis in the dentate gyrus vary significantly among wild-living rodents, and that they are downregulated with age, but at species-specific time points.     

Cluster of Capillaria hepatica infections in non-commensal rodents from the canton of Geneva, Switzerland

We trapped 664 rodents belonging to five non-commensal species in the canton of Geneva, Switzerland, and found a significant cluster of Capillaria hepatica infections in three species in rural and urbanized areas of the northern part of the canton. C. hepatica infections were discovered in the yellow-necked mouse Apodemus flavicollis (n=99) with an overall prevalence (OP) of 7.0% and a clustered prevalence (CP) of 20%, in the bank vole Clethrionomys glareolus (n=58, OP 5.2%; CP 19%), and in the water vole Arvicola terrestris scherman (n=466; OP 0.2%; CP 4%). The estimated numbers of C. hepatica eggs isolated from infected livers ranged from 1,914 to 938,000 per animal.