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The kinetics of infection and the pathogenic effects on the reproductive function of laboratory mice infected with Bartonella birtlesii recovered from an Apodemus species are described. B. birtlesii infection, as determined by bacteremia, occurred in BALB/c mice inoculated intravenously. Inoculation with a low-dose inoculum (1.5 ؋ 10 3 CFU) induced bacteremia in only 75% of the mice compared to all of the mice inoculated with higher doses (>1.5 ؋ 10 4 ). Mice became bacteremic for at least 5 weeks (range, 5 to 8 weeks) with a peak ranging from 2 ؋ 10 3 to 10 5 CFU/ml of blood. The bacteremia level was significantly higher in virgin females than in males but the duration of bacteremia was similar. In mice infected before pregnancy (n ‫؍‬ 20), fetal loss was evaluated by enumerating resorption and fetal death on day 18 of gestation. The fetal death and resorption percentage of infected mice was 36.3% versus 14.5% for controls (P < 0.0001). Fetal suffering was evaluated by weighing viable fetuses. The weight of viable fetuses was significantly lower for infected mice than for uninfected mice (P < 0.0002). Transplacental transmission of Bartonella was demonstrated since 76% of the fetal resorptions tested was culture positive for B. birtlesii. The histopathological analysis of the placentas of infected mice showed vascular lesions in the maternal placenta, which could explain the reproductive disorders observed. BALB/c mice appeared to be a useful model for studying Bartonella infection. This study provides the first evidence of reproductive disorders in mice experimentally infected with a Bartonella strain originating from a wild rodent.

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Three strains isolated from Apodemus spp. were similar to Bartonella species on the basis of phenotypic characteristics. Futhermore, genotypic analysis based on sequence analysis of the 16S rRNA and gltA genes and on DNA-DNA hybridization showed that the three isolates represented a distinct and new species of Bartonella. The name Bartonella birtlesii is proposed for the new species. The type strain of B. birtlesii sp. nov. is IBS 325 T (l CIP 106294 T l CCUG 44360 T ).

SUMMARYWe have previously shown that physiological hormone differences related to pregnancy or sex affect the age-related distribution of mononuclear cell populations during murine ageing. To determine whether such changes are involved in the age-related changes in functions of T cells, we examined the secretion of major T cell immunoregulatory cytokines (IL-2, IL-4, interferon-gamma (IFN-g), IL-3, IL-6 and granulocyte-macrophage colony-stimulating factor (GM-CSF)) of in vitro concanavalin A-activated spleen cells of C57Bl/6 mice. The study included multiparous and virgin females and males at 2, 8, 15 and 23 months of age. Short-term effects of parity (8 months) were evidenced by the decrease of IFN-g and the preserved IL-2 production in multiparous females (8 months), while IFN-g was unchanged and IL-2 decreased in virgin mice. The increase in IL-4 production appeared earlier in multiparous females (15 months) than in virgin mice (23 months). The increase in IL-4/IFN-g and IL-4/IL-2 ratios at 8 and 15 months, respectively, in multiparous females, suggests that pregnancy modifies the Th1/Th2 equilibrium. In late adulthood (15 months), IL-6 and GM-CSF production was higher in multiparous females than in virgin males or females. Sex differences were also noticed: IFN-g secretion capacity was lower in males than in females during ageing. This study underlines that the onset, magnitude and kinetics of the age-related changes in cytokine production are parity-and sex-dependent. These changes probably influence the incidence of age-related diseases and may explain the greater longevity of females.

Two strains of bacteria isolated from the blood of French domestic cows were found to be similar to Bartonella species on the basis of phenotypic characteristics. Genotypic analysis based on sequence comparison of the 16S rRNA and citrate synthase (gltA) genes and on DNA-DNA hybridization showed that the two isolates represent a distinct and new species of Bartonella. Moreover, the phylogenetic analysis inferred from comparison of 16S rRNA and gltA sequences demonstrated that the new Bartonella species is related to other ruminant-derived Bartonella species. The name Bartonella chomelii is proposed for the new species. The type strain of Bartonella chomelii sp. nov. is A828 T (=CIP 107869 T =CCUG47497 T ).

SUMMARYSo far all studies on the murine ageing process have been conducted on virgin mice. Immune ageing may be influenced by sex hormone differences related to sex or pregnancies. The aim of this study was to investigate whether pregnancies and gender influence the cell changes observed during ageing in a peripheral lymphoid compartment of C57Bl/6 mice. Using flow cytometry, changes in (Thy1:2 þ ) T cell, (B220 þ ) B cell and (CD11b/Mac-1) macrophage spleen populations were monitored in 2, 8 (3 months after last pregnancy) 15 and 23-month-old mice including males, virgin and multiparous females. The development of naive (CD44 low ), memory (CD44 high ), activated/memory (MEL-14, CD62L) cells were investigated in CD4 þ and CD8 þ T cell subsets. Both short term (at 8 months) and long term (at 15 and 23 months) effects of multiparity were obvious in the lymphocyte/macrophage population changes associated with the ageing process. Short-term effects included delayed appearance of CD4 þ CD44 high memory lymphocytes and increased numbers of both CD4 þ MEL-14 low activated/memory cells and Mac-1 þ macrophages when compared with virgin control mice. Later effects of multiparity were increased CD8a dull populations and increased T/B cell ratios and the ratio of memory to naive CD4. A sex effect was noticed: males exhibited lower Mac-1 þ levels and memory/naive ratio in CD4 þ subset than virgin females throughout life. These results suggest that gender and/or pregnancies affect the age-related distribution of lymphoid and macrophage cell populations in the spleen of C57Bl/6 mice.

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