Bartonella species in small mammals and their potential vectors in Asia

In this article,authors review the current knowledge of Bartonella infection in small mammals including rodents,insectivores,bats and exotic small mammal pets and their vectors in Asia.Species of Bartonella are Gram-negative intracellular bacteria that infect erythrocytes of various mammalian and non-mammalian animals and mainly transmitted by blood sucking arthropod vectors.The genus Bartonella includes several species of important human diseases with severe clinical signs.Several new Bartonella species were isolated from rodents and other small mammals,and from human patients in Asia.Bartonella species are identified using standard polymerase chain reaction amplification and a sequencing targeting two housekeeping genes(glt.A and rpoB) and the internal transcribed spacer fragment.Authors also discuss the implications in term of potential emerging zoonotic diseases.

Macrophage populations and self-renewal:Changing the paradigm

The origin of macrophages has been considered since several decades to be a continuum from bone marrow(BM) to tissue via monocytes as precursors. The development of new tools such as genetic lineage tracing,parabiosis and BM chimeras changed the paradigm of macrophage origin. In steady state,most resident macrophages are of embryonic origin,whereas a monocyte origin remains prominent in pathological conditions. The findings of a proliferation of mature macrophages will oblige us to reappraise the relationship between proliferation and differentiation in macrophages. This review is based on the recent explosion of high impact articles on macrophage biology. It summarizes new data on the origin of macrophages and their selfrenewal potential in steady states. While monocytes are required for intestinal macrophage development,the microglia is independent of monocyte influx and skin macrophages provide an excellent model of the balance between monocyte input and self-renewal. In addition,macrophage proliferation requires intrinsic and extrinsic factors including growth factors and cytokines. It also analyzes the impact of this new paradigm in human diseases such as athrosclerosis,cancer,infectious diseases and neurodegenerative diseases. In atherosclerosis,the finding of macrophage proliferation within the lesions will change our understanding of disease pathophysiology,this new paradigm may have therapeutical impact in the future.

Modulation of monocyte subsets in infectious diseases

Monocytes are effector immune cells but a precise analysis of their role in immune response has been precluded by their heterogeneity. Indeed,human monocytes are composed of at least three different subsets with different phenotypic characteristics and functional properties,the so-called classical,intermediate and nonclassical monocytes. A review of the literature shows that these monocyte subsets are differently affected during viral,bacterial,parasitic and fungal infections.The expansion of the CD16+ compartment(intermediate and non-classical monocytes) is typically observed in the majority of infectious diseases and the increased proportion of CD16+ monocytes is likely related to their activation through their direct interaction with the pathogen or the inflammatory context. In contrast,the number of non-classical and intermediate monocytes is decreased in Q fever endocarditis,suggesting that complex mechanisms govern the equilibrium among monocyte subsets. The measurement of monocyte subsets would be useful in better understanding of the role of monocyte activation in the pathophysiology of infectious diseases.

Mass Spectrometric Identification of Propionibacterium Isolates Requires Database Enrichment

Propionibacterium species are mostly environmental bacteria, some being commensal of mammals including humans, and sometimes pathogenic. These bacteria are poorly identified using routine laboratory methods. Recently, Matrix Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF-MS) has emerged as a rapid and efficient method to identify bacterial species. We evaluated the use of MALDI-TOF-MS for identification of all validated Propionibacterium species. Only four of the 15 tested reference strains (26.7%) were correctly identified at the species level, and P. acnes, the most common human pathogenic species was not identified. When applying MALDI-TOF-MS to 48 P. acnes strains, only 18.7% were correctly identified, suggesting an intraspecific variability of proteic profiles among Propionibacterium strains. However, by enriching the Bruker database with spectra from five of these strains and re-testing the other 43 strains against this new database, 93.0% were correctly identified. Our study demonstrates that MALDI-TOF-MS may be used for the identification of Propionibacterium isolates but requires a database enrichment in spectra from additional isolates.

蜱中贝氏考克次体流行状况调查

目的:了解法国新喀里多尼亚地区蜱中贝氏考克次体的流行状况。方法:以贝氏考克次体的16SrRNA为靶基因,病原体的RNA自蜱中提取,使用荧光定量PCR技术,检测法国新喀里多尼亚地区三种蜱共456株中贝氏考克次体的流行率。结果:以30为CT值,共检测出阳性334株,阳性率73.2%。按蜱种分类:硬蜱虫2株皆为阴性;血红扇头蜱阳性163株,阳性率69.9%;边缘革蜱阳性171株,阳性率77.4%。结论:法国蜱中贝氏考克次体的流行率很高,不同种蜱阳性率不同。