Two new bacteria isolated from vagina of a patient with vaginosis: Atopobium massiliense sp. nov. and Butyricimonas vaginalis sp. nov.

Two new bacterial strains, Marseille-P4126 (=CSURP4126) and Marseille-P4593 (=CSURP4593), were isolated from the vaginal sample of a French woman with vaginosis. These strains were identified and characterized using the taxonogenomics method. The findings from phylogenetic tree interpretation, phenotypic criteria and genomic analysis provided here distinctly display that Atopobium massiliense sp. nov. and Butyricimonas vaginalis sp. nov. are new members of the genus Atopobium and Butyricimonas, respectively.

Megasphaera vaginalis sp. nov. and Anaerococcus vaginimassiliensis sp. nov., new bacteria isolated from vagina of French woman with bacterial vaginosis.

Using the culturomics method, two strains were isolated, identified and characterized following the taxonogenomics concept. Megasphaera vaginalis sp. nov. strain Marseille-P4512 (= CSURP4512) and Anaerococcus vaginimassiliensis sp. nov. strain Marseille-P4857 (= CSURP4857) were isolated from the vagina of a French woman. The phylogenic tree, phenotypic criteria and genomic analysis described here clearly show that these two bacteria are different from previously known bacterial species with standing in nomenclature and new members of Firmicutes phylum.

Oyster hemolymph is a complex and dynamic ecosystem hosting bacteria, protists and viruses.

BACKGROUND: The impact of the microbiota on host fitness has so far mainly been demonstrated for the bacterial microbiome. We know much less about host-associated protist and viral communities, largely due to technical issues. However, all microorganisms within a microbiome potentially interact with each other as well as with the host and the environment, therefore likely affecting the host health. RESULTS: We set out to explore how environmental and host factors shape the composition and diversity of bacterial, protist and viral microbial communities in the Pacific oyster hemolymph, both in health and disease. To do so, five oyster families differing in susceptibility to the Pacific oyster mortality syndrome were reared in hatchery and transplanted into a natural environment either before or during a disease outbreak. Using metabarcoding and shotgun metagenomics, we demonstrate that hemolymph can be considered as an ecological niche hosting bacterial, protist and viral communities, each of them shaped by different factors and distinct from the corresponding communities in the surrounding seawater. Overall, we found that hemolymph microbiota is more strongly shaped by the environment than by host genetic background. Co-occurrence network analyses suggest a disruption of the microbial network after transplantation into natural environment during both non-infectious and infectious periods. Whereas we could not identify a common microbial community signature for healthy animals, OsHV-1 µVar virus dominated the hemolymph virome during the disease outbreak, without significant modifications of other microbiota components. CONCLUSION: Our study shows that oyster hemolymph is a complex ecosystem containing diverse bacteria, protists and viruses, whose composition and dynamics are primarily determined by the environment. However, all of these are also shaped by oyster genetic backgrounds, indicating they indeed interact with the oyster host and are therefore not only of transient character. Although it seems that the three microbiome components respond independently to environmental conditions, better characterization of hemolymph-associated viruses could change this picture.

Viral metagenomics: are we missing the giants?

Amoeba-infecting giant viruses are recently discovered viruses that have been isolated from diverse environments all around the world. In parallel to isolation efforts, metagenomics confirmed their worldwide distribution from a broad range of environmental and host-associated samples, including humans, depicting them as a major component of eukaryotic viruses in nature and a possible resident of the human/animal virome whose role is still unclear. Nevertheless, metagenomics data about amoeba-infecting giant viruses still remain scarce, mainly because of methodological limitations. Efforts should be pursued both at the metagenomic sample preparation level and on in silico analyses to better understand their roles in the environment and in human/animal health and disease.

Computational tools for viral metagenomics and their application in clinical research.

There are 100 times more virions than eukaryotic cells in a healthy human body. The characterization of human-associated viral communities in a non-pathological state and the detection of viral pathogens in cases of infection are essential for medical care and epidemic surveillance. Viral metagenomics, the sequenced-based analysis of the complete collection of viral genomes directly isolated from an organism or an ecosystem, bypasses the "single-organism-level" point of view of clinical diagnostics and thus the need to isolate and culture the targeted organism. The first part of this review is dedicated to a presentation of past research in viral metagenomics with an emphasis on human-associated viral communities (eukaryotic viruses and bacteriophages). In the second part, we review more precisely the computational challenges posed by the analysis of viral metagenomes, and we illustrate the problem of sequences that do not have homologs in public databases and the possible approaches to characterize them.

Inside the lifestyle of the virophage.

OBJECTIVE(S): We sought to better characterize Sputnik, the first isolated virophage, and to analyze its parasitic lifestyle during co-infection with Marseillevirus (a new giant virus) in Acanthamoeba castellanii. METHODS: A combination of electron microscopy, immunofluorescence microscopy, and real-time PCR was used to characterize the kinetics of the viral replication cycle. RT-PCR was performed to detect RNAs inside the Sputnik virions. RESULTS: Sputnik is a new viral entity carrying an almost complete ready-to-use set of viral RNAs (20 out of 21). Sputnik does not replicate with Marseillevirus but delays its replication cycle. While Marseillevirus is successfully internalized by A. castellanii following co-infections with Mamavirus and Sputnik, it does not initiate a replication cycle. In contrast, both Marseillevirus and Mamavirus can replicate in the amoeba in case of co-infection, but the development of one is exclusive from the other inside a single amoeba cell. CONCLUSIONS: This work provides new insight into the Sputnik replication cycle with another giant virus and confirms that Sputnik is a virophage. It shows new dimensions of the interactions existing among giant viruses.