About this Research Topic
The human microbiome comprises dense and taxonomically diverse consortia of microorganisms, including bacteria, archaea, fungi, protozoa, and viruses, inhabiting various regions of the human body. While the bacterial components of the microbiome have received considerable attention, much remains to be discovered about the composition and physiological significance of viral populations (the virome).
Important strides are being made towards a better understanding of the interactions between microbes and their viruses, and the direct or indirect effects of these interactions on the human host. It has been estimated that up to 1014 viruses reside in the human body, the overwhelming majority of which are bacteriophages (the phageome). Metagenomic analyses are revealing the identities of the constituents of the virome and revealing their coding potential. Computational approaches are illuminating these data, generating predictions about the form, function, and evolution of the players. Ground-breaking experiments are providing new insights into the mechanisms at play, spanning molecular, regulatory, and ecological interactions. However, it is unclear to what extent these viruses are responsible for shaping the microbiome and how this affects humans. Thus, this Research Topic focuses on the effects of viruses on the human microbiome.
Associations are being detected between the virome and human phenotype such as inflammatory bowel disease (IBD), recurrent C. difficile infection (CDI), malnutrition, and AIDS. These results need to be verified in larger scale cross-sectional and longitudinal studies and the underlying mechanisms elucidated. Exciting preliminary evidence has been presented, suggesting that sterile fecal filtrate transplantation (FFT), that still contains viruses, has efficacy comparable to that of fecal microbial transplantation (FMT). Deeper studies are required to understand the role of the virome in such conditions, as well as variation in a healthy human population associated with factors including genetic background, age, sex, diet, exposure to environmental factors, and lifestyle.
The interactions between viruses, micro-organisms, and the human host are intriguing and highly complex. Several processes are at play, but their relative importance remains unknown. For example, what is the balance between phage infection and killing of specific bacteria on the one hand versus the benefits to the host bacteria of phage-mediated horizontal gene transfer on the other? How do phages and other microbial viruses contribute towards maintaining taxonomic and functional diversity of the microbiome? Do viruses enhance resilience to stress and adaptability to changes? How can we use microbial viruses to understand and potentially manipulate the microbiome?
This Research Topic welcomes research articles addressing these and other questions that address the significance of the abundant viruses in shaping the microbiome.
Keywords: Virome, Phageome, Microbiome, Faecal Microbial Transplantation, Horizontal Gene Transfer
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