Abstract
The gut microbiota has emerged as a key factor in the pathogenesis of intestinal viruses, including enteroviruses, noroviruses and rotaviruses (RVs), where stimulatory and inhibitory effects on infectivity have been reported. With the aim of determining whether members of the microbiota interact with RVs during infection, a combination of anti-RV antibody labeling, fluorescence-activated cell sorting and 16S rRNA amplicon sequencing was used to characterize the interaction between specific bacteria and RV in stool samples of children suffering from diarrhea produced by G1P[8] RV. The genera Ruminococcus and Oxalobacter were identified as RV binders in stools, displaying enrichments between 4.8- and 5.4-fold compared to samples nonlabeled with anti-RV antibodies. In vitro binding of the G1P[8] Wa human RV strain to two Ruminococcus gauvreauii human isolates was confirmed by fluorescence microscopy. Analysis in R. gauvreauii with antibodies directed to several histo-blood group antigens (HBGAs) indicated that these bacteria express HBGA-like substances on their surfaces, which can be the target for RV binding. Furthermore, in vitro infection of the Wa strain in differentiated Caco-2 cells was significantly reduced by incubation with R. gauvreauii. These data, together with previous findings showing a negative correlation between Ruminococcus levels and antibody titers to RV in healthy individuals, suggest a pivotal interaction between this bacterial group and human RV. These results reveal likely mechanisms of how specific bacterial taxa of the intestinal microbiota could negatively affect RV infection and open new possibilities for antiviral strategies.
Highlights
Despite vaccination, group A rotavirus (RV) continues to be the leading etiologic agent of viral gastroenteritis in infants and young children worldwide [1] and is responsible for an estimated 130,000 deaths each year, mostly in developing countries [2]
By using FACS coupled with a FITC-labeled anti-RV antibody, we identified bacteria interacting with RV in stool samples from five children suffering from RV diarrhea, clinically diagnosed as originating from the G1P[8] genotype
Total DNA was isolated from both sorted bacterial subpopulations, and their microbial composition was determined by 16S rDNA sequencing
Summary
Group A rotavirus (RV) continues to be the leading etiologic agent of viral gastroenteritis in infants and young children worldwide [1] and is responsible for an estimated 130,000 deaths each year, mostly in developing countries [2]. Polioviruses and other intestinal viruses rely on the intestinal microbiota for infection by exploiting microbial-derived substances (e.g., lipopolysaccharide and peptidoglycan) to increase virion stability or to enhance attachment to host cells [8]. The dual role of the microbiota in enteric virus infectivity (promoting or restricting) suggests that some microorganisms can be considered risk factors while others can lead to protection against infection. In agreement with this concept, diverse bacterial groups have been correlated to diminished or increased antibody titers (reflecting previous infections) against RV and norovirus [18]. An important breakthrough has been recently achieved after identifying that segmented filamentous bacteria (SFB), a group of microorganisms present in rodents and other vertebrates, and intimately associated with the intestinal epithelium, protect mice against RV [19]
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