lunes, 18 de junio de 2012

PLoS ONE: A Metagenomic Approach to Characterization of the Vaginal Microbiome Signature in Pregnancy

PLoS ONE: A Metagenomic Approach to Characterization of the Vaginal Microbiome Signature in Pregnancy

A Metagenomic Approach to Characterization of the Vaginal Microbiome Signature in Pregnancy

Kjersti Aagaard1,3*, Kevin Riehle3, Jun Ma1,3, Nicola Segata4, Toni-Ann Mistretta2, Cristian Coarfa3, Sabeen Raza2, Sean Rosenbaum1, Ignatia Van den Veyver1, Aleksandar Milosavljevic3, Dirk Gevers5, Curtis Huttenhower4, Joseph Petrosino6, James Versalovic2
1 Department of Obstetrics & Gynecology, Division of Maternal-Fetal Medicine, Baylor College of Medicine and Texas Children’s Hospital, Houston, Texas, United States of America, 2 Department of Pathology & Immunology, Baylor College of Medicine and Texas Children’s Hospital, Houston, Texas, United States of America, 3 Bioinformatics Research Laboratory, Baylor College of Medicine and Texas Children’s Hospital, Houston, Texas, United States of America, 4 Harvard School of Public Health, Harvard University, Cambridge, Massachusetts, United States of America, 5 Broad Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America, 6 Department of Molecular Virology and Microbiology, Baylor College of Medicine and Texas Children’s Hospital, Houston, Texas, United States of America

Abstract Top

While current major national research efforts (i.e., the NIH Human Microbiome Project) will enable comprehensive metagenomic characterization of the adult human microbiota, how and when these diverse microbial communities take up residence in the host and during reproductive life are unexplored at a population level. Because microbial abundance and diversity might differ in pregnancy, we sought to generate comparative metagenomic signatures across gestational age strata. DNA was isolated from the vagina (introitus, posterior fornix, midvagina) and the V5V3 region of bacterial 16S rRNA genes were sequenced (454FLX Titanium platform). Sixty-eight samples from 24 healthy gravidae (18 to 40 confirmed weeks) were compared with 301 non-pregnant controls (60 subjects). Generated sequence data were quality filtered, taxonomically binned, normalized, and organized by phylogeny and into operational taxonomic units (OTU); principal coordinates analysis (PCoA) of the resultant beta diversity measures were used for visualization and analysis in association with sample clinical metadata. Altogether, 1.4 gigabytes of data containing >2.5 million reads (averaging 6,837 sequences/sample of 493 nt in length) were generated for computational analyses. Although gravidae were not excluded by virtue of a posterior fornix pH >4.5 at the time of screening, unique vaginal microbiome signature encompassing several specific OTUs and higher-level clades was nevertheless observed and confirmed using a combination of phylogenetic, non-phylogenetic, supervised, and unsupervised approaches. Both overall diversity and richness were reduced in pregnancy, with dominance of Lactobacillus species (L. iners crispatus, jensenii and johnsonii, and the orders Lactobacillales (and Lactobacillaceae family), Clostridiales, Bacteroidales, and Actinomycetales. This intergroup comparison using rigorous standardized sampling protocols and analytical methodologies provides robust initial evidence that the vaginal microbial 16S rRNA gene catalogue uniquely differs in pregnancy, with variance of taxa across vaginal subsite and gestational age.

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