The potential of metatranscriptomics for identifying screening targets for bacterial vaginosis

Abstract

Background: The ribosomal RNA content of a sample collected from a woman with bacterial vaginosis (BV) was analysed to determine the active microbial community, and to identify potential targets for further screening.

Methodology/principal findings: The sample from the BV patient underwent total RNA extraction, followed by physical subtraction of human rRNA and whole transcriptome amplification. The metatranscriptome was sequenced using Roche 454 titanium chemistry. The bioinformatics pipeline MG-RAST and desktop DNA analysis platforms were utilised to analyse results. Bacteria of the genus Prevotella (predominately P. amnii) constituted 36% of the 16S rRNA reads, followed by Megasphaera (19%), Leptotrichia/Sneathia (8%) and Fusobacterium (8%). Comparison of the abundances of several bacteria to quantitative PCR (qPCR) screening of extracted DNA revealed comparable relative abundances. This suggests a correlation between what was present and transcriptionally active in this sample: however distinct differences were seen when compared to the microbiome determined by 16S rRNA gene amplicon sequencing. To assess the presence of P. amnii in a larger pool of samples, 90 sexually active women were screened using qPCR. This bacterium was found to be strongly associated with BV (P<0.001, OR 23.3 (95%CI:2.9-190.7)) among the 90 women.

Conclusions/significance: This study highlighted the potential of metatranscriptomics as a tool for characterising metabolically active microbiota and identifying targets for further screening. Prevotella amnii was chosen as an example target, being the most metabolically active species present in the single patient with BV, and was found to be detected at a high concentration by qPCR in 31% of cohort with BV, with an association with both oral and penile-vaginal sex.

Figure 1. Overview of experiment.

Flow chart of the work plan for this study.

Figure 2. Bacterial diversity of cDNA library.

Graphical representation of the bacterial genera identified through 16S rRNA gene matches for the Nugent = 10 cDNA using the RDP database search tool in MG-RAST.