Fig 1.

Relative positions of primers and LB-blockers on 16S rRNA gene. The 16S rRNA gene is depicted with its variable domains based on E. coli. The positions of BU4F and BU6R used in this paper as broad-spectrum primers are shown above. Also included are other primers used for this purpose in published vaginal microbiome studies (see Table S1 in the supplemental material). LB-blockers overlap BU4F and BU6R primers and complement only Lactobacillus species. PB primers are positioned below the 16S rRNA gene (primers are detailed in Table S2). Primers overlapping 27F and 1501R were used as first-round primers in nested PCR to detect some targets at lower titers. uc, uncultured; +, other related genera in the target as described in Table S2.