Compositions and methods for detecting bacterial nucleic acid and diagnosing bacterial vaginosis
Disclosed are methods for diagnosing Bacterial Vaginosis in a subject comprising performing an assay for the detection of any one or more of Lactobacillus sp., Atopobium vaginae, and Gardneralla vaginalis in a subject sample. Also disclosed are compositions and methods for detecting Lactobacillus sp., Atopobium vaginae, and/or Gardneralla vaginalis nucleic acid in a sample.
1. A method for determining the presence or absence of Bacterial Vaginosis (BV) in a subject, the method comprising:
(a) providing a sample from a subject suspected of having BV;
(b) performing a nucleic-acid-based detection assay for the detection of Lactobacillus sp., A. vaginae , and G. vaginalis in the sample, wherein the detection assay is an amplification-based assay comprising an in vitro nucleic acid amplification reaction, and wherein performing the detection assay comprises contacting the sample with
(i) first, second, third, and fourth Lactobacillus -specific amplification oligomers for amplifying a target region of a Lactobacillus sp. target nucleic acid, wherein each of the first, second, third, and fourth Lactobacillus -specific amplification oligomers comprises a target-hybridizing sequence for hybridizing to the target region of the Lactobacillus sp. target nucleic acid, wherein
the first Lactobacillus -specific amplification oligomer comprises a first target-hybridizing sequence consisting of the nucleotide sequence of residues 28-45 of SEQ ID NO: 10, wherein the first Lactobacillus -specific amplification oligomers is a promoter primer or a promoter provider further comprising a promoter sequence located 5′ to the target-hybridizing sequence;
the second Lactobacillus -specific amplification oligomer comprises a second target-hybridizing sequence consisting of the nucleotide sequence of SEQ ID NO:7;
the third Lactobacillus -specific amplification oligomer comprises a third target-hybridizing sequence consisting of the nucleotide sequence of SEQ ID NO:8; and
the fourth Lactobacillus -specific amplification oligomer comprises a fourth target-hybridizing sequence consisting of the nucleotide sequence of SEQ ID NO:9;
(ii) first and a second A. vaginae -specific amplification oligomers for amplifying a target region of a A. vaginae target nucleic acid, wherein each of the first and second A. vaginae -specific amplification oligomers comprises a target-hybridizing sequence for hybridizing to the target region of the A. vaginae target nucleic acid; and
(iii) first and a second G. vaginalis -specific amplification oligomers for amplifying a target region of a G. vaginalis target nucleic acid, wherein each of the first and second G. vaginalis -specific amplification oligomers comprises a target-hybridizing sequence for hybridizing to the target region of the G. vaginalis target nucleic acid;
(c) for each of Lactobacillus sp., A. vaginae , and G. vaginalis , assigning a quantitative value based on the detection assay;
(d) subtracting the Lactobacillus sp. quantitative value from the greater of the A. vaginae quantitative value and the G. vaginalis quantitative value, wherein step (d) further comprises adding an internal control (IC) adjustment factor that compensates for sample inhibition of the detection assay, wherein the IC adjustment factor is based on a ratio of (i) an observed internal control (IC) value generated from the detection assay to (ii) an expected IC value for the detection assay;
(e) assigning a single BV score based on step (d); and
(f) determining the presence or absence of BV in the subject based on a comparison of the BV score to a cutoff value.
2. The method of claim 1 , wherein the in vitro nucleic acid amplification reaction is an isothermal amplification reaction.
3. The method of claim 2 , wherein the isothermal amplification reaction is a transcription-mediated amplification (TMA) reaction.
4. The method of claim 2 , wherein the isothermal amplification reaction is a real-time amplification reaction.
5. The method of claim 1 , wherein (i) the first A. vaginae -specific amplification oligomer comprises a first A. vaginae -specific target-hybridizing sequence consisting of the nucleotide sequence of residues 28-45 of SEQ ID NO:18 and (ii) the second A. vaginae -specific amplification oligomer comprises a second A. vaginae -specific target-hybridizing sequence consisting of the nucleotide sequence of SEQ ID NO:17.
6. The method of claim 5 , wherein the first A. vaginae -specific amplification oligomer is a promoter primer or a promoter provider further comprising a promoter sequence located 5′ to the target hybridizing sequence.
7. The method of claim 1 , wherein (i) the first G. vaginalis -specific amplification oligomer comprises a first G. vaginalis -specific target-hybridizing sequence consisting of the nucleotide sequence of residues 36-52 of SEQ ID NO:15 and (ii) the second G. vaginalis -specific amplification oligomer comprises a second G. vaginalis -specific target-hybridizing sequence consisting of the nucleotide sequence of SEQ ID NO:14.
8. The method of claim 7 , wherein the first G. vaginalis -specific amplification oligomer is a promoter primer or a promoter provider further comprising a promoter sequence located 5′ to the target hybridizing sequence.
9. The method of claim 1 , wherein the promoter sequence is a T7 promoter sequence.
10. The method of claim 9 , wherein the T7 promoter sequence has a nucleotide sequence of residues 1-27 of SEQ ID NO:10.
11. The method of claim 1 , wherein the BV score is assigned using the equation
BV score= C 0 +W L Max( L S ,F LS )+ W GA Max( As,Gs,F GAS )+ W IC Log 2(ICRatio),
wherein C 0 is an adjustment constant;
W L is a weighting constant for Lactobacillus sp.; Max (L S , F LS ) is the greater of L S and F LS ,
wherein L S is an observed standardized quantitative value for Lactobacillus sp. and F LS is an imposed minimum standardized quantitative value for Lactobacillus sp.;
W GA is a weighting constant for A. vaginae and G. vaginalis;
Max (As, Gs, F GAS ) is the greater of As, Gs, and F GAS , wherein As is an observed standardized quantitative value for A. vaginae , Gs is an observed standardized quantitative value for G. vaginalis , and F GAS is an imposed minimum standardized quantitative value for A. vaginae and G. vaginalis;
W IC is an internal control (IC) weighting constant; and
ICRatio is the ratio of (i) the observed internal control (IC) value generated from the detection assay to (ii) the expected IC value for the detection assay.