The T vaginalis TMA assay (manufactured by Hologic®) is an alternative to other T vaginalis tests such as culture, wet-mount, or direct probe testing (Affirm™ Bacterial Vaginosis/Vaginitis Panel). The T vaginalis test is FDA cleared and combines the technologies of target capture, TMA, and hybridization.
After the specimen is collected for TMA testing, it is placed into a special transport solution that releases the trichomonad target rRNA and protects it from degradation. During the initial phase of testing, the target rRNA is separated by washing from the remainder of the sample. This is performed by capturing the target rRNA through the use of a specific oligomer and magnetic microparticles.
After the wash cycle has been completed, the target rRNA is ready for amplification. The target amplification assay is based upon the ability of complementary oligonucleotide primers to specifically anneal and allow enzymatic amplification of the target nucleic acid strands. The TMA process amplifies a specific portion of the target 16S rRNA from T vaginalis through various DNA and RNA intermediates; ultimately RNA amplicon molecules are generated.
The detection of the final RNA amplicon product is achieved through the use of nucleic acid hybridization. A labeled chemiluminescent DNA probe, complementary to a region on the amplicon product, binds the RNA to form stable RNA: DNA hybrids. A selection reagent is able to differentiate hybridized from unhybridized probes, based on chemiluminescence.