Method Description

Borrelia miyamotoi:

The assay is performed on the Roche LightCycler (LC) 2.0 instrument, following DNA extraction on the Roche MagNA Pure. The LC 2.0 instrument amplifies and monitors the development of target nucleic acid (amplicon) after each cycle of polymerase chain reaction (PCR).

The DNA target for this PCR assay is a gene encoding the glycerophosphodiester phosphodiesterase (glpQ) gene specific to Borrelia species in the relapsing fever group. This gene is not found in Borrelia species that cause Lyme disease.

The specific base pair DNA target sequence is amplified by PCR. The detection of amplicon is based on fluorescence resonance energy transfer (FRET), which utilizes 1 hybridization probe with a donor fluorophore, fluorescein, at the 3' end and a second hybridization probe with an acceptor fluorophore, LC-Red 640, at the 5' end. When the target amplicon is present, the LC-Red 640 emits a measurable and quantifiable light signal at a specific wavelength. Presence of the specific organism nucleic acid is confirmed by performing a melting temperature analysis of the amplicon; the presence or absence of a melting peak in the appropriate temperature range is used to determine if a specimen is positive or negative.(Unpublished Mayo method)

Ehrlichia/Anaplasma:

Nucleic acid is extracted from the pathogens in blood using the automated MagNA Pure LC system. The extract is then transferred to individual self-contained capillary cuvettes for amplification. The LightCycler is an automated instrument that amplifies and monitors the development of target nucleic acid (amplicon) after each cycle of PCR. The DNA target for PCR assay is groEL, the open reading frame gene segment of the heat-shock protein operon (groEL), which is present at a frequency of 1 copy per organism in pathogenic species of Anaplasma and Ehrlichia. A specific base pair DNA target sequence is amplified by PCR. The detection of amplicon is based on FRET, which utilizes a hybridization probe with a donor fluorophore, fluorescein, at the 3' end and a second hybridization probe with an acceptor fluorophore, LC-Red 640, at the 5' end. When the target amplicon is present, the LC-Red 640 emits a measurable and quantifiable light signal at a specific wavelength. Presence of the specific organism nucleic acid may be confirmed by performing a melting curve analysis of the amplicon. Using features of the melting curve analysis, the assay primers and specific hybridization probes are able to detect and differentiate among Anaplasma phagocytophilum, Ehrlichiosis chaffeensis, Ehrlichia muris eauclairensis, and Ehrlichia ewingii/canis. Due to close proximity of the melting curves of E ewingii and E canis, this assay cannot distinguish between these 2 organisms.(Unpublished Mayo method)

Babesia:

Nucleic acid is extracted from EDTA whole blood using the automated MagNA Pure bead-based system (Roche Molecular Systems). The extract is then transferred to individual self-contained capillary cuvettes for amplification. The LightCycler is an automated instrument that amplifies and monitors the development of target nucleic acid (amplicon) after each cycle of PCR.

The DNA target for PCR assay is a gene encoding the nuclear small subunit ribosomal RNA.

This assay consists of 2 forward primers, 1 reverse primer, and 2 probes, which are specific for the Babesia species target DNA. The specific base pair DNA target sequence is first amplified by PCR using the target-specific primers. Amplicon is then detected during melting curve analysis using FRET probes, which utilizes 1 hybridization probe with a donor fluorophore, fluorescein, at the 3' end and a second hybridization probe with an acceptor fluorophore, LC-Red 640, at the 5' end. Fluorescence is produced when the 2 probes anneal to the target sequence in close proximity to one another. The LC-Red 640 then emits a measurable and quantifiable light signal at a specific wavelength.(Burgess MJ, Rosenbaum ER, Pritt BS, et al. Possible transfusion-transmitted Babesia divergens-like/MO-1 in an Arkansas patient. Clin Infect Dis. 2017 Jun;64(11):1622-1625)