Development of absolute quantification method for genotype-specific Babesia microti using real-time PCR and practical experimental tips of real-time PCR

Mkit: A mobile nucleic acid assay based on a chitosan-modified minimalistic microfluidic chip (CM3-chip) and smartphone

Mobile sensing enabled by MS² technology, which integrates microfluidic and smartphone components, has seen many applications in recent years. In this direction, we developed an MS² platform (an integrated kit) for nucleic acid assay, which included a chitosan-modified minimalistic microfluidic chip (CM³-chip), a smartphone-based fluorescence detector (SF-detector), an APP for imaging and analysis, reagents, and accessories. Once the lysed sample was loaded into the CM³-chip modified by 1% concentration and 200-260 kDa molecular weight of chitosan, the following assay can be completed in approximately 1 h. The Mkit can detect 3 × 10° copies μL^-1 of plasmid DNA and its polymerase chain reaction (PCR) efficiency was 96.8%. The CM³-chip equipped for the Mkit can enrich nucleic acid from the pH = 5 of lysis buffer, instead of using conventional adsorption mediums such as the magnetic beads and silica gel membranes, which could result in unexpected impurity residuals and tedious cleaning operations. In addition, the performance of the Mkit equipped with the pristine chip was demonstrated to perform poorer than that coupled with the CM³-chip in which the enriched nucleic acid can be all used for "in-situ PCR". The universality, selectivity, and user-friendliness of the Mkit were also validated. We finally demonstrated the feasibility of the Mkit for testing artificially prepared infected samples. H5N6 and IAV-infected saliva samples provided the limits of detection of 5 × 10² copies mL^-1 and 3.24 × 10² copies mL^-1 per chamber, respectively. The streamlined assay and compact device should enable the great potential of the Mkit in research and potential diagnostic uses.

Efficient detection of symptomatic and asymptomatic patient samples for Babesia microti and Borrelia burgdorferi infection by multiplex qPCR

BACKGROUND

Tick-borne infections have been increasing steadily over the years, with co-infections with Borrelia burgdorferi and Babesia microti/divergens emerging as a serious health problem. B. burgdorferi is a spirochetal bacterium that causes Lyme disease while protozoan pathogens belonging to Babesia species are responsible for babesiosis. Currently used serological tests do not always detect acute Lyme disease or babesiosis, and fail to differentiate cured patients from those who get re-infected. This is a major problem for proper diagnosis particularly in regions endemic for tick-borne diseases. Microscopy based evaluation of babesiosis is confirmatory but is labor intensive and insensitive such that many asymptomatic patients remain undetected and donate blood resulting in transfusion transmitted babesiosis.

RESULTS

We conducted multiplex qPCR for simultaneous diagnosis of active Lyme disease and babesiosis in 192 blood samples collected from a region endemic for both diseases. We document qPCR results obtained from testing of each sample three times to detect infection with each pathogen separately or together. Results for Lyme disease by qPCR were also compared with serological tests currently used for Lyme disease when available. Considering at least two out of three test results for consistency, 18.2% of patients tested positive for Lyme disease, 18.7% for co-infection with B. burgdorferi and B. microti and 6.3% showed only babesiosis.

CONCLUSIONS

With an 80% sensitivity for detection of Lyme disease, and ability to detect co-infection with B. microti, multiplex qPCR can be employed for diagnosis of these diseases to start appropriate treatment in a timely manner.