Multicenter evaluation of the GenomEra SARS-CoV-2 assay kit.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) first emerged in late 2019, and quickly spread to every continent causing the global coronavirus disease 2019 (COVID-19) pandemic. Fast propagation of the disease presented numerous challenges to the health care industry in general and especially placed enormous pressure on laboratory testing. Throughout the pandemic, reverse transcription-PCR (RT-PCR)-based nucleic acid amplification tests have been the primary technique to identify acute infections caused by SARS-CoV-2. Since the start of the pandemic, there has been a constantly growing need for accurate and fast tests to enable timely protective and isolation means, as well as rapid therapeutic interventions. Here we present an evaluation of the GenomEra test for SARS-CoV-2. Analytical and clinical performance was evaluated in a multicenter setting with specimens analyzed using standard-of-care (SOC) techniques. Analytical sensitivity was assessed from spiked respiratory swab samples collected into different viral transport media, and in the best performer eSwab, the limit of detection was found to be 239 IU/mL in a heat processed sample. The GenomEra SARS-CoV-2 Assay Kit did not show specificity/cross-reactivity issues with common micro-organisms or other substances commonly found in respiratory specimens when analyzed both in vitro and in silico. Finally, the clinical performance was assessed in comparison to SOC techniques used at four institutions. Based on the analysis of 274 clinical specimens, the positive agreement of the GenomEra SARS-CoV-2 Assay Kit was 90.7%, and the negative agreement was 100%. The GenomEra SARS-CoV-2 Assay Kit provided accurate detection of SARS-CoV-2 with a short turnaround time in under 90 min.

Homogeneous duplex polymerase chain reaction assay using switchable lanthanide fluorescence probes.

We have developed a duplex polymerase chain reaction (PCR) assay based on switchable lanthanide chelate complementation probes. In the complementation probe technology, two nonfluorescent oligonucleotide probes, one labeled with a lanthanide ion carrier chelate and another with a light absorbing antenna ligand, form a fluorescent complex by self-assembly of the reporter molecules when the two probes are hybridized in adjacent positions to the target DNA. Here we report the synthesis of a new terbium(III) (Tb(III)) ion carrier chelate and a new light-absorbing antenna ligand for Tb(III) and the development of a duplex Chlamydia trachomatis (Ct) PCR assay. For the detection of Ct in urine samples, a specific sequence in Ct cryptic plasmid was amplified and detected using europium(III) (Eu(III)) complementation probes. An internal amplification control was amplified in each reaction and detected using Tb(III) complementation probes to verify the Ct negative results. Ct bacteria were concentrated from urine samples with a rapid and simple centrifugation-based sample preparation method. Good diagnostic accuracy (99-100%) was achieved, and also Ct positive reactions yielded a very high Eu(III) signal-to-background ratio (maximum of 244). High performance of the complementation probes is advantageous when sample may contain impurities after a simple sample preparation.

High-performance closed-tube PCR based on switchable luminescence probes.

We introduce a switchable lanthanide luminescence reporter technology based closed-tube PCR for the detection of specific target DNA sequence. In the switchable lanthanide chelate complementation based reporter technology hybridization of two nonfluorescent oligonucleotide probes to the adjacent positions of the complementary strand leads to the formation of a highly fluorescent lanthanide chelate complex. The complex is self-assembled from a nonfluorescent lanthanide chelate and a light-harvesting antenna ligand when the reporter molecules are brought into close proximity by the oligonucleotide probes. Outstanding signal-to-background discrimination in real-time PCR assay was achieved due to the very low background fluorescence level and high specific signal generation. High sensitivity of the reporter technology allows the detection of a lower concentration of amplified DNA in the real-time PCR, resulting in detection of the target at the earlier amplification cycle compared to commonly used methods.

Rapid homogeneous PCR assay for the detection of Chlamydia trachomatis in urine samples.

Chlamydia trachomatis infection is the most common bacterial sexually transmitted disease and a major public health problem worldwide. Fast and sensitive point-of-care diagnostics including non-invasive sample collection would be of value for the prevention of C. trachomatis transmission. The aim of this study was to develop a fast, reliable, non-invasive and easy-to-use homogenous PCR assay for the detection of C. trachomatis. Bacteria were concentrated from urine by a simple and fast centrifugation-based urine pretreatment method. Novel automated GenomEra technology was utilized for the rapid closed-tube PCR including time-resolved fluorometric detection of the target using lanthanide chelate labeled probes. We have developed a rapid C. trachomatis assay which provides qualitative results in 1 h with diagnostic sensitivity and specificity of 98.7% and 97.3%, respectively. The novel assay can be performed with minimal laboratory expertise and without sophisticated DNA-extraction devices and has performance comparable to current gold standard assays.