Optimization and Improvement of qPCR Detection Sensitivity of SARS-CoV-2 in Saliva.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been a major public health threat globally, especially during the beginning of the pandemic in 2020. Reverse transcription-quantitative PCR (RT-qPCR) is utilized for viral RNA detection as part of control measures to limit the spread of COVID-19. Collecting nasopharyngeal swabs for RT-qPCR is a routine diagnostic method for COVID-19 in clinical settings, but its large-scale implementation is hindered by a shortage of trained health professionals. Despite concerns over its sensitivity, saliva has been suggested as a practical alternative sampling approach to the nasopharyngeal swab for viral RNA detection. In this study, we spiked saliva from healthy donors with inactivated SARS-CoV-2 from an international standard to evaluate the effect of saliva on viral RNA detection. On average, the saliva increased the cycle threshold (CT) values of the SARS-CoV-2 RNA samples by 2.64 compared to the viral RNA in viral transport medium. Despite substantial variation among different donors in the effect of saliva on RNA quantification, the outcome of the RT-qPCR diagnosis was largely unaffected for viral RNA samples with CT values of <35 (1.55 log10 IU/mL). The saliva-treated viral RNA remained stable for up to 6 h at room temperature and 24 h at 4°C. Further supplementing protease and RNase inhibitors improved the detection of viral RNA in the saliva samples. Our data provide practical information on the storage conditions of saliva samples and suggest optimized sampling procedures for SARS-CoV-2 diagnosis. IMPORTANCE The primary method for detection of SARS-CoV-2 is using nasopharyngeal swabs, but a shortage of trained health professionals has hindered its large-scale implementation. Saliva-based nucleic acid detection is a widely adopted alternative, due to its convenience and minimally invasive nature, but the detection limit and direct impact of saliva on viral RNA remain poorly understood. To address this gap in knowledge, we used a WHO international standard to evaluate the effect of saliva on SARS-CoV-2 RNA detection. We describe the detection profile of saliva-treated SARS-CoV-2 samples under different storage temperatures and incubation periods. We also found that adding protease and RNase inhibitors could improve viral RNA detection in saliva. Our research provides practical recommendations for the optimal storage conditions and sampling procedures for saliva-based testing, which can improve the efficiency of COVID-19 testing and enhance public health responses to the pandemic.

Incidence of JAK2V617F mutation in myeloproliferative diseases and its clinical significance / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To investigate the incidence of JAK2V617F gene point mutation in patients with myeloproliferatives diseases (MPD) and its clinical significance.</p><p><b>METHODS</b>Genomic DNA from bone marrow and peripheral blood cells were extracted from 68 patients with MPD. Allele specific polymerase chain reaction was used to amplify the exon 12 of JAK2 gene which harbours V617F mutation. The PCR products were identified by DNA sequencing. JAK2V617F gene point mutation and its impact on peripheral blood cells were analyzed.</p><p><b>RESULTS</b>The incidence of JAK2V617F mutation in 68 patients with MPD was 65.28 %. The positive rate of JAK2V617F point mutation was 77.77 % in patients with PV (36/59), 56.52 % in patients with ET (23/59) and 44.44 % in patients with IMF (4/9). In all groups, the incidence of JAK2V617F point mutation in bone marrow and peripheral blood were equal. Patients with JAK2V617F mutation in PV group had higher counts of white blood cell and hemoglobin in peripheral blood than patients without JAK2V617F point mutation (P <0.05). Patients with JAK2V617F mutation in ET group had higher counts of white blood cell than those without JAK2V617F mutation (P <0.05); there was no significant difference in platelet count.</p><p><b>CONCLUSION</b>JAK2V617F point mutation can affect the hematologic features, which may be of diagnostic value for MDP with negative BCR-ABL gene.</p>