No abstract

Background: Up to 40% of test results for COVID-19 in the presence of clinical manifestations of the disease might be negative. The reason for a false-negative result might originate from any step of the analysis: poor-quality or empty swab, poor RNA isolation, inactivation of reverse transcriptase or Taq polymerase in the test. Methods: Here we describe a PCR approach for SARS-CoV-2 detection with swab quality and integrity controlled by human ABL1 mRNA amplification. Designed primers work with the cDNA of the ABL1 gene, not genomic DNA. Results: The simultaneous appearance of three signals corresponding to the nucleocapsid, spike, and ABL1 gene indicates infection with the Omicron strain. The amplification of ABL1 gene and nucleocapsid only indicate other than Omicron infection. The appearance of ABL1 amplification only indicates a true negative result for SARS-CoV-2. All other variants are null and void. Conclusions: A system has been developed for multiplex PCR diagnostics of SARS-CoV-2, which makes it possible to eliminate errors leading to false-negative and false-positive results at all stages of analysis. This is accomplished by the presence of specific primers for human RNA, controlling proper swab application, handling, and all the stages of RT-PCR.

Many genetic markers are known to distinguish tumor cells from normal. Genetic lesions found at disease onset often belong to a predominant tumor clone, and further observation makes it possible to assess the fate of this clone during therapy. However, minor clones escape monitoring and become unidentified, leading to relapses. Here we report the results of in vitro study of clonal evolution in cultured tumor cell line (Jurkat) compared to the cell line of non-tumor origin (WIL2-S). Cell lines were cultured and cloned by limiting dilutions. Subclones were tested by short tandem repeats (STR) profiling. Spontaneous STR aberrations in cells of non-tumor origin occur in less than 1 of 100 cultured cells. While in the cells of tumor origin, new aberrations appear in 1 or even more of 3 cultured cells. At the same time, a significant relationship was found between the accumulation of aberrations in the pool of subclones and the rate of cell growth. One can speculate that this approach could be applied for the analysis of primary patient tumor cell culture to obtain information concerning the evolutionary potential of the tumor cells that may be useful for the selection of a therapy approach.

Objective. To identify mutations in UL97 gene associated with antiviral drug resistance in recipients of allogeneic hematopoietic stem cells transplants (allo-HSCT). Materials and Methods. A total of 9 HCMV DNA samples were studied. These samples were received from the blood of 8 allo-HSCT recipients who were infected with HCMV and undergoing treatment at NMRC of Hematology (Russia) over the period of 2016 to 2017. Sanger sequencing was used to find mutations. The sequenced part of the virus DNA was analyzed using nucleotide BLAST and Genome compiler. Mutations were identified using MRA program which compared the obtained nucleotide sequence with the reference sequence of UL97 gene from Merlin strain. Results. Rate of detection of viruses with mutations that may lead to drug resistance is relatively high – 3 of 8 patients. The following mutations were identified: C592G, C607F and C603W. The obtained data shows that the presence and characteristics of mutations affect the viral load and the time when HCMV DNA is identified in blood. Conclusions. Obtained data show that presence of mutations impacts the course infection, leading to higher viral load and longer persistence of viral DNA in blood samples. Identified mutations had different resistance factor, which also impacted on the pattern of infection.