Search

Introduction. Human cytomegalovirus (Orthoherpesviridae: Herpesvirales: Cytomegalovirus: Cytomegalovirus humanbeta 5) (HCMV) is one of the most commonly detected viruses in recipients of allogeneic hematopoietic stem cell (allo-HSCT) transplants. However, the emergence of resistance to antiviral drugs such as ganciclovir (GCV) poses a challenge in managing these patients. This study aims to investigate the prevalence and impact of mutations in the HCMV UL97 gene associated with resistance to GCV on the course of infection among allo-HSCT patients. Materials and methods. The study examined the association between UL97 mutations and the clinical course of HCMV infection in allo-HSCT patients. Genetic sequencing was performed to identify mutations, and their impact on viral replication and resistance to GCV was assessed. Results and discussion. Six mutations were identified (D490A, T502A, C592G, C592F, E596G, C603W). C592G, C592F, E596G, and C603W are associated with resistance to antiviral drugs, while D490A and T502A described for the first time. When comparing patients with wild-type and those carrying the mutant variant, several parameters of peripheral blood were significantly lower in the former group. The median time to peak viral load following allo-HSCT, duration of viremia, and rate of virological response to high-dose therapy also differed significantly between the two groups. Conclusion. It was shown that approximately one third (4 out of 14) of allogeneic stem cell transplant recipients had mutations associated with resistance to GCV. Patients carrying the mutant variant of HCMV had longer viremia and took longer to achieve a negative virological test result after starting high-dose therapy. Performing genotyping may help make more evidence-based therapeutic decisions.

Introduction. Infection caused by cytomegalovirus (CMV) is a serious problem for patients with weakened immunity, including patients with hematopoietic depression. The cases of complications associated with cytomegalovirus require antiviral therapy. However, during the natural mutation process, especially with prolonged use of drugs in suboptimal doses, CMV strains resistant to the action of antiviral drugs (such as ganciclovir, valganciclovir) may occur. Hypothetically, the emergence of resistance in the virus may cause a more aggressive course of infection, the ineffectiveness of antiviral therapy and, as a result, an increase in the number of deaths. In this regard, timely detection of mutations that can potentially lead to the resistance of the virus to antiviral drugs during hematopoietic stem cell transplantation (HSCT), as well as during organ and tissue transplantation, may be important when making a therapeutic decision. We describe three clinical cases for which the dynamics of the appearance of a mutant strain of CMV by the UL97 gene, which correlates with the viral load and clinical picture, is analyzed. The aim of the study was to determine the timing of the occurrence of mutations in CMV phosphotransferase UL97 gene associated with resistance to antiviral drugs in patients with hemoblastoses after allogeneic hematopoietic stem cell (allo-HSCs) transplantation. Material and methods. The study included 48 samples of CMV DNA isolated from the peripheral blood of three allo-HSCs recipients with CMV infection who were treated in the clinics of the FSBI «National Medical Research Center for Hematology» of the Ministry of Health of Russia with oncohematological diseases during 2015–2017. Patients received conditional codes (PR, PD, and FS). Mutations associated with antiviral therapy (AVT) resistance were identified in all patients. Sanger sequencing was used for mutation detection. The obtained DNA sequences were analyzed using Nucleotide BLAST and Genome compiler software. Mutations were searched in MRA mutation resistance analyzer software. The nucleotide sequences were compared with the UL97 reference sequence of the Merlin CMV strain using this software environment. Results and discussion. For all patients in whom the virus strains containing C592G (PR), C607F (PD) and C603W (FS) mutations were detected, the timing of the mutation occurrence was determined at days 187, 124 and 1184, respectively. The emergence of mutations with a high resistance factor was shown to be accompanied by an increase in viral load (VL), the appearance of a clinical picture characteristic of CMV infection and a lack of an adequate response to therapy with ganciclovir and its derivatives. Conclusion. Using these results, it is proposed to develop the test system based on random polymerase chain reaction (rPCR) to detect mutations in the most frequently encountered codons: M460I/V, C592G, A591V, A594T/V, L595F/S, C603W. Given that the data on the prevalence of these mutations were obtained from foreign sources, it is advisable to conduct similar studies on the frequency of mutations in the UL97 gene among the population of the Russian Federation in order to improve the quality and accuracy of test systems.