ИСТИНА

Human herpes simplex virus type 1 (HSV-1) is the most abundant pathogen accounting for herpetic diseases. When accompanying other diseases or in immunocompromised patients, HSV may cause serious health problems and even be lethal. Currently HSV infection is treated mainly with acyclovir (ACV) and its analogs, which are phosphorylated in infected cells by several enzymes including viral thymidine kinases (TK), and the resulting triphosphates act as terminators of DNA synthesis. However, their prolonged use often leads to emergence of drug-resistant strains, which in most cases encode an inactivated viral TK gene. Therefore, search of new compounds effective against drug-resistant HSV strains is still important. Previously we described acyclovir 5’-H-phosphonate (HpACV), which exhibited activity against ACV-resistant TK- HSV-1 variants. Here we present an analysis of DNA-polymerase and TK genes from clinical and laboratory HSV isolates resistant to ACV and HpACV. Compared to the ACV-sensitive L2 strain, we identified several mutations in the DNA-polymerase gene: M880T, F716L, I529M, E545D, V585M, F716S, L1049M, N608S, N962D, A987T, F820Y, and G948S. Mutations were located in or close to the conserved domains and presumably affected DNA-polymerase activity and/or specificity, individually or in combination with other DNA-polymerase or TK mutations. Interestingly, some of these mutations were also observed in case of ACV-resistant HSV-1 strain. To explore mechanisms of formation of resistance to HpACV, we analyzed metabolism of the compound in uninfected Vero cells. It was revealed that Hp-ACV was not only hydrolyzed to give ACV but was also directly converted to the ACV 5’-monophosphate (ACVMP). Thus the compound could partially avoid phosphorylation by HSV-1 TK and retain activity against ACV-resistant TK- strains. This work was supported by the RFBR (#12-04-00581-а) and RAS Presidium project “Molecular and Cellular Biology”.