Pre-Senescence Induction in Hepatoma Cells Favors Hepatitis C Virus Replication and Can Be Used in Exploring Antiviral Potential of Histone Deacetylase Inhibitors.

Recent evidence suggests that fibrotic liver injury in patients with chronic hepatitis C correlates with cellular senescence in damaged liver tissue. However, it is still unclear how senescence can affect replication of the hepatitis C virus (HCV). In this work, we report that an inhibitor of cyclin-dependent kinases 4/6, palbociclib, not only induced in hepatoma cells a pre-senescent cellular phenotype, including G1 arrest in the cell cycle, but also accelerated viral replicon multiplication. Importantly, suppression of HCV replication by direct acting antivirals (DAAs) was barely affected by pre-senescence induction, and vice versa, the antiviral activities of host-targeting agents (HTAs), such as inhibitors of human histone deacetylases (HDACi), produced a wide range of reactions-from a dramatic reduction to a noticeable increase. It is very likely that under conditions of the G1 arrest in the cell cycle, HDACi exhibit their actual antiviral potency, since their inherent anticancer activity that complicates the interpretation of test results is minimized.

The Fate of Exogenous Human HSP70 Introduced into Animal Cells by Different Means.

Over the last decade, it has become evident that in mammals, including humans, heat shock protein 70 (HSP70), apart from its intracellular localization, is found in extracellular space, where it may execute various protective functions. Furthermore, the upregulation of HSP70 family members can be beneficial in the prevention and treatment of various human neurodegenerative diseases and cancer. Here, we demonstrate that recombinant human HSP70 after intranasal administration can penetrate various brain regions of mice in its native form and subsequently undergo rapid degradation. It was also shown that labeled HSP70 added to culture medium of different human and mouse cell lines enters the cells with strikingly different kinetics, which positively correlates with the basic levels of membrane bound Toll-like receptors (TLR) that are characteristic of these cell lines. HSP70 administration does not significantly modulate the level of TLR expression at the protein or RNA level. The degradation of the introduced recombinant HSP70 after entering the cells is likely proteasome-dependent and varies significantly depending on the cells type and origin. These results should be considered when developing HSP70-based therapies.

Transmembrane protein polymorphisms and resistance to T-20 (Enfuvirtide, Fuzeon) in HIV-1 infected therapy-naive seroconverters and AIDS patients under HAART-T-20 therapy.

The human immunodeficiency virus type 1 fusion inhibitor T-20 (Enfuvirtide, Fuzeon) has recently been introduced into clinical practice. T-20 in combination with HAART efficiently inhibits HIV-1 replication, however T-20 resistance has been reported and the number of confirmed resistant-associated mutations is growing. In this study we aimed to analyze HIV-1 gp41 transmembrane protein (TM) variability and primary resistance to T-20 in plasma viruses from 10 HIV-1 subtype B infected homosexuals. Nine out of ten were documented seroconverters. Nine individuals (including one long time infected therapy naïve individual) were part of four linked virus infection chains. We also examined TM polymorphism in two AIDS patients under HAART and T-20 therapy. Obtained TM amplicons were examined for minor variants by clonal analysis.Sequences polymorphism of the N-terminal regions of the fusion domain (FD) and the heptad repeat 2 (HR2) domain were demonstrated in examined seroconverters. Analysis of the heptad repeat 1 (HR1) domain revealed T-20 resistance in cloned sequences from 3/10 individuals. In two individuals these mutations were present as minor viral quasispecies. Transmission of the resistant virus to the sexual partner was traced in virus infection chain.Baseline TM amplicons (population sequence) and clones from two patients under HAART did not contain T-20 resistance associated mutations. After onset of T-20 therapy only resistant viruses were identified in plasma from the patients. As shown by clonal analysis of plasma from one patient, treatment interruption results in viruses reverting to a T-20-sensitive genotype.