Block of death-receptor apoptosis protects mouse cytomegalovirus from macrophages and is a determinant of virulence in immunodeficient hosts.

The inhibition of death-receptor apoptosis is a conserved viral function. The murine cytomegalovirus (MCMV) gene M36 is a sequence and functional homologue of the human cytomegalovirus gene UL36, and it encodes an inhibitor of apoptosis that binds to caspase-8, blocks downstream signaling and thus contributes to viral fitness in macrophages and in vivo. Here we show a direct link between the inability of mutants lacking the M36 gene (ΔM36) to inhibit apoptosis, poor viral growth in macrophage cell cultures and viral in vivo fitness and virulence. ΔM36 grew poorly in RAG1 knockout mice and in RAG/IL-2-receptor common gamma chain double knockout mice (RAGγC(-/-)), but the depletion of macrophages in either mouse strain rescued the growth of ΔM36 to almost wild-type levels. This was consistent with the observation that activated macrophages were sufficient to impair ΔM36 growth in vitro. Namely, spiking fibroblast cell cultures with activated macrophages had a suppressive effect on ΔM36 growth, which could be reverted by z-VAD-fmk, a chemical apoptosis inhibitor. TNFα from activated macrophages synergized with IFNγ in target cells to inhibit ΔM36 growth. Hence, our data show that poor ΔM36 growth in macrophages does not reflect a defect in tropism, but rather a defect in the suppression of antiviral mediators secreted by macrophages. To the best of our knowledge, this shows for the first time an immune evasion mechanism that protects MCMV selectively from the antiviral activity of macrophages, and thus critically contributes to viral pathogenicity in the immunocompromised host devoid of the adaptive immune system

Специфическая эффективность микроэмульсионной матричной трансдермальной терапевтической системы инсулина (экспериментальная модель сахарного диабета 1-го типа )

Aim. To study the specific activity of the microemulsion form of the matrix insulin transdermal delivery system in vivo on the experimental streptozotocin model of type I diabetes.Materials and methods. Male rats (n = 25) were randomized to the experimental and control groups. TDS insulin with a microemulsion composition was applicated to the animals of the experimental group (n = 15) for 4 days with daily replacement of TDS and control of the glycemia level. The glycemia level of the control group rats (n = 10) was determined throughout the experiment. The blood glucose concentration was measured using glucometer One Touch Select (USA). Results. The average blood glucose level in experimental group was 28.4 ± 2.3 mmol/l before application of TDS insulin. The average glycemic index was 21.2 ± 3.1 mmol/l (p < 0.001) during of TDS application. The blood glucose decrease was 26 ± 8% relative to baseline values. The glycemia was 28.4 ± 1.4 mmol/l in the control group rats throughout the experiment.Conclusion. A significant decrease of blood glucose level with TDS insulin application in rats with experimental type 1 diabetes demonstrates the existence of the specific activity of the microemulsion matrix transdermal delivery system of insulin.Цель. Изучение in vivo специфической активности микроэмульсионной формы матричной трансдермальной терапевтической системы инсулина на экспериментальной модели сахарного диабета 1-го типа.Материалы и методы. Крысы-самцы (n = 25) линии Wistar с экспериментальным стрептозотоциновым сахарным диабетом 1-го типа были рандомизированы на подопытную и контрольную группы. Животным подопытной группы (n = 15) наклеивали ТТС инсулина (100 Ед) с микроэмульсионной композицией на протяжении 4 суток с ежедневной заменой препарата и контролем уровня гликемии. Крысам контрольной группы (n = 10) также ежедневно определяли уровень гликемии в течение всего эксперимента. Концентрацию глюкозы в крови измеряли с помощью глюкометра One Touch Select (США).Результаты. У всех животных подопытной группы средняя величина уровня глюкозы в крови до аппликации ТТС инсулина составила 28,4 ± 2,3 ммоль/л. Средний показатель гликемии на фоне аппликации ТТС инсулина составил 21,2 ± 3,1 ммоль/л (p < 0,001). В процентном соотношении снижение уровня глюкозы крови составило 26 ± 8% относительно исходных значений. В контрольной группе крыс гликемия оставалась стабильно высокой на протяжении всего эксперимента и составляла 28,4 ± 1,4 ммоль/л.Заключение. Достоверное снижение уровня глюкозы крови при аппликации ТТС инсулина у крыс с экспериментальным сахарным диабетом демонстрирует наличие специфической активности микроэмульсионной формы матричной ТТС инсулина

Viral Control of Mitochondrial Apoptosis

Throughout the process of pathogen–host co-evolution, viruses have developed a battery of distinct strategies to overcome biochemical and immunological defenses of the host. Thus, viruses have acquired the capacity to subvert host cell apoptosis, control inflammatory responses, and evade immune reactions. Since the elimination of infected cells via programmed cell death is one of the most ancestral defense mechanisms against infection, disabling host cell apoptosis might represent an almost obligate step in the viral life cycle. Conversely, viruses may take advantage of stimulating apoptosis, either to kill uninfected cells from the immune system, or to induce the breakdown of infected cells, thereby favoring viral dissemination. Several viral polypeptides are homologs of host-derived apoptosis-regulatory proteins, such as members of the Bcl-2 family. Moreover, viral factors with no homology to host proteins specifically target key components of the apoptotic machinery. Here, we summarize the current knowledge on the viral modulation of mitochondrial apoptosis, by focusing in particular on the mechanisms by which viral proteins control the host cell death apparatus

HtrA2/Omi Terminates Cytomegalovirus Infection and Is Controlled by the Viral Mitochondrial Inhibitor of Apoptosis (vMIA)

Viruses encode suppressors of cell death to block intrinsic and extrinsic host-initiated death pathways that reduce viral yield as well as control the termination of infection. Cytomegalovirus (CMV) infection terminates by a caspase-independent cell fragmentation process after an extended period of continuous virus production. The viral mitochondria-localized inhibitor of apoptosis (vMIA; a product of the UL37x1 gene) controls this fragmentation process. UL37x1 mutant virus-infected cells fragment three to four days earlier than cells infected with wt virus. Here, we demonstrate that infected cell death is dependent on serine proteases. We identify mitochondrial serine protease HtrA2/Omi as the initiator of this caspase-independent death pathway. Infected fibroblasts develop susceptibility to death as levels of mitochondria-resident HtrA2/Omi protease increase. Cell death is suppressed by the serine protease inhibitor TLCK as well as by the HtrA2-specific inhibitor UCF-101. Experimental overexpression of HtrA2/Omi, but not a catalytic site mutant of the enzyme, sensitizes infected cells to death that can be blocked by vMIA or protease inhibitors. Uninfected cells are completely resistant to HtrA2/Omi induced death. Thus, in addition to suppression of apoptosis and autophagy, vMIA naturally controls a novel serine protease-dependent CMV-infected cell-specific programmed cell death (cmvPCD) pathway that terminates the CMV replication cycle

Chronic Viral Infection and Primary Central Nervous System Malignancy

Primary central nervous system (CNS) tumors cause significant morbidity and mortality in both adults and children. While some of the genetic and molecular mechanisms of neuro-oncogenesis are known, much less is known about possible epigenetic contributions to disease pathophysiology. Over the last several decades, chronic viral infections have been associated with a number of human malignancies. In primary CNS malignancies, two families of viruses, namely polyomavirus and herpesvirus, have been detected with varied frequencies in a number of pediatric and adult histological tumor subtypes. However, establishing a link between chronic viral infection and primary CNS malignancy has been an area of considerable controversy, due in part to variations in detection frequencies and methodologies used among researchers. Since a latent viral neurotropism can be seen with a variety of viruses and a widespread seropositivity exists among the population, it has been difficult to establish an association between viral infection and CNS malignancy based on epidemiology alone. While direct evidence of a role of viruses in neuro-oncogenesis in humans is lacking, a more plausible hypothesis of neuro-oncomodulation has been proposed. The overall goals of this review are to summarize the many human investigations that have studied viral infection in primary CNS tumors, discuss potential neuro-oncomodulatory mechanisms of viral-associated CNS disease and propose future research directions to establish a more firm association between chronic viral infections and primary CNS malignancies