Role of potassium in human immunodeficiency virus production and cytopathic effects

Regulatory effects of potassium channel blockers on potassium channel genes upon nervous necrosis virus infection in sevenband grouper Hyporthodus septumfasciatus

Ion channels in fishes regulate the flow of important ions that play an active role in the excitation and transmission of impulses through neuronal cells. Specific housekeeping genes translates into proteins and selectively permeabilize and facilitate ion crossover transmissions. Potassium (K+) channels play a crucial role in a wide range of functions such as cell volume regulation, hormone secretion, synaptic transmission and muscle contraction. The dysfunction of ion channels result in channelopathies, which hinder critical cellular activities. Recent studies have indicated that viral pathogens tend to regulate cellular ion channels for entry into host cells. Hence, the present study aimed to elucidate the role of K+ channels during nervous necrosis virus (NNV) infections in the sevenband grouper (Hyporthodus septumfasciatus). Real-time PCR with the standardized potassium genes revealed the downregulation of potassium two pore domain channel subfamily member - KCNK10, KCNK9, KCNK2, and KCNK1 genes post infection at both 17 °C and 25 °C whereas an upregulation was noted in the case of gill tissues. SMART analysis revealed a transmembrane region in all genes. Multiple sequence alignment using MultAlin and phylogenetic analysis revealed true homology of potassium genes with other higher vertebrates. In vitro and in vivo challenge study of NNV using Tetra ethyl ammonium (TEA) as potential drug showed inverse relation to that of viral replication and a corresponding downregulation of K+ channel gene expression was observed which was further confirmed by an immunofluorescence assay. These findings indicate that K+ channels play a crucial role during viral infection. Moreover, the observed downregulation can be related to rapid endocytosis resulting from recycling endosomes during a viral infection. Hence, further studies are warranted to better understand the role of K+ channel genes during NNV infection.

Broad spectrum post-entry inhibitors of coronavirus replication: Cardiotonic steroids and monensin

A small molecule screen identified several cardiotonic steroids (digitoxin and ouabain) and the ionophore monensin as potent inhibitors of HCoV-229E, HCoV-OC43, and SARS-CoV-2 replication with EC50s in the low nM range. Subsequent tests confirmed antiviral activity in primary cell models including human nasal epithelial cells and lung organoids. Addition of digitoxin, ouabain, or monensin strongly reduced viral gene expression as measured by both viral protein and RNA accumulation. Furthermore, the compounds acted post virus entry. While the antiviral activity of digitoxin was dependent upon activation of the MEK and JNK signaling pathways but not signaling through GPCRs, the antiviral effect of monensin was reversed upon inhibition of several signaling pathways. Together, the data demonstrates the potent anti-coronavirus properties of two classes of FDA approved drugs that function by altering the properties of the infected cell, rendering it unable to support virus replication.

A cohort-based study of host gene expression: tumor suppressor and innate immune/inflammatory pathways associated with the HIV reservoir size

The major barrier to an HIV cure is the HIV reservoir: latently-infected cells that persist despite effective antiretroviral therapy (ART). There have been few cohort-based studies evaluating host genomic or transcriptomic predictors of the HIV reservoir. We performed host RNA sequencing and HIV reservoir quantification (total DNA [tDNA], unspliced RNA [usRNA], intact DNA) from peripheral CD4+ T cells from 191 ART-suppressed people with HIV (PWH). After adjusting for nadir CD4+ count, timing of ART initiation, and genetic ancestry, we identified two host genes for which higher expression was significantly associated with smaller total DNA viral reservoir size, P3H3 and NBL1, both known tumor suppressor genes. We then identified 17 host genes for which lower expression was associated with higher residual transcription (HIV usRNA). These included novel associations with membrane channel (KCNJ2, GJB2), inflammasome (IL1A, CSF3, TNFAIP5, TNFAIP6, TNFAIP9, CXCL3, CXCL10), and innate immunity (TLR7) genes (FDR-adjusted q<0.05). Gene set enrichment analyses further identified significant associations of HIV usRNA with TLR4/microbial translocation (q = 0.006), IL-1/NRLP3 inflammasome (q = 0.008), and IL-10 (q = 0.037) signaling. Protein validation assays using ELISA and multiplex cytokine assays supported these observed inverse host gene correlations, with P3H3, IL-10, and TNF-α protein associations achieving statistical significance (p<0.05). Plasma IL-10 was also significantly inversely associated with HIV DNA (p = 0.016). HIV intact DNA was not associated with differential host gene expression, although this may have been due to a large number of undetectable values in our study. To our knowledge, this is the largest host transcriptomic study of the HIV reservoir. Our findings suggest that host gene expression may vary in response to the transcriptionally active reservoir and that changes in cellular proliferation genes may influence the size of the HIV reservoir. These findings add important data to the limited host genetic HIV reservoir studies to date.

High Levels of Extracellular Potassium Can Delay Myxoma Virus Replication by Preventing Release of Virions from the Endosomes

Potassium (K+) is one of the most abundant cations in the human body. Under normal conditions, the vast majority of K+ is found within cells, and the extracellular [K+] is tightly regulated to within 3.0 to 5.0 mM. However, it has recently been shown that high levels of localized necrosis can increase the extracellular concentration of K+ to above 50 mM. This raises the possibility that elevated extracellular K+ might influence a variety of biological processes that occur within regions of necrotic tissue. For example, K+ has been shown to play a central role in the replication cycles of numerous viral families, and in cases of lytic infection, localized regions containing large numbers of necrotic cells can be formed. Here, we show that the replication of the model poxvirus myxoma virus (MYXV) is delayed by elevated levels of extracellular K+. These increased K+ concentrations alter the cellular endocytic pathway, leading to increased phagocytosis but a loss of endosomal/lysosomal segregation. This slows the release of myxoma virus particles from the endosomes, resulting in delays in genome synthesis and infectious particle formation as well as reduced viral spread. Additionally, mathematical modeling predicts that the extracellular K+ concentrations required to impact myxoma virus replication can be reached in viral lesions under a variety of conditions. Taken together, these data suggest that the extracellular [K+] plays a role in determining the outcomes of myxoma infection and that this effect could be physiologically relevant during pathogenic infection. IMPORTANCE Intracellular K+ homeostasis has been shown to play a major role in the replication of numerous viral families. However, the potential impact of altered extracellular K+ concentrations is less well understood. Our work demonstrates that increased concentrations of extracellular K+ can delay the replication cycle of the model poxvirus MYXV by inhibiting virion release from the endosomes. Additionally, mathematical modeling predicts that the levels of extracellular K+ required to impact MYXV replication can likely be reached during pathogenic infection. These results suggest that localized viral infection can alter K+ homeostasis and that these alterations might directly affect viral pathogenesis.

Differences in expression of tumor suppressor, innate immune, inflammasome, and potassium/gap junction channel host genes significantly predict viral reservoir size during treated HIV infection

The major barrier to an HIV cure is the persistence of infected cells that evade host immune surveillance despite effective antiretroviral therapy (ART). Most prior host genetic HIV studies have focused on identifying DNA polymorphisms (e.g., CCR5Δ32 , MHC class I alleles) associated with viral load among untreated "elite controllers" (~1% of HIV+ individuals who are able to control virus without ART). However, there have been few studies evaluating host genetic predictors of viral control for the majority of people living with HIV (PLWH) on ART. We performed host RNA sequencing and HIV reservoir quantification (total DNA, unspliced RNA, intact DNA) from peripheral CD4+ T cells from 191 HIV+ ART-suppressed non-controllers. Multivariate models included covariates for timing of ART initiation, nadir CD4+ count, age, sex, and ancestry. Lower HIV total DNA (an estimate of the total reservoir) was associated with upregulation of tumor suppressor genes NBL1 (q=0.012) and P3H3 (q=0.012). Higher HIV unspliced RNA (an estimate of residual HIV transcription) was associated with downregulation of several host genes involving inflammasome ( IL1A, CSF3, TNFAIP5, TNFAIP6, TNFAIP9 , CXCL3, CXCL10 ) and innate immune ( TLR7 ) signaling, as well as novel associations with potassium ( KCNJ2 ) and gap junction ( GJB2 ) channels, all q<0.05. Gene set enrichment analyses identified significant associations with TLR4/microbial translocation (q=0.006), IL-1β/NRLP3 inflammasome (q=0.008), and IL-10 (q=0.037) signaling. HIV intact DNA (an estimate of the "replication-competent" reservoir) demonstrated trends with thrombin degradation ( PLGLB1 ) and glucose metabolism ( AGL ) genes, but data were (HIV intact DNA detected in only 42% of participants). Our findings demonstrate that among treated PLWH, that inflammation, innate immune responses, bacterial translocation, and tumor suppression/cell proliferation host signaling play a key role in the maintenance of the HIV reservoir during ART. Further data are needed to validate these findings, including functional genomic studies, and expanded epidemiologic studies in female, non-European cohorts.

Author Summary

Although lifelong HIV antiretroviral therapy (ART) suppresses virus, the major barrier to an HIV cure is the persistence of infected cells that evade host immune surveillance despite effective ART, "the HIV reservoir." HIV eradication strategies have focused on eliminating residual virus to allow for HIV remission, but HIV cure trials to date have thus far failed to show a clinically meaningful reduction in the HIV reservoir. There is an urgent need for a better understanding of the host-viral dynamics during ART suppression to identify potential novel therapeutic targets for HIV cure. This is the first epidemiologic host gene expression study to demonstrate a significant link between HIV reservoir size and several well-known immunologic pathways (e.g., IL-1β, TLR7, TNF-α signaling pathways), as well as novel associations with potassium and gap junction channels (Kir2.1, connexin 26). Further data are needed to validate these findings, including functional genomic studies and expanded epidemiologic studies in female, non-European cohorts.

The role of ion channels in immune-related diseases

Ion channel is an integral membrane protein that allows the permeation of charge ions across hydrophobic phospholipid membranes, including plasma membranes and organelle membranes (such as mitochondria, endoplasmic reticulum and vacuoles), which are widely distributed in various cells and tissues, such as cardiomyocytes, smooth muscle cells, and nerve cells. Ion channels establish membrane potential by regulating ion concentration and membrane potential. Membrane potential plays an important role in cells. Studies have shown that ion channels play a role in a number of immune-related diseases caused by functional defects in ion channels on immune or non-immune cells in major human organs, usually affecting specific organs or multiple organs. The present review discusses the relationship between ion channels and immune diseases in major organs of the human body.

Inflammasomes in T cells

The concept of non-self recognition through germ-line encoded pattern recognition receptors (PRRs) has been well-established for professional innate immune cells. However, there is growing evidence that also T cells employ PRRs and associated effector functions in response to certain non-self or damage signals. Inflammasomes constitute a special subgroup of PRRs that is hardwired to a signaling cascade that culminates in the activation of caspase-1. Active caspase-1 processes pro-inflammatory cytokines of the IL-1 family and also triggers a lytic programmed cell death pathway known as pyroptosis. An increasing body of literature suggests that inflammasomes are also functional in T cells. On the one hand, conventional inflammasome signaling cascades have been described that operate similarly to pathways characterized in innate immune cells. On the other hand, unconventional functions have been suggested, in which certain inflammasome components play a role in unrelated processes, such as cell fate decisions and functions of T helper cells. In this review, we discuss our current knowledge on inflammasome functions in T cells and the biological implications of these findings for health and disease.

Trends and Adaptive Optimal Set Points of CD4+ Count Clinical Covariates at Each Phase of the HIV Disease Progression

In response to invasion by the human immunodeficiency virus (HIV), the self-regulatory immune system attempts to restore the CD4+ count fluctuations. Consequently, many clinical covariates are bound to adapt too, but little is known about their corresponding new optimal set points. It has been reported that there exist few strongest clinical covariates of the CD4+ count. The objective of this study is to harness them for a streamlined application of multidimensional viewing lens (statistical models) to zoom into the behavioural patterns of the adaptive optimal set points. We further postulated that the optimal set points of some of the strongest covariates are possibly controlled by dietary conditions or otherwise to enhance the CD4+ count. This study investigated post-HIV infection (acute to therapy phases) records of 237 patients involving repeated measurements of 17 CD4+ count clinical covariates that were found to be the strongest. The overall trends showed either downwards, upwards, or irregular behaviour. Phase-specific trends were mostly different and unimaginable, with LDH and red blood cells producing the most complex CD4+ count behaviour. The approximate optimal set points for dietary-related covariates were total protein 60-100 g/L (acute phase), <85 g/L (early phase), <75 g/L (established phase), and >85 g/L (ART phase), whilst albumin approx. 30-50 g/L (acute), >45 g/L (early and established), and <37 g/L (ART). Sodium was desirable at approx. <45 mEq/L (acute and early), <132 mEq/L (established), and >134 mEq/L (ART). Overall, desirable approximates were albumin >42 g/L, total protein <75 g/L, and sodium <137 mEq/L. We conclude that the optimal set points of the strongest CD4+ count clinical covariates tended to drift and adapt to either new ranges or overlapped with the known reference ranges to positively influence the CD4+ cell counts. Recommendation for phase-specific CD4+ cell count influence in adaptation to HIV invasion includes monitoring of the strongest covariates related to dietary conditions (sodium, albumin, and total protein), tissue oxygenation (red blood cells and its haematocrit), and hormonal control (LDH and ALP).

An Evaluation to Determine the Strongest CD4 Count Covariates during HIV Disease Progression in Women in South Africa

INTRODUCTION

Past endeavours to deal with the obstacle of expensive Cluster of Difference 4 (CD4+) count diagnostics in resource-limited settings have left a long trail of suggested continuous CD4+ count clinical covariates that turned out to be a potentially important integral part of the human immunodeficiency virus (HIV) treatment process during disease progression. However, an evaluation to determine the strongest candidates among these CD4+ count covariates has not been well documented.

METHODS

The Centre for the AIDS Programme of Research in South Africa (CAPRISA) initially enrolled HIV-negative (phase 1) patients into different study cohorts. The patients who seroconverted (237) during follow-up care were enrolled again into a post-HIV infection cohort where they were further followed up with weekly to fortnightly visits up to 3 months (phase 2: acute infection), monthly visits from 3-12 months (phase 3: early infection) and quarterly visits thereafter (phase 4: established infection) until antiretroviral therapy (ART) initiation (phase 5). The CD4+ count and 46 covariates were repeatedly measured at each phase of the HIV disease progression. A multilevel partial least squares approach was applied as a variable reduction technique to determine the strongest CD4+ count covariates.

RESULTS

Only 18 of the 46 investigated clinical attributes were the strongest CD4+ count covariates and the top 8 were positively and independently associated with the CD4+ count. Besides the confirmatory lymphocytes, these were basophils, albumin, haematocrit, alkaline phosphatase (ALP), mean corpuscular volume (MCV), platelets, potassium and monocytes. Overall, electrolytes, proteins and red blood cells were the dominant categories for the strongest covariates.

CONCLUSION

Only a few of the many previously suggested continuous CD4+ count clinical covariates showed the potential to become an important integral part of the treatment process. Prolonging the pre-treatment period of the HIV disease progression by effectively incorporating and managing the covariates for long-term influence on the CD4+ cell response has the potential to delay challenges associated with ART side effects.

Covariate random effects on the CD4 count variation during HIV disease progression in women

Purpose: To investigate the variation in CD4 count between HIV positive patients due to clinical covariates at each phase of the HIV disease progression. Patients and methods: The Centre for the AIDS Programme of Research in South Africa (CAPRISA) conducted different studies in which female patients were initially enrolled in HIV negative cohorts (phase 1). Seroconverts were further followed-up weekly to fortnightly visits up to 3 months (phase 2: acute infection), monthly visits from 3 to 12 months (phase 3: early infection), quarterly visits thereafter (phase 4: established infection) until antiretroviral therapy (ART) initiation (phase 5). Results: Eighteen out of the 46 CD4 count covariates investigated were significant. Low average CD4 counts at acute and early phase entry improved at a faster rate than entries at higher average CD4 count. During therapy, all the 18 covariates induced significantly different patients' average CD4 counts. The rate of change of CD4 count greatly varied in response to lactate dehydrogenase during the acute phase. Red blood cells increase resulted in the patients' CD4 counts approaching a common higher level during the early phase. During therapy, the already high CD4 counts improved faster than lower ones in response to the red blood cells increase. As the monocytes increased, patients with lower average CD4 counts became worse than those with higher average CD4 counts. Conclusion: Changes in the covariates measurements either induced no variation effects in certain phases or improved the CD4 count at a faster rate for those patients whose average CD4 was already high or worsen the CD4 level which was already low or caused the patients' CD4 counts to approach the same level - higher or lower than the general cohort. The studied covariates induced wide variations in the CD4 count between HIV positive patients during the ART phase.

G protein-coupled and ATP-sensitive inwardly rectifying potassium ion channels are essential for HIV entry

The high genetic diversity of Human Immunodeficiency virus (HIV), has hindered the development of effective vaccines or antiviral drugs against it. Hence, there is a continuous need for identification of new antiviral targets. HIV exploits specific host proteins also known as HIV-dependency factors during its replication inside the cell. Potassium channels play a crucial role in the life cycle of several viruses by modulating ion homeostasis, cell signaling, cell cycle, and cell death. In this study, using pharmacological tools, we have identified that HIV utilizes distinct cellular potassium channels at various steps in its life cycle. Members of inwardly rectifying potassium (Kir) channel family, G protein-coupled (GIRK), and ATP-sensitive (KATP) are involved in HIV entry. Blocking these channels using specific inhibitors reduces HIV entry. Another member, Kir 1.1 plays a role post entry as inhibiting this channel inhibits virus production and release. These inhibitors are not toxic to the cells at the concentration used in the study. We have further identified the possible mechanism through which these potassium channels regulate HIV entry by using a slow-response potential-sensitive probe DIBAC4(3) and have observed that blocking these potassium channels inhibits membrane depolarization which then inhibits HIV entry and virus release as well. These results demonstrate for the first time, the important role of Kir channel members in HIV-1 infection and suggest that these K+ channels could serve as a safe therapeutic target for treatment of HIV/AIDS.

Oral epithelial changes in HIV-positive individuals

HIV infections frequently affect the oral cavity, and local changes may be utilized as indicators of immunosuppression in HIV-positive patients. Morphometric and morphological features of the lining, masticatory, and specialized epithelium of the oral mucosa were studied in 12 HIV-positive and 12 HIV-negative patients autopsied from 2007 to 2010. Mucosal samples from the cheek, gingival, and tongue of 24 individuals were fixed in Carnoy solution and stained with hematoxylin-eosin. Various morphometric characteristics (epithelial thickness, number of cell layers, mean cell diameter) and morphological parameters (basal layer hyperplasia, exocytosis of inflammatory cells, glycogenic acanthosis, cell ballooning degeneration) were then measured. The HIV-positive group had a greater epithelial thickness (mean: 304.4μm) and a higher mean cell diameter (11.84μm), whereas the HIV-negative group had more epithelial layers (26.7). Basal layer hyperplasia did not differ significantly between the two groups, but exocytosis of inflammatory cells, glycogenic acanthosis, cell ballooning, and spongiosis were more prevalent in the HIV-positive group. Our findings demonstrate that HIV infection causes diverse epithelial changes in the oral cavity, including thickening, increased cell diameter, increased migration of inflammatory cells, and inter- and intra-cellular edema.

Morphological and immunological changes in the skin of autopsied women with AIDS

Acquired immunodeficiency syndrome (AIDS) is characterized by decreased immunity, making a patient more susceptible to opportunistic infections which can have cutaneous manifestations. The aim of this study was to evaluate the local immunity of the skin through morphological and immunohistochemical analysis. Skin samples of 52 women, 27 without AIDS and 25 with AIDS, autopsied in an academic referral hospital in Brazil were evaluated. The autopsy reports and medical records were reviewed, and histochemical Hematoxylin-eosin, Picrosirius red, and Verhoeff stains as well as morphometric (Image J and KS-300 Kontron-Zeiss) and immunohistochemical (S-100 and anti-IgA) analyses of the skin were performed. Women with AIDS presented a thinner epidermis than women without AIDS (33.33 [12.00-317.66] vs 67.42 [12.00-530.02] μm; p < 0.001), with a lower number of epithelial cell layers (4.00 [2.00-11.00] vs 4.00 [2.00-16.00]; p < 0.001), a smaller cell diameter (12.92 [6.00-28.87] vs 24.32 [6.00-33.12] μm; p < 0.001), and a lower number of Langerhans cells (LC) (12.58 [0.00-81.74] vs 31.44 [0.00-169.77] LC/mm(2); p < 0.001). The dermis contained more collagen fibers (8.20 % [2.40-19.40] vs 6.30 % [0.40-13.90]; p < 0.001). Some of these parameters were negatively correlated with viral load and positively correlated with the number of CD4+ T-lymphocytes. We conclude that a decrease of the local skin immunity in women with AIDS may contribute to the development of skin lesions.

The influence of gender and of AIDS on the immunity of autopsied patients' esophagus

Previous studies have shown that males who have AIDS are more frequently affected by infectious diseases than females. The esophagus is the organ in the digestive tube that is more commonly affected by opportunistic infections during the syndrome. The aim of this study was to assess the influence of AIDS and of gender on local immunity of the esophageal epithelium. Fragments of the esophagus from 29 autopsied women and 37 autopsied men were collected at a university hospital from 1980 to 2009 and were divided in groups with and without AIDS. The IgA-, IgG-, and IgM-positive cells and Langerhans cells (LCs) were immunostained, respectively, with anti-IgA, anti-IgG, anti-IgM, and anti-S100. The software Image J was used to measure the esophageal epithelium and to count the epithelium cellular layers. Patients with AIDS, apart from gender, showed an increase in IgA-, IgG-, and IgM-positive cells and a reduction of Langerhans cells, in thickness and in number of cellular layers in the esophageal epithelium. However, among individuals with AIDS, men presented lower secretory expression of IgA-, IgG-, and IgM-positive cells than women and more intense reduction of LCs. Women have naturally presented better local esophageal immunity than men. Although AIDS possibly causes immunological and morphological alterations in the esophageal epithelium in both genders, women have better esophageal immunity, which may explain a greater frequency of hospital admissions due to infection of men with AIDS when compared with women.

Alterations in intracellular potassium concentration by HIV-1 and SIV Nef

Background

HIV-1 mediated perturbation of the plasma membrane can produce an alteration in the transmembrane gradients of cations and other small molecules leading to cell death. Several HIV-1 proteins have been shown to perturb membrane permeability and ion transport. Xenopus laevis oocytes have few functional endogenous ion channels, and have proven useful as a system to examine direct effects of exogenously added proteins on ion transport.

Results

HIV-1 Nef induces alterations in the intracellular potassium concentration in CD4+ T-lymphoblastoid cells, but not intracellular pH. Two electrode voltage-clamp recording was used to determine that Nef did not form ion channel-like pores in Xenopus oocytes.

Conclusion

These results suggest that HIV-1 Nef regulates intracellular ion concentrations indirectly, and may interact with membrane proteins such as ion channels to modify their electrical properties.

Viroporin potential of the lentivirus lytic peptide (LLP) domains of the HIV-1 gp41 protein

Background

Mechanisms by which HIV-1 mediates reductions in CD4+ cell levels in infected persons are being intensely investigated, and have broad implications for AIDS drug and vaccine development. Virally induced changes in membrane ionic permeability induced by lytic viruses of many families contribute to cytopathogenesis. HIV-1 induces disturbances in plasma membrane ion transport. The carboxyl terminus of TM (gp41) contains potential amphipathic α-helical motifs identified through their structural similarities to naturally occurring cytolytic peptides. These sequences have been dubbed lentiviral lytic peptides (LLP) -1, -2, and -3.

Results

Peptides corresponding to the LLP domains (from a clade B virus) partition into lipid membranes, fold into α-helices and disrupt model membrane permeability. A peptide corresponding to the LLP-1 domain of a clade D HIV-1 virus, LLP-1D displayed similar activity to the LLP-1 domain of the clade B virus in all assays, despite a lack of amino acid sequence identity.

Conclusion

These results suggest that the C-terminal domains of HIV-1 Env proteins may form an ion channel, or viroporin. Increased understanding of the function of LLP domains and their role in the viral replication cycle could allow for the development of novel HIV drugs.

Cytopathic mechanisms of HIV-1

The human immunodeficiency virus type 1 (HIV-1) has been intensely investigated since its discovery in 1983 as the cause of acquired immune deficiency syndrome (AIDS). With relatively few proteins made by the virus, it is able to accomplish many tasks, with each protein serving multiple functions. The Envelope glycoprotein, composed of the two noncovalently linked subunits, SU (surface glycoprotein) and TM (transmembrane glycoprotein) is largely responsible for host cell recognition and entry respectively. While the roles of the N-terminal residues of TM is well established as a fusion pore and anchor for Env into cell membranes, the role of the C-terminus of the protein is not well understood and is fiercely debated. This review gathers information on TM in an attempt to shed some light on the functional regions of this protein.

Ionic Contra-Viral Therapy (ICVT); a new approach to the treatment of DNA virus infections

The sequestration of cellular K(+) has been shown elsewhere to elicit a broad spectrum of antiviral activity. The obligatory, coupled cotransports of Na(+), K(+) and Cl(-) (NKCC1) and of Na(+) and K(+) (NKATPase) effect net cellular K(+) influx. We examined the effects of specific inhibitors of these transports; a cardiac glycoside (Digoxin) and a loop diuretic (Furosemide) on virus replication in vitro. The replication of the DNA viruses, herpes simplex virus, varicella zoster virus, human cytomegalovirus and adenovirus was inhibited. There was normal replication of the RNA virus encephalomyocarditis virus. Antiviral activities of both drugs were influenced by extracellular K(+). Antiviral effects were most potent when Digoxin and Furosemide were used in combination. Targeting the host cell in this way is fundamentally different to other antiviral drug developments to date and we propose the descriptive term Ionic Contra Viral Therapy (ICVT) for the purpose of definition. We believe that specific inhibitors of coupled K(+) transports merit controlled clinical trial for a broad spectrum of DNA virus infections by local application.

HCV RNA levels in hepatocellular carcinomas and adjacent non-tumorous livers

To determine the antiviral effects of drugs targeted to hepatitis C virus (HCV) in chronic hepatitis patients, an accurate quantitative method with high sensitivity is needed. Reverse transcription nested polymerase chain reaction (RT-PCR) is the most sensitive method for the detection of HCV sequences in clinical specimens. However, this method is not quantitative. For this purpose, a quantitative competitive assay was developed that combines RT and PCR followed by image analysis to quantify HCV RNA. This assay targets the highly conserved 5' non-coding region of HCV and is based on the co-amplification of wild type HCV RNA with known amounts of mutant synthetic RNA. The mutant internal control used in these experiments differs from the wild type RNA by two nucleotide substitutions, which introduces an internal restriction enzyme site. In this report, this method was used to determine the levels of positive strand RNA in 11 HCV positive hepatocellular carcinomas (HCC) and compared these with adjacent non-tumorous liver tissue. To confirm that the difference in viral titers is not related to variations in the amount of RNA used in the assay, glyceraldehyde 3-phosphate dehydrogenase (GAPDH) mRNA was also assessed by competitive RT-PCR in all tissue extracts. Using this competitive assay it was determined that HCV RNA levels in the liver and tumor samples ranged from 10(3) to 10(6) molecules per microg of total RNA which is similar to previous reports. Interestingly, the amount of HCV in all the non-tumorous liver specimens were found to be significantly higher (P<0.05) than the surrounding tumors, while the GAPDH mRNA levels were found to be similar in both liver and tumor. Competitive RT-PCR is a sensitive, accurate and reliable method to determine HCV titers in clinical specimens. Using this method it was determined that malignant tumor cells harbor less HCV as compared with the surrounding non-tumorous liver cells.