A binding pocket for a small molecule inhibitor of HIV-1 entry within the transmembrane helices of CCR5

HIV-1 entry into CD4+ cells requires the sequential interactions of the viral envelope glycoproteins with CD4 and a coreceptor such as the chemokine receptors CCR5 and CXCR4. A plausible approach to blocking this process is to use small molecule antagonists of coreceptor function. One such inhibitor has been described for CCR5: the TAK-779 molecule. To facilitate the further development of entry inhibitors as antiviral drugs, we have explored how TAK-779 acts to prevent HIV-1 infection, and we have mapped its site of interaction with CCR5. We find that TAK-779 inhibits HIV-1 replication at the membrane fusion stage by blocking the interaction of the viral surface glycoprotein gp120 with CCR5. We could identify no amino acid substitutions within the extracellular domain of CCR5 that affected the antiviral action of TAK-779. However, alanine scanning mutagenesis of the transmembrane domains revealed that the binding site for TAK-779 on CCR5 is located near the extracellular surface of the receptor, within a cavity formed between transmembrane helices 1, 2, 3, and 7.

Efficient pyrophosphorolysis by a hepatitis B virus polymerase may be a primer-unblocking mechanism

Effective antiviral agents are thought to inhibit hepatitis B virus (HBV) DNA synthesis irreversibly by chain termination because reverse transcriptases (RT) lack an exonucleolytic activity that can remove incorporated nucleotides. However, since the parameters governing this inhibition are poorly defined, fully delineating the catalytic mechanism of the HBV-RT promises to facilitate the development of antiviral drugs for treating chronic HBV infection. To this end, pyrophosphorolysis and pyrophosphate exchange, two nonhydrolytic RT activities that result in the removal of newly incorporated nucleotides, were characterized by using endogenous avian HBV replication complexes assembled in vivo. Although these activities are presumed to be physiologically irrelevant for every polymerase examined, the efficiency with which they are catalyzed by the avian HBV-RT strongly suggests that it is the first known polymerase to catalyze these reactions under replicative conditions. The ability to remove newly incorporated nucleotides during replication has important biological and clinical implications: these activities may serve a primer-unblocking function in vivo. Analysis of pyrophosphorolysis on chain-terminated DNA revealed that the potent anti-HBV drug β-l-(−)-2′,3′-dideoxy-3′-thiacytidine (3TC) was difficult to remove by pyrophosphorolysis, in contrast to ineffective chain terminators such as ddC. This disparity may account for the strong antiviral efficacy of 3TC versus that of ddC. The HBV-RT pyrophosphorolytic activity may therefore be a novel determinant of antiviral drug efficacy, and could serve as a target for future antiviral drug therapy. The strong inhibitory effect of cytoplasmic pyrophosphate concentrations on viral DNA synthesis may also partly account for the apparent slow rate of HBV genome replication.

RNA virus error catastrophe: Direct molecular test by using ribavirin

RNA viruses evolve rapidly. One source of this ability to rapidly change is the apparently high mutation frequency in RNA virus populations. A high mutation frequency is a central tenet of the quasispecies theory. A corollary of the quasispecies theory postulates that, given their high mutation frequency, animal RNA viruses may be susceptible to error catastrophe, where they undergo a sharp drop in viability after a modest increase in mutation frequency. We recently showed that the important broad-spectrum antiviral drug ribavirin (currently used to treat hepatitis C virus infections, among others) is an RNA virus mutagen, and we proposed that ribavirin's antiviral effect is by forcing RNA viruses into error catastrophe. However, a direct demonstration of error catastrophe has not been made for ribavirin or any RNA virus mutagen. Here we describe a direct demonstration of error catastrophe by using ribavirin as the mutagen and poliovirus as a model RNA virus. We demonstrate that ribavirin's antiviral activity is exerted directly through lethal mutagenesis of the viral genetic material. A 99.3% loss in viral genome infectivity is observed after a single round of virus infection in ribavirin concentrations sufficient to cause a 9.7-fold increase in mutagenesis. Compiling data on both the mutation levels and the specific infectivities of poliovirus genomes produced in the presence of ribavirin, we have constructed a graph of error catastrophe showing that normal poliovirus indeed exists at the edge of viability. These data suggest that RNA virus mutagens may represent a promising new class of antiviral drugs.

Restricted expression of Kaposi sarcoma-associated herpesvirus (human herpesvirus 8) genes in Kaposi sarcoma.

Kaposi sarcoma (KS) is the leading neoplasm of HIV-infected patients and is also found in several HIV-negative populations. Recently, DNA sequences from a novel herpesvirus, termed KS-associated herpesvirus (KSHV), or human herpesvirus 8 (HHV-8) have been identified within KS tissue from both HIV-positive and HIV-negative cases; infection with this agent has been proposed as a possible factor in the etiology or pathogenesis of the tumor. Here we have examined the pattern of KSHV/HHV-8 gene expression in KS and find it to be highly restricted. We identify and characterize two small transcripts that represent the bulk of the virus-specific RNA transcribed from over 120 kb of the KSHV genome in infected cells. One transcript is predicted to encode a small membrane protein; the other is an unusual polyadenylylated RNA that accumulates in the nucleus to high copy number. This pattern of viral gene expression suggests that most infected cells in KS are latently infected, with lytic viral replication likely restricted to a much smaller subpopulation of cells. These findings have implications for the therapeutic utility of currently available antiviral drugs targeted against the lytic replication cycle.

Simian virus 40 late gene expression is regulated by members of the steroid/thyroid hormone receptor superfamily.

Transcription of the late genes of simian virus 40 (SV40) is repressed during the early phase of the lytic cycle of infection of binding of cellular factors, called IBP-s, to the SV40 late promoter; repression is relieved after the onset of viral DNA replication by titration of these repressors. Preliminary data indicated that one of the major components of IBP-s was human estrogen-related receptor 1 (hERR1). We show here that several members of the steroid/thyroid hormone receptor superfamily, including testis receptor 2, thyroid receptor alpha 1 in combination with retinoid X receptor alpha, chicken ovalbumin upstream promoter transcription factors 1 and 2 (COUP-TF1 and COUP-TF2), as well as hERR1, possess the properties of IBP-s. These receptors bind specifically to hormone receptor binding sites present in the SV40 major late promoter. Recombinant COUP-TF1 specifically represses transcription from the SV40 major late promoter in a cell-free transcription system. Expression of COUP-TF1, COUP-TF2, or hERR1 in monkey cells results in repression of the SV40 late promoter, but not the early promoter, in the absence of the virally encoded large tumor antigen. Overexpression of COUP-TF1 leads to a delay in the early-to-late switch in SV40 gene expression during the lytic cycle of infection. Thus, members of this superfamily can play major direct roles in regulating expression of SV40. Possibly, natural or synthetic ligands to these receptors can serve as antiviral drugs. Our findings also provide the basis for the development of assays to screen for the ligands to testis receptor 2 and hERR1.

Proline and pyrrolidine derivatives: new drug cadidates for hepatitis C treatment

The more advantageous hepatitis C virus (HCV) inhibitors (most of them incorporating polysubstituted prolines or pyrrolidines) are detailed in this paper. The improvement of current treatments by combination of antiviral drugs is the driving force of this race to reduce the fast proliferation of this virus. The enhancement of efficiency in short periods of treatment is crucial in the economical point of view and for the hope of all infected people. New protease or polymerase inhibitors have been recently developed in order to substitute the traditional highly toxic PEG-interferon α-2b/ribavirin tandem. The contribution of our group in this field concerns the elaboration of the first and second generation GSK polymerase inhibitors through enantioselective processes based on silver(I)- and gold(I)-catalyzed 1,3-dipolar cycloadditions of azomethine ylides.

Touch of AIDS : A love story

Touch of AIDS: A Love Story is a memoir covering the ten years since my husband, Steven's HIV positive diagnosis in 1987. The story begins when we find our circumstances redefined and our future challenged by the plague of this century. Steven's inability to withstand the toxic effects of the earliest approved antiviral drugs leads us to turn to alternative therapies. After his conversion to AIDS we return to Western medicine but continue on a quest that takes us from Taoist studies at home in Florida to sacred Navajo ceremonies in Arizona. As Steven finds that healing comes in great part from the journey itself and that he is stronger physically, emotionally and spiritually than he was before his HIV diagnosis, I realize that we can live with fear as long as we don't become its victims. Love and hope empower our lives as we live with AIDS.

Stigmatisering - Personers upplevelser av att leva med HIV/AIDS

Bakgrund: HIV är en infektionssjukdom som kan överföras vid bland annat oskyddade samlag, via blod och transplanterad vävnad. Då det idag finns antivirala läkemedel ses HIV inte längre som en dödlig utan en kronisk sjukdom. Personer med HIV/AIDS upplever att sjukdomen påverkar den fysiska och psykiska hälsan negativt. Sjuksköterskor har bristande kunskaper om sjukdomen samt är ovilliga att ge omvårdnad till dessa personer. Syfte: Syftet med litteraturöversikten var att beskriva personers upplevelser av att leva med HIV/AIDS. Metod: Litteraturöversikten baserades på 13 artiklar med kvalitativ design som analyserades enligt Fribergs femstegsmodell. En induktiv ansats användes. Resultat: Huvudtemat stigmatisering identifierades tillsammans med temat transition med tillhörande fem underteman samt temat rädsla med tillhörande tre underteman. Slutsats: Personerna med HIV/AIDS upplevde sig stigmatiserade av närstående, i samhället och i kontakt med hälso- och sjukvården. För att stigmatiseringen ska upphöra behöver sjuksköterskor mer kunskap om HIV/AIDS. För att nå ett personcentrerat förhållningssätt behöver sjuksköterskor se personerna bakom sjukdomen samt medvetandegöra sina attityder och förutfattade meningar mot personerna som lever med HIV/AIDS.

Identification and Characterization of New Small Molecule Inhibitors of Picornavirus Replication

The Picornaviridae family consists of positive-strand RNA viruses that are the causative agents of a variety of diseases in humans and animals. Few drugs targeting picornaviruses are available, making the discovery of new antivirals a high priority. Here, we identified and characterized three compounds from a library of kinase inhibitors that block replication of poliovirus, coxsackievirus B3, and encephalomyocarditis virus. The antiviral effect of these compounds is not likely related to their known cellular targets because other inhibitors targeting the same pathways did not inhibit viral replication. Using an in vitro translation-replication system, we showed that these drugs inhibit different stages of the poliovirus life cycle. A4(1) inhibited the formation of a functional replication complex, while E5(1) and E7(2) affected replication after the replication complex had formed. A4(1) demonstrated partial protection from paralysis in a murine model of poliomyelitis. Poliovirus resistant to E7(2) had a single mutation in the 3A protein. This mutation was previously found to confer resistance to enviroxime-like compounds, which target either PI4KIIIβ (major enviroxime-like compounds) or OSBP (minor enviroxime-like compounds), cellular factors involved in lipid metabolism and shown to be important for replication of diverse positive-strand RNA viruses. We classified E7(2) as a minor enviroxime-like compound, because the localization of OSBP changed in the presence of this inhibitor. Interestingly, both E7(2) and major enviroxime-like compound GW5074 interfered with the viral polyprotein processing. Multiple attempts to isolate resistant mutants in the presence of A4(1) or E5(1) were unsuccessful, showing that effective broad-spectrum antivirals could be developed on the basis of these compounds. Studies with these compounds shed light on pathways shared by diverse picornaviruses that could be potential targets for the development of broad-spectrum antiviral drugs.

Antiviral and antiparasite properties of an L-amino acid oxidase from the Snake Bothrops jararaca: Cloning and identification of a complete cDNA sequence (Retracted article. See vol. 80, pg. 288, 2010)

L-Amino acid oxidases (LAAOs, EC 1.4.3.2) are flavoenzymes that catalyze the stereospecific oxidative deamination of an L-amino acid substrate to the corresponding a-ketoacid with hydrogen peroxide and ammonia production. The present work describes the first report on the antiviral (Dengue virus) and antiprotozoal (trypanocidal and leishmanicide) activities of a Bothrops jararaca L-amino acid oxidase (BjarLAAO-I) and identify its cDNA sequence. Antiparasite effects were inhibited by catalase, suggesting that they are mediated by H(2)O(2) production. Cells infected with DENV-3 virus previously treated with BjarLAAO-I, showed a decrease in viral titer (13-83-fold) when compared with cells infected with untreated viruses. Untreated and treated promastigotes (T. cruzi and L. amazonensis) were observed by transmission electron microscopy with different degrees of damage. Its complete cDNA sequence, with 1452 bp, encoded an open reading frame of 484 amino acid residues with a theoretical molecular weight and pl of 54,771.8 and 5.7, respectively. The cDNA-deduced amino acid sequence of BjarLAAO shows high identity to LAAOs from other snake venoms. Further investigations will be focused on the related molecular and functional correlation of these enzymes. Such a study should provide valuable information for the therapeutic development of new generations of microbicidal drugs. (C) 2008 Elsevier Inc. All rights reserved.

Antiretroviral treatment of adult HIV infection: 2012 recommendations of the International Antiviral Society-USA panel.

CONTEXT: New trial data and drug regimens that have become available in the last 2 years warrant an update to guidelines for antiretroviral therapy (ART) in human immunodeficiency virus (HIV)-infected adults in resource-rich settings. OBJECTIVE: To provide current recommendations for the treatment of adult HIV infection with ART and use of laboratory-monitoring tools. Guidelines include when to start therapy and with what drugs, monitoring for response and toxic effects, special considerations in therapy, and managing antiretroviral failure. DATA SOURCES, STUDY SELECTION, AND DATA EXTRACTION: Data that had been published or presented in abstract form at scientific conferences in the past 2 years were systematically searched and reviewed by an International Antiviral Society-USA panel. The panel reviewed available evidence and formed recommendations by full panel consensus. DATA SYNTHESIS: Treatment is recommended for all adults with HIV infection; the strength of the recommendation and the quality of the evidence increase with decreasing CD4 cell count and the presence of certain concurrent conditions. Recommended initial regimens include 2 nucleoside reverse transcriptase inhibitors (tenofovir/emtricitabine or abacavir/lamivudine) plus a nonnucleoside reverse transcriptase inhibitor (efavirenz), a ritonavir-boosted protease inhibitor (atazanavir or darunavir), or an integrase strand transfer inhibitor (raltegravir). Alternatives in each class are recommended for patients with or at risk of certain concurrent conditions. CD4 cell count and HIV-1 RNA level should be monitored, as should engagement in care, ART adherence, HIV drug resistance, and quality-of-care indicators. Reasons for regimen switching include virologic, immunologic, or clinical failure and drug toxicity or intolerance. Confirmed treatment failure should be addressed promptly and multiple factors considered. CONCLUSION: New recommendations for HIV patient care include offering ART to all patients regardless of CD4 cell count, changes in therapeutic options, and modifications in the timing and choice of ART in the setting of opportunistic illnesses such as cryptococcal disease and tuberculosis.

Antiviral therapy against chronic hepatitis B in Brazil: high rates of lamivudine resistance mutations and correlation with HBV genotypes

The effectiveness of antiviral treatments of chronic hepatitis B has been poorly studied in Brazil. Here, hepatitis B virus (HBV) DNA positivity, drug resistance mutations and their association with HBV genotypes were evaluated in chronically HBV-infected patients under different drug regimens in Brazil. The study involved 129 patients under interferon or nucleos(t)ide analogue therapy for a median treatment time of 12 months. One hundred and five (81%) of these patients were treated with lamivudine (LAM), either in monotherapy or in combination with newer drugs, such as entecavir (ETV) or tenofovir (TDF). High (37.5-100%) rates of HBV DNA positivity were observed with all but one drug regimen (LAM + ETV). However, patients that were treated with ETV alone, TDF alone or with LAM combination therapies had a mean viral load that was 3-4 log lower than patients treated with LAM monotherapy. Of the patients treated with LAM, 47% developed resistance mutations. HBV genotypes A (59.1%), D (30.3%) and F (9.1%) were found. There was no association between the presence of LAM resistance mutations and genotypes, HBeAg status or treatment duration. Nevertheless, the rtM204V mutation was observed more frequently (12/13, 92%) in genotype A than in the others (p = 0.023). Six out of nine isolates that contained the rtM204I mutation belonged to genotype D and half of them displayed a single mutation. Genotype D isolates with the rtM204V variant preferentially displayed a triple mutation, while genotype A preferentially displayed a double mutation (p = 0.04).

Oseltamivir-resistant influenza A(H1N1)pdm2009 strains found in Brazil are endowed with permissive mutations, which compensate the loss of fitness imposed by antiviral resistance

The 2009 pandemic influenza A virus outbreak led to the systematic use of the neuraminidase (NA) inhibitor oseltamivir (OST). Consequently, OST-resistant strains, carrying the mutation H275Y, emerged in the years after the pandemics, with a prevalence of 1-2%. Currently, OST-resistant strains have been found in community settings, in untreated individuals. To spread in community settings, H275Y mutants must contain additional mutations, collectively called permissive mutations. We display the permissive mutations in NA of OST-resistant A(H1N1)pdm09 virus found in Brazilian community settings. The NAs from 2013 are phylogenetically distinct from those of 2012, indicating a tendency of positive selection of NAs with better fitness. Some previously predicted permissive mutations, such as V241I and N369K, found in different countries, were also detected in Brazil. Importantly, the change D344N, also predicted to compensate loss of fitness imposed by H275Y mutation, was found in Brazil, but not in other countries in 2013. Our results reinforce the notion that OST-resistant A(H1N1)pdm09 strains with compensatory mutations may arise in an independent fashion, with samples being identified in different states of Brazil and in different countries. Systematic circulation of these viral strains may jeopardise the use of the first line of anti-influenza drugs in the future.

Cost effectiveness of a new combined immunosuppressive and antiviral regimen on the one-year follow-up of kidney transplant patients.

Background: Medical prescription after organ transplant must prevent both rejection and infectious complications. We assessed the 1-year effectiveness and cost of introducing a new combined regimen in kidney transplantation. Methods: Patients transplanted from January 2000 to March 2003 (Period 1) were compared to patients transplanted from April 2003 to July 2005 (Period 2). In period 1, patients were treated with Basiliximab, Cyclosporin, steroids and Mycophenolate (MMF) or Azathioprine. Prophylaxis with Valacyclovir was prescribed only in CMV D+/R- patients. In period 2, immunosuppressive drugs were Basiliximab, Tacrolimus, steroids and MMF. A 3-month universal CMV prophylaxis with Valganciclovir was used. Medical charts of outpatient visits allowed identifying drug, laboratory and radiological tests use, and hospital information system causes of hospitalisation and length of stay (LOS) over the first year after transplant. Patients with incomplete costs data were excluded. Results: 53 patients were analysed in period 1, and 60 in period 2. CMV serostatus patterns were not significantly different between the 2 periods. Over 12 months, acute rejection decreased from 22 patients (42%) in period 1 to 4 patients (7%) in period 2 (p<0.001), and CMV infection from 25 patients (47%) to 9 patients (15%, p<0.001). Average total rehospitalisation LOS decreased from 28±19 to 20±11 days (p<0.007). Average outpatient visits decreased from 49±10 to 39±8 (p<0.001). Average immunosuppression and CMV prophylaxis costs increased from US$ 18,362±6,546 to 24,637±5,457 (p<0.001), while average graft rejection costs decreased form US$ 4,135±9,164 to 585±2,850 (p=0.005), and average CMV treatment costs from US$ 2,043±5,545 to 91±293 (p=0.008). Average outpatient visits costs decreased from US$ 7,619±1,549 to 6,074±1,043 (p<0.001), and other hospital costs from US$ 3,801±6,519 to 1,196±3,146 (p=0.007). Altogether, average 1-year treatment costs decreased from US$ 35,961±14,916 to 32,584±6,211 (p=0.115). Cost-effectiveness ratios to avoid graft rejection and CMV infection decreased from US$ 61,482±9,292 to 34,911± 1,639 (p=0.006) and US$ 68,070±11,122 to 39,899±2,650 (p=0.015), respectively. Conclusion: The new combined regimen administered in period 2 was significantly more effective. Its additional cost was more than offset by savings linked with complications avoidance.

Targeting the proteolytic processing of the viral glycoprotein precursor is a promising novel antiviral strategy against arenaviruses.

A crucial step in the arenavirus life cycle is the biosynthesis of the viral envelope glycoprotein (GP) responsible for virus attachment and entry. Processing of the GP precursor (GPC) by the cellular proprotein convertase site 1 protease (S1P), also known as subtilisin-kexin-isozyme 1 (SKI-1), is crucial for cell-to-cell propagation of infection and production of infectious virus. Here, we sought to evaluate arenavirus GPC processing by S1P as a target for antiviral therapy using a recently developed peptide-based S1P inhibitor, decanoyl (dec)-RRLL-chloromethylketone (CMK), and the prototypic arenavirus lymphocytic choriomeningitis virus (LCMV). To control for off-target effects of dec-RRLL-CMK, we employed arenavirus reverse genetics to introduce a furin recognition site into the GPC of LCMV. The rescued mutant virus grew to normal titers, and the processing of its GPC critically depended on cellular furin, but not S1P. Treatment with the S1P inhibitor dec-RRLL-CMK resulted in specific blocking of viral spread and virus production of LCMV. Combination of the protease inhibitor with ribavirin, currently used clinically for treatment of human arenavirus infections, resulted in additive drug effects. In cells deficient in S1P, the furin-dependent LCMV variant established persistent infection, whereas wild-type LCMV underwent extinction without the emergence of S1P-independent escape variants. Together, the potent antiviral activity of an inhibitor of S1P-dependent GPC cleavage, the additive antiviral effect with ribavirin, and the low probability of emergence of S1P-independent viral escape variants make S1P-mediated GPC processing by peptide-derived inhibitors a promising strategy for the development of novel antiarenaviral drugs.