The use of oral ganciclovir in the treatment of cytomegalovirus retinitis in patients with AIDS.

OBJECTIVE: To recommend the appropriate use of oral ganciclovir as an alternative to intravenous (i.v.) maintenance therapy for cytomegalovirus (CMV) retinitis in patients with AIDS. OPTIONS: i.v. infusion of ganciclovir and foscarnet have been the only approved choices for maintenance therapy until the introduction of oral ganciclovir. OUTCOMES: Ease of administering maintenance therapy and improved quality of life for patients with AIDS. VALUES: The medical advisory group comprised physicians treating patients with AIDS therapy. Ease of administration of maintenance therapy and quality of patients'' lives were considered important. BENEFITS, HARMS AND COSTS: Oral ganciclovir is a safe and convenient alternative to i.v. maintenance therapy for patients with CMV retinitis. However, its low bio-availability precludes its use for induction therapy and necessitates careful monitoring for compliance. Compared with i.v. administration of ganciclovir, oral maintenance therapy is cost effective. EVIDENCE: Evidence for the guidelines was gathered from data presented at a symposium on CMV retinitis and oral ganciclovir, clinical trials of oral ganciclovir and input from a visiting expert. It was presented at a meeting of the advisory board whose members are involved in the care of patients with AIDS and the management of CMV retinitis. The guidelines were approved by each member of the advisory board. RECOMMENDATIONS: Diagnosis, treatment and follow-up of CMV retinitis should always be in consultation with an ophthalmologist who is experienced in treating this disease. The patient should be fully informed about the limitations of the oral form of ganciclovir; he or she should be involved in decision making and carefully monitored. Oral ganciclovir should not be used for induction therapy or for maintenance therapy in high-risk patients. VALIDATION: Similar guidelines have been produced in England where the drug has been available since January 1995. SPONSOR: The deliberations of the advisory board and the preparation of this report were funded through an educational grant from Hoffmann-La Roche (Canada).     

A three-nucleotide deletion in the UL97 open reading frame is responsible for the ganciclovir resistance of a human cytomegalovirus clinical isolate.

Multiple human cytomegalovirus (HCMV) strains frequently coexist in patients with AIDS, and chronic ganciclovir treatment may favor the emergence of ganciclovir-resistant viral mutants. We report the molecular and biochemical characterization of a HCMV ganciclovir-resistant strain (VR3480) previously recovered from a patient with AIDS who was undergoing multiple courses of ganciclovir treatment (G. Gerna, F. Baldanti, M. Zavattoni, A. Sarasini, E. Percivalle, and M. G. Revello, Antiviral Res. 19:333-345, 1992). Ganciclovir resistance of strain VR3480 was related to impaired ability to monophosphorylate the drug, as indicated by the finding that ganciclovir phosphorylation values for VR3480 were 30% of those shown by the HCMV reference strain AD169 in an in vitro activity assay. Sequencing of the UL97 gene of VR3480, which encodes the viral kinase responsible for ganciclovir phosphorylation, showed an in-frame deletion of three nucleotides resulting in the loss of a leucine at position 595 in the polypeptide. Mutant VR3480 UL97 DNA was able to transfer resistance to the AD169 strain in marker rescue experiments. Analysis of virus isolates and blood polymorphonuclear leukocyte samples spanning the 2-year follow-up period of the patient showed that ganciclovir-resistant strain VR3480 arose ex novo during prolonged antiviral treatment and accounted for the majority of virus load circulating in blood during the period of clinical resistance to ganciclovir treatment.     

Expression of glutamine synthetase in mutant strains of the cyanobacterium Anabaena variabilis which liberate ammonia

Abstract The nucleoside analogue ganciclovir has clinical efficacy in the treatment of serious infections with human cytomegalovirus (CMV) in AIDS patients. The mechanism of action of the drug against CMV is different from that described for herpes simplex viruses (HSVs) as the crucial formation of the monophosphate derivative appears to be carried out by cellular rather than virus-coded enzymes. Adenovirus infections also induce the expression of cellular genes including kinase activity and a novel DNA polymerase and the results reported here show that these viruses are sensitive to ganciclovir. The 50% effective dose (ED₅₀) range for known serotypes and one clinical isolate was 4.5−33 μM. By comparison with the sensitivity of CMV in vitro and the known clinical response of infections with this virus to ganciclovir, our results suggest that this drug or its analogous may form the basis of chemotherapy for adenovirus infections.     

Three-dimensional modeling of cytomegalovirus DNA polymerase and preliminary analysis of drug resistance

Cytomegalovirus (CMV) is the leading cause of congenital infection and a frequent opportunistic agent in immunocompromised hosts such as transplant recipients and AIDS patients. CMV DNA polymerase, a member of the polymerase B family, is the primary target of all available antivirals (ganciclovir, cidofovir, and foscarnet) and certain variations of this enzyme could lead to drug resistance. However, understanding the drug resistance mechanisms at the atomic level is hampered by the lack of its three-dimensional (3D) structure. In the present work, 3D models of two different conformations (closed and open) for CMV DNA polymerase have been built based on the crystal structures of bacteriophage RB69 DNA polymerase (a member of the polymerase B family) by using the 3D-Jury Meta server and the program MODELLER. Most of the variations on CMV DNA polymerase pertinent to ganciclovir/cidofovir and foscarnet resistance can be explained well based on the open and closed conformation models, respectively. These results constitute a first step towards facilitating our understanding of drug resistance mechanisms for CMV and the interpretation of novel viral mutations.     

South African public sceptical about new AIDS "cure"

Against a background of scams to treat HIV/AIDS, the government's erratic approach to the epidemic, and an increasingly cynical but desperate public, a team from the Medical University of South Africa recently announced Inactivan as an anabolic steroid which stops HIV from replicating in white blood cells. The development of the drug was announced in a well-publicized press conference after a 5-day trial on humans. However, few people in South Africa are ready to accept the team's findings since it comes shortly after 2 poorly-qualified scientists claimed to have found a cure for AIDS in 1998. Their drug, Virodene, was actually a toxic industrial solvent. South Africa's minister of health, Dr. Nkosazana Dlamini-Zuma, tarnished her reputation by associating herself with the drug, which had not been through any of the usual research protocols, peer review, or drug regulatory mechanisms.     

Selective killing of Kaposi's sarcoma-associated herpesvirus lytically infected cells with a recombinant immunotoxin targeting the viral gpK8.1A envelope glycoprotein

Kaposi sarcoma-associated herpesvirus (KSHV, human herpesvirus 8) is etiologically associated with three neoplastic syndromes: Kaposi sarcoma and the uncommon HIV-associated B-cell lymphoproliferative disorders primary effusion lymphoma and multicentric Castleman disease. The incidence of the latter B-cell pathology has been increasing in spite of antiretroviral therapy; its association with lytic virus replication has prompted interest in therapeutic strategies aimed at this phase of the virus life cycle. We designed and expressed a recombinant immunotoxin (2014-PE38) targeting the gpK8.1A viral glycoprotein expressed on the surface of the virion and infected cells. We show that this immunotoxin selectively kills KSHV-infected cells in dose-dependent fashion, resulting in major reductions of infectious virus release. The immunotoxin and ganciclovir, an inhibitor of viral DNA replication, showed marked reciprocal potentiation of antiviral activities. These results suggest that the immunotoxin, alone or in combination, may represent a new approach to treat diseases associated with KSHV lytic replication.Key words: targeted cytotoxic proteins, human herpesvirus-8, KSHV surface glycoprotein, KSHV lytic infection, multicentric Castleman disease, pseudomonas exotoxin A, ganciclovir, reciprocal drug potentiation     

Finding Candidate Drugs for Hepatitis C Based on Chemical-Chemical and Chemical-Protein Interactions

Hepatitis C virus (HCV) is an infectious virus that can cause serious illnesses. Only a few drugs have been reported to effectively treat hepatitis C. To have greater diversity in drug choice and better treatment options, it is necessary to develop more drugs to treat the infection. However, it is time-consuming and expensive to discover candidate drugs using experimental methods, and computational methods may complement experimental approaches as a preliminary filtering process. This type of approach was proposed by using known chemical-chemical interactions to extract interactive compounds with three known drug compounds of HCV, and the probabilities of these drug compounds being able to treat hepatitis C were calculated using chemical-protein interactions between the interactive compounds and HCV target genes. Moreover, the randomization test and expectation-maximization (EM) algorithm were both employed to exclude false discoveries. Analysis of the selected compounds, including acyclovir and ganciclovir, indicated that some of these compounds had potential to treat the HCV. Hopefully, this proposed method could provide new insights into the discovery of candidate drugs for the treatment of HCV and other diseases.     

Pulmonary Mycobacterium tuberculosis in acquired immune deficiency syndrome.

A case of pulmonary infection with Mycobacterium tuberculosis in a patient with the acquired immune deficiency syndrome (AIDS) was studied. Diagnosis of AIDS was confirmed by the finding of pulmonary M tuberculosis with oral and oesophageal candidiasis accompanied by characteristic immunological changes with evidence of infection with human T cell lymphotropic virus III. Treatment of this patient was complicated by an unusual drug interaction between rifampicin and ketoconazole, leading to subtherapeutic serum concentrations and poor clinical response to treatment. Intravenous treatment was more effective than oral treatment. This drug interaction should be studied in greater detail as ketoconazole and rifampicin may be used together to treat patients with candidiasis and infection with M tuberculosis.     

Selective elimination of recombinant genes in vivo with a suicide retroviral vector.

The ability to express recombinant genes in vivo offers potential new treatments for human disease if questions of safety and toxicity can be addressed. Complications of gene transfer could include, for example, overexpression of introduced genes for growth or angiogenic factors or insertional mutagenesis, both of which could cause uncontrolled cell growth. We report the development of a suicide retroviral vector that provides a method to eliminate cells undergoing rapid growth in vivo. A murine amphotropic retroviral vector was constructed in which the gene for herpesvirus thymidine kinase was included to render proliferating cells sensitive to ganciclovir, and the Escherichia coli beta-galactosidase gene served as a reporter. This vector's efficacy was first assessed in vitro, and beta-galactosidase activity was abolished in several cell lines after treatment with ganciclovir. In vivo, a transplantable murine CT26 adenocarcinoma whose cells were transduced with this vector regressed completely after administration of ganciclovir. In contrast, expression in nondividing cells within rabbit arteries transduced by retroviral infection in vivo was unaffected. This suicide vector therefore eliminates transformed cells but allows survival of normal nondividing cells that express its specific recombinant genes in vivo, and may thus improve the safety and efficacy of gene transfer into living organisms.     

Proteases as drug targets

The effective management of AIDS with HIV protease inhibitors, or the use of angiotensin-converting enzyme inhibitors to treat hypertension, indicates that proteases do make good drug targets. On the other hand, matrix metalloproteinase (MMP) inhibitors from several companies have failed in both cancer and rheumatoid arthritis clinical trials. Mindful of the MMP inhibitor experience, this chapter explores how tractable proteases are as drug targets from a chemistry perspective. It examines the recent success of other classes of drug for the treatment of rheumatoid arthritis, and highlights the need to consider where putative targets lie on pathophysiological pathways--regardless of what kind of therapeutic entity would be required to target them. With genome research yielding many possible new drug targets, it explores the likelihood of discovering proteolytic enzymes that are causally responsible for disease processes and that might therefore make better targets, especially if they lead to the development of drugs that can be administered orally. It also considers the impact that biologics are having on drug discovery, and in particular whether biologically derived therapeutics such as antibodies are likely to significantly alter the way we view proteases as targets and the methods used to discover therapeutic inhibitors.     

Studies on a novel doughnut-shaped minitablet for intraocular drug delivery

The objective of this study was to evaluate the effect of 2 independent formulation variables on the drug release from a novel doughnut-shaped minitablet (DSMT) in order to optimize formulations for intraocular drug delivery. Formulations were based on a 3(2) full-factorial design. The 2 independent variables were the concentration of Resomer (% wt/wt) and the type of Resomer grade (RG502, RG503, and RG504), respectively. The evaluated response was the drug release rate constant computed from a referenced marketed product and in vitro drug release data obtained at pH 7.4 in simulated vitreous humor. DSMT devices were prepared containing either of 2 model drugs, ganciclovir or foscarnet, using a Manesty F3 tableting press fitted with a novel central-rod, punch, and die setup. Dissolution data revealed biphasic drug release behavior with 55% to 60% drug released over 120 days. The inherent viscosity of the various Resomer grades and the concentration were significant to achieve optimum release rate constants. Using the resultant statistical relationships with the release rate constant as a response, the optimum formulation predicted for devices formulated with foscarnet was 70% wt/wt of Resomer RG504, while 92% wt/wt of Resomer RG503 was ideal for devices formulated with ganciclovir. The results of this study revealed that the full-factorial design was a suitable tool to predict an optimized formulation for prolonged intraocular drug delivery.     

High-performance liquid chromatographic determination of ganciclovir in plasma

A rapid, selective and sensitive isocratic reversed-phase high-performance liquid chromatographic method for the determination of ganciclovir in plasma samples was developed. This method, which was applied to the analysis of plasma ganciclovir from heart transplant patients under ganciclovir therapy for cytomegalovirus infections, represents a suitable analytical tool for drug monitoring and pharmacokinetic investigations.     

Five myths about AIDS that have misdirected research and treatment

A number of widely repeated and factually incorrect myths have pervaded the AIDS research literature, misdirecting research and treatment. Five of the most outstanding are: 1) that all risk groups develop AIDS at the same rate following HIV infection; 2) that there are no true seroreversions following HIV infection; 3) that antibody is protective against HIV infection; 4) that the only way to treat AIDS effectively is through retroviral therapies; and 5) that since HIV is so highly correlated with AIDS incidence, it must be the sole necessary and sufficient cause of AIDS. A huge body of research, reviewed in this paper, demonstrates the falsity of these myths. 1) The average number of years between HIV infection and AIDS is greater than 20 years for mild hemophiliacs, 14 years for transfussion severe hemophiliacs, 10 years for old severe hemophiliacs, 10 years for homosexual men, 6 years for transfusion patients of all ages, 2 years for transplant patients, and 6 months for perinatally infected infants. These differences can only be explained in terms of risk-group associated cofactors. 2) Seroreversions are common. Between 10 and 20 percent of HIV-seronegative people in high risk groups have T-cell immunity to HIV, and may have had one or more verified positive HIV antibody tests in the past. 3) Antibody, far from being protective against HIV, appears to be highly diagnostic of loss of immune regulation of HIV, and some evidence of antibody-enhancement of infection exists. 4) Non-retroviral treatments of HIV infection, including safer sex practices, elimination of drug use, high nutrient diets, and limited reexposure to HIV and its cofactors have proven to be effective means of preventing or delaying onset of AIDS. 5) Many immunosuppressive factors, including drug use, multiple concurrent infections, and exposure to alloantigens, are as highly correlated with AIDS risk groups as HIV. These data are more consistent with AIDS being a multifactorial or synergistic disease than a monofactorial one.     

Advances in algal drug research with emphasis on enzyme inhibitors

Enzyme inhibitors are now included in all kinds of drugs essential to treat most of the human diseases including communicable, metabolic, cardiovascular, neurological diseases and cancer. Numerous marine algae have been reported to be a potential source of novel enzyme inhibitors with various pharmaceutical values. Thus, the purpose of this review is to brief the enzyme inhibitors from marine algae of therapeutic potential to treat common diseases. As per our knowledge this is the first review for the potential enzyme inhibitors from marine origin. This review contains 86 algal enzyme inhibitors reported during 1989–2013 and commercial enzyme inhibitors available in the market. Compounds in the review are grouped according to the disease conditions in which they are involved; diabetes, obesity, dementia, inflammation, melanogenesis, AIDS, hypertension and other viral diseases. The structure-activity relationship of most of the compounds are also discussed. In addition, the drug likeness properties of algal inhibitors were evaluated using Lipinski's 'Rule of Five'.     

Cytomegalovirus Viral Load Kinetics in Patients with HIV/AIDS Admitted to a Medical Intensive Care Unit: A Case for Pre-Emptive Therapy

Background

Cytomegalovirus (CMV) infection is associated with severe diseases in immunosuppressed patients; however, there is a lack of data for pre-emptive therapy in patients with HIV/AIDS.

Method

This was a retrospective study, which enrolled patients diagnosed with HIV/AIDS (CD4<200 cells/μl), who had detectable CMV viral load (VL) during their stay in an adult medical intensive care unit between 2009–2012.

Results

After screening 82 patients’ records, 41 patients met the enrolment criteria. Their median age was 37 (interquartile range [IQR]: 31–46), and median CD4 count was 29 cells/μl (IQR: 5–55). Sixteen patients (39%) had serial measurements of CMV VL before treatment with ganciclovir. Patients whose baseline CMV VL values were between 1,000–3,000 copies/ml had significantly higher values (median of 14,650 copies/ml) on follow-up testing done 4–12 days later. Those with undetectable VLs at baseline testing had detectable VLs (median of 1,590 copies/ml) mostly within 20 days of follow-up testing. Patients who had VLs >1,000 copies/ml at baseline testing had significantly higher mortality compared to those who had <1,000 copies/ml {hazard ratio of 3.46, p = 0.003 [95% confidence interval (CI): 1.55–7.71]}. Analysis of the highest CMV VL per patient showed that patients who had VLs of >5,100 copies/ml and did not receive ganciclovir had 100% mortality compared to 58% mortality in those who received ganciclovir at VLs of >5,100 copies/ml, 50% mortality in those who were not treated and had low VLs of <5,100 copies/ml, and 44% mortality in those who had ganciclovir treatment at VLs of <5,100 copies/ml (p = 0.084, 0.046, 0.037, respectively).

Conclusion

This study showed a significantly increased mortality in patients with HIV/AIDS who had high CMV VLs, and suggests that a threshold value of 1,000 copies/ml may be appropriate for pre-emptive treatment in this group.     

Injection drug use and HIV/AIDS transmission in China

After nearly three decades of being virtually drug free, use of heroin and other illicit drugs has re-emerged in China as a major public health problem. One result is that drug abuse, particularly heroin injection, has come to play a predominant role in fueling China's AIDS epidemic. The first outbreak of HIV among China's IDUs was reported in the border area of Yunnan province between China and Myanmar where drug trafficking is heavy. Since then drug-related HIV has spread to all 31 provinces, autonomous regions and municipalities. This paper provides an overview to HIV/AIDS transmission through injection drug use in China. It begins with a brief history of the illicit drug trade in China, followed by a discussion of the emergence of drug related AIDS, and a profile of drug users and their sexual partners who have contracted the virus or who are vulnerable to infection. It ends by summarizing three national strategies being used by China to address both drug use and AIDS as major health threats.     

Neurology of AIDS virus infection: a clinical classification

Infection with the AIDS virus itself (HIV, HTLV-III, LAV, ARV) is associated with a full spectrum of neurological disorders. The application of diagnostic studies for HTLV-III infection has demonstrated that these neurologic disorders can be the first manifestation of AIDS or occur in the absence of AIDS. The most common conditions associated with HTLV-III infection alone are a subacute encephalopathy (AIDS dementia) and peripheral neuropathy; however, vacuolar myelopathy and both acute and chronic aseptic meningitis are also common. Congenital (or neonatal) transmission of the virus can result in a mental retardation syndrome of delayed onset. The AIDS virus is neurotropic as well as targeting T-helper lymphocytes. The virus has been readily identified in neural tissues and cerebrospinal fluid, including instances in which other central nervous system infections, such as toxoplasmosis, coexist. Hence, recognition of an appropriate syndrome, neurodiagnostic studies, and exclusion (or treatment) of other infections, as well as evidence for HTLV-III infection are required for diagnosis. The development of successful therapy will require agents which cross the blood-brain barrier.     

Structures of Cryptococcus neoformans protein farnesyltransferase reveal strategies for developing inhibitors that target fungal pathogens

Cryptococcus neoformans is a fungal pathogen that causes life-threatening infections in immunocompromised individuals, including AIDS patients and transplant recipients. Few antifungals can treat C. neoformans infections, and drug resistance is increasing. Protein farnesyltransferase (FTase) catalyzes post-translational lipidation of key signal transduction proteins and is essential in C. neoformans. We present a multidisciplinary study validating C. neoformans FTase (CnFTase) as a drug target, showing that several anticancer FTase inhibitors with disparate scaffolds can inhibit C. neoformans and suggesting structure-based strategies for further optimization of these leads. Structural studies are an essential element for species-specific inhibitor development strategies by revealing similarities and differences between pathogen and host orthologs that can be exploited. We, therefore, present eight crystal structures of CnFTase that define the enzymatic reaction cycle, basis of ligand selection, and structurally divergent regions of the active site. Crystal structures of clinically important anticancer FTase inhibitors in complex with CnFTase reveal opportunities for optimization of selectivity for the fungal enzyme by modifying functional groups that interact with structurally diverse regions. A substrate-induced conformational change in CnFTase is observed as part of the reaction cycle, a feature that is mechanistically distinct from human FTase. Our combined structural and functional studies provide a framework for developing FTase inhibitors to treat invasive fungal infections.     

Foreign-protein-mediated immunodeficiency in hemophiliacs with and without HIV

Hemophilia-AIDS has been interpreted in terms of two hypotheses: the foreign-protein-AIDS hypothesis and the Human Immunodeficiency Virus (HIV)-AIDS hypothesis. The foreign-protein-AIDS hypothesis holds that proteins contaminating commercial clotting factor VIII cause immunosuppression. The foreign-protein hypothesis, but not the HIV hypothesis, correctly predicts seven characteristics of hemophilia-AIDS: 1) The increased life span of American hemophiliacs in the two decades before 1987, although 75% became infected by HIV —because factor VIII treatment, begun in the 1960s, extended their lives and simultaneously disseminated harmless HIV. After 1987 the life span of hemophiliacs appears to have decreased again, probably because of widespread treatment with the cytotoxic anti-HIV drug AZT. 2) The distinctly low, 1.3–2%, annual AIDS risk of hemophiliacs, compared to the higher 5–6% annual risk of intravenous drug users and male homosexual aphrodisiac drug users — because transfusion of foreign proteins is less immunosuppressive than recreational drug use. 3) The age bias of hemophilia-AIDS, i.e. that the annual AIDS risk increased 2-fold for each 10-year increase in age —because immunosuppression is a function of the lifetime dose of foreign proteins received from transfusions. 4) The restriction of hemophilia-AIDS to immunodeficiency diseases — because foreign proteins cannot cause non-immunodeficiency AIDS diseases, like Kaposi's sarcoma. 5) The absence of AIDS diseases above their normal background in sexual partners of hemophiliacs — because transfusion-mediated immunotoxicity is not contagious. 6) The occurrence of immunodeficiency in HIV-free hemophiliacs — because foreign proteins, not HIV, suppress their immune system. 7) Stabilization, even regeneration, of immunity of HIV-positive hemophiliacs by long-term treatment with pure factor VIII. This shows that neither HIV nor factor VIII plus HIV are immunosuppressive by themselves. Therefore, AIDS cannot be prevented by elimination of HIV from the blood supply and cannot be rationally treated with genotoxic antiviral drugs, like AZT. Instead, hemophilia-AIDS can be prevented and has even been reverted by treatment with pure factor VIII.     

An integrated approach of network-based systems biology,molecular docking,and molecular dynamics approach to unravel the role of existing antiviral molecules against AIDS-associated cancer

A serious challenge in cancer treatment is to reposition the activity of various already known drug candidates against cancer. There is a need to rewrite and systematically analyze the detailed mechanistic aspect of cellular networks to gain insight into the novel role played by various molecules. Most Human Immunodeficiency Virus infection-associated cancers are caused by oncogenic viruses like Human Papilloma Viruses and Epstein–Bar Virus. As the onset of AIDS-associated cancers marks the severity of AIDS, there might be possible interconnections between the targets and mechanism of both the diseases. We have explored the possibility of certain antiviral compounds to act against major AIDS-associated cancers: Kaposi’s Sarcoma, Non-Hodgkin Lymphoma, and Cervical Cancer with the help of systems pharmacology approach that includes screening for targets and molecules through the construction of a series of drug–target and drug–target–diseases network. Two molecules (Calanolide A and Chaetochromin B) and the target “HRAS” were finally screened with the help of molecular docking and molecular dynamics simulation. The results provide novel antiviral molecules against HRAS target to treat AIDS defining cancers and an insight for understanding the pharmacological, therapeutic aspects of similar unexplored molecules against various cancers.