Antiviral agents

Sulfoglycodendron Antivirals with Scalable Architectures and Activities

Many viruses initiate their cell-entry by binding their multisubunit receptors to human heparan sulfate proteoglycans (HSPG) and other molecular components present on cellular membranes. These viral interactions could be blocked and the whole viruses could be eliminated by suitable HSPG-mimetics providing multivalent binding to viral protein receptors. Here, large sulfoglycodendron HSPG-mimetics of different topologies, structures, and sizes were designed to this purpose. Atomistic molecular dynamics simulations were used to examine the ability of these broad-spectrum antivirals to block multiprotein HSPG-receptors in HIV, SARS-CoV-2, HPV, and dengue viruses. To characterize the inhibitory potential of these mimetics, their binding to individual and multiple protein receptors was examined. In particular, vectorial distributions of binding energies between the mimetics and viral protein receptors were introduced and calculated along the simulated trajectories. Space-dependent residual analysis of the mimetic-receptor binding was also performed. This analysis revealed the detailed nature of binding between these antivirals and viral protein receptors and provided evidence that large inhibitors with multivalent binding might act like a molecular glue initiating the self-assembly of protein receptors in enveloped viruses.

Sulfoglycodendron Antivirals with Scalable Architectures and Activities

Many viruses initiate their cell-entry by binding their multi-protein receptors to human heparan sulfate proteoglycans (HSPG) and other molecular components present on cellular membranes. These viral interactions could be blocked and the whole viruses could be eliminated by suitable HSPG-mimetics providing multivalent binding to viral protein receptors. Here, large sulfoglycodendron HSPG-mimetics of different topologies, structures, and sizes were designed to this purpose. Atomistic molecular dynamics simulations were used to examine the ability of these broad-spectrum antivirals to block multi-protein HSPG-receptors in HIV, SARS-CoV-2, HPV, and dengue viruses. To characterize the inhibitory potential of these mimetics, their binding to individual and multiple protein receptors was examined. In particular, vectorial distributions of binding energies between the mimetics and viral protein receptors were introduced and calculated along the simulated trajectories. Space-dependent residual analysis of the mimetic-receptor binding was also performed. This analysis revealed detail nature of binding between these antivirals and viral protein receptors, and provided evidence that large inhibitors with multivalent binding might act like a molecular glue initiating the self-assembly of protein receptors in enveloped viruses.

Central nervous system infectious complications early after liver transplantation

Infectious complications contribute to significant patient morbidity and mortality in orthotopic liver transplant (OLT) recipients. Early central nervous system (CNS) involvement (within the first month after OLT) by infectious disease is essentially set off by aggressive surgical procedures, severe morbid conditions of the pretransplant period, initial graft dysfunction, permanence of intravascular catheters, and prolonged mechanical ventilation. The type and severity of CNS infection may be determined by many factors, such as posttransplant adverse events; prolonged or repeated surgery with massive intraoperative transfusions, net state of immunosuppression, recurrence of infections by immunomodulating viruses, and retransplantation. Bacteria, viruses, and fungi can spread to the CNS just as they affect the abdomen, blood stream, respiratory tract, urine, drainages, etc. Because immunosuppressive drugs may modify the clinical presentation of CNS infections, it is very important to maintain vigilance and attend to minor neurologic symptoms. Special attention should therefore be given to cerebral investigation in patients with prolonged pulmonary contamination, unresponsive fever, and heavy corticosteroid therapy, primarily when they became disoriented, develop seizures, or exhibit focal neurologic signs. Clinical response to medical therapy may sometimes be poor because of chronic encapsulation of the pathogen, development of resistance, and/or catastrophic hemorrhagic complications.

Infecciones en los pacientes trasplantados de hígado

Infection is the main cause of morbidity and mortality in liver transplant patients. Infections appear in three different periods following transplantation and are related to surgical factors, the degree of immunosuppression, environmental exposure and the type of prophylaxis used. Bacterial infections occur in the first two months after transplantation as bacteremia, surgical wound and intra-abdominal infection, or pneumonia. Tuberculosis in the liver transplant recipient is more aggressive than in immunocompetent persons. Viruses produce direct infection in these patients; moreover, some viruses (e.g., cytomegalovirus and human herpes virus 6) are immunomodulators and can facilitate other infections and graft rejection. Polymerase chain reaction and antigenemia techniques have made possible prompt diagnosis of cytomegalovirus infection and the implementation of prophylactic strategies. Fungal infections still have a high associated mortality rate, despite new diagnostic techniques and new antifungal drugs.

Treatment of Acute Retinal Necrosis Syndrome with Oral Antiviral Medications

OBJECTIVE

Acute retinal necrosis (ARN) is a distinct ocular viral syndrome traditionally treated with intravenous acyclovir followed by oral acyclovir. We investigated the use of the oral antiviral medications valacyclovir and famciclovir as the sole treatment for patients with newly diagnosed ARN syndrome.

DESIGN

Retrospective, uncontrolled, interventional case series.

PARTICIPANTS

Eight consecutive patients with newly diagnosed ARN treated solely with oral antiviral medications.

INTERVENTION

All patients received famciclovir or valacyclovir without antecedent intravenous therapy. One patient with bilateral ARN treated with famciclovir received a single intravitreal injection of foscarnet in the more severely involved eye.

MAIN OUTCOME MEASURES

Clinically and photographically documented complete resolution of retinitis and best-corrected visual acuity on final follow-up.

RESULTS

Active retinitis resolved completely in 10/10 (100%) affected eyes. Initial response to treatment was seen as early as 4 days (in 5 eyes), with a median time to complete resolution of 14 days. At the last examination, visual acuity was improved (> or = 2 Snellen lines) in 6 (60%) eyes, stable in 2 (20%) eyes, and worse in 2 (20%) eyes. Over a mean follow-up of 36 weeks (range, 7-72 weeks), 3 eyes developed rhegmatogenous retinal detachment that was successfully repaired with 1 vitrectomy surgery. No patient with initially unilateral involvement developed disease in the contralateral eye.

CONCLUSIONS

In this pilot study, the use of the oral drugs valacyclovir and famciclovir resulted in complete regression of herpetic necrotizing retinitis. Additional studies are necessary to evaluate the role of these antiherpetic medications in the treatment of the ARN syndrome.

Viral and fungal infections after liver transplantation--part II

Viral and fungal infections in liver transplant recipients are important to recognize and treat early because of their association with substantial morbidity and mortality. Some viruses, such as cytomegalovirus and human herpesvirus 6, have immunomodulatory properties and can facilitate other infections, including fungal infections. Cytomegalovirus has long been recognized as an important virus in transplantation, but in the past decade other viruses have also received attention in the medical literature because of their association with particular clinical syndromes. Although human herpesvirus 6 has been associated with fever, rash, and encephalitis, a direct cause-and-effect relationship is still lacking. Human herpesvirus 8 has been found to be the cause of Kaposi sarcoma. Molecular techniques (e.g., pp65 antigenemia and polymerase chain reaction) that have been introduced for routine diagnosis of viruses have facilitated the diagnosis of asymptomatic viral infections and the institution of preemptive therapy. Nonetheless, the diagnosis of invasive fungal infections in liver transplant recipients is often delayed and thus associated with high mortality. Despite the use of new antifungal agents in clinical practice and the reduced incidence of fungal infections because of antifungal prophylaxis regimens, mortality has not decreased. Future patient outcomes may improve with early identification of patients who have risk factors for invasive fungal infections and with the development of new molecular diagnostic techniques for early detection.

Antiviral therapies in children: has their time arrived?

The increase in the number and classes of antiviral agents that has occurred since the 1980s is remarkable. The rapid expansion in therapeutic options for previously untreatable illnesses challenges clinicians to gain familiarity and experience with these new drugs, especially with regard to their use in children. This article describes the clinical utilities, pharmacokinetics, and adverse effects of these new drugs to empower practitioners to use them appropriately.

New strategies for prevention and therapy of cytomegalovirus infection and disease in solid-organ transplant recipients

In the past three decades since the inception of human organ transplantation, cytomegalovirus (CMV) has gained increasing clinical import because it is a common pathogen in the immunocompromised transplant recipient. Patients may suffer from severe manifestations of this infection along with the threat of potential fatality. Additionally, the dynamic evolution of immunosuppressive and antiviral agents has brought forth changes in the natural history of CMV infection and disease. Transplant physicians now face the daunting task of recognizing and managing the changing spectrum of CMV infection and its consequences in the organ recipient. For the microbiology laboratory, the emphasis has been geared toward the development of more sophisticated detection assays, including methods to detect emerging antiviral resistance. The discovery of novel antiviral chemotherapy is an important theme of clinical research. Investigations have also focused on preventative measures for CMV disease in the solid-organ transplant population. In all, while much has been achieved in the overall management of CMV infection, the current understanding of CMV pathogenesis and therapy still leaves much to be learned before success can be claimed.

Polymorphisms of thymidine kinase gene in herpes simplex virus type 1: analysis of clinical isolates from herpetic keratitis patients and laboratory strains

Drug-resistance of herpes simplex virus (HSV) is caused most frequently by mutation of the viral thymidine kinase (TK) gene. To elucidate the significance of detecting nucleotide changes of the TK gene for screening drug-resistant viruses, the frequency and variation of the genetic polymorphisms in the whole coding region of the TK gene were studied in 14 acyclovir-susceptible HSV type 1 (HSV-1) clinical isolates from 14 patients with epithelial herpetic keratitis. Two reference HSV-1 laboratory strains, McKrae and PH, and two acyclovir-resistant variants of the PH strain were also studied as controls. Polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) and direct sequencing detected nucleotide differences at 24 positions, and amino acid substitutions at 12 codons in the TK gene of the examined viruses. Nucleotide diversity of 0.0029 per base (the average number of nucleotide substitutions of 3.3 per 1,131 base pairs) in the TK gene in the clinical isolates was comparable to 0.0037 per base of the whole HSV-1 genome in Japanese isolates reported previously. PCR-SSCP analysis of the acyclovir-resistant strains easily detected aberrantly shifted bands by comparing them with those of the parental strain, followed by the quick determination of mutated sequences. These results suggest that detection of nucleotide changes of the TK gene is useful for serial observation of persistent or recurrent HSV infection as observed in immunocompromised hosts, but that it is not useful for screening drug-resistant viruses from nonepidemic clinical isolates because of the comparable genetic polymorphisms in the TK gene as in the whole HSV-1 genome.

What clinicians need to know about antiviral drugs and viral resistance

The development of safe and effective antiviral therapies for the management of a variety of viral infections has expanded tremendously in recent years. Treatment is now possible for serious and potentially life-threatening infections with herpesviruses, respiratory viruses such as influenza A and respiratory syncytial virus, and the human immunodeficiency virus. The increased availability and use of antiviral drugs, however, has led to the emergence of drug-resistant viruses, especially in immunocompromised hosts. With this review, the major antiviral agents are presented with a description of the mechanisms of action, the evolution of drug resistance, and the need for in vitro antiviral susceptibility testing.

Immunologic Profile of Patients Suffering from Herpes Simplex Virus (HSV) -Associated Oral Lesions Treated with Natural Human Interferon Alpha (Egiferon)

10 consecutive patients with HSV-associated chronic oral lesions were treated with Egiferon for ten days. There were a statistically significant increase in the Large Granule Lymphocyte (LGL) counts and the number of spontaneous E rosette forming cells by the end of the treatment period. Interferon alpha brought about a preferential expression of CD8, CD11b, CD14, CD25 and CD45RO cell surface molecules without any effect on the expression of CD2, CD3, CD4, CD20 and HLA-DR.

Infections in solid-organ transplant recipients

Solid-organ transplantation is a therapeutic option for many human diseases. Infections are a major complication of solid-organ transplantation. All candidates should undergo a thorough infectious-disease screening prior to transplantation. There are three time frames, influenced by surgical factors, the level of immunosuppression, and environmental exposures, during which infections of specific types most frequently occur posttransplantation. Most infections during the first month are related to surgical complications. Opportunistic infections typically occur from the second to the sixth month. During the late posttransplant period (beyond 6 months), transplantation recipients suffer from the same infections seen in the general community. Opportunistic bacterial infections seen in transplant recipients include those caused by Legionella spp., Nocardia spp., Salmonella spp., and Listeria monocytogenes. Cytomegalovirus is the most common cause of viral infections. Herpes simplex virus, varicella-zoster virus, Epstein-Barr virus and others are also significant pathogens. Fungal infections, caused by both yeasts and mycelial fungi, are associated with the highest mortality rates. Mycobacterial, pneumocystis, and parasitic diseases may also occur.

Cytomegalovirus prophylaxis and treatment following bone marrow transplantation

OBJECTIVE

To provide an overview of the role of cytomegalovirus (CMV) in the bone marrow transplant (BMT) population and update the current methods of prevention and treatment of CMV infection and disease, with emphasis on CMV interstitial pneumonia (CMV-IP).

DATA SOURCES

The current medical literature, including abstracts presented at recent national and international meetings, is reviewed. References were identified by searching the MEDLINE database from January 1988 through June 1994. The reference lists of the published studies and reviews obtained from the initial literature search were reviewed as well.

STUDY SELECTION

Data regarding the epidemiology of CMV, the risk factor associated with CMV infection and disease, as well as data on the prevention and the treatment of CMV infection and disease in the BMT population are cited. Specific attention was focused on randomized, placebo-controlled studies pertaining to the prevention of CMV infection and disease in CMV-immunoglobulin G positive recipients undergoing allogeneic BMT. Information from nonrandomized, placebo-controlled studies was included in the absence of stronger data.

DATA EXTRACTION

Information contributing to CMV in the BMT population was reviewed. Data supporting and disputing specific preventive and treatment modalities are presented.

DATA SYNTHESIS

The incidence of CMV seropositivity in the general population is high and while BMT becomes a widely accepted treatment modality, CMV reactivation and subsequent disease, especially CMV-IP, becomes a significant prognostic factor of morbidity and mortality. Even though antiviral agents such as ganciclovir and foscarnet can inhibit the viral replication in vivo, they have not been able to treat CMV-IP effectively. It has been suggested that CMV-IP is an immunopathologic process that can cause irreversible damage, hence, the low efficacy of antiviral therapy and the associated high mortality. Immunomodulating agents such as intravenous immune globulin and cytomegalovirus hyperimmune globulin can increase the efficacy of antivirals in the treatment of CMV-IP. This further supports the postulated immunopathologic process of this disease. The lack of understanding of the pathophysiology of the disease compromised the efforts of treatment and led to the development of preventive interventions with antiviral and immunomodulatory regimens that resulted in a significantly lower incidence of infection and disease. As a result of current data, the Eastern Cooperative Oncology Group has published guidelines for the prevention and treatment of CMV infection and disease.

CONCLUSIONS

The prognosis of CMV disease in the BMT recipients has improved as a result of a wide variety of modifications in the management of BMT recipients. These include an increased understanding of the risk factors associated with CMV infection, routine screening for CMV replication and excretion, and more effective prophylactic regimens. Still, more than half of the patients who develop pneumonia will die, indicating that more studies are needed to increase the understanding of the pathophysiology and refine the preventive and therapeutic regimens against CMV.

Androscopy and treatment of human papillomavirus (HPV) with CO2 laser surgery

Dysplasia and cancer of the cervix may be related to human papillomavirus infection. To determine the presence of cancer in cases of genital warts we have been using a technique, androscopy, for examining male genitals with magnified lens previously sprayed with white vinegar (5% acetic acid). This paper explores the methods of using colposcopy and androscopy on both sexual partners for a thorough examination of genitals and the anorectal area. It also discusses treatment advantages of the CO2 laser. In our investigation plain, pedunculated warts and a giant condyloma (Buschke-Loewenstein tumor) were found and treated with CO2 laser surgery.

The progressive outer retinal necrosis syndrome. A variant of necrotizing herpetic retinopathy in patients with AIDS

BACKGROUND

The progressive outer retinal necrosis syndrome is a recently recognized variant of necrotizing herpetic retinopathy. This report characterizes more fully its clinical features and course.

METHODS

Using standardized clinical criteria, patients with progressive outer retinal necrosis syndrome from four institutions were identified. Patient records were reviewed retrospectively for the following data: medical and demographic characteristics, presenting symptoms, physical findings, course, responses to treatment, and outcomes.

RESULTS

Thirty-eight patients (65 involved eyes) were studied. All had acquired immune deficiency syndrome. A known history of cutaneous zoster was documented in 22 (67%) of 33 patients. Median CD4 lymphocyte count was 21/mm3 (range, 0-130/mm3). Median follow-up was 12 weeks. The most common presenting symptom was unilateral decreased vision (35 of 65 eyes, 54%); median visual acuity at presentation was 20/30 (range, 20/20 to no light perception [NLP]). Anterior chamber and vitreous inflammatory reactions were absent or minimal in all patients. Typical retinal lesions were multifocal, deep opacities scattered throughout the periphery, although macular lesions also were present in 21 eyes (32%) at diagnosis. Lesions progressed rapidly to confluence. Initial intravenous antiviral therapy appeared to reduce disease activity in 17 (53%) of 32 eyes, but treatment did not alter final visual outcome. Visual acuity was NLP in 42 (67%) of 63 eyes within 4 weeks after diagnosis. Retinal detachment occurred in 43 (70%) of 61 eyes, including 13 (93%) of 14 eyes that received prophylactic laser retinopexy.

CONCLUSION

The progressive outer retinal necrosis syndrome is characterized by features that distinguish it from cytomegalovirus retinopathy, acute retinal necrosis syndrome, and other necrotizing herpetic retinopathies. Visual prognosis is poor with current therapies.

Oral manifestations in HIV-infected patients: diagnosis and management

Oral lesions have been observed since the beginning of the AIDS epidemic. The number of HIV-infected patients is still increasing, especially in the heterosexual population. Oral diseases in HIV-infected patients are often more difficult to diagnose because the clinical presentations may differ from the same diseases in HIV-negative patients. HIV-associated oral lesions have diagnostic, prognostic, and therapeutic impact. Approximately 10% of the HIV-infected population will have oral manifestations as a first sign of their disease. In HIV-infected men oral hairy leukoplakia and oral candidiasis are useful markers for disease progression. This article summarizes the oral manifestations and the management of oral health in persons with HIV infection.

Recurrence of presumed varicella-zoster virus retinopathy in patients with acquired immunodeficiency syndrome

Five patients with acquired immunodeficiency syndrome (AIDS) and presumed varicella-zoster virus retinopathy had recurrence of retinopathy after stabilization with initial intravenous antiviral therapy. Recurrences were recognized as increased retinal opacification at the borders of preexisting lesions or as new lesions. In four of the five patients, recurrences were temporally associated with a reduction in the amount of antiviral medication being received. Changes included switch from intravenous to oral acyclovir (two patients), taper of oral acyclovir (one patient), and discontinuation of medications (one patient). In four patients disease was initially unilateral; in three of these four, disease subsequently developed in the previously unaffected fellow eye at the time of recurrence. The median time from stabilization of disease to recurrence was 51 days (range, 14 to 90 days). In contrast to the management of varicella-zoster virus retinopathy in immunocompetent patients and varicella-zoster virus lesions of the skin, varicella-zoster virus retinopathy in patients with AIDS appears to require chronic suppressive antiviral therapy to prevent recurrences. In this respect it is similar to other opportunistic retinal infections in patients with AIDS. The best drugs and optimal treatment regimens for maintenance antiviral therapy remain unknown.

Viral encephalitis

Viral encephalitis represents an important source of morbidity and mortality worldwide. Numerous viruses possess neurovirulence, producing encephalitic disorders that usually consist of fever, headache, vomiting, altered consciousness, focal or generalized seizures, and motor dysfunction. Contemporary virologic methods frequently allow rapid and specific identification of viral pathogens, but the etiologic agent remains uncertain in 25% or more of encephalitis patients. Although acyclovir substantially reduces mortality and improves outcome for patients with herpes simplex virus encephalitis, supportive care remains the only therapy available for most patients with virus encephalitis.

Assessment of a selective inhibitor of herpes simplex virus thymidine kinase (L-653,180) as therapy for experimental recurrent genital herpes

Herpes simplex virus (HSV)-coded thymidine kinase (TK) is important in efficient reactivation of latent infection. These studies were designed to investigate whether treatment of latently infected animals with a TK inhibitor altered the natural history of recurrent HSV disease. 9-([(Z)-2-(hydroxymethyl)cyclohexyl]methyl) guanine (L-653,180) is a potent and selective nonsubstrate inhibitor of HSV TK which can suppress or delay reactivation of HSV-1 from latently infected cells in vitro without affecting viral replication. In an initial study, six female Hartley guinea pigs were treated with L-653,180 in their diet (25 mg/30 g of food) and water (300 mg/liter) for 7 days. Blood, urine, kidney, liver, spinal cord, and cerebral cortex specimens were collected. L-653,180 was detected in all specimens at concentrations which, although low, were higher than the in vitro 50% inhibitory concentration of the drug against HSV TK. In the second study, 20 female Hartley guinea pigs were randomized into two groups following recovery from primary genital HSV-2 infection. One group received L-653,180 in diet and water for 4 weeks beginning 21 days postinoculation. Animals were examined daily for recurrent lesions for 10 weeks. Treated animals experienced fewer recurrences during the treatment period but the results were not significantly different from results with controls. During the first 2-week posttreatment period, L-653,180-treated animals had significantly fewer recurrences than control animals (P = 0.02). Over the entire 10-week observation period, treated animals experienced fewer recurrences (P = 0.06). These results suggest that inhibitors of viral TK may be useful in limiting reactivation of latent virus and thus recurrent infections. In these experiments, the amount of drug that could be administered to the animals was limited by its poor solubility. Further studies with more potent and soluble inhibitors of HSV TK appear to be warranted.