Inhibition of respiratory virus infection by locally applied interferon

Type-I interferons in the immunopathogenesis and treatment of Coronavirus disease 2019

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), is currently the major global health problem. Still, it continues to infect people globally and up to the end of February 2022, over 436 million confirmed cases of COVID-19, including 5.95 million deaths, were reported to the world health organization (WHO). No specific treatment is currently available for COVID-19, and the discovery of effective therapeutics requires understanding the effective immunologic and immunopathologic mechanisms behind this infection. Type-I interferons (IFN-Is), as the critical elements of the immediate immune response against viral infections, can inhibit the replication and spread of the viruses. However, the available evidence shows that the antiviral IFN-I response is impaired in patients with the severe form of COVID-19. Moreover, the administration of exogenous IFN-I in different phases of the disease can lead to various outcomes. Therefore, understanding the role of IFN-I molecules in COVID-19 development and its severity can provide valuable information for better management of this disease. This review summarizes the role of IFN-Is in the pathogenesis of COIVD-19 and discusses the importance of autoantibodies against this cytokine in the spreading of SARS-CoV-2 and control of the subsequent excessive inflammation.

Review: The Nose as a Route for Therapy. Part 2 Immunotherapy

The nose provides a route of access to the body for inhalants and fluids. Unsurprisingly it has a strong immune defense system, with involvement of innate (e.g., epithelial barrier, muco- ciliary clearance, nasal secretions with interferons, lysozyme, nitric oxide) and acquired (e.g., secreted immunoglobulins, lymphocytes) arms. The lattice network of dendritic cells surrounding the nostrils allows rapid uptake and sampling of molecules able to negotiate the epithelial barrier. Despite this many respiratory infections, including SARS-CoV2, are initiated through nasal mucosal contact, and the nasal mucosa is a significant "reservoir" for microbes including Streptococcus pneumoniae, Neisseria meningitidis and SARS -CoV-2. This review includes consideration of the augmentation of immune defense by the nasal application of interferons, then the reduction of unnecessary inflammation and infection by alteration of the nasal microbiome. The nasal mucosa and associated lymphoid tissue (nasopharynx-associated lymphoid tissue, NALT) provides an important site for vaccine delivery, with cold-adapted live influenza strains (LAIV), which replicate intranasally, resulting in an immune response without significant clinical symptoms, being the most successful thus far. Finally, the clever intranasal application of antibodies bispecific for allergens and Intercellular Adhesion Molecule 1 (ICAM-1) as a topical treatment for allergic and RV-induced rhinitis is explained.

Are we fully exploiting type I Interferons in today's fight against COVID-19 pandemic?

Coronavirus disease 2019 (COVID-19) first emerged in late 2019 in China. At the time of writing, its causative agent SARS-CoV-2 has spread worldwide infecting over 9 million individuals and causing more than 460,000 deaths. In the absence of vaccines, we are facing the dramatic challenge of controlling COVID-19 pandemic. Among currently available drugs, type I Interferons (IFN-I) - mainly IFN-α and β -represent ideal candidates given their direct and immune-mediated antiviral effects and the long record of clinical use. However, the best modalities of using these cytokines in SARS-CoV-2 infected patients is a matter of debate. Here, we discuss how we can exploit the current knowledge on IFN-I system to tailor the most promising dosing, timing and route of administration of IFN-I to the disease stage, with the final aim of making these cytokines a valuable therapeutic strategy in today's fight against COVID-19 pandemic.

The Role of IFN-alpha in Experimental and Clinical Uveitis

PURPOSE

IFN-α is the only treatment capable of inducing long-term remission in some patients with ocular Behçet's disease. In this review, we focus on immune mechanisms of IFN-α in animal models and patients and compare the outcome of different clinical studies.

METHODS

Review of literature using PubMed and Google and original data from rat models with monophasic/chronic or relapsing experimental autoimmune uveitis treated with IFN-α.

RESULTS

The role of IFN-α and its effect on various cell types were investigated, in some cases with contradictory results. Some patients respond very well to IFN-α treatment, while others are non-responders, which was reflected in the uveitis rat models: relapsing uveitis was ameliorated, the monophasic/chronic disease even aggravated.

CONCLUSIONS

Despite intensive investigations in patients and animal models, the immune mechanisms explaining the therapeutic effect of IFN-α in ocular Behçet's disease are not yet fully understood and need further investigation.

Biological Therapies of Immunologic Diseases: Strategies for Immunologic Interventions

The immune system possesses a vast number of potential targets for therapeutic intervention. Although therapies for many pathways have been pursued, only few have yielded significant success. Hindrances in altering biologic pathways include the potential for unwanted downstream effects, ineffectiveness owing to biological redundancy, recognition of a therapeutic molecule as foreign by the body's innate immune system, and the risks of subsequent malignancy and/or autoimmunity. This article covers currently available biotherapeutic agent classes as well as potential direction for future therapy.

Randomized controlled trials for influenza drugs and vaccines: a review of controlled human infection studies

OBJECTIVES

Controlled human infection, the intentional infection of healthy volunteers, allows disease pathogenesis to be studied and vaccines and therapeutic interventions to be evaluated in a controlled setting. A systematic review of randomized controlled trials of countermeasures for influenza that used the experimental human infection platform was performed. The primary objective was to document the scope of trials performed to date and the main efficacy outcome in the trials. The secondary objective was to assess safety and identify serious adverse events.

METHODS

The PubMed database was searched for randomized controlled influenza human challenge studies with predetermined search terms. Review papers, papers without outcomes, community-acquired infections, duplicated data, pathogenesis studies, and observational studies were excluded.

RESULTS

Twenty-six randomized controlled trials published between 1947 and 2014 fit the study inclusion criteria. Two-thirds of these trials investigated antivirals and one-third investigated influenza vaccines. Among 2462 subjects inoculated with influenza virus, the incidence of serious adverse events was low (0.04%). These challenge studies helped to down-select three antivirals and one vaccine that were subsequently approved by the US Food and Drug Administration (FDA).

CONCLUSIONS

Controlled human infection studies are an important research tool in assessing promising influenza vaccines and antivirals. These studies are performed quickly and are cost-effective and safe, with a low incidence of serious adverse events.

Inhaled anti-infective chemotherapy for respiratory tract infections: successes, challenges and the road ahead

One of the most common causes of illnesses in humans is from respiratory tract infections caused by bacterial, viral or fungal pathogens. Inhaled anti-infective drugs are crucial for the prophylaxis and treatment of respiratory tract infections. The benefit of anti-infective drug delivery via inhalation is that it affords delivery of sufficient therapeutic dosages directly to the primary site of infection, while minimizing the risks of systemic toxicity or avoiding potential suboptimal pharmacokinetics/pharmacodynamics associated with systemic drug exposure. This review provides an up-to-date treatise of approved and novel developmental inhaled anti-infective agents, with particular attention to effective strategies for their use, pulmonary pharmacokinetic properties and safety.

Low-dose oral interferon alpha as prophylaxis against viral respiratory illness: a double-blind, parallel controlled trial during an influenza pandemic year

BACKGROUND AND OBJECTIVE

Interferon alpha (IFNα) is a known antiviral agent. A double-blind, placebo-controlled clinical trial was conducted investigating the use of low-dose oral interferon alpha for preventing acute viral respiratory illnesses.

METHODS

Two hundred healthy adults aged 18-75 years were enrolled and completed weekly health data questionnaires to monitor for symptoms and impact of respiratory illness. Serum samples were tested for antibodies against influenza and other common respiratory viruses.

RESULTS

Low-dose oral IFNα prophylaxis did not reduce the incidence or impact of acute respiratory illness (ARI) or the impact of illness on daily activities. Post hoc analysis of participant subgroups, however, identified significant reductions in the incidence of ARI reported by males, those aged 50 years or more and those who received the 2009 seasonal influenza vaccine. Interferon alpha prophylaxis had a significant impact on the reporting of moderate-to-severe feverishness by the study population. Seropositive participants in the IFN group were more likely to report asymptomatic or mild symptoms compared with those in the placebo group who were more likely to report stronger symptoms.

CONCLUSIONS

Low-dose oral IFNα prophylaxis was not effective in limiting the overall incidence of ARI in our study population. However, there was evidence that prophylaxis reduced the severity of symptoms and had a beneficial effect in some subpopulations, including those who received the 2009 seasonal trivalent influenza vaccination.

Biodegradable nanogels for oral delivery of interferon for norovirus infection

Norwalk virus (NV) replicon-harboring cells have provided an excellent tool to the development of antivirals. Previously we demonstrated that the expression levels of replicon RNA and proteins were significantly reduced in the presence of various interferons (IFNs) including IFN-α and IFN-γ in a dose-dependent manner in the NV replicon-harboring cells, and suggested that IFNs could be therapeutic options for norovirus infection. It was also demonstrated that innate immunity including IFNs is crucial in the replication and pathogenicity of murine norovirus (MNV) in vitro (RAW267.4 cells) and in vivo. IFNs have a short half-life in vitro and in vivo due to low stability. Thus it is important to have a good delivery system to improve the stability of IFNs. Nanogels are nanosized networks of chemically cross-linked polymers that swell in physiologic solutions and provide improved stability and bioavailability to drugs. We have synthesized nanogels based on cross-linked polyethyleneimine (PEI)-polyethylenglycol (PEG). The PEI/PEG nanogels were further acetylated (AcNg) to reduce cellular penetration and cytotoxicity. The IFN-AcNg complex was prepared by incubating two components together at 4 °C and lyophilization. The IFN activity of IFN-AcNg was evaluated in the NV- and HCV-replicon-harboring cells and against MNV-1 in RAW267.4 cells in comparison to IFN without AcNg. The AcNg improved the stability of IFN stored at 4 °C, and was well tolerated in the cells. Furthermore, the activity of IFN was significantly higher when combined with AcNg in the replicon-harboring cells and against MNV-1 in RAW267.4 cells. We concluded that AcNg may be pursued further as a vehicle for oral delivery of IFNs in norovirus infection.

The anti-tumor agent, 5,6-dimethylxanthenone-4-acetic acid (DMXAA), induces IFN-beta-mediated antiviral activity in vitro and in vivo

The 2009 outbreak of pandemic H1N1 influenza, increased drug resistance, and the significant delay in obtaining adequate numbers of vaccine doses have heightened awareness of the need to develop new antiviral drugs that can be used prophylactically or therapeutically. Previously, we showed that the experimental anti-tumor drug DMXAA potently induced IFN-β but relatively low TNF-α expression in vitro. This study confirms these findings in vivo and demonstrates further that DMXAA induces potent antiviral activity in vitro and in vivo. In vitro, DMXAA protected RAW 264.7 macrophage-like cells from VSV-induced cytotoxicity and moreover, inhibited replication of influenza, including the Tamiflu®-resistant H1N1 influenza A/Br strain, in MDCK cells. In vivo, DMXAA protected WT C57BL/6J but not IFN-β(-/-) mice from lethality induced by the mouse-adapted H1N1 PR8 influenza strain when administered before or after infection. Protection was accompanied by mitigation of weight loss, increased IFN-β mRNA and protein levels in the lung, and significant inhibition of viral replication in vivo early after DMXAA treatment. Collectively, this study provides data to support the use of DMXAA as a novel antiviral agent.

Treatment of hepatitis C infections with interferon: a historical perspective

Interferons were first described in 1957, but it was not until 34 years after their discovery that sufficient quantities of it were available for treatment of hepatitis C virus (HCV) infections, Clinicians now have an excellent understanding of the basis for the effectiveness of interferon alpha (IFN-α) in the therapy of this disease. Treatment with IFN-α is more efficient when it complemented by the antiviral ribavirin and the IFN-α is conjugated with polyethylene glycol to form peginterferon. In the near future treatment of HCV with IFN-α may involve new anti-HCV agents that are currently under development.

Viral infections of the respiratory tract: prevention and treatment

The rapid discovery of specific viral agents as the cause of many acute respiratory diseases was accompanied by considerable optimism that vaccines or other control measures could be developed quickly. Subsequent experience has demonstrated that effective control of these important public health problems has been an elusive goal. However, recent exciting developments in our understanding of the molecular biology and immunology of these viruses may provide the basis for more effective strategies in the future.

Oromucosal Administration of Interferon to Humans

The prevailing dogma is that, to be systemically effective, interferon-alpha (IFNα) must be administered in sufficiently high doses to yield functional blood concentrations. Such an approach to IFNa therapy has proven effective in some instances, but high-dose parenteral IFNα therapy has the disadvantage of causing significant adverse events. Mounting evidence suggests that IFNα delivered into the oral cavity in low doses interacts with the oral mucosa in a unique manner to induce systemic host defense mechanisms without IFNα actually entering the circulation, thus reducing the potential for toxic side effects. A better understanding of the applications and potential benefits of this treatment modality are under active investigation. This paper provides a review of the relevant literature on the clinical use of the oromucosal route of administration of interferon, with an emphasis on the treatment of influenza.

Interferons as Therapy for Viral and Neoplastic Diseases: From Panacea to Pariah to Paragon

For more than 20 years after the excitement engendered by their discovery in 1957 as antiviral agents, there were no significant clinical uses of interferons; however, following their cloning they have been employed as effective treatment for several viral, autoimmune, and neoplastic diseases.

Chapter 7 Orthomyxovirus infections

The earth is a unity for influenza A virus in a manner not yet found for probably any other parasite and epidemics occur in all inhabited parts of the globe regardless of latitude, longitude, altitude, climate, rainfall, temperature, humidity, race and sex. Influenza A is the classic pandemic virus infection of man and influenza B virus also can cause sharp outbreaks, resulting in significant mortality. An overwhelming amount of data has accumulated on the biochemistry, cell biology, and epidemiology of influenza, but prospects of control of epidemics in the near future are dim. Meanwhile, a holding operation can be achieved using inactivated vaccine and rimantadine (100 mg/daily) in special risk groups in the population until new more effective vaccines and broad spectrum antivirals (active against influenza A and B virus) are developed. Research work is centered on biotechnology to produce immunogenic peptides and proteins and more logical searches for antivirals using amino acid sequence data and also virus specific enzymes such as the virion transcriptase as targets.

Chapter 4 Picornavirus infections

The oldest member of the Picornaviruses group is polio virus, which was recognized early by clinicians because of its characteristic paralytic disease. This chapter examines the polio virus in regard to its virology, disease, and prevention by vaccines and chemoprophylaxis. Polio has been well controlled in most developed countries using live or inactivated vaccines. Research work has intensified using genetic engineering techniques to produce live attenuated viruses with defined and stable mutations so as to prevent reversion to virulence, and also to produce immunogenic oligopeptides or proteins for a new generation of inactivated polio vaccines. Chemotherapy is therefore not required for polio infections. In contrast, neither vaccines have been developed against rhinovirus infections, nor are the vaccines thought to have a use, unless broadly reacting antigenic determinants can be located. Several interesting but only weakly effective antiviral compounds have been selected against rhinoviruses and this is a major research area at present. Studies continue also with interferon, but because of toxicity problems these look less interesting at present. Sequence and biochemical data is now available for several additional enterovirus strains and this could open new possibilities both with antivirals or vaccines (for example synthetic peptides) in the near future.

Time lines of infection and disease in human influenza: a review of volunteer challenge studies

The dynamics of viral shedding and symptoms following influenza virus infection are key factors when considering epidemic control measures. The authors reviewed published studies describing the course of influenza virus infection in placebo-treated and untreated volunteers challenged with wild-type influenza virus. A total of 56 different studies with 1,280 healthy participants were considered. Viral shedding increased sharply between 0.5 and 1 day after challenge and consistently peaked on day 2. The duration of viral shedding averaged over 375 participants was 4.80 days (95% confidence interval: 4.31, 5.29). The frequency of symptomatic infection was 66.9% (95% confidence interval: 58.3, 74.5). Fever was observed in 37.0% of A/H1N1, 40.6% of A/H3N2 (p = 0.86), and 7.5% of B infections (p = 0.001). The total symptoms scores increased on day 1 and peaked on day 3. Systemic symptoms peaked on day 2. No such data exist for children or elderly subjects, but epidemiologic studies suggest that the natural history might differ. The present analysis confirms prior expert opinion on the duration of viral shedding or the frequency of asymptomatic influenza infection, extends prior knowledge on the dynamics of viral shedding and symptoms, and provides original results on the frequency of respiratory symptoms or fever.

Clinical uses of interferons

Interferons were first described by Isaacs & Lindenmann working at the National Institute for Medical Research, Mill Hill in 1957. Thus, the fiftieth year of their discovery is being celebrated this year at Oxford in a meeting of the International Society for Interferon and Cytokine Research. This then is an appropriate time to review the clinical applications of the interferons. To accomplish this coherently it is necessary also to review briefly what led to the discovery of interferons, why their clinical applications were so slow in coming, and the impact of interferon research on the biomedical sciences.

Interferons at age 50: past, current and future impact on biomedicine

The family of interferon (IFN) proteins has now more than reached the potential envisioned by early discovering virologists: IFNs are not only antivirals with a spectrum of clinical effectiveness against both RNA and DNA viruses, but are also the prototypic biological response modifiers for oncology, and show effectiveness in suppressing manifestations of multiple sclerosis. Studies of IFNs have resulted in fundamental insights into cellular signalling mechanisms, gene transcription and innate and acquired immunity. Further elucidation of the multitude of IFN-induced genes, as well as drug development strategies targeting IFN production via the activation of the Toll-like receptors (TLRs), will almost certainly lead to newer and more efficacious therapeutics. Our goal is to offer a molecular and clinical perspective that will enable IFNs or their TLR agonist inducers to reach their full clinical potential.

Interferons: The pathways of discovery

This article analyzes the conceptual and technological context in which, over a period of 50 years, exploration of the biological and clinical significance of type I interferon has evolved. The elaboration of techniques for production and purification of mouse and human interferons and the establishment of laboratory-size production units have been of crucial importance in this process. Animal experiments have been invaluable for elucidation of mechanisms underlying the in vivo antiviral, anti-tumour and immunomodulatory potential of interferon, but have been of limited help to define the areas of clinical applicability. Proof of principle for applications as they are established today has come from clinical trials performed quite independently of evidence from animal experiments.

WITHDRAWN: Antivirals for the common cold

BACKGROUND

The common cold is a ubiquitous short and usually mild illness for which preventive and treatment interventions have been under development since the mid-40s. As our understanding of the disease has increased, more experimental antivirals have been developed. This review attempts to draw together experimental evidence of the effects of these compounds.

OBJECTIVES

To identify, assemble, evaluate and (if possible) synthesise the results of published and unpublished randomised controlled trials of the effects of antivirals to prevent or minimise the impact of the common cold.

SEARCH STRATEGY

We searched electronic databases, corresponded with researchers and handsearched the archives of the MRC's Common Cold Unit (CCU).

SELECTION CRITERIA

We included original reports of randomised and quasi-randomised trials assessing the effects of antivirals on volunteers artificially infected and in individuals exposed to colds in the community.

DATA COLLECTION AND ANALYSIS

We included 241 studies assessing the effects of Interferons, interferon-inducers and other antivirals on experimental and naturally occurring common colds, contained in 230 reports. We structured our comparisons by experimental or community setting.

MAIN RESULTS

Although intranasal interferons have high preventive efficacy against experimental colds (protective efficacy 46%, 37% to 54%) and to a lesser extent against natural colds (protective efficacy 24%, 21% to 27%) and are also significantly more effective than placebo in attenuating the course of experimental colds (WMD 15.90, 13.42 to 18.38), their safety profile makes compliance with their use difficult. For example, prolonged prevention of community colds with interferons causes blood-tinged nasal discharge (OR 4.52, 3.78 to 5.41). Dipyridamole (protective efficacy against natural colds 49%, 30% to 62%), ICI 130, 685 (protective efficacy against experimental colds 58%, 35% to 74% ), Impulsin (palmitate) (protective efficacy against natural colds 44%, CI 35% to 52% ) and Pleconaril (protective efficacy against experimental colds 71%, 15% to 90% ) appear to have important antiviral properties and are well-tolerated. The evidence of effectiveness of other compounds in the treatment of experimental or natural colds is sparse.

AUTHORS' CONCLUSIONS

There are no licensed effective antivirals for the common cold. Because prolonged intranasal administration causes a clinical picture which is not distinguishable from the common cold, interferons have no place in everyday use. Further assessment of the effects of dipyridamole, ICI 130, 685, Impulsin (palmitate) and Pleconaril in preventing the common cold should be carried out. Given the multi-agent nature of the causes of the common cold, future research efforts should focus on non virus-specific compounds.

Protection from lethal influenza virus challenge by oral type 1 interferon

The persistence of highly pathogenic avian influenza within wild bird populations has forged interest in control measures to limit a possible human pandemic. We therefore investigated the efficacy of low dose oral administration of IFN-alpha as a potential therapy against influenza infection in a murine model. We have identified an optimal low oral dose of IFN-alpha that when delivered daily as prophylactic therapy protects C57BL/6J mice from a lethal challenge with mouse adapted human influenza virus A/PR/8/34 (H1N1). These results provide strong support for the application of low dose type 1 IFN pretreatment to human influenza control.

Fifty years of interferon research: aiming at a moving target

Nearly half a century has passed since the first published description of interferons (IFNs). This commentary introduces the four accompanying review articles on type I IFN research and attempts to relate how the field of IFN research has been changing during its history.

Development of rhinovirus study model using organ culture of turbinate mucosa

To better understand the pathophysiology of rhinovirus (RV) infection, a development of a study model using organ culture of turbinate mucosa was sought. Inferior turbinate mucosal tissues were cultured using air-liquid interface methods, on a support of gelfoam soaked in culture media. RV-16 was applied to the mucosal surface and washed off, and histological changes were evaluated. The success of RV infection was assayed by semi-nested RT-PCR of the mucosal surface fluid taken 48h after incubation. Intracellular RVs were visualized by in situ hybridization (ISH). Secretion of the cytokines, IL-6 and IL-8, into the culture media was quantitated by ELISA. After 7 days of culture, the turbinate mucosae did not show significant damage. A PCR product indicating successful RV infection was detected in 5 out of 10 mucosal tissues. ISH showed a very small number of positively stained cells focally located in the epithelial layer. In the beginning 24h after infection, secretion of IL-6 and IL-8 into the culture media of infected mucosae was significantly greater than into the media of control mucosae. Our results indicate that the air-liquid interface organ culture of turbinate mucosa could serve as an acceptable in vitro model for studying RV infection.

In vitro and in vivo assay systems for study of influenza virus inhibitors

Evaluation of potential influenza virus inhibitors may utilize multiple steps. First would be to determine if the viral target (e.g. influenza virus neuraminidase) being focused upon will be inhibited in the appropriate assay. Standard in vitro antiviral assays, used next in antiviral evaluations, may utilize inhibition of viral plaques, viral cytopathic effect (CPE), and viral hemagglutinin or other protein, with inhibition of viral yield used in follow-up evaluations. The CPE can be determined visually and by dye uptake. Animal models used for study of potential influenza virus inhibitors include the ferret, the laboratory mouse, and the chicken, with a variety of parameters used to indicate the severity of the infection and its inhibition by therapy. Multiple parameters are recommended in any in vivo antiviral evaluation. The ferret and the mouse infection models have been useful in studying the development of drug resistance and the relative virulence of drug-resistant viruses. The influenza mouse model has also been of value for the evaluation of immunomodulating effects of test compounds and for the study of the utility of antiviral drugs for use against influenza virus infections in the immunocompromised host. In considering the use of any animal model, species differences in drug pharmacology and metabolism must be taken into account. This review has described the systems which have been used most frequently by antiviral investigators, using, as examples, recent studies with the clinically approved influenza virus neuraminidase inhibitors oseltamivir and zanamivir.

Oral use of interferon

Interferon-alpha (IFN-alpha) given orally has biological activity in humans and other animals. The dose providing the most benefit delivers IFN-alpha to the oral mucosa in a concentration (10(2)-10(3) IU), similar to that naturally produced in the nasal secretions during respiratory infections. In contrast, conventional IFN therapy employs parenteral doses of > 10(6) IU and, for this reason, orally administered IFN therapies have been called low-dose treatments. Efficacy in both animal disease models and human studies has been reported, and the mechanisms whereby oral administration has a systemic effect are under active study in a number of laboratories.

Severe Hypoxemia after Open-Heart Surgery Due to Respiratory Syncytial Virus Infection

A 5-year-old male with a ventricular septal defect associated with Down's syndrome, who had a previous history of pulmonary artery banding, underwent intracardiac repair. Severe hypoxemia occurred during the weaning from cardiopulmonary bypass. In postoperative evaluations, a severe intrapulmonary shunt was detected. There was no residual pulmonary stenosis or cardiac failure. Extracorporeal membrane oxygenation and intravenous gamma globulin infusion were attempted for a period of 5 days for the treatment of the hypoxemia. These therapies were not effective and the patient died 10 days after surgery from mediastinitis which occurred on postoperative day 7. Respiratory syncytial virus antibody was detected and lung specimens, which were resected on postoperative day 3, revealed an emphysematous distension of alveolar air space without pulmonary hypertension or pulmonary artery hypoplasia histologically. Respiratory syncytial virus infection in children may be an additional risk in cardiovascular surgery.

Oral application of cytokines

A number of different laboratories reported on studies with orally administered interferons and cytokines. Their observations extend previous observations which showed that orally administered interferons and cytokines can exert both local and systemic effects. As difficult as it may be to understand how orally administered interferons and cytokines may exert both effects, the increasing number of laboratories that demonstrate biological effects with orally administered cytokines suggests that serious consideration be given to the possibility that orally administered interferons and cytokines can indeed exert effects. They also raise the possibility that these effects may have biological relevance for the treatment of human disease. Moreover, they may indicate that the nasal/oral region is a window on the environment. It is most important, however, to assure that these experiments are performed with special care to avoid presenting preliminary data that is not properly controlled. It is essential to carry out these studies with sufficient animals or patients to ascertain their significance; and to plan the studies as double-blind evaluations to avoid misinterpretations when subjective tests are used. Nevertheless, the overall data presented give one the impression of an area that should be pursued.

Development of antiviral therapy with alpha interferons: promises, false hopes and accomplishments

This overview describes the development of interferon therapy in four different types of viral diseases. (1) Upper respiratory infections: despite extensive efforts interferons have not found a place in the treatment of these very common diseases. (2) Herpes keratitis: alpha interferons are highly active in combination therapy, but have gained only very limited clinical use. (3) Papillomavirus infections: alpha interferons have been approved for the treatment of papillomavirus infections of skin and mucous membranes and are in fairly wide clinical use. (4) Chronic hepatitis B, C and D: alpha interferons have become the treatment of choice and are used very extensively worldwide. The four examples illustrate both the clinical potentials and the limitations of alpha interferons and give some guidelines for future work. The overall conclusion is that chronic viral diseases lend themselves to interferon therapy more readily than acute viral infections. The general trend is toward the use of interferons in combination therapy.

Cytokines in the treatment of virus infections

The interferon (IFN) system consists of both the formation of the various IFN proteins, and the diverse cellular responses which these induce: these result from the intracellular changes which follow their binding to a specific cell surface receptor. There is only a single human gamma, omega and beta IFN; in contrast, there are 13 closely related chemical species ("subtypes") of human alpha IFN, which are nevertheless chemically and biologically distinct. IFN preparations made from mass cultured human cells or by using recombinant DNA techniques are now readily available for clinical use. IFN have a major role in the defence of the body against virus infections. In acute virus infections, preformed exogenous IFN cannot be given soon enough to be of value. However, IFN-alpha and IFN-beta have proved of considerable value in some chronic virus infections, particularly chronic virus hepatitis and chronic papillomavirus infections. The doses routinely used are associated with both acute and chronic toxic side effects. Also, some patients form specific neutralising antibodies against the particular IFN preparation injected, which may abrogate all the benefits of the treatment. Nevertheless, IFN are now established as agents for use in routine medical practice.

Biological response modifiers and infectious diseases: actual and potential therapeutic agents

Biological response modifiers (BRMs) are agents which can modify the immune response to cancer or invasion of the organism by infectious agents. An explosive appearance of new BRMs has resulted from the development of recombinant gene technology and the availability of monoclonal antibodies. Colony-stimulating factors first became available for the prevention of neutropenia but may also have a role in the treatment of infections. Interleukin-1 is being tested as a modular of hematopoiesis and may be useful as a helper factor for T- and B-cell function. Immunoglobulins are being used against viral and bacterial infections while interferons can prevent viral upper respiratory infections and suppress or irradicate some viral hepatitides. Other BRMs which show promise include chemical agents and traditional herbal medicines.

Clinical study with recombinant interferon gamma versus interferon alpha-2c in patients with condylomata acuminata

A multi-centre, randomized, open-label trial was conducted to evaluate the safety and efficacy of recombinant interferon (rIFN) alpha-2c versus rIFN gamma in patients with recurrent or persistent condylomata acuminata (CA). Thirty-three such patients were treated either with 6 micrograms rIFN alpha-2c or with 0.1 mg rIFN gamma (both equivalent to 2 x 10E6 IU), single dose, subcutaneously 3 times a week for 6 weeks. In case of no complete clearance at week 10, a second course of treatment with the other type of rIFN was given. There was no significant difference in the complete clearance proportions at week 10 between the two treatment groups (3/16 vs 6/17). No relapses occurred in these patients during the 16 weeks' follow-up. Further clearances during the follow-up resulted in a total complete clearance proportion of 14/33 at the end of study. The treatment was well tolerated. Repeated interferon therapy has its place in treating persistent or recurrent condylomas.

A view from the Common Cold Unit

I have been asked to stand back and describe in broad terms the view I have had of common colds--probably the most frequent of acute human diseases and a long-lasting scientific problem--and in particular our recent work on antivirals. I should be able to do this for two reasons. Like everyone else I have suffered from colds, but in addition I have been studying the problem from the virological and clinical point of view for over 35 years--for the last 31 at the Common Cold Unit, Salisbury. As a result I may have problems with perspective--it is not possible to give a personal view and at the same time to describe something from every possible angle, and quite impossible to be comprehensive, but I have done my best and readers will make their own judgements and corrections.

Zinc gluconate and the common cold: a controlled clinical study

A report in 1984 on the success of zinc gluconate against common cold symptoms could not be confirmed in three subsequent studies, which are now known to have used formulations that inactivated zinc. A non-chelating formulation including glycine, which releases 93% of contained zinc into saliva, was tested in a randomized, placebo-controlled, double-blind trial in 73 young adults. Efficacy was recorded in symptom diaries using a symptom severity rating. Patients' symptoms first appeared 1.34 days prior to entry to the study in both groups. Disappearance of symptoms occurred after an additional 4.9 days for zinc-treated patients versus 6.1 days for placebo-treated patients. A difference was noted in the efficacy of treatment if it was started 1 day after symptom onset: cold duration was an additional 4.3 days in zinc-treated patients compared with 9.2 days for placebo-treated patients. Cough, nasal drainage and congestion were the symptoms most affected, and only mild side-effects were noted.

Antiviral therapy: current concepts and practices

Drugs capable of inhibiting viruses in vitro were described in the 1950s, but real progress was not made until the 1970s, when agents capable of inhibiting virus-specific enzymes were first identified. The last decade has seen rapid progress in both our understanding of antiviral therapy and the number of antiviral agents on the market. Amantadine and ribavirin are available for treatment of viral respiratory infections. Vidarabine, acyclovir, ganciclovir, and foscarnet are used for systemic treatment of herpesvirus infections, while ophthalmic preparations of idoxuridine, trifluorothymidine, and vidarabine are available for herpes keratitis. For treatment of human immunodeficiency virus infections, zidovudine and didanosine are used. Immunomodulators, such as interferons and colony-stimulating factors, and immunoglobulins are being used increasingly for viral illnesses. While resistance to antiviral drugs has been seen, especially among AIDS patients, it has not become widespread and is being intensely studied. Increasingly, combinations of agents are being used: to achieve synergistic inhibition of viruses, to delay or prevent resistance, and to decrease dosages of toxic drugs. New approaches, such as liposomes carrying antiviral drugs and computer-aided drug design, are exciting and promising prospects for the future.

Prophylactic intranasal alpha 2 interferon and viral exacerbations of chronic respiratory disease

BACKGROUND As respiratory virus infections often lead to exacerbations of chronic bronchitis and asthma an effective antiviral drug may be helpful in such patients. Alpha 2 interferon has been shown to give protection against rhinovirus infections in field studies. METHODS Patients with chronic respiratory disease exposed to close contacts with symptoms of upper respiratory tract infection were randomly allocated to receive nasal sprays of recombinant alpha 2 interferon (3 x 10(6) IU) or placebo twice daily for five days. Of the 123 patients recruited into the study, 69 took 117 courses of medication; 11 courses were excluded from analysis. RESULTS No important side effects were recorded and the incidence of possible adverse effects was similar in the two groups. Interferon treatment did not reduce the number or severity of symptomatic episodes; 11 of 48 patients given interferon and 16 of 58 given placebo developed lower respiratory symptoms. There were no differences in mean symptom scores (51 interferon and 52 placebo), number of symptomatic days (3.3 interferon and 5.0 placebo), peak flow values, number of general practitioner consultations, or use of antibiotics. CONCLUSION Alpha 2 interferon 3 x 10(6) IU taken twice daily for five days does not protect patients with chronic respiratory disease from exacerbations after they have been in contact with an upper respiratory tract infection.

Interferon as an agent against herpes simplex virus

The effectiveness and limitations of interferon as an antiviral agent in man is exemplified by its actions against herpes simplex types 1 and 2. Given in adequate doses parenterally before or shortly after infection, interferon can ameliorate or reduce clinical manifestations or reduce the virus yield. It usually cannot completely prevent disease and may be particularly problematical if used late after infection in an acute disease. It is ineffective against the state of latent infection in ganglia. Interferon may have more potential in slower virus diseases and diseases in which other pathogenetic mechanisms affected by interferon's pleiotropic actions are operative.

Ineffectiveness of postexposure prophylaxis of rhinovirus infection with low-dose intranasal alpha 2b interferon in families

Past studies conducted in Australian and American families have demonstrated that alpha 2b interferon (IFN) is effective in preventing rhinovirus-associated illnesses in exposed family members. IFN had been used by intranasal application for 7 days after exposure (5 x 10(6) IU/day). We used the same approach but with only 5 days of spraying (5 x 10(6) IU on day 1 and 2.5 x 10(6) IU on each subsequent day). This amount has been effective in studies involving seasonal prophylaxis. During the study period, a total of 178 rhinoviruses were isolated from the 199 enrolled families in Tecumseh, Mich. There were 434 courses of IFN use and 434 courses of placebo use. Although rhinoviruses were less frequently isolated from those using IFN than those using the placebo, no differences favoring IFN treatment could be found in any of the symptomatic episodes. In fact, more episodes were observed in IFN recipients than in placebo recipients, although the differences were not statistically significant. Additionally, there was no evidence of modification of the severity of episodes of illness. It was concluded that prevention of rhinovirus illness episodes postexposure required a dosage of at least 5 x 10(6) IU of IFN-alpha 2b.

A study of intranasally administered interferon A (rIFN-alpha 2A) for the seasonal prophylaxis of natural viral infections of the upper respiratory tract in healthy volunteers

The efficacy of interferon A (rIFN-alpha 2A), an Escherichia coli-derived interferon, in the prophylaxis of acute upper respiratory tract infection, was evaluated in a community-based double-blind placebo-controlled study in the Australian winter of 1985. The trial population of 412 healthy volunteers (190 males and 222 females, aged 18-65 years) self-administered 1.5, 3.0 and 6.0 megaunits (MU) of interferon A per day or a placebo, intranasally for 28 days. The period of study coincided with an outbreak of H3N2 influenza A (detected in 35 of the 107 acute specimens) as well as substantial numbers of respiratory syncytial virus and adenovirus infections. Rhinoviruses were isolated from only three specimens. In many cases, subjects had laboratory and clinical evidence of having had more than one respiratory tract infection during the period of the study. Viruses were detected in 54 or 107 acute specimens (49%). No statistically significant differences were noted between the various treatment groups in the incidence of laboratory-proven viral infection (virus isolation and/or antibody response). Analysis of reported symptoms indicated that blood-tinged mucus and nasal stuffiness occurred more frequently with higher doses of interferon. There appeared to be no clinical benefit from the use of interferon A in the amelioration of symptoms.

Modification of experimental rhinovirus colds by receptor blockade

Human rhinovirus (HRV) infection can be inhibited in vitro by antibody directed against the cellular receptor for the major HRV group representing 90% of serotypes. We assessed the prophylactic effectiveness and safety of intranasally administered rhinovirus receptor murine monoclonal antibody (RRMA) in two double-blind, place-controlled, randomized studies of volunteers experimentally inoculated with HRV-39. In the first study, RRMA administration (135 micrograms/subject in 9 applications, -17 to +48 h) did not reduce infection (RRMA 12/15 vs. placebo 13/15) or illness (8/12 vs. 7/13) rates or modify the clinical course of experimental HRV-39 colds. In the second trial, a higher RRMA dosage (1 mg/subject in 10 applications, -3 to +36 h), similarly did not reduce overall infection (11/13 vs. 12/13) or illness (7/11 vs. 9/12) rates, but was associated with a 1-2 day delay in the onset of viral shedding and cold symptoms and with significant reductions in viral titers and nasal symptoms on the second day after challenge and in mucus weights on the third day after challenge. No toxicity related to RRMA was recognized. The results indicate that intranasal RRMA modified infection and illness after experimental HRV-39 challenge and suggest that blockade of host cell receptors offers a novel antiviral approach against HRV infections.

Promising new antiviral drugs

We now have a basis for a more rational approach to rapid evaluation and development of antiviral drugs by screening for activity in vitro, testing for toxicity and efficacy in animals, and clinical testing in humans. Acyclovir is a prototype of this improved process. Interferon has a beneficial effect against CMV infection in renal transplant patients and has promising results in the treatment of papillomas and rhinovirus infections. It does not seem to be as effective against genital herpes or varicella zoster as acyclovir. Ribavirin is effective against respiratory syncytial virus infections and Lassa fever. Varicella-zoster virus is highly sensitive to bromovinyl deoxyuridine in vitro. Phosphonoformate is effective in herpes simplex in animals but of little clinical benefit topically in human recurrent A2 herpes. Zidovudine may decrease mortality rates and infectious complications in patients with acquired immunodeficiency syndrome. DHPG (9-(1,3-dihydroxy-2-propoxymethyl]guanine is useful in treatment of cytomegalovirus and infection in immunocompromised patients. The prodrug of acyclovir results in high blood levels of acyclovir and shows promise in the treatment of varicella-zoster infections. Many halogenated pyrimidine nucleoside analogs are being developed. Buciclovir is another acyclic guanosine analog effective against herpes simplex virus in vitro. 2'-nor-cyclic guanosine monophosphate has a broad antiviral spectrum of action. Interleukin-2 is being investigated. Combined therapies of two or more antiviral drugs or antiviral drugs and other treatments are being studied.