Prevention of natural colds by contact prophylaxis with intranasal alpha 2-interferon

Pharmacodynamic of Recombinant Human Interferon Alpha-2b Nasal Drops and Effective Prophylaxis Against SARS-COV-2 Infection

The recombinant human interferon alpha-2b (IFN-α2b) nasal drop formulation (Nasalferon) was studied as prophylaxis for SARS-CoV-2. Healthy volunteers between 19 and 80 years of age received 0.5 million international units of IFN in one drop (0.05 mL ) in each nostril, twice a day, for 10 consecutive days. The nondetection of SARS-CoV-2 by real-time polymerase chain reaction was the primary outcome variable. Several IFN-α biomarkers, including intranasal gene expression and innate immune effector activity, were increased in participants who received intranasal IFN-α2b. The study included 2,930 international travelers and 5,728 persons who were their close contacts. The subjects were treated with Nasalferon in January 2021, and 9,162 untreated travelers were included as controls. COVID-19 rate in treated subjects was significantly lower than in untreated subjects (0.05% vs. 4.84%). The proportion of travelers with COVID-19 decreased from 60.9% to 2.2% between December 2020 and February 2021. Furthermore, 1,719 tourism workers also received Nasalferon, and no cases of SARS-CoV-2 infection were detected, whereas 39 COVID-19 cases (10.6%) were reported in 367 untreated subjects. The main adverse events associated with the use of intranasal IFN-α2b were nasal congestion, headache, and rhinorrhea. Our prophylactic health interventions study demonstrates that the daily administration of Nasalferon for 10 days decreases the risk of developing COVID-19 in healthy volunteers. [Figure: see text].

Understanding Rhinovirus Circulation and Impact on Illness

Rhinoviruses (RVs) have been reported as one of the main viral causes for severe respiratory illnesses that may require hospitalization, competing with the burden of other respiratory viruses such as influenza and RSV in terms of severity, economic cost, and resource utilization. With three species and 169 subtypes, RV presents the greatest diversity within the Enterovirus genus, and despite the efforts of the research community to identify clinically relevant subtypes to target therapeutic strategies, the role of species and subtype in the clinical outcomes of RV infection remains unclear. This review aims to collect and organize data relevant to RV illness in order to find patterns and links with species and/or subtype, with a specific focus on species and subtype diversity in clinical studies typing of respiratory samples.

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.

Human Type I Interferon Antiviral Effects in Respiratory and Reemerging Viral Infections

Type I interferons (IFN-I) are a group of related proteins that help regulate the activity of the immune system and play a key role in host defense against viral infections. Upon infection, the IFN-I are rapidly secreted and induce a wide range of effects that not only act upon innate immune cells but also modulate the adaptive immune system. While IFN-I and many IFN stimulated genes are well-known for their protective antiviral role, recent studies have associated them with potential pathogenic functions. In this review, we summarize the current knowledge regarding the complex effects of human IFN-I responses in respiratory as well as reemerging flavivirus infections of public health significance and the molecular mechanisms by which viral proteins antagonize the establishment of an antiviral host defense. Antiviral effects and immune modulation of IFN-stimulated genes is discussed in resisting and controlling pathogens. Understanding the mechanisms of these processes will be crucial in determining how viral replication can be effectively controlled and in developing safe and effective vaccines and novel therapeutic strategies.

Elucidating the Interaction of CF Airway Epithelial Cells and Rhinovirus: Using the Host-Pathogen Relationship to Identify Future Therapeutic Strategies

Chronic lung disease remains the primary cause of mortality in cystic fibrosis (CF). Growing evidence suggests respiratory viral infections are often more severe in CF compared to healthy peers and contributes to pulmonary exacerbations (PEx) and deterioration of lung function. Rhinovirus is the most prevalent respiratory virus detected, particularly during exacerbations in children with CF <5 years old. However, even though rhinoviral infections are likely to be one of the factors initiating the onset of CF lung disease, there is no effective targeted treatment. A better understanding of the innate immune responses by CF airway epithelial cells, the primary site of infection for viruses, is needed to identify why viral infections are more severe in CF. The aim of this review is to present the clinical impact of virus infection in both young children and adults with CF, focusing on rhinovirus infection. Previous in vitro and in vivo investigations looking at the mechanisms behind virus infection will also be summarized. The review will finish on the potential of transcriptomics to elucidate the host-pathogen responses by CF airway cells to viral infection and identify novel therapeutic targets.

Antibiotic Treatment of Rhinitis and Sinusitis

The most common organisms causing bacterial sinusitis are pneumococci and Haemophilus influenzae. Accordingly, in a patient not allergic to penicillin, ampicillin or amoxicillin appears to be the antibiotic of choice in empirical treatment of bacterial sinusitis. In penicillin-allergic patients, or in areas with a high incidence of β-lactamase-producing H. influenzae, co-trimoxazole would probably be a better choice. Organisms obtained by culture of nasal secretions do not correlate well with organisms obtained from sinuses by direct puncture aspiration. Therefore, culture of nasal secretions is not recommended.

Comparison of Symptom Severity in Natural and Experimentally Induced Colds

Antiviral and symptomatic therapies for the common cold have been evaluated in studies that use either natural colds in the community or colds induced by experimental infection with rhinovirus. The purpose of this study was to compare the severity and natural history of experimentally induced and naturally occurring colds of undetermined etiology. Forty-one subjects with natural colds were compared to 24 subjects with experimental rhinovirus colds. The highest mean daily symptom score, rhinorrhea score, and nasal obstruction score in the natural cold subjects were 14.2, 2.1, and 2.5 respectively. In contrast, the highest mean daily symptom score, rhinorrhea score, and nasal obstruction score in the experimental rhinovirus colds were 9.3, 1.8, and 1.8, respectively (P < 0.005 compared to natural colds). Similarly, the highest mean daily mucus weight in the natural colds, 2.9 gms, was significantly higher than in the experimental colds, 2.3 gms (P = 0.01). There was no significant difference in the lowest mean nasal airflow in the natural and experimental models, .552 l/sec and .508 l/sec, respectively. These results suggest that subjects with natural colds have more severe symptoms than subjects with experimental colds, however, these differences may be due to selection bias inherent in the natural cold study design. Both study designs have potential advantages and selection of the most appropriate design is dependent on the specific aims of the study.

Exposure to cold impairs interferon-induced antiviral defense

It is commonly believed that exposure to low temperature increases susceptibility to viral infection in the human respiratory tract, but a molecular mechanism supporting this belief has yet to be discovered. In this study, we investigated the effect of low temperature on viral infection and innate defense in cell lines from the human respiratory tract and found that interferon-induced antiviral responses were impaired at low temperatures. Cells maintained at 25°C and 33°C expressed lower levels of myxovirus resistance protein 1 (MxA) and 2'5'-oligoadenylate synthetase 1 (OAS1) mRNAs when compared to cells maintained at 37°C after infection by seasonal influenza viruses. Exogenous β-interferon treatment reduced the viral replication at 37°C, but not at 25°C. Our results suggest that the impairment of interferon-induced antiviral responses by low temperature is one of several mechanisms that could explain an increase in host susceptibility to respiratory viruses after exposure to cold temperature.

Viral Upper Respiratory Tract Infections

The upper respiratory system is one of the most common sites of infection for adults, but even more so for children. Several viruses, from variable families, cause upper respiratory infections which, although generally underestimated due to their typically self-limiting nature, underlie enormous healthcare resource utilization and financial burden. Such, otherwise “benign” infections, can have very significant sequelae both in the form of bringing about local complications but also inducing asthma attacks, thus greatly increasing morbidity. Their enormous prevalence also indicates that rigorous research should be undertaken in order to tackle them, in both the prevention and treatment field.

Intranasal Treatment of Picornavirus and Coronavirus Respiratory Infections in Rodents Using 7-Thia-8-Oxoguanosine

Since common cold viruses are responsive to interferon, we developed two animal models to test the efficacy of the interferon inducer 7-thia-8-oxoguanosine: (i) an intranasal coronavirus infection in suckling rats; and (ii) an intranasal encephalomyocarditis (EMC) virus infection in adult mice. Concentrations of 0.3 and 1% 7-thia-8-oxoguanosine delivered intranasally to rats 24 and 18 hours before virus inoculation were highly protective against the otherwise lethal coronavirus infection. A 1% concentration of drug administered 4 and 8 hours after virus challenge increased mean survival times of rats but did not increase numbers of survivors. Intranasal treatment of an EMC infection produced moderate improvements in mean survival times and survival. Titrations of EMC virus indicated >300-fold reductions in nasal titres in drug-treated relative to placebo control animals on days 2–4 following virus challenge. The distribution of [14C]-7-thia-8-oxoguanosine was determined shortly after intranasal delivery to mice and rats. Approximately 50% of total doses were deposited in the inner noses and mouths of both species. Most of the rest was found on/in the outer noses, stomachs, tracheas, oesophagi, and lungs. By analogy, the infecting viruses were deposited on/in the same organs and tissues of each species. The results suggest that containment of the viruses primarily occurred in the nasopharyngeal area prior to their spread to the lungs (rat coronavirus) or the brain (EMC), where fatal pathologies were manifest. Intranasal application of an interferon-inducing nucleoside analogue represents a new approach for the study of treatment of the common cold.

Infections and Asthma

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Wheezing viral respiratory illnesses are the most common initial presentation of childhood asthma.

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Once asthma is established, viral infections, most notably rhinovirus (RV), are the most frequent trigger of severe asthma exacerbations. RV-C appears to be a particularly pathogenic virus in children with asthma.

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Evidence has recently emerged to suggest that bacterial pathogens in the lower airway may contribute to the expression of asthma. Ongoing studies are critical to our understanding of the role of the airway microbiome in asthma inception and exacerbation.

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Synergistic interactions between underlying allergy and virus infections play an important mechanistic role in asthma inception and exacerbation, and are an important therapeutic target.

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Novel therapies are needed to prevent and treat virus-induced wheezing and asthma exacerbations.

Design, recruitment, and microbiological considerations in human challenge studies

Since the 18th century a wealth of knowledge regarding infectious disease pathogenesis, prevention, and treatment has been accumulated from findings of infection challenges in human beings. Partly because of improvements to ethical and regulatory guidance, human challenge studies-involving the deliberate exposure of participants to infectious substances-have had a resurgence in popularity in the past few years, in particular for the assessment of vaccines. To provide an overview of the potential use of challenge models, we present historical reports and contemporary views from experts in this type of research. A range of challenge models and practical approaches to generate important data exist and are used to expedite vaccine and therapeutic development and to support public health modelling and interventions. Although human challenge studies provide a unique opportunity to address complex research questions, participant and investigator safety is paramount. To increase the collaborative effort and future success of this area of research, we recommend the development of consensus frameworks and sharing of best practices between investigators. Furthermore, standardisation of challenge procedures and regulatory guidance will help with the feasibility for using challenge models in clinical testing of new disease intervention strategies.

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.

Virus-induced modulation of lower airway diseases: pathogenesis and pharmacologic approaches to treatment

Uncomplicated upper respiratory viral infections are the most common cause of days lost from work and school and exert a major economic burden. In susceptible individuals, however, common respiratory viruses, particularly human rhinoviruses, also can have a major impact on diseases that involve the lower airways, including asthma, chronic obstructive pulmonary diseases (COPD) and cystic fibrosis (CF). Respiratory virus-induced wheezing illnesses in early life are a significant risk factor for the subsequent development of asthma, and virus infections may also play a role in the development and progression of airway remodeling in asthma. It is clear that upper respiratory tract virus infections can spread to the lower airway and trigger acute attacks of asthma, COPD or CF. These exacerbations can be life-threatening, and exert an enormous burden on health care systems. In recent years we have gained new insights into the mechanisms by which respiratory viruses may induce acute exacerbations of lower airway diseases, as well as into host defense pathways that may regulate the outcomes to viral infections. In the current article we review the role of viruses in lower airway diseases, including our current understanding on pathways by which they may cause remodeling and trigger acute exacerbations. We also review the efficacy of current and emerging therapies used to treat these lower airway diseases on the outcomes due to viral infection, and discuss alternative therapeutic approaches for the management of virus-induced airway inflammation.

Interferon response and respiratory virus control are preserved in bronchial epithelial cells in asthma

BACKGROUND

Some investigators find a deficiency in IFN production from airway epithelial cells infected with human rhinovirus in asthma, but whether this abnormality occurs with other respiratory viruses is uncertain.

OBJECTIVE

To assess the effect of influenza A virus (IAV) and respiratory syncytial virus (RSV) infection on IFN production and viral level in human bronchial epithelial cells (hBECs) from subjects with and without asthma.

METHODS

Primary-culture hBECs from subjects with mild to severe asthma (n = 11) and controls without asthma (hBECs; n = 7) were infected with live or ultraviolet-inactivated IAV (WS/33 strain), RSV (Long strain), or RSV (A/2001/2-20 strain) with multiplicity of infection 0.01 to 1. Levels of virus along with IFN-β and IFN-λ and IFN-stimulated gene expression (tracked by 2'-5'-oligoadenylate synthetase 1 and myxovirus (influenza virus) resistance 1 mRNA) were determined up to 72 hours postinoculation.

RESULTS

After IAV infection, viral levels were increased 2-fold in hBECs from asthmatic subjects compared with nonasthmatic control subjects (P < .05) and this increase occurred in concert with increased IFN-λ1 levels and no significant difference in IFNB1, 2'-5'-oligoadenylate synthetase 1, or myxovirus (influenza virus) resistance 1mRNA levels. After RSV infections, viral levels were not significantly increased in hBECs from asthmatic versus nonasthmatic subjects and the only significant difference between groups was a decrease in IFN-λ levels (P < .05) that correlated with a decrease in viral titer. All these differences were found only at isolated time points and were not sustained throughout the 72-hour infection period.

CONCLUSIONS

The results indicate that IAV and RSV control and IFN response to these viruses in airway epithelial cells is remarkably similar between subjects with and without asthma.

Advances in antivirals for non-influenza respiratory virus infections

Progress in the development of antivirals for non‐influenza respiratory viruses has been slow with the result that many unmet medical needs and few approved agents currently exist. This commentary selectively reviews examples of where specific agents have provided promising clinical benefits in selected target populations and also considers potential therapeutics for emerging threats like the SARS and Middle East respiratory syndrome coronaviruses. Recent studies have provided encouraging results in treating respiratory syncytial virus infections in lung transplant recipients, serious parainfluenza virus and adenovirus infections in immunocompromised hosts, and rhinovirus colds in outpatient asthmatics. While additional studies are needed to confirm the efficacy and safety of the specific agents tested, these observations offer the opportunity to expand therapeutic studies to other patient populations.

Effect of exogenous interferons on rhinovirus replication and airway inflammatory responses

BACKGROUND

Human rhinoviruses (HRVs) are the most common cause of asthma exacerbations. In airway epithelial cells, the primary site of HRV infection, decreased production of interferons (IFNs) may result in greater susceptibility to HRV and worsened symptoms. Thus, exogenous IFN could supplement the innate immune response and provide a treatment for virus-induced asthma exacerbations. Furthermore, the effects of exogenous IFN could be type specific in part because of the cellular distribution of type 1 and type 2 IFN receptors.

OBJECTIVE

To investigate the effects of exogenous IFNs on HRV replication in bronchial epithelial cells.

METHODS

Frozen stocks of primary human bronchial epithelial cells from healthy donors were cultured in monolayers; pretreated (24 hours) with 0.1-ng/mL, 1-ng/mL, or 10-ng/mL doses of IFN-α, -β, -λ1, or -λ2; and infected with HRV-1A. Viral replication was quantified using real-time reverse transcription-polymerase chain reaction, and cytokine and chemokine secretion 24 hours after infection was measured by multiplex enzyme-linked immunosorbent assay.

RESULTS

Compared with untreated samples, IFN-α, IFN-β, IFN-λ1, and IFN-λ2 (0.1 ng/mL) significantly reduced HRV replication after high- (P < .02) and low-dose inoculation (P < .05). Similar effects were seen in 1-ng/mL and 10-ng/mL doses of IFN, where HRV replication was significantly decreased in both high- (P < .001) and low-dose inoculation (P < .001). Treatment with IFNs also enhanced HRV-induced IFN-γ-induced protein 10 secretion (P < .001). Finally, treatment with either IFN-λ1 or IFN-λ2 significantly increased HRV-induced secretion of RANTES (regulated on activation, normal T-expressed, and presumably secreted) (P < .05) but not IL-1β or vascular endothelial growth factor.

CONCLUSION

These findings suggest that exogenous IFNs, IFN-λ1 in particular, warrant further study as a potential therapy for virus-induced asthma exacerbations.

New horizons: Current and potential future self-treatments for acute upper respiratory tract conditions

Acute upper respiratory tract conditions (URTCs), including the common cold, allergic rhinitis (AR), and acute sinusitis, are among the most common afflictions worldwide, affecting millions of individuals annually in the United States alone. A common theme among these conditions is that they share similar symptomatology and are often inadequately treated. These conditions typically cause mild, albeit bothersome, symptoms for a typical duration of 7 to 10 days in the case of the common cold, ≥ 2 weeks for AR exacerbations, and > 4 weeks for acute sinusitis. The common cold and AR elicit localized (upper airway) and systemic inflammatory cascades responsible for symptoms such as cough, nasal congestion, rhinorrhea, watery eyes, sneezing, headache, and general malaise. Acute sinusitis typically occurs because of a secondary bacterial or fungal infection of mucus-clogged nasal and sinus cavities and has symptoms similar to those previously listed, with the addition of increased facial and ear pressure/pain. Acute URTC symptoms are frequently managed with over-the-counter (OTC) products. Currently available OTC options can have limited efficacy in treating the broad array of symptoms associated with acute URTCs, and some have unwanted side effects. There is an unmet need for OTC therapies that have broad clinical activity, can reduce the severity and duration of illness when taken at the first sign of symptoms, and/or provide prophylaxis. This review article examines the available evidence supporting emerging and potentially new OTC pharmacologic, nutraceutical, and nonpharmacologic therapies on the horizon for the treatment of acute URTCs. This review is not intended to be a comprehensive evaluation of all potential URTC therapies, and the approvability of many of the agents discussed for OTC use in the United States may be subject to debate.

Virus shedding after human rhinovirus infection in children, adults and patients with hypogammaglobulinaemia

The shedding of human rhinovirus (HRV) after an acute, naturally acquired infection has not been described in detail. We determined the duration of HRV shedding in immunocompetent children and adults, and in patients with primary hypogammaglobulinaemia. Subjects with symptoms of respiratory tract infection, and their household contacts, were screened for HRV by reverse transcription PCR. They were followed by serial, self-collected nasal swab specimens until negative for HRV or infected by another HRV type. We followed 62 HRV infections in 54 subjects. The mean (95% CI) duration of HRV shedding was 11.4 (8.2-14.7) days in children, 10.1 (7.4-12.9) days in adults, and 40.9 (26.4-55.4) days in patients with hypogammaglobulinaemia (p <0.001). The duration of respiratory tract symptoms correlated with the duration of virus shedding (p 0.002). A new infection by another HRV type soon after the first episode was common. We conclude that the shedding times of HRV are relatively short in otherwise healthy individuals. In contrast, prolonged shedding over 28 days is frequent in patients with hypogammaglobulinaemia despite immunoglobulin replacement therapy.

George K, Walsh TJ. Human rhinoviruses

Human rhinoviruses (HRVs), first discovered in the 1950s, are responsible for more than one-half of cold-like illnesses and cost billions of dollars annually in medical visits and missed days of work. Advances in molecular methods have enhanced our understanding of the genomic structure of HRV and have led to the characterization of three genetically distinct HRV groups, designated groups A, B, and C, within the genus Enterovirus and the family Picornaviridae. HRVs are traditionally associated with upper respiratory tract infection, otitis media, and sinusitis. In recent years, the increasing implementation of PCR assays for respiratory virus detection in clinical laboratories has facilitated the recognition of HRV as a lower respiratory tract pathogen, particularly in patients with asthma, infants, elderly patients, and immunocompromised hosts. Cultured isolates of HRV remain important for studies of viral characteristics and disease pathogenesis. Indeed, whether the clinical manifestations of HRV are related directly to viral pathogenicity or secondary to the host immune response is the subject of ongoing research. There are currently no approved antiviral therapies for HRVs, and treatment remains primarily supportive. This review provides a comprehensive, up-to-date assessment of the basic virology, pathogenesis, clinical epidemiology, and laboratory features of and treatment and prevention strategies for HRVs.

Exogenous IFN-β has antiviral and anti-inflammatory properties in primary bronchial epithelial cells from asthmatic subjects exposed to rhinovirus

BACKGROUND

Rhinoviruses are the major cause of asthma exacerbations. Previous studies suggest that primary bronchial epithelial cells (PBECs) from asthmatic subjects are more susceptible to rhinovirus infection because of deficient IFN-β production. Although augmenting the innate immune response might provide a novel approach for treatment of virus-induced asthma exacerbations, the potential of IFN-β to modulate antiviral and proinflammatory responses in asthmatic epithelium is poorly characterized.

OBJECTIVES

We sought to compare responses of PBECs from nonasthmatic and asthmatic subjects to exogenous IFN-β and test the inflammatory effects of IFN-β in response to rhinovirus infection.

METHODS

PBECs were treated with IFN-β and infected with a low inoculum of human rhinovirus serotype 1B to simulate a natural viral infection. Expression of interferon-responsive genes and inflammatory responses were analyzed by using reverse transcription-quantitative real-time PCR, cytometric bead arrays, or both; viral titers were assessed by using the 50% tissue culture infection dose.

RESULTS

Expression of IFN-β-stimulated antiviral genes was comparable in PBECs from nonasthmatic or asthmatic donors. Exogenous IFN-β significantly protected PBECs from asthmatic donors against rhinovirus infection by suppressing viral replication. Interferon-inducible protein 10 (IP-10), RANTES, and IL-6 release in response to rhinovirus infection was triggered only in PBECs from asthmatic donors. Although exogenous IFN-β alone stimulated some release of IP-10 (but not IL-6 or RANTES), it significantly reduced rhinovirus-induced IP-10, RANTES, and IL-6 expression when tested in combination with rhinovirus.

CONCLUSIONS

PBECs from asthmatic donors have a normal antiviral response to exogenous IFN-β. The ability of IFN-β to suppress viral replication suggests that it might limit virus-induced exacerbations by shortening the duration of the inflammatory response.

Transmission route of rhinovirus type 39 in a monodispersed airborne aerosol

The common cold affects millions of people. Unfortunately, it remains unknown whether cold viruses enter the respiratory tract only through the nose and mouth or whether they can also enter through the tear ducts. Transocular exposure to an airborne infectious dose of human rhinovirus did not lead to infection.

Host immune responses to rhinovirus: mechanisms in asthma

Viral respiratory infections can have a profound effect on many aspects of asthma including its inception, exacerbations, and, possibly, severity. Of the many viral respiratory infections that influence asthma, the common cold virus, rhinovirus, has emerged as the most frequent illness associated with exacerbations and other aspects of asthma. The mechanisms by which rhinovirus influences asthma are not fully established, but current evidence indicates that the immune response to this virus is critical in this process. Many airway cell types are involved in the immune response to rhinovirus, but most important are respiratory epithelial cells and possibly macrophages. Infection of epithelial cells generates a variety of proinflammatory mediators to attract inflammatory cells to the airway with a subsequent worsening of underlying disease. Furthermore, there is evidence that the epithelial airway antiviral response to rhinovirus may be defective in asthma. Therefore, understanding the immune response to rhinovirus is a key step in defining mechanisms of asthma, exacerbations, and, perhaps most importantly, improved treatment.

Antiviral therapy for respiratory tract infections

Viruses are important pathogens causing respiratory tract infections both in the community and health-care facility settings. They are extremely common causes of morbidity in the competent hosts and some are associated with significant mortality in the compromised individuals. With wider application of molecular techniques, novel viruses are being described and old viruses are found to have new significance in different epidemiological and clinical settings. Some of these emerging pathogens may have the potential to cause pandemics or global spread of a severe disease, as exemplified by severe acute respiratory syndrome and avian influenza. Antiviral therapy of viral respiratory infections is often unnecessary in the competent hosts because most of them are selflimiting and effective agents are not always available. In the immunocompromised individuals or for infections caused by highly pathogenic viruses, such as avian influenza viruses (AIV), antiviral treatment is highly desirable, despite the fact that many of the agents may not have undergone stringent clinical trials. In immunocompetent hosts, antiviral therapy can be stopped early because adaptive immune response can usually be mounted within 5-14 days. However, the duration of antiviral therapy in immunosuppressed hosts depends on clinical and radiological resolution, the degree and duration of immunosuppression, and therefore maintenance therapy is sometimes needed after the initial response. Immunotherapy and immunoprophylaxis appear to be promising directions for future research. Appropriate and targeted immunomodulation may play an important adjunctive role in some of these infections by limiting the extent of end-organ damage and multi-organ failure in some fulminant infections.

Iota-Carrageenan is a potent inhibitor of rhinovirus infection

Background

Human rhinoviruses (HRVs) are the predominant cause of common cold. In addition, HRVs are implicated in the worsening of COPD and asthma, as well as the loss of lung transplants. Despite significant efforts, no anti-viral agent is approved for the prevention or treatment of HRV-infection.

Results

In this study we demonstrate that Iota-Carrageenan, a sulphated polysaccharide derived from red seaweed, is a potent anti-rhinoviral substance in-vitro. Iota-Carrageenan reduces HRV growth and inhibits the virus induced cythopathic effect of infected HeLa cells. In addition, Iota-Carrageenan effectively prevents the replication of HRV1A, HRV2, HRV8, HRV14, HRV16, HRV83 and HRV84 in primary human nasal epithelial cells in culture. The data suggest that Iota-Carrageenan acts primarily by preventing the binding or the entry of virions into the cells.

Conclusion

Since HRV infections predominately occur in the nasal cavity and the upper respiratory tract, a targeted treatment with a product containing Iota-Carrageenan is conceivable. Clinical trials are needed to determine whether Iota-Carrageenan-based products are effective in the treatment or prophylaxis of HRV infections.

Respiratory viruses other than influenza virus: impact and therapeutic advances

Though several antivirals have been developed and marketed to treat influenza virus infections, the development of antiviral agents with clinical activity against other respiratory viruses has been more problematic. Here we review the epidemiology of respiratory viral infections in immunocompetent and immunocompromised hosts, examine the evidence surrounding the currently available antivirals for respiratory viral infections other than influenza, highlight those that are in the pipeline, and discuss the hurdles for development of such agents.

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.

Viral upper respiratory tract infections in young children with emphasis on acute otitis media

Viral upper respiratory infection is the most common reason for seeking medical care for children. Recurrent viral respiratory infections and subsequent complications (e.g. acute otitis media (AOM)) are a burden for children, their families and society. Over the past decade, our knowledge on the significance of respiratory viruses has broadened remarkably. Viruses cause large variety of respiratory diseases and cause alone diseases, which previously have been assumed to be bacterial only (e.g. AOM and pneumonia). Methods for detection analysis of respiratory viruses are developing making both the diagnosis and epidemiological investigations of respiratory infections easier. Accurate diagnosis of respiratory infections and awareness of possible viral etiology could reduce the use of antibiotics. Etiologic studies of viral infections are becoming increasingly important, with the emergence of new antiviral drugs and vaccines.

Antivirals for influenza: historical perspectives and lessons learned

The development of the currently available classes of antivirals, the M2 proton channel inhibitors and the neuraminidase inhibitors, provides valuable perspectives relevant to the field of antiviral chemotherapy in general and insights into aspects of viral pathogenesis and antiviral resistance relevant specifically to influenza. The efficacy observed with these antiviral drugs has proven the importance of these antiviral targets, as well as the principle that chemoprophylaxis and early treatment are possible in influenza infections with small molecular weight inhibitors.

Rhinovirus chemotherapy

Human rhinoviruses (HRV), members of the Picornaviridae family, are comprised of over 100 different virus serotypes. HRV represent the single most important etiological agents of the common cold [Arruda, E., Pitkaranta, A., Witek Jr., T.J., Doyle, C.A., Hayden, F.G., 1997. Frequency and natural history of rhinovirus infections in adults during autumn. J. Clin. Microbiol. 35, 2864–2868; Couch, R.B., 1990. Rhinoviruses. In: Fields, B.N., Knipe, D.M. (Eds.), Virology. Raven Press, New York, pp. 607–629; Turner, R.B., 2001. The treatment of rhinovirus infections: progress and potential. Antivir. Res. 49 (1), 1–14]. Although HRV-induced upper respiratory illness is often mild and self-limiting, the socioeconomic impact caused by missed school or work is enormous and the degree of inappropriate antibiotic use is significant. It has been estimated that upper respiratory disease accounts for at least 25 million absences from work and 23 million absences of school annually in the United States [Anzueto, A., Niederman, M.S., 2003. Diagnosis and treatment of rhinovirus respiratory infections. Chest 123 (5), 1664–1672; Rotbart, H.A., 2002. Treatment of picornavirus infections. Antivir. Res. 53, 83–98]. Increasing evidences also describe the link between HRV infection and more serious medical complications. HRV-induced colds are the important predisposing factors to acute otitis media, sinusitis, and are the major factors in the induction of exacerbations of asthma in adults and children. HRV infections are also associated with lower respiratory tract syndromes in individuals with cystic fibrosis, bronchitis, and other underlying respiratory disorders [Anzueto, A., Niederman, M.S., 2003. Diagnosis and treatment of rhinovirus respiratory infections. Chest 123 (5), 1664–1672; Gern, J.E., Busse, W.W., 1999. Association of rhinovirus infections with asthma. Clin. Microbiol. Rev. 12 (1), 9–18; Pitkaranta, A., Arruda, E., Malmberg, H., Hayden, F.G., 1997. Detection of rhinovirus in sinus brushings of patients with acute community-acquired sinusitis by reverse transcription-PCR. J. Clin. Microbiol. 35, 1791–1793; Pitkaranta, A., Virolainen, A., Jero, J., Arruda, E., Hayden, F.G., 1998. Detection of rhinovirus, respiratory syncytial virus, and coronavirus infections in acute otitis media by reverse transcriptase polymerase chain reaction. Pediatrics 102, 291–295; Rotbart, H.A., 2002. Treatment of picornavirus infections. Antivir. Res. 53, 83–98]. To date, no effective antiviral therapies have been approved for either the prevention or treatment of diseases caused by HRV infection. Thus, there still exists a significant unmet medical need to find agents that can shorten the duration of HRV-induced illness, lessen the severity of symptoms, minimize secondary bacterial infections and exacerbations of underlying disease and reduce virus transmission. Although effective over-the-counter products have been described that alleviate symptoms associated with the common cold [Anzueto, A., Niederman, M.S., 2003. Diagnosis and treatment of rhinovirus respiratory infections. Chest 123 (5), 1664–1672; Gwaltney, J.M., 2002a. Viral respiratory infection therapy: historical perspectives and current trials. Am. J. Med. 22 (112 Suppl. 6A), 33S–41S; Turner, R.B., 2001. The treatment of rhinovirus infections: progress and potential. Antivir. Res. 49 (1), 1–14; Sperber, S.J., Hayden, F.G., 1988. Chemotherapy of rhinovirus colds. Antimicrob. Agents Chemother. 32, 409–419], this review will primarily focus on the discovery and development of those agents that directly or indirectly impact virus replication specifically highlighting new advances and/or specific challenges with their development.

[Acute viral respiratory tract infections and childhood asthma]

Les infections virales respiratoires sont de très importants facteurs déclenchants des crises d'asthme. Chez l'enfant les études épidémiologiques les plus récentes, utilisant la PCR, leur attribuent le déclenchement de 80 à 85 % des crises, aussi bien pour les crises modérées que les crises nécessitant une hospitalisation. Le virus respiratoire syncytial et les virus parainfluenzae prédominent chez le nourrisson, les rhinovirus et le mycoplasme chez l'enfant plus grand. Les mécanismes précis de l'induction des crises d'asthme par les virus restent mal compris, toutefois de récentes études montrent une augmentation de l'activation des cellules inflammatoires dans le lavage alvéolaire. Les sujets atopiques, en dehors des périodes d'allergie, ne semblent pas avoir plus de manifestations respiratoires viro-induites que les non-atopiques. En revanche, chez le sujet asthmatique, l'infection virale aggrave les réactions immédiate et retardée de l'hypersensibilité immédiate après test de provocation allergénique, en augmentant la libération des médiateurs mastocytaires et le recrutement des éosinophiles dans les voies aériennes inférieures. Les études chez l'homme et l'animal suggèrent que la production locale de cytokines (IL4, IL8, RANTES, MIP-1a...) et l'expression accrue chez l'asthmatique de la molécule d'adhésion ICAM1 aient un rôle important pour le recrutement et l'activation des cellules de l'inflammation dans les voies aériennes. Une hypothèse, qui reste à démontrer serait que dans des situations où, comme dans l'asthme, les lymphocytes Th2 prédominent, un excès d'Il4 pourrait inhiber les CD8 cytotoxiques, les cellules NK et les Th1 et ainsi entraîner une diminution des défenses antivirales et une réaction inflammatoire broncho-pulmonaire plus sévère que chez le non-asthmatique.

Interferons, interferon-like cytokines, and their receptors

Recombinant interferon-alpha (IFN-alpha) was approved by regulatory agencies in many countries in 1986. As the first biotherapeutic approved, IFN-alpha paved the way for the development of many other cytokines and growth factors. Nevertheless, understanding the functions of the multitude of human IFNs and IFN-like cytokines has just touched the surface. This review summarizes the history of the purification of human IFNs and the key aspects of our current state of knowledge of human IFN genes, proteins, and receptors. All the known IFNs and IFN-like cytokines are described [IFN-alpha, IFN-beta, IFN-epsilon, IFN-kappa, IFN-omega, IFN-delta, IFN-tau, IFN-gamma, limitin, interleukin-28A (IL-28A), IL-28B, and IL-29] as well as their receptors and signal transduction pathways. The biological activities and clinical applications of the proteins are discussed. An extensive section on the evolution of these molecules provides some new insights into the development of these proteins as major elements of innate immunity. The overall structure of the IFNs is put into perspective in relation to their receptors and functions.

Human rhinoviruses

Human rhinoviruses are the most important causative agents of upper respiratory infections and are also implicated in more severe clinical entities. Although often present, very little is known about human rhinoviruses. Molecular methods have been used in the classification of this large group of viruses into two separate clades. In addition, one known serotype was found to be a member of enterovirus group D. Laboratory diagnosis of human rhinovirus infection is based on reverse transcription polymerase chain reaction methods or the more tedious virus culture but a rapid "bedside" method is unavailable. Anti-rhinoviral therapy has been under extensive study over the past few decades but symptomatic treatment of the common cold is still the only useful approach in clinical use. More data on circulating human rhinovirus strains would facilitate both detection and treatment of these common pathogens.

Viral respiratory infections due to rhinoviruses: current knowledge, new developments

Viral respiratory infections (VRIs) are among the most common reasons for which primary care providers are consulted. VRIs due to rhinoviruses-the most commonly implicated etiologic agent-constitute a syndrome characterized by signs and symptoms of a cold. Rhinoviruses have been implicated in respiratory tract illnesses such as sinusitis and otitis media, as well as lower respiratory complications in high-risk populations. Most patients treat VRI with over-the-counter remedies that have been demonstrated to produce marginal clinical benefits. The development of novel antiviral agents has intensified interest in VRIs. Pleconaril, a capsid-function inhibitor currently under FDA review, has been shown in clinical trials to reduce the duration and severity of rhinovirus VRIs. By targeting the cause of illness, antiviral agents represent an opportunity to reduce the substantial clinical burden of VRI. Furthermore, effective therapies can potentially reduce inappropriate antibiotic use for viral infections.

Viral respiratory infection therapy: historical perspectives and current trials

Attempts to relieve the misery of the common cold have been made since long before current understanding of its viral origin. Although current symptomatic therapies provide some relief, any effective treatment must incorporate an antiviral to address the infection. Symptom production is related not only to viral cytopathic effect but also to the early activation of several inflammatory pathways. Antiviral treatment alone may not be able to prevent these events. Combining an antiviral with selected therapeutic agents that block these inflammatory pathways has been shown to improve the effectiveness of cold treatment. Early diagnosis and initiation of treatment combined with regular dosing until symptoms subside appears to be the most effective treatment strategy to maximize therapeutic outcomes. This strategy reduces viral shedding in nasal fluid, provides treatment for the period of maximum symptom burden, and may reduce the frequency and severity of the sinus disease that accompanies colds.

Rhinovirus respiratory infections and asthma

Viral infections, particularly respiratory illnesses caused by rhinovirus, are the most common cause of asthma exacerbations in children and contribute in large part to asthma morbidity in adults. Epidemiologic studies and increasingly sophisticated viral detection methodologies have helped to define the role of rhinovirus as a potential causative agent in asthma exacerbations. Rhinovirus-induced lung disease is multifaceted and can be characterized in terms of a variety of physiologic, immunologic, and viral processes. The precise direct and indirect mechanisms of viral contribution to exacerbations must still be elucidated. Understanding them will have an impact on the design of future treatment modalities.

Treatment of picornavirus infections

The picornaviruses are a diverse group of viral pathogens that together comprise the most common causes of infections of humans in the developed world. Within the picornavirus family are three well-known groups of human pathogens-the enteroviruses (including polioviruses, coxsackieviruses, and echoviruses), the rhinoviruses, and the hepatoviruses (including hepatitis A). Recently, the parechoviruses (formerly, echoviruses 22 and 23) have been classified as a fourth genus of human picornaviruses. This article will focus on the enteroviruses and rhinoviruses agents, for which substantial effort has been expended and recent successes reported towards the development of safe and effective antiviral therapy.

The role of viral infections in the natural history of asthma

Viral infections have been related to the inception of recurrent wheezing illnesses and asthma in infants and are probably the most frequent cause of exacerbations of established disease in older children and adults. The well-recognized clinical effects of viral infections are mainly caused by virus-induced immune responses. Clinical studies of natural and experimentally induced viral infections have led to the identification of mechanisms of inflammation that could be involved in producing airway obstruction and lower airway symptoms. In addition, host factors that are associated with more vigorous viral replication or severe clinical illness are beginning to be identified. Advances in molecular virology and our understanding of immune responses to viral infections may lead to the development of new strategies for the prevention and treatment of virus-induced respiratory disorders.

Antiviral therapy for enteroviruses and rhinoviruses

The picornaviruses are a diverse group of viral pathogens that together comprise the most common causes of infection of humans in the developed world. Within the picornavirus family are three well-known groups of human pathogens--the rhinoviruses, the enteroviruses (including polioviruses, coxsackieviruses and echoviruses) and the hepatoviruses (including hepatitis A virus). This article will focus on the rhinoviruses and enteroviruses, agents for which substantial effort has been expended, and recent successes reported, toward the development of safe and effective antiviral therapy.

Spectrum of clinical illness in hospitalized patients with "common cold" virus infections

The viruses associated most frequently with the "common cold" are rhinoviruses and coronaviruses. The first prospective cohort study to determine the prevalence of rhinovirus and coronavirus infections in patients of all ages hospitalized for acute respiratory illnesses is described. Hospital admissions for acute respiratory illnesses were identified, and cell culture for rhinovirus and serologic assays on paired sera for coronaviruses 229E and OC43 were performed. A total of 61 infections with rhinoviruses and coronaviruses were identified from 1198 respiratory illnesses (5.1%); in addition, 9 additional infections associated with >/=1 other respiratory viruses were identified. Of those infected with only rhinovirus or coronavirus, underlying cardiopulmonary diseases were present in 35% of the patients aged <5 years, in 93% aged between 5 and 35 years, and in 73% aged >35 years. The predominant clinical syndromes varied by age: pneumonia and bronchiolitis in children aged <5 years; exacerbations of asthma in older children and young adults; and pneumonia and exacerbations of chronic obstructive pulmonary disease and congestive heart failure in older adults. Therefore, rhinovirus and coronavirus infections in hospitalized patients were associated with lower respiratory tract illnesses in all age groups.

Systemic effects of orally administered interferons and interleukin-2

Orally administered interferons (IFN-alpha, IFN-beta, and IFN-gamma) have been shown to exert a number of systemic effects. Orally administered IFNs exert dose-dependent suppressive effects on the peripheral white blood cell (WBC) count. The suppression of the peripheral WBC count is mediated by a suppression of the function of the bone marrow, as measured in an in vitro bone marrow colony-forming assay. The peripheral WBC and bone marrow suppressive effects of orally administered IFNs are at least as potent as those occurring with parenterally administered IFNs. However, the mechanism by which orally administered IFNs exert these peripheral WBC suppressive and bone marrow suppressive effects differs significantly from that of parenterally administered IFNs: orally administered IFN is not detectable in the serum, the effect of orally administered IFN is not blocked by circulating antibody, the effect of orally administered IFN can be adoptively transferred by injection with peripheral white blood cells from donor mice, and the effect of orally administered IFN develops more slowly than that of parenterally administered interferon. Orally administered IFN-alpha employed alone and in synergistic combination with intraperitoneally administered IFN-gamma can exert an antitumor effect. Finally, orally administered interleukin-2 can exert a suppressive effect on both the peripheral white blood cell count and on the bone marrow. These observations suggest that the oral route may be an effective and novel mechanism for the efficacious administration of IFNs and other lymphokines/cytokines.

Chemotherapy of respiratory viruses: prospects and challenges

Billions of people are infected with respiratory viruses annually. Infants and young children, the elderly, immunocompromised individuals and those debilitated by other diseases or nutritional deficiencies are most at risk for serious disease. There are few vaccines available for use against these viruses, and even where there are (influenza, measles and adenovirus), infections remain common. The continued prevalence of respiratory virus infections has lead to renewed efforts to find safe agents effective against the most medically important respiratory viruses: influenza, respiratory syncytial, parainfluenza, measles, rhino- and adenovirus. Copyright 1999 Harcourt Publishers Ltd.