Pathogenesis and management of adenoviral keratoconjunctivitis

Systems approach to design multi-epitopic peptide vaccine candidate against fowl adenovirus structural proteins for Gallus gallus domesticus

Introduction

Fowl adenovirus (FAdV) is a significant pathogen in poultry, causing various diseases such as hepatitis-hydropericardium, inclusion body hepatitis, and gizzard erosion. Different serotypes of FAdV are associated with specific conditions, highlighting the need for targeted prevention strategies. Given the rising prevalence of FAdV-related diseases globally, effective vaccination and biosecurity measures are crucial. In this study, we explore the potential of structural proteins to design a multi-epitope vaccine targeting FAdV.

Methods

We employed an in silico approach to design the multi-epitope vaccine. Essential viral structural proteins, including hexon, penton, and fiber protein, were selected as vaccine targets. T-cell and B-cell epitopes binding to MHC-I and MHC-II molecules were predicted using computational methods. Molecular docking studies were conducted to validate the interaction of the multi-epitope vaccine candidate with chicken Toll-like receptors 2 and 5.

Results

Our in silico methodology successfully identified potential T-cell and B-cell epitopes within the selected viral structural proteins. Molecular docking studies revealed strong interactions between the multi-epitope vaccine candidate and chicken Toll-like receptors 2 and 5, indicating the structural integrity and immunogenic potential of the designed vaccine.

Discussion

The designed multi-epitope vaccine presents a promising approach for combating FAdV infections in chickens. By targeting essential viral structural proteins, the vaccine is expected to induce a robust immunological response. The in silico methodology utilized in this study provides a rapid and cost-effective means of vaccine design, offering insights into potential vaccine candidates before experimental validation. Future studies should focus on in vitro and in vivo evaluations to further assess the efficacy and safety of the proposed vaccine.

Global Prevalence of Preexisting Antibodies against Human Adenoviruses, Surveyed from 1962 to 2021

BACKGROUND

Human adenoviruses (HAdVs) are extensively used as vectors for vaccines development and cancer therapy. People who already have antibodies against HAdVs, on the other hand, would have an impact on the preventative or therapeutic effect. This review focuses primarily on the prevalence of pre-existing antibodies against HAdVs in distinct geographical populations.

SUMMARY

After screening, 64 studies from 31 countries between 1962 and 2021 were selected, totaling 39,427 samples. The total prevalence of preexisting antibodies to HAdVs varied by country or location, ranging from 2.00 to 95.70%. Southeast Asia had the highest prevalence (54.57%) while Europe had the lowest (18.17%). The prevalence in practically all developing nations was higher than in developed nations. Adults have a greater frequency than children and newborns in most nations. The primary HAdV antibody types varied by country. Adults in China, the USA, the United Kingdom, and Belgium had the lowest prevalence of preexisting antibodies against HAdV55, HAdV37, HAdV8, and HAdV36, respectively. Children in the USA, China, the United Kingdom, and Japan had the lowest rates of HAdV48, HAdV11, HAdV8, and HAdV40. The frequency of antibodies differed significantly between military and civilian groups.

KEY MESSAGES

Preexisting antibodies against various types of HAdVs differed greatly throughout worldwide populations. Future development of HAdV-vector vaccines and medicines should focus on preexisting antibodies in target groups rather than a "one-size-fits-all" strategy. It might be advantageous in selecting HAdV vectors for studying the prevalence of preexisting antibodies against HAdVs in different locations and people throughout the world.

Common and Potential Emerging Foodborne Viruses: A Comprehensive Review

Human viruses and viruses from animals can cause illnesses in humans after the consumption of contaminated food or water. Contamination may occur during preparation by infected food handlers, during food production because of unsuitably controlled working conditions, or following the consumption of animal-based foods contaminated by a zoonotic virus. This review discussed the recent information available on the general and clinical characteristics of viruses, viral foodborne outbreaks and control strategies to prevent the viral contamination of food products and water. Viruses are responsible for the greatest number of illnesses from outbreaks caused by food, and risk assessment experts regard them as a high food safety priority. This concern is well founded, since a significant increase in viral foodborne outbreaks has occurred over the past 20 years. Norovirus, hepatitis A and E viruses, rotavirus, astrovirus, adenovirus, and sapovirus are the major common viruses associated with water or foodborne illness outbreaks. It is also suspected that many human viruses including Aichi virus, Nipah virus, tick-borne encephalitis virus, H5N1 avian influenza viruses, and coronaviruses (SARS-CoV-1, SARS-CoV-2 and MERS-CoV) also have the potential to be transmitted via food products. It is evident that the adoption of strict hygienic food processing measures from farm to table is required to prevent viruses from contaminating our food.

Case for conservative management of adenoviral pseudomembranous conjunctivitis

The clinical course of adenoviral pseudomembranous conjunctivitis is mostly self-limiting and requires only supportive management measures; however, a minority of patients may develop severe inflammation in response to the virus, which can present as subepithelial infiltrates and pseudomembranes. In its most severe form, symblepharon can result from the inflammatory response resulting in longer-term clinical sequelae. The optimal management of adenoviral pseudomembranous conjunctivitis is poorly defined and while debridement is commonly recommended, there is limited evidence base to support this practice. In this paper, we present two cases of PCR-proven adenoviral pseudomembranous conjunctivitis managed conservatively with topical lubricants and corticosteroids rather than debridement to good effect.

In Vitro efficacy of cyclosporine a and various antiseptics and antiviral drugs on adenovirus genotype 8, a common cause of epidemic keratoconjunctivitis

PURPOSE

To evaluate the in vitro efficacy of cidofovir, ganciclovir, povidone-iodine, chlorhexidine, and cyclosporine A on adenovirus genotype 8.

METHODS

Conjunctival samples were collected from patients with adenoviral conjunctivitis and cultured in A549 cells. Adenovirus diagnosis was confirmed by RT-PCR. For each drug, the 50% cytotoxic concentration (CC 50 ) was determined. Subsequently, the antiviral activity was tested at concentrations below CC 50, and the 50% inhibitor concentration (IC 50 ) of drugs was determined RESULTS: While the IC 50 of cidofovir against adenovirus genotype 8 was 3.07 ± 0.8 µM, ganciclovir, povidone-iodine, chlorhexidine, and cyclosporine A were not found to be effective against adenovirus genotype 8 at concentrations below the CC 50 value.

CONCLUSIONS

Cidofovir was found effective and the IC 50 value was within the ranges in the literature. Ganciclovir and cyclosporine A were found to be ineffective at doses below the cytotoxic dose, povidone-iodine and chlorhexidine was found to be highly cytotoxic.

Molecular Epidemiology of Adenoviral Keratoconjunctivitis in Korea

Human adenoviruses (HAdVs) are a major cause of epidemic keratoconjunctivitis. We investigated the types of adenoviruses responsible for the recent epidemic of keratoconjunctivitis in Korea. From January to November 2019, 218 conjunctival swab samples were collected from patients clinically suspected as having adenoviral keratoconjunctivitis. Genotyping targeting of adenovirus capsid hexon genes was performed using PCR and sequencing. Of the 218 samples collected, 128 (58.7%) were positive for the adenovirus genes by PCR, and 126 samples were successfully genotyped. Adenovirus type 8 (HAdV-D8) was the most common type (67.5%), followed by HAdV-D64 (11.1%), HAdV-D37 (9.5%), HAdV-B3 (5.6%), HAdV-D53 (4.0%), HAdV-E4 (1.6%), and HAdV-D56 (0.8%). Adenoviral keratoconjunctivitis cases were the most frequent in July and August 2019, which were mainly caused by type 8. Phylogenetic analyses revealed little genetic distance among adenoviruses of the same type detected in our study. Our results provide basic data for further studies of adenoviral keratoconjunctivitis.

Antiviral Drugs in Adenovirus-Induced Keratoconjunctivitis

Human adenovirus (HAdV) is one of the most common causes of conjunctivitis worldwide. Depending on specific serotypes and other factors, it can lead to several ocular manifestations, ranging from isolated, self-limited disease to epidemic and potentially sight-threatening keratoconjunctivitis. To date, no antiviral agent against ocular adenovirus has been licensed, and its management is still based on hygienic and supportive measures alone. In this review, a literature search up to August 2021 was performed to find peer-reviewed articles, with the primary aim to investigate drugs or other compounds with any antiviral activity against adenovirus. Finally, we included 70 articles, consisting of both in vitro, and in vivo studies on animal models and clinical trials of any phase, as well as a case-report, and analyzed each compound separately. Many antiviral agents proved to be effective on in vivo and in vitro studies on animal models, and in pre-clinical trials, but lacked reliability in large, controlled clinical investigations. The design of such studies, though, presented several hurdles, due to the nature and the specific characteristics of adenovirus-induced ocular diseases. Nevertheless, some promising compounds are currently under study, and further investigations are needed to prove their efficacy in the management of adenovirus conjunctivitis.

Diagnostic accuracy of clinical signs, symptoms and point-of-care testing for early adenoviral conjunctivitis

CLINICAL RELEVANCE

This study identifies key signs and symptoms of acute conjunctivitis, that when combined with a point-of-care test, can improve clinician accuracy of diagnosing adenoviral conjunctivitis.

BACKGROUND

Adenoviral conjunctivitis is a common ocular infection with the potential for high economic impact due to widespread outbreaks and subsequent furloughs from work and school. In this report, we describe clinical signs and participant-reported symptoms that most accurately identify polymerase chain reaction (PCR)-confirmed adenoviral conjunctivitis.

METHODS

Adults with 'red eye' symptoms of four days or less were enrolled. Participants rated 10 ocular symptoms from 0 (not bothersome) to 10 (very bothersome), and indicated the presence or absence of systemic flu-like symptoms. Clinicians determined the presence or absence of swollen lymph nodes and rated the severity of eight ocular signs using a 5-point scale. An immunoassay targeting adenovirus antigen was utilised for the point-of-care test, and conjunctival swab samples were obtained for subsequent adenovirus detection by PCR analyses. Univariate and multivariate logistic regression models were used to identify symptoms and signs associated with PCR-confirmed adenoviral conjunctivitis. The diagnostic accuracy of these clinical findings, and the potential benefit of incorporating point-of-care test results, was assessed by calculating areas under the receiver operating characteristic curves (AUC).

RESULTS

Clinician-rated bulbar conjunctival redness, participant-rated eyelid swelling and overall ocular discomfort had the best predictive value in the multivariate logistic regression model with an AUC of 0.83. The addition of the point-of-care test results to these three clinical sign/symptom scores improved diagnostic accuracy, increasing the AUC to 0.94.

CONCLUSIONS

Conjunctival redness severity and participant-reported eyelid swelling and overall discomfort, along with adenoviral point-of-care test results, were highly predictive in identifying individuals with PCR-confirmed adenoviral conjunctivitis. Improved diagnostic accuracy by clinicians at the initial presenting visit could prevent unnecessary work furloughs and facilitate earlier treatment decisions.

Efficacy and tolerability of polyvinylpyrrolidone-iodine 0.6% treatment in adenoviral keratoconjunctivitis: a Prospective Randomized Controlled Study

OBJECTIVES

To analyze the effect of the employment of polyvinylpyrrolidone-iodine (PVP-I) 0.6% eye drop on the clinical course of patients affected by Adenoviral Keratoconjunctivitis (AKC).

METHODS

Consecutive patients with clinical signs of AKC and positive results of AdenoPlus test were enrolled from four Italian Centres. Patients were randomized to receive: PVP-I 0.6% eye drops four times/daily for 20 days (Group A) or hyaluronate-based tear substitutes four times/daily for 20 days (Group B). Best-corrected visual acuity (BCVA), optical coherence tomography (OCT) Optovue iVue pachymetry map; corneal haze; conjunctival injection and chemosis; subepithelial corneal infiltrates (SEIs); corneal and conjunctival staining and corneal densitometry were recorded at diagnosis and at every follow-up visit. The primary outcome was the resolution time of AKC.

RESULTS

Overall, 59 AKC patients (34 for Group A and 25 for Group B) completed the study. Patients of Group A showed a significantly shorter resolution time and lower incidence of SEIs compared to patients of Group B. In particular, SEIs were present at the last visit in 3/34 (8.82%) patients of the Group A vs 11/25 (44%) of the Group B (p = 0.005). Patients of Group A showed a significantly lower incidence of corneal haze compared to patients of Group B (0/34 vs 3/25; p = 0.038). No side effects were reported for both groups.

CONCLUSIONS

Although further clinical evaluations are needed, according to our data the use of PVP-I 0.6% eye drop in the setting of AKC reduces the risk of SEIs as well as the resolution time of the disease.

[Diagnosis and treatment of adenoviral keratoconjunctivitis]

PURPOSE

To improve the treatment of adenoviral lesions of the eye based on express diagnostics by the fluorescent antibody technique (FAT) and the use of modern drugs.

MATERIAL AND METHODS

The study included 184 patients (333 eyes) with various manifestations of adenoviral lesions of the ocular surface, who were divided into two groups: group 1 (149 patients, 196 eyes) - acute form, and group 2 (76 patients, 137 eyes) - long lasting form. Effectiveness of the proposed treatment was evaluated against separate group 3 (controls) consisting of 28 people (46 eyes) with completed acute adenovirus infection, who had previously received antibiotic and corticosteroid therapy in other clinics. Conjunctival scrapings of study patients were examined with FAT in our proposed modification. Study patients received local therapy with modern drugs (Okomistin, Aktipol).

RESULTS

FAT detected the adenovirus antigen in 169 cases in group 1 (86%) and in 99 cases in group 2 (72%). Treatment duration amounted to 12±6 days in group 1, 18±8 days in group 2, and 29±7 days in controls. In both study groups, the duration of treatment was significantly reduced in comparison with the controls (p<0.01). Stable clinical effect and complete restoration of visual acuity have been achieved in most cases. There were no allergic and side effects from the therapy.

CONCLUSION

Fluorescent antibody technique is a fast and effective way to diagnose adenovirus infection in ophthalmology. In terms of therapy, the use of an antiseptic, an antiviral drug and diluted corticosteroids is the most rational approach.

Human adenovirus infections in pediatric population - an update on clinico-pathologic correlation

Human adenoviruses can cause infections at any age but most commonly in pediatric population, especially in young children and infants. By the time of 10 years old, most children have had at least one episode of adenovirus infection. Adenoviruses can cause many symptoms similar to common cold, including rhinorrhea, fever, cough, and sore throat. Lower respiratory infections such as bronchitis, bronchiolitis, and pneumonia can be severe and even fatal. Other diseases such as conjunctivitis, gastroenteritis, cystitis, myocarditis, cardiomyopathy, and meningoencephalitis can also be associated with adenovirus infections. A variety of recent advancement of structural and molecular biology methods have revamped the taxonomy of adenoviruses and furthered our understanding of the diversity of related clinical diseases. Because of the wide spectrum and complexity of diseases associated with human adenovirus infections, the scope of this review is limited to basic virology and epidemiology of adenoviruses with a main focus on the clinico–pathologic correlation. Clinical manifestations and pathology of any infectious disease are always related; therefore, it is logical to review clinico–pathologic correlation within the specific disease entity caused by adenoviruses to better understand this common viral infection in pediatric population.

Epidemic keratoconjunctivitis: efficacy of outbreak management

Purpose

Epidemic keratoconjunctivitis (EKC) is one of the most severe ocular viral infections. The aim of this interruptive time series study was to quantitatively evaluate the effectiveness of a hygienic EKC outbreak management concept developed in our ophthalmological department.

Methods

All patients with suspected EKC in the period from August to November 2018 were included in the study. Data were retrospectively collected from the patient’s medical documents and records. The disease was diagnosed clinically and confirmed by virus detection through polymerase chain reaction (PCR) from conjunctival swabs. With the beginning of the epidemic, an outbreak management plan was implemented to reduce the nosocomial spread.

Results

The outbreak lasted 77 days (20th August 2018 to 4th November 2018) and affected a total of 120 patients. This corresponds to a mean of 1.5 patients per outbreak day. The median age was 58 [1–92] years. Of all patients, 61 (50.8%) were female. Conjunctival swabs were collected in 100/120 (83.3%) cases, the adenovirus being detected in all positive smears (63/63, 100%). The implementation of our outbreak management plan reduced significantly the number of EKC cases per outbreak day and resulted in a reduction of the basic reproduction number by a factor of 2.2.

Conclusion

The detection of EKC together with the immediate implementation of hygienic outbreak measures can significantly reduce the spread of infection. The implementation of a strict outbreak management concept can significantly reduce the number of EKC cases, thus avoiding possible complications and therefore unnecessary health-related costs.

Predictive Accuracy and Densitometric Analysis of Point-of-Care Immunoassay for Adenoviral Conjunctivitis

Purpose

Accurate diagnosis of adenoviral conjunctivitis (Ad-Cs) is important for timely and appropriate patient management to reduce disease transmission. This study assessed the diagnostic accuracy of a commercially available point-of-care adenovirus immunoassay and determined whether its predictive accuracy is influenced by signal intensities of test result bands.

Methods

Point-of-care immunoassay (AdenoPlus) testing and quantitative polymerase chain reaction (qPCR) testing was performed on conjunctival swab samples obtained from eyes of 186 eligible adult participants with presumed infectious conjunctivitis and symptoms of ≤4 days. Masked observers assessed signal intensities of the immunoassay test and control bands using densitometry.

Results

Ad-Cs was confirmed by qPCR in 28 of the 56 eyes that tested positive on the AdenoPlus, a 50% positive predictive value (95% confidence interval [CI] = 36.9, 63.1). No adenovirus was detected by qPCR in 128 of 130 eyes that tested negative on AdenoPlus, a 98.5% negative predictive value (CI = 96.3, 100). Sensitivity and specificity were 93% (CI = 84.4, 100) and 82% (CI = 76.0, 88.1), respectively. Viral titers significantly correlated with ratio of test band signal intensities (R² = 0.32, P = 0.002). Higher positive predictive value was associated with higher densitometry ratios (receiver operating characteristic [ROC] area = 0.71; 95% CI = 0.59, 0.83).

Conclusions

Densitometric analyses suggest that the diagnostic accuracy of AdenoPlus is influenced by the signal intensity of the test result bands. Visual comparison of the test band intensities by clinicians could reduce the false positive rate of point-of-care immunoassays and aid in the diagnosis of viral infections.

Translational Relevance

Ratiometric densitometry of point-of-care immunoassays could aid clinicians’ decision making in diagnosing infectious diseases, including Ad-Cs.

An outbreak of adenovirus D8 keratoconjunctivitis in Leicester, United Kingdom, from March to August 2019

We report a large epidemic (n = 126) of keratoconjunctivitis predominantly with two lineages of adenovirus (AdV) type D8 in patients seen in eye casualty between march and August 2019. Other AdV species identified by viral sequencing included B, C, and E. Despite various features of more severe eye disease being present, these were not significantly different between the different AdV species, with similar rates of pseudomembrane formation and keratitis observed in patients with AdV species B as for those with AdV species D.

Vaccination inhibits the human adenoviral transduction in a mouse keratoconjunctivitis model

Adenovirus infections are a major cause of epidemic keratoconjunctivitis (EKC), which can lead to corneal subepithelial infiltrates and multifocal corneal opacity. In the current study, we investigated the use of an E1/E3-deleted adenovirus serotype 5 (Ad5) vector as a vaccine administered intramuscularly (IM) or intranasally (IN) against subsequent challenges with a luciferase-expressing Ad5 (Ad5-Luci) vector via eyedrop. We evaluated the adaptive immune response to Ad5 vector vaccination and confirmed a robust polyfunctional CD8 T cell response in splenic cells. Neutralizing Ad5 antibodies were also measured in the sera of vaccinated mice as well as Ad5 antibody in the eye wash solutions. Upon challenge with Ad5-Luci vector 8 weeks post the primary immunization, transduction was significantly reduced by > 70% in the vaccinated mice, which was slightly better in IM- vs. that in IN-vaccinated animals. Resistance to subsequent challenge was observed 10 months post primary IM vaccination, with sustained reduction up to 60% in the Ad5-Luci vector transduction. Passive immunization of naive mice with antisera from IM to vaccinated mice subsequently challenged with the Ad5-Luci vector resulted in approximately 40% loss in transduction efficiency. Furthermore, the mice that received IM immunization with or without CD8 T cell depletion showed > 40% and 70% reductions, respectively, in Ad8 genomic copies after Ad8 topical challenge. We conclude that Ad-vector vaccination successfully induced an adaptive immune response that prevented subsequent Ad transduction in the cornea and conjunctiva-associated tissues in a mouse model of adenovirus keratoconjunctivitis, and that both cellular and humoral immunity play an important role in preventing Ad transduction.

The Transmission of SARS-CoV-2 Infection on the Ocular Surface and Prevention Strategies

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a global health problem. Although the respiratory system is the main impaired organ, conjunctivitis is one of its common findings. However, it is not yet understood if SARS-CoV-2 can infect the eye and if the ocular surface can be a potential route of SARS-CoV-2 transmissions. Our review focuses on the viral entry mechanisms to give a better understanding of the interaction between SARS-CoV-2 and the eye. We highlighted findings that give evidence for multiple potential receptors of SARS-CoV-2 on the ocular surface. Additionally, we focused on data concerning the detection of viral RNA and its spike protein in the various ocular tissues from patients. However, the expression level seemed to be relatively low compared to the respiratory tissues as a result of a unique environment surrounding the ocular surface and the innate immune response of SARS-CoV-2. Nevertheless, our review suggests the ocular surface as a potential route for SARS-CoV-2 transmission, and as a result of this study we strongly recommend the protection of the eyes for ophthalmologists and patients at risk.

Povidone iodine for the treatment of adenoviral conjunctivitis

Adenoviral conjunctivitis is the most common cause of ocular viral infection in the world, but currently has no approved therapeutic treatments. The antiseptic povidone-iodine (PVP-I) has been used as an off-label treatment for the condition, but high-quality evidence for its use is limited. This paper aims to review the literature surrounding the use of PVP-I in the management of adenoviral conjunctivitis. Unfortunately, treatment regimens, inclusion criteria, outcome measures, and review periods vary widely between studies, making direct comparisons between outcomes difficult. The majority of studies investigate daily instillation of 0.4 to 2.0% PVP-I rather than one-time instillation of PVP-I as has been used anecdotally in practice. In addition, only one treatment arm investigates daily PVP-I alone, with no significant difference in the duration of disease or clinical outcome compared to placebo. All other treatment arms investigate PVP-I in combination with dexamethasone which generally improve outcomes. Tolerability of PVP-I is generally good for low concentrations <1.0%, but efficacy of treatment is generally reported to be concentration dependent. Future research should investigate the optimal concentration, dosing regimen and role of each agent in combination treatment and aim to use laboratory techniques to improve diagnosis and provide quantifiable outcomes.

SARS-COV-2 and Ocular Surface: From Physiology to Pathology, a Route to Understand Transmission and Disease

Coronaviruses gained public attention during the severe acute respiratory syndrome (SARS) outbreak in East Asia in 2003 and spread of Middle Eastern respiratory syndrome (MERS) in 2012. Direct human-to-human contact and droplet are the main methods of transmission. Viral stability in aerosols on different surfaces supports evidence on indirect viral acquisition from fomites through the mucous membranes of the mouth, nose, and eyes. Given the pandemic circumstances, the level of evidence in COVID-19 and ophthalmology regarding eye infection, conjunctival transmission, and viral shedding through tears is insufficient. Presently, conjunctival transmission of coronaviruses has not been confirmed and remains controversial. Considering the physiology of the lacrimal system and ocular surface, the eyes are considered an immunoprotective site, with several antiviral molecules and anti-inflammatory proteins. Nevertheless, they represent an interface with the exterior world and face daily putative aggressors. Understanding the host's ocular surface immunological and protective environment is crucial to clarify the potential of the conjunctiva as an entry route for SARS-CoV-2 and as part of this viral infection. We will discuss hypothetical ocular surface transmission mechanisms and related counterarguments addressed to both angiotensin-converting enzyme 2 receptors found on the conjunctival and corneal epithelia and lactoferrin, lysozyme, lipocalin and secretory IgA levels in the tear film. Hopefully, we will promote better understanding of this organ in COVID-19 infection and the potential transmission route that can be helpful in setting recommendations on best practices and protective guidelines to mitigate the disease spread.

Filociclovir Is a Potent In Vitro and In Vivo Inhibitor of Human Adenoviruses

Human adenovirus (HAdV) infection is common in the general population and can cause a range of clinical manifestations, among which pneumonia and keratoconjunctivitis are the most common. Although HAdV infections are mostly self-limiting, infections in immunocompromised individuals can be severe. No antiviral drug has been approved for treating adenoviruses. Filociclovir (FCV) is a nucleoside analogue which has successfully completed phase I human clinical safety studies and is now being developed for treatment of human cytomegalovirus (HCMV)-related disease in immunocompromised patients. In this report, we show that FCV is a potent broad-spectrum inhibitor of HAdV types 4 to 8, with 50% effective concentrations (EC50s) ranging between 1.24 and 3.6 μM and a 50% cytotoxic concentration (CC50) of 100 to 150 μM in human foreskin fibroblasts (HFFs). We also show that the prophylactic oral administration of FCV (10 mg/kg of body weight) 1 day prior to virus challenge and then daily for 14 days to immunosuppressed Syrian hamsters infected intravenously with HAdV6 was sufficient to prevent morbidity and mortality. FCV also mitigated tissue damage and inhibited virus replication in the liver. The 10-mg/kg dose had similar effects even when the treatment was started on day 4 after virus challenge. Furthermore, FCV administered at the same dose after intranasal challenge with HAdV6 partially mitigated body weight loss but significantly reduced pathology and virus replication in the lung. These findings suggest that FCV could potentially be developed as a pan-adenoviral inhibitor.

Conjunctivitis: A Systematic Review

Conjunctivitis is a commonly encountered condition in ophthalmology clinics throughout the world. In the management of suspected cases of conjunctivitis, alarming signs for more serious intraocular conditions, such as severe pain, decreased vision, and painful pupillary reaction, must be considered. Additionally, a thorough medical and ophthalmic history should be obtained and a thorough physical examination should be done in patients with atypical findings and chronic course. Concurrent physical exam findings with relevant history may reveal the presence of a systemic condition with involvement of the conjunctiva. Viral conjunctivitis remains to be the most common overall cause of conjunctivitis. Bacterial conjunctivitis is encountered less frequently and it is the second most common cause of infectious conjunctivitis. Allergic conjunctivitis is encountered in nearly half of the population and the findings include itching, mucoid discharge, chemosis, and eyelid edema. Long-term usage of eye drops with preservatives in a patient with conjunctival irritation and discharge points to the toxic conjunctivitis as the underlying etiology. Effective management of conjunctivitis includes timely diagnosis, appropriate differentiation of the various etiologies, and appropriate treatment.

The role of ozonized oil and a combination of tobramycin/dexamethasone eye drops in the treatment of viral conjunctivitis: a randomized clinical trial

Purpose

To determine whether topical tobramycin 0.3%/dexamethasone 0.1% plus ozonized oil eye drops reduces clinical signs and infectious viral titers of presumed viral conjunctivitis more than tobramycin/dexamethasone eye drops alone.

Methods

Prospective, single-blind, randomized, parallel-groups trial. Eighty patients with a clinical diagnosis of presumed viral conjunctivitis were randomizedly divided into two treatment groups: a study group and a control group, 40 for each group. Patients in the study group received topical tobramycin 0.3%/dexamethasone 0.1% eye drops, plus ozonized oil eye drops, both four times daily; patients in the control group received only topical tobramycin 0.3%/dexamethasone eye drops four times daily. The treatment was for seven days in both groups. Swabs were taken from the conjunctival fornix for adenovirus PCR analysis on the day of recruitment and at seven days follow-up. Clinical signs were also recorded on the day of recruitment and at follow-up examination: the main outcomes were conjunctival injection and conjunctival chemosis, graded on a 4-point clinical scale, presence or absence of superficial punctate keratitis and subepithelial corneal infiltrates.

Results

No statistically significant difference was reached in adenoviral infection negativization between the two groups, although the study group showed a higher number of PCR negative results at seven days follow-up. PCR real time detected adenoviral infection in 17 of 24 patients on the day of recruitment and it was positive in 4 patients on the seventh day (viral positivity reduction of 76%). In the control group PCR was positive for adenovirus in 18 of 24 patients on the day of recruitment and in 7 patients at seven days follow-up (reduction of 61%). There was statistically significant difference on conjunctival clinical signs between the study and control groups. Significant difference was also found on superficial punctate keratitis resolution between the study and the control group. In the former superficial punctate keratitis was detected in 14 eyes on the first day and in 5 eyes after seven days while in the latter superficial punctate keratitis was found in 124 eyes on the first day and in 6 eyes on the seventh day. No difference was found in subepithelial corneal infiltrates appearance between the two groups.

Conclusions

The use of ozonized-oil containing eye drops in combination with topical tobramycin 0.3%/dexamethasone 0.1% eye drops four times daily seems to reduce the signs of conjunctivitis, and the duration of viral infection, although it does not affect the subepithelial corneal infiltrates appearance.

Late-term topical tacrolimus for subepithelial infiltrates resistant to topical steroids and ciclosporin secondary to adenoviral keratoconjunctivitis

PURPOSE

Investigation of the efficacy and safety of 12 months of topical tacrolimus 0.03% ointment treatment against the subepithelial infiltrates (SEIs) due to adenoviral keratoconjunctivitis (AKC) resisting at least 2 years was aimed.

METHODS

This case series included consecutive patients with SEIs secondary to AKC who were resistant to topical steroid and ciclosporin-A (CSA) treatment and treated with topical 0.03% tacrolimus (Protopic; Fujisawa Healthcare, Teva, Deerfield, Illinois, USA) for 12 months, at least 2 years after AKC. For the evaluation of treatment efficacy, best-corrected visual acuity (BCVA), Fantes score, corneal subepithelial infiltrate score (CSIS), Oxford score, Schirmer and tear breakup time results were evaluated. Intraocular pressure and complaints of the patients were followed for evaluating the safety profile of the treatment. The patients were followed after the baseline visit at the 1st, 3rd, 6th and 12th month.

RESULTS

15 eyes of 11 patients with SEIs and 16 eyes of 16 healthy controls were included in this study. 1 patient (9.1%) could not tolerate the treatment. Significant improvements in BCVA, CSIS, Fantes score and Schirmer results were observed in the study group starting from the 3rd-month visit, and the improvements persisted until the end of 12 months of treatment.

CONCLUSION

Topical 0.03% tacrolimus might show efficacy against the SEIs persisting at least 2 years despite corticosteroid and/or CSA treatment without any prominent side effect. While at least a period of 3 months was necessary for a significant improvement in the BCVA, SEIs and Schirmer results, a period of 6 months was necessary for a decrease in Oxford score.

Management of Adenoviral Keratoconjunctivitis: Challenges and Solutions

Human adenovirus (HAdV) is the most common cause of infectious conjunctivitis, accounting for up to 75% of all conjunctivitis cases and affecting people of all ages and demographics. In addition to ocular complications, it can cause systemic infections in the form of gastroenteritis, respiratory disease, and dissemination in immunocompromised individuals. HAdV causes lytic infection of the mucoepithelial cells of the conjunctiva and cornea, as well as latent infection of lymphoid and adenoid cells. Epidemic keratoconjunctivitis (EKC) is the most severe ocular manifestation of HAdV infection, in which the presence of subepithelial infiltrates (SEIs) in the cornea is a hallmark feature of corneal involvement. SEIs have the tendency to recur and may lead to long-term visual disability. HAdV persistence and dissemination are linked to sporadic outbreaks of adenoviral keratoconjunctivitis. There is no FDA-approved antiviral for treating adenoviral keratoconjunctivitis, and as such, solutions should be proffered to handle the challenges associated with viral persistence and dissemination. Several treatment modalities have been investigated, both systemically and locally, to not only mitigate symptoms but reduce the course of the infection and prevent the risk of long-term complications. These options include systemic and topical antivirals, in-office povidone-iodine irrigation (PVI), immunoglobulin-based therapy, anti-inflammatory therapy, and immunotherapy. More recently, combination PVI/dexamethasone ophthalmic formulations have shown favorable outcomes and were well tolerated in clinical trials for the treatment of EKC. Possible, future treatment considerations include sialic acid analogs, cold atmospheric plasma, N-chlorotaurine, and benzalkonium chloride. Continued investigation and evaluation of treatment are warranted to reduce the economic burden and potential long-term visual debilitation in affected patients. This review will focus on how persistence and dissemination of HAdV pose a significant challenge to the management of adenoviral keratoconjunctivitis. Furthermore, current and future trends in prophylactic and therapeutic modalities for adenoviral keratoconjunctivitis will be discussed.

Disparate Entry of Adenoviruses Dictates Differential Innate Immune Responses on the Ocular Surface

Human adenovirus infection of the ocular surface is associated with severe keratoconjunctivitis and the formation of subepithelial corneal infiltrates, which may persist and impair vision for months to years following infection. Long term pathology persists well beyond the resolution of viral replication, indicating that the prolonged immune response is not virus-mediated. However, it is not clear how these responses are sustained or even initiated following infection. This review discusses recent work from our laboratory and others which demonstrates different entry pathways specific to both adenovirus and cell type. These findings suggest that adenoviruses may stimulate specific pattern recognition receptors in an entry/trafficking-dependent manner, leading to distinct immune responses dependent on the virus/cell type combination. Additional work is needed to understand the specific connections between adenoviral entry and the stimulation of innate immune responses by the various cell types present on the ocular surface.

TRIM21-From Intracellular Immunity to Therapy

Tripartite motif containing-21 (TRIM21) is a cytosolic ubiquitin ligase and antibody receptor that provides a last line of defense against invading viruses. It does so by acting as a sensor that intercepts antibody-coated viruses that have evaded extracellular neutralization and breached the cell membrane. Upon engagement of the Fc of antibodies bound to viruses, TRIM21 triggers a coordinated effector and signaling response that prevents viral replication while at the same time inducing an anti-viral cellular state. This dual effector function is tightly regulated by auto-ubiquitination and phosphorylation. Therapeutically, TRIM21 has been shown to be detrimental in adenovirus based gene therapy, while it may be favorably utilized to prevent tau aggregation in neurodegenerative disorders. In addition, TRIM21 may synergize with the complement system to block viral replication as well as transgene expression. TRIM21 can also be utilized as a research tool to deplete specific proteins in cells and zebrafish embryos. Here, we review our current biological understanding of TRIM21 in light of its versatile functions.

Sialic Acid-Containing Glycans as Cellular Receptors for Ocular Human Adenoviruses: Implications for Tropism and Treatment

Human adenoviruses (HAdV) are the most common cause of ocular infections. Species B human adenovirus type 3 (HAdV-B3) causes pharyngoconjunctival fever (PCF), whereas HAdV-D8, -D37, and -D64 cause epidemic keratoconjunctivitis (EKC). Recently, HAdV-D53, -D54, and -D56 emerged as new EKC-causing agents. HAdV-E4 is associated with both PCF and EKC. We have previously demonstrated that HAdV-D37 uses sialic acid (SA)-containing glycans as cellular receptors on human corneal epithelial (HCE) cells, and the virus interaction with SA is mediated by the knob domain of the viral fiber protein. Here, by means of cell-based assays and using neuraminidase (a SA-cleaving enzyme), we investigated whether ocular HAdVs other than HAdV-D37 also use SA-containing glycans as receptors on HCE cells. We found that HAdV-E4 and -D56 infect HCE cells independent of SAs, whereas HAdV-D53 and -D64 use SAs as cellular receptors. HAdV-D8 and -D54 fiber knobs also bound to cell-surface SAs. Surprisingly, HCE cells were found resistant to HAdV-B3 infection. We also demonstrated that the SA-based molecule i.e., ME0462, designed to bind to SA-binding sites on the HAdV-D37 fiber knob, efficiently prevents binding and infection of several EKC-causing HAdVs. Surface plasmon resonance analysis confirmed a direct interaction between ME0462 and fiber knobs. Altogether, we demonstrate that SA-containing glycans serve as receptors for multiple EKC-causing HAdVs, and, that SA-based compound function as a broad-spectrum antiviral against known and emerging EKC-causing HAdVs.

Decoy Receptor Interactions as Novel Drug Targets against EKC-Causing Human Adenovirus

Epidemic keratoconjunctivitis (EKC) is a severe ocular disease and can lead to visual impairment. Human adenovirus type-37 (HAdV-D37) is one of the major causative agents of EKC and uses sialic acid (SA)-containing glycans as cellular receptors. Currently, there are no approved antivirals available for the treatment of EKC. Recently, we have reported that sulfated glycosaminoglycans (GAGs) bind to HAdV-D37 via the fiber knob (FK) domain of the viral fiber protein and function as decoy receptors. Based on this finding, we speculated that GAG-mimetics may act as artificial decoy receptors and inhibit HAdV-D37 infection. Repurposing of approved drugs to identify new antivirals has drawn great attention in recent years. Here, we report the antiviral effect of suramin, a WHO-approved drug and a widely known GAG-mimetic, against HAdV-D37. Commercially available suramin analogs also show antiviral effects against HAdV-D37. We demonstrate that suramin exerts its antiviral activity by inhibiting the attachment of HAdV-D37 to cells. We also reveal that the antiviral effect of suramin is HAdV species-specific. Collectively, in this proof of concept study, we demonstrate for the first time that virus binding to a decoy receptor constitutes a novel and an unexplored target for antiviral drug development.

Sulfated Glycosaminoglycans as Viral Decoy Receptors for Human Adenovirus Type 37

Glycans on plasma membranes and in secretions play important roles in infection by many viruses. Species D human adenovirus type 37 (HAdV-D37) is a major cause of epidemic keratoconjunctivitis (EKC) and infects target cells by interacting with sialic acid (SA)-containing glycans via the fiber knob domain of the viral fiber protein. HAdV-D37 also interacts with sulfated glycosaminoglycans (GAGs), but the outcome of this interaction remains unknown. Here, we investigated the molecular requirements of HAdV-D37 fiber knob:GAG interactions using a GAG microarray and demonstrated that fiber knob interacts with a broad range of sulfated GAGs. These interactions were corroborated in cell-based assays and by surface plasmon resonance analysis. Removal of heparan sulfate (HS) and sulfate groups from human corneal epithelial (HCE) cells by heparinase III and sodium chlorate treatments, respectively, reduced HAdV-D37 binding to cells. Remarkably, removal of HS by heparinase III enhanced the virus infection. Our results suggest that interaction of HAdV-D37 with sulfated GAGs in secretions and on plasma membranes prevents/delays the virus binding to SA-containing receptors and inhibits subsequent infection. We also found abundant HS in the basement membrane of the human corneal epithelium, which may act as a barrier to sub-epithelial infection. Collectively, our findings provide novel insights into the role of GAGs as viral decoy receptors and highlight the therapeutic potential of GAGs and/or GAG-mimetics in HAdV-D37 infection.