Anti-adenoviral effect of anti-HIV agents in vitro in serotypes inducing keratoconjunctivitis

Establishing an accurate and sensitive in vitro drug screening system for human adenovirus infection with human corneal cells

Epidemic keratoconjunctivitis (EKC) is a hazardous and highly contagious disease, with the potential to cause epidemic outbreaks in hospitals and other community settings. There are currently no approved drugs for human adenovirus (HAdV), the causative agent of EKC. To establish a novel drug screening system for ocular HAdV infections, we employed CRL11516, a non-cancerous but immortalized human corneal epithelial cell line. Brincidoforvir and 3'-deoxy-3'-fluorothymidine inhibit replication of HAdV species C type 1 (C1), C2, E4, and C6 to the same extent. This alternative assay system may allow for the evaluation of anti-HAdV activity and cell cytotoxicity of compounds within 2 days and without the need of the rabbit eye infection model.

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.

Ganciclovir ophthalmic gel treatment shortens the recovery time and prevents complications in the adenoviral eye infection

The purpose of this study was to determine the effectiveness of ganciclovir ophthalmic gel (GOG) in the treatment of adenoviral eye infection (AEI) by looking at the effect of the drug on shortening recovery time, preventing transmission, reducing sequelae, and on complications such as corneal infiltrates and conjunctival pseudomembranes. 200 patients' examination records were evaluated retrospectively. Patients who were within the first 3 days of AEI were divided into two groups: Group 1 with 100 patients who used artificial tears as treatment, and Group 2 with 100 patients who used GOG plus artificial tears (GAT). All patients underwent an eye examination by the same ophthalmologist on the 1st, 5th, 10th, and 15th day after treatment. Using the examination records, variables were compared using SPSS 22.0. There was a statistically significant difference between Groups 1 and 2. Group 2 showed better and faster response to treatment. There was less transmission to the contralateral eye and environment, and less formation of corneal subepithelial infiltrate and conjunctival pseudomembrane in Group 2. Only three patients in Group 2 had corneal involvement. A comparison of each group pre-treatment and during treatment revealed improved signs and symptoms in Group 2 (p < 0.005). The study showed a trend toward more rapid improvement, less corneal and conjunctival involvement, and less transmission to the contralateral eye and environment in the GAT group. These results need to be confirmed by additional studies.

Antiadenoviral effects of ganciclovir in types inducing keratoconjunctivitis by quantitative polymerase chain reaction methods

Purpose

The most common external ocular viral infections are caused by several human adenovirus (HAdV) types. Ganciclovir has been reported to inhibit cytomegalovirus, herpes simplex virus types 1 and 2, varicella zoster virus, and Epstein–Barr virus. Ganciclovir ophthalmic gel, 0.15% (Virgan®) is commercially available for cytomegalovirus or herpes virus keratitis. However its inhibitory activity against HAdV is reported only for types 2 and 5. We investigated the antiadenoviral activity of ganciclovir in vitro in several common types currently inducing keratoconjunctivitis.

Materials and methods

A549 cells were used for viral cell culture, and adenovirus types 3 (HAdV3; species B), 4 (species E), and 8, 19a, and 37 (species D) were used. After pretreatment of A549 with serial dilutions of ganciclovir for 24 hours, adenovirus was cultured for 7 days, and adenoviral deoxyribonucleic acid was quantitatively measured by real-time polymerase chain reaction (PCR).

Results

The 50% cytotoxic concentration of ganciclovir was 212 μg/mL. The 50% effective concentration of ganciclovir obtained by real-time PCR ranged between 2.64 and 5.10 μg/mL. A significant inhibitory effect of ganciclovir on adenoviral proliferation was found in all types in a dose-dependent manner. The selectivity index of ganciclovir ranged between 41.6 and 80.3.

Conclusion

Ganciclovir showed significant inhibitory activity against HAdV3, 4, 8, 19a, and 37, which induce epidemic keratoconjunctivitis. These results indicate that ganciclovir is a possible candidate for the treatment of HAdV keratoconjunctivitis, and ganciclovir ophthalmic gel could be applied to adenoviral keratoconjunctivitis in the future.

Anti-adenoviral effects of human cationic antimicrobial protein-18/LL-37, an antimicrobial peptide, by quantitative polymerase chain reaction

PURPOSE

Antimicrobial peptides have an important role in self-protection of the ocular surface. Human cationic antimicrobial protein (hCAP)-18 is a linear, α-helical peptide that consists of a conserved pro-sequence called a cathelin-like domain and a C-terminal peptide named LL-37. We investigated the in vitro anti-adenoviral activity of hCAP-18/LL-37 in several adenovirus types, inducing keratoconjunctivitis.

METHODS

A549 cells were used for viral cell culture, and human adenovirus (HAdV) types 3 (HAdV3, species B), 4 (species E), 8, 19a, and 37 (species D) were used. The cytotoxicity of LL-37 was evaluated by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay to obtain 50% cytotoxic concentration. After pretreatment of A549 cells with serial dilutions of LL-37 for 24 hours, adenovirus was cultured for seven days, and adenoviral DNA was quantitatively measured by real-time polymerase chain reaction (PCR).

RESULTS

The 50% effective concentration of LL-37 obtained by real-time PCR ranged between 118 and 270 µM. LL-37 showed a significant inhibitory effect on adenoviral proliferation in all adenovirus types except HAdV4 in a dose-dependent manner.

CONCLUSIONS

LL-37 has significant inhibitory activity against HAdV3, 8, and 19, which induce keratoconjunctivitis. These results indicate that hCAP-18/LL-37 may be a possible candidate for the treatment of HAdV keratoconjunctivitis.

In vitro anti-HMPV activity of meroditerpenoids from marine alga Stypopodium zonale (Dictyotales)

In this paper, we evaluated the antiviral activity against HMPV replication of crude extract of the marine algae Stypopodium zonale and of two meroditerpenoids obtained from it, atomaric acid and epitaondiol, and a methyl ester derivative of atomaric acid. Their selectivity indexes were 20.78, >56.81, 49.26 and 12.82, respectively. Compared to ribavirin, the substances showed a relatively low cytotoxicity on LLC-MK2 cells, with a significant antiviral activity, inhibiting at least 90% of viral replication in vitro, which demonstrates the potential of these marine natural products to combat infections caused by HMPV in vitro.

Treatment of viral conjunctivitis with antiviral drugs

Viral conjunctivitis is one of the most common disorders observed in ophthalmic emergency departments, yet no established treatment exists. Lately, antiviral medications have been introduced into clinical practice; however, a systematic review focusing on their use and effectiveness in the treatment of viral conjunctivitis has not been previously reported. We systemically reviewed the literature to identify studies where antiviral drugs were used to treat viral conjunctivitis. Currently, aciclovir, trifluridine and valaciclovir are commonly used as antiviral agents to treat herpesvirus infections. Cidofovir has been used successfully to treat some cases of adenoviral conjunctivitis, although toxicity has also been reported. The use of other medications, such as idoxuridine, has been minimized in clinical practice due to their high toxicity. Interestingly, most of the antiviral drugs developed are used to treat herpesvirus infections, while less progress has been made in the field of adenoviral infections. For other viral causes of conjunctivitis, no effective remedy is currently available, and treatment focuses on the relief of symptoms. Caution should be exercised when coadministering other pharmacological agents, such as corticosteroids, because of emerging adverse effects.

Clinical and antiviral efficacy of an ophthalmic formulation of dexamethasone povidone-iodine in a rabbit model of adenoviral keratoconjunctivitis

PURPOSE

To determine the efficacy of a new formulation of topical dexamethasone 0.1%/povidone-iodine 0.4% (FST-100) in reducing clinical symptoms and infectious viral titers in a rabbit model of adenoviral keratoconjunctivitis.

METHODS

Rabbit corneas were inoculated bilaterally with 2×10(6) plaque-forming-units (PFU) of adenovirus type 5 (Ad5) after corneal scarification. Animals were randomized 1:1:1:1 (five rabbits per group) to FST-100, 0.5% cidofovir, tobramycin/dexamethasone (Tobradex; Alcon Laboratories, Fort Worth, TX) ophthalmic suspension, and balanced salt solution (BSS; Alcon Laboratories). Treatment began 12 hours after viral inoculation and continued for 7 consecutive days. The eyes were clinically scored daily for scleral inflammation (injection), ocular neovascularization, eyelid inflammation (redness), friability of vasculature, inflammatory discharge (pus), and epiphora (excessive tearing). Eye swabs were collected daily before treatment for the duration of the study. Virus was eluted from the swabs and PFU determined by titration on human A549 cells, according to standard procedures.

RESULTS

The FST-100 treatment resulted in significantly lower clinical scores (P<0.05) than did the other treatments. The 0.5% cidofovir exhibited the most ocular toxicity compared with FST-100, tobramycin/dexamethasone, and balanced salt solution treatments. FST-100 and 0.5% cidofovir significantly (P<0.05) reduced viral titers compared with tobramycin/dexamethasone or balanced salt solution.

CONCLUSIONS

FST-100 was the most efficacious in minimizing the clinical symptoms of adenovirus infection in rabbit eyes. FST-100 and 0.5% cidofovir were both equally effective in reducing viral titers and decreasing the duration of viral shedding. By providing symptomatic relief in addition to reducing infectious virus titers, FST-100 should be a valuable addition to treatment of epidemic adenoviral keratoconjunctivitis.

Antiadenoviral effects of N-chlorotaurine in vitro confirmed by quantitative polymerase chain reaction methods

PURPOSE

Adenoviral keratoconjunctivitis is recognized as one of the major pathogens of ophthalmological nosocomial infection worldwide. N-Chlorotaurine (Cl-HN-CH(2)-CH(2)-SO(3)H, NCT) is the N-chloro derivative of the amino acid taurine, which is an oxidant produced by human granulocytes and monocytes during inflammatory reactions. Using conventional viral plaque assay, it was previously shown that NCT causes inactivation of several human adenovirus (HAdV) serotypes. In this study, we evaluated the antiadenoviral effect of NCT by quantitative polymerase chain reaction (PCR) methods.

METHODS

A549 cells were used for viral cell culture, and HAdV serotypes 3, 4, 8, 19, and 37 were used. After calculating 50% cytotoxic concentration (CC(50)) of NCT by MTS (3-(4,5- dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) method, HAdV was cultured with NCT for 7 days, and extracted adenoviral DNA was quantitatively measured by real-time PCR.

RESULTS

A statistically significant (P < 0.05) dose-dependent inhibition was indicated for all serotypes except HAdV type 4 (HAdV4), which was maximally inhibited by only ~50%. Among the serotypes, NCT was particularly effective against HAdV8, HAdV19a, and HAdV37. The 50% effective concentration (EC(50)) obtained by real-time PCR of NCT ranged between 49 and 256 μM. EC(50) of NCT against HAdV3 was slightly higher than that against serotypes of species D. The selective index (CC(50)/EC(50)) ranged between 41 and 60 except for HAdV4 (11.5).

CONCLUSIONS

These results show that NCT has an antiviral effect against most serotypes of human HAdV inducing keratoconjunctivitis, indicating its possible therapeutic use.

Real time PCR for rapid determination of susceptibility of adenovirus to antiviral drugs

Human adenoviruses (HAdV) are associated with respiratory, ocular and gastrointestinal infections as well as potentially fatal disseminated disease in highly immunocompromised patients. Although there is no specific FDA approved treatment for HAdV infections, some antivirals are used in certain patients. The in vitro antiviral assays for HAdV are not standardized and are usually time consuming. The objective of this study was to evaluate a real time PCR assay for rapid determination of susceptibility of HAdV to antiviral drugs. The nucleoside analogue stavudine (d4T) was used as test drug in A549 cells infected with HAdV5. The antiviral assay measured the reduction of the HAdV DNA levels in culture supernatants by real time PCR using specific primers that amplify a conserved region of the hexon gene. This real time PCR assay demonstrated that stavudine was a selective inhibitor for HAdV5, since the effective concentration 50% (EC(50)) ranged from 0.08 to 0.12 mM at multiplicity of infection between 0.001 and 1. Furthermore, EC(50) showed a high correlation with plaque reduction and virus yield inhibition assays (r(2)=0.9938 and r(2)=0.9468, respectively). In conclusion, the real time PCR-based antiviral assay is rapid, reproducible and could replace classical and more labor-intensive infectivity assays.

The challenge of respiratory virus infections in hematopoietic cell transplant recipients

Respiratory virus infections in hematopoietic cell transplant (HCT) recipients are a major cause of morbidity and mortality. While respiratory syncytial virus (RSV), human metapneumovirus, parainfluenzaviruses, and influenza viruses are well known for their potential to cause fatal pneumonia, information has only recently emerged regarding the significance of the newly discovered viruses, such as human coronaviruses NL63 and HKU1, and human bocavirus. Lymphopenia seems to be the most important risk factor for progression to lower respiratory tract disease. Airflow obstruction is another complication of respiratory virus infections after HCT, and data to date indicate this complication may occur following parainfluenza virus and RSV infection. Infection control procedures are key for prevention. Unfortunately, there are no randomized treatment studies, which make the interpretation of the literature on interventions difficult. This article reviews the spectrum of pathogens, epidemiology, risk factors and clinical manifestations of infection, as well as recent advances in diagnostic and clinical management.