Ocular Surface Infection by SARS-CoV-2 in COVID-19 Pneumonia Patients Admitted to Sub-Intensive Unit: Preliminary Results

A rapid, high-throughput, viral infectivity assay using automated brightfield microscopy with machine learning

Infectivity assays are essential for the development of viral vaccines, antiviral therapies, and the manufacture of biologicals. Traditionally, these assays take 2-7 days and require several manual processing steps after infection. We describe an automated viral infectivity assay (AVIATM), using convolutional neural networks (CNNs) and high-throughput brightfield microscopy on 96-well plates that can quantify infection phenotypes within hours, before they are manually visible, and without sample preparation. CNN models were trained on HIV, influenza A virus, coronavirus 229E, vaccinia viruses, poliovirus, and adenoviruses, which together span the four major categories of virus (DNA, RNA, enveloped, and non-enveloped). A sigmoidal function, fit between virus dilution curves and CNN predictions, results in sensitivity ranges comparable to or better than conventional plaque or TCID50 assays, and a precision of ∼10%, which is considerably better than conventional infectivity assays. Because this technology is based on sensitizing CNNs to specific phenotypes of infection, it has potential as a rapid, broad-spectrum tool for virus characterization, and potentially identification.

Broad-Spectrum Antimicrobial Activity of Oftasecur and Visuprime Ophthalmic Solutions

Due to the wide etiology of conjunctivitis, the expensive and time-consuming diagnosis requires new therapeutic strategies with broad-spectrum antimicrobial activity and nonselective mechanisms of action. In this context, eye drops could provide an alternative to conventional antimicrobial therapies. Here, we compare the antibacterial and antiviral activity of Oftasecur and Visuprime, commercially available ophthalmic solutions. Cytotoxicity assay was performed on Vero CCL-81 cells by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) test. Antibacterial efficacy was evaluated on Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae by disk diffusion, broth microdilution methods, and time-killing tests. Furthermore, the antiviral activity against HSV-1 was estimated by co-treatment, cell and viral pretreatment and post-treatment, via plaque reduction assay, fluorescence assessment (GFP-engineered HSV-1), and real-time PCR. After 24 h of exposure, Oftasecur and Visuprime showed a volume-inducing 50% of cytotoxicity of 125 and 15.8 μL, respectively Oftasecur and Visuprime induced 90% antibacterial activity in response to mean volume of 10.0 and 4.4 µL for Gram-positive and Gram-negative strains, respectively. Oftasecur exerted bactericidal action on both bacterial populations, while Visuprime was bacteriostatic on Gram-negative strains and slightly bactericidal on Gram-positive bacteria. A major impact on infectivity occurred by exposure of viral particles to the ophthalmic solutions. In detail, 50% of inhibition was verified by exposing the viral particles to 3.12 and 0.84 μL of Oftasecur and Visuprime, respectively, for 1 h. The reduction of the fluorescence and the expression of the viral genes confirmed the recorded antiviral activity. Due to their high antimicrobial efficiency, Oftasecur and Visuprime could represent a valid empirical strategy for the treatment of conjunctivitis.

Detection of Airborne Influenza A and SARS-CoV-2 Virus Shedding following Ocular Inoculation of Ferrets

Despite reports of confirmed human infection following ocular exposure with both influenza A virus (IAV) and SARS-CoV-2, the dynamics of virus spread throughout oculonasal tissues and the relative capacity of virus transmission following ocular inoculation remain poorly understood. Furthermore, the impact of exposure route on subsequent release of airborne viral particles into the air has not been examined previously. To assess this, ferrets were inoculated by the ocular route with A(H1N1)pdm09 and A(H7N9) IAVs and two SARS-CoV-2 (early pandemic Washington/1 and Delta variant) viruses. Virus replication was assessed in both respiratory and ocular specimens, and transmission was evaluated in direct contact or respiratory droplet settings. Viral RNA in aerosols shed by inoculated ferrets was quantified with a two-stage cyclone aerosol sampler (National Institute for Occupational Safety and Health [NIOSH]). All IAV and SARS-CoV-2 viruses mounted a productive and transmissible infection in ferrets following ocular inoculation, with peak viral titers and release of virus-laden aerosols from ferrets indistinguishable from those from ferrets inoculated by previously characterized intranasal inoculation methods. Viral RNA was detected in ferret conjunctival washes from all viruses examined, though infectious virus in this specimen was recovered only following IAV inoculation. Low-dose ocular-only aerosol exposure or inhalation aerosol exposure of ferrets to IAV similarly led to productive infection of ferrets and shedding of aerosolized virus. Viral evolution during infection was comparable between all inoculation routes examined. These data support that both IAV and SARS-CoV-2 can establish a high-titer mammalian infection following ocular exposure that is associated with rapid detection of virus-laden aerosols shed by inoculated animals. IMPORTANCE Documented human infection with influenza viruses and SARS-CoV-2 has been reported among individuals wearing respiratory protection in the absence of eye protection, highlighting the capacity of these respiratory tract-tropic viruses to exploit nonrespiratory routes of exposure to initiate productive infection. However, comprehensive evaluations of how ocular exposure may modulate virus pathogenicity and transmissibility in mammals relative to respiratory exposure are limited and have not investigated multiple virus families side by side. Using the ferret model, we show that ocular exposure with multiple strains of either coronaviruses or influenza A viruses leads to an infection that results in shedding of detectable aerosolized virus from inoculated animals, contributing toward onward transmission of both viruses to susceptible contacts. Collectively, these studies support that the ocular surface represents a susceptible mucosal surface that, if exposed to a sufficient quantity of either virus, permits establishment of an infection which is similarly transmissible as that following respiratory exposure.

Conjunctival Swabs Reveal Higher Detection Rate Compared to Schirmer Strips for SARS-CoV-2 RNA Detection in Tears of Hospitalized COVID-19 Patients

Purpose: To determine the prevalence of SARS-CoV-2 in tear samples and to investigate whether it correlates with ocular findings and patients’ prognosis in Brazil. Methods: Tears were collected using Schirmer strips (SS) and conjunctival swabs (CS) from patients hospitalized with laboratory-confirmed SARS-CoV-2 infection. Samples were analyzed using qRT-PCR. Demographic and clinical data, ocular symptoms, and Schirmer tests (ST) were collected from patients. Charlson Comorbidity Index (CCI) was used to rate comorbidities, and patients were monitored until hospital discharge or death. Results: There were 61 hospitalized patients, 33 of which were diagnosed with COVID-19. Within the confirmed COVID-19 patients, SARS-CoV-2 was detected in 18.2% (n = 6) of CS and 12.1% (n = 4) of SS samples. Subjective and objective parameters for dry eye syndrome (e.g., ST COVID-19: 8.3 ± 6.4mm, non-COVID-19: 8.9 ± 6.6mm, p > 0.05) were comparable between COVID-19 (n = 33) and non-COVID-19 patients (n = 28). Among the 16 COVID-19 patients exhibiting ocular symptoms, only tearing was reported significantly more frequently when tear samples were positive for SARS-CoV-2 (p < 0.05). Strikingly, patients whose tears tested positive for SARS-CoV-2 had significantly inferior CCI (pos.: 34.0 ± 31.8%, neg.: 67.6 ± 36.4%, p < 0.05) and higher mortality rates (pos.: 50.0%, neg.: 7.4%, p < 0.01). Conclusions: SARS-CoV-2 was detected with a prevalence of 18.2% on the ocular surface. Decreased CCI and increased mortality rate in the positive tear group suggests that viral detection may relate to prognosis and highlight the need of personal protective measures for healthcare professionals. Most of the patients, regardless of COVID-19 diagnosis, had low tear production and eye discomfort, possibly pointing to the need for artificial tear use during hospitalization.

Therapeutic potential of the MDM2 inhibitor Nutlin-3 in counteracting SARS-CoV-2 infection of the eye through p53 activation

Starting from the beginning of the severe acute respiratory syndrome Coronavirus-2 (SARS-CoV-2) global pandemic, most of the published data has concentrated on the respiratory signs and symptoms of Covid-19 infection, underestimating the presence and importance of ocular manifestations, such as conjunctivitis, usually reported in SARS-CoV-2 infected patients. With the present review we intend to resume the ocular involvement in SARS-CoV-2 infection and the recent discoveries about the different cell types and tissues of the eye that can be directly infected by SARS-CoV-2 and propagate the infection. Moreover, reviewing literature data about p53 expression in normal and diseased eye tissues, we hypothesize that the pleiotropic protein p53 present at high levels in cornea, conjunctiva and tear film might play a protective role against SARS-CoV-2 infection. Since p53 can be easily up-regulated by using small molecule non-genotoxic inhibitors of MDM2, we propose that topical use of Nutlin-3, the prototype member of MDM2 inhibitors, might protect the anterior surface of the eye from SARS-CoV-2 infection, reducing the spreading of the virus.

Evaluating Ocular Symptoms and Tear Film Cytokine Profiles in Symptomatic COVID-19 Patients

Background: This study investigated the presence and duration of ophthalmic symptoms in the early phase of COVID-19 to assess the corresponding local immune response on the ocular surface. Methods: The study included data from 180 COVID-19 patients and 160 age-matched healthy controls. The main finding was the occurrence of ophthalmological manifestations at the time of admission to the hospital and during the preceding 7 days. Tear film concentrations of TNF-α, IL-1b, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12 p70, GM-CSF, and IFN-γ were determined by a magnetic bead assay. Results: Among the COVID-19 patients, 12.64% had at least one ocular symptom at the time of admission, and 24.14% had symptoms within the preceding 7 days (p < 0.001 vs. controls). We found that the COVID-19 patients complained more frequently about eye tearing (p = 0.04) and eye pain (p = 0.01) than controls. A multivariate analysis of the patients and controls adjusted for age and sex revealed that COVID-19 was an independent factor associated with higher VEGF and IL-10 tear film concentrations (β = +0.13, p = 0.047 and β = +0.34, p < 0.001, respectively) and lower IL-1β, IL-8, and GM-CSF levels (β = −0.25, p < 0.001; β = −0.18, p = 0.004; and β = −0.82, p = 0.0 respectively). Conclusions: SARS-CoV-2 does not attract a strong local response of the conjunctival immune system; therefore, ophthalmic symptoms may not constitute a substantial element in the clinical picture of novel COVID-19 infection.