The membrane-anchored spike (S) protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has a pivotal role in directing the fusion of the virus particle mediated by the host cell receptor angiotensin-converting enzyme 2 (ACE-2). The fusion peptide region of the S protein S2 domain provides SARS-CoV-2 with the biological machinery needed for direct fusion to the host lipid membrane. In our present study, computer-aided drug design strategies were used for the identification of FDA-approved small molecules using the optimal structure of the S2 domain, which exhibits optimal interaction ratios, structural features, and energy variables, which were evaluated based on their performances in molecular docking, molecular dynamics simulations, molecular mechanics/generalized Born model and solvent accessibility binding free energy calculations of molecular dynamics trajectories, and statistical inferences. Among the 2,625 FDA-approved small molecules, chloramphenicol succinate, imipenem, and imidurea turned out to be the molecules that bound the best at the fusion peptide hydrophobic pocket. The principal interactions of the selected molecules suggest that the potential binding site at the fusion peptide region is centralized amid the Lys790, Thr791, Lys795, Asp808, and Gln872 residues. IMPORTANCE The present study provides the structural identification of the viable binding residues of the SARS-CoV-2 S2 fusion peptide region, which holds prime importance in the virus’s host cell fusion and entry mechanism. The classical molecular mechanics simulations were set on values that mimic physiological standards for a good approximation of the dynamic behavior of selected drugs in biological systems. The drug molecules screened and analyzed here have relevant antiviral properties, which are reported here and which might hint toward their utilization in the coronavirus disease 2019 (COVID-19) pandemic owing to their attributes of binding to the fusion protein binding region shown in this study.

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Metastatic endophthalmitis (ME) is rare form of secondary uveitis commonly prevalent in immunocompromised patients. A 55-year-old immunocompetent woman presented with painful decrease in left eye vision (referred to us as cytomegalovirus retinochoroiditis). Ocular examination revealed diffuse yellowish-white retinitis lesion (diagnosed as subretinal abscess on macular optical coherence tomography). Vitreous tap was unremarkable, but vitreous biopsy from the posterior vitreous overlying the subretinal abscess confirmed the growth of methicillin-sensitive Staphylococcus aureus (MSSA). Detailed systemic examination revealed a forearm furuncle, which yielded MSSA on culture. The infection followed relentless course despite aggressive treatment with pars plana vitrectomy and antibiotics (topical, systemic and intravitreal). This case is presented due to rarity of presentation of ME as subretinal abscess following skin infection, which became a management challenge. Due to its rapid progression and irreversible damage to ocular tissue, high index of suspicion and aggressive management is needed in such cases. The disease course, management and prognosis of such cases are dismal in majority of the patients.