Hydroxychloroquine: A Comprehensive Review and Its Controversial Role in Coronavirus Disease 2019

Hydroxychloroquine, initially used as an antimalarial, is used as an immunomodulatory and anti-inflammatory agent for the management of autoimmune and rheumatic diseases such as systemic lupus erythematosus. Lately, there has been interest in its potential efficacy against severe acute respiratory syndrome coronavirus 2, with several speculated mechanisms. The purpose of this review is to elaborate on the mechanisms surrounding hydroxychloroquine. The review is an in-depth analysis of the antimalarial, immunomodulatory, and antiviral mechanisms of hydroxychloroquine, with detailed and novel pictorial explanations. The mechanisms of hydroxychloroquine are related to potential cardiotoxic manifestations and demonstrate potential adverse effects when used for coronavirus disease 2019 (COVID-19). Finally, current literature associated with hydroxychloroquine and COVID-19 has been analyzed to interrelate the mechanisms, adverse effects, and use of hydroxychloroquine in the current pandemic. Currently, there is insufficient evidence about the efficacy and safety of hydroxychloroquine in COVID-19.KEY MESSAGES HCQ, initially an antimalarial agent, is used as an immunomodulatory agent for managing several autoimmune diseases, for which its efficacy is linked to inhibiting lysosomal antigen processing, MHC-II antigen presentation, and TLR functions. HCQ is generally well-tolerated although severe life-threatening adverse effects including cardiomyopathy and conduction defects have been reported. HCQ use in COVID-19 should be discouraged outside clinical trials under strict medical supervision

Vitamin D and COVID‐19 in an immunocompromised patient with multiple comorbidities—A Case Report

Routine 25-OH-Vitamin D3 measurement in COVID-19 patients could be of great importance, either for clinical course estimation or deciding on supplementatio

Neck and capsid architecture of the robust Agrobacterium phage Milano

Abstract Large gaps exist in our understanding of how bacteriophages, the most abundant biological entities on Earth, assemble and function. The structure of the “neck” region, where the DNA-filled capsid is connected to the host-recognizing tail remains poorly understood. We describe cryo-EM structures of the neck, the neck-capsid and neck-tail junctions, and capsid of the Agrobacterium phage Milano. The Milano neck 1 protein connects the 12-fold symmetrical neck to a 5-fold vertex of the icosahedral capsid. Comparison of Milano neck 1 homologs leads to four proposed classes, likely evolved from the simplest one in siphophages to more complex ones in myo- and podophages. Milano neck is surrounded by the atypical collar, which covalently crosslinks the tail sheath to neck 1. The Milano capsid is decorated with three types of proteins, a minor capsid protein (mCP) and two linking proteins crosslinking the mCP to the major capsid protein. The extensive network of disulfide bonds within and between neck, collar, capsid and tail provides an exceptional structural stability to Milano

An extensive disulfide bond network prevents tail contraction in Agrobacterium tumefaciens phage Milano

Abstract A contractile sheath and rigid tube assembly is a widespread apparatus used by bacteriophages, tailocins, and the bacterial type VI secretion system to penetrate cell membranes. In this mechanism, contraction of an external sheath powers the motion of an inner tube through the membrane. The structure, energetics, and mechanism of the machinery imply rigidity and straightness. The contractile tail of Agrobacterium tumefaciens bacteriophage Milano is flexible and bent to varying degrees, which sets it apart from other contractile tail-like systems. Here, we report structures of the Milano tail including the sheath-tube complex, baseplate, and putative receptor-binding proteins. The flexible-to-rigid transformation of the Milano tail upon contraction can be explained by unique electrostatic properties of the tail tube and sheath. All components of the Milano tail, including sheath subunits, are crosslinked by disulfides, some of which must be reduced for contraction to occur. The putative receptor-binding complex of Milano contains a tailspike, a tail fiber, and at least two small proteins that form a garland around the distal ends of the tailspikes and tail fibers. Despite being flagellotropic, Milano lacks thread-like tail filaments that can wrap around the flagellum, and is thus likely to employ a different binding mechanism