The immune paradox of SARS-CoV-2: Lymphocytopenia and autoimmunity evoking features in COVID-19 and possible treatment modalities.

SARS-CoV-2 causes multiorgan damage to vital organs and tissue that are known to be due to a combination of tissue tropisms and cytokine-mediated damage that it can incite in COVID-19. The effects of SARS-Co-2 on the lymphocytes and therefore on the immune response have attracted attention recently in COVID-19 to understand its effects in causing a chronic state of ongoing infection with Long-COVID. The associated lymphopaenia and autoimmune disease state, which is an apparent paradox, needs to be researched to dissect possible mechanisms underlying this state. This paper attempts to unravel the aforesaid immune paradox effects of SARS-CoV-2 on the lymphocytes and discusses appropriate treatment modalities with antiviral drugs and nutraceuticals which could prove virucidal in SARS-CoV-2 seeding monocytes and lymphocytes in patients with COVID-19 and Long-COVID. Importantly it proposes a new in vitro treatment modality of immune regulating cells that can help patients fight the lymphopaenia associated with COVID-19 and Long-COVID.

Underlying Causes and Treatment Modalities for Neurological Deficits in COVID-19 and Long-COVID.

With reports of diverse neurological deficits in the acute phase of COVID-19, there is a surge in neurological findings in Long-COVID─a protracted phase of SARS-CoV-2 infection. Very little is known regarding the pathogenic mechanisms of Neuro-COVID in the above two settings in the current pandemic. Herein, we hint toward the possible molecular mechanism that can contribute to the signs and symptoms of patients with neurological deficits and possible treatment and prevention modalities in the acute and chronic phases of COVID-19.

Differential diagnosis and pathogenesis of the neurological signs and symptoms in COVID-19 and long-COVID syndrome.

Neurological features have now been reported very frequently in the ongoing COVID-19 pandemic caused by SARS-CoV-2. The neurological deficits associated features are observed in both acute and chronic stages of COVID-19 and they appear to overlap with wide-ranging symptoms that can be attributed to being of non-neural origins, thus obscuring the definitive diagnosis of neuro-COVID. The pathogenetic factors acting in concert to cause neuronal injury are now emerging, with SARS-CoV-2 directly affecting the brain coupled with the neuroinflammatory factors have been implicated in the causation of disabilities in acute COVID-19 and patients with Long-COVID syndrome. As the differentiation between a neural origin and other organ-based causation of a particular neurological feature is of prognostic significance, it implores a course of action to this covert, yet important neurological challenge.

Correlating Biochemical and Structural Changes in the Brain with Clinical Features in COVID-19.

With emerging reports of the deleterious effects of SARS-CoV-2 reflecting as neurological deficits in COVID-19, the biochemical and morphological changes it casts on the brain are also being investigated. This is an important niche of research as it is expected to predict and relate the neurological clinical features in the acute phase and chronic syndromic forms of COVID-19. Here debated are the biochemical and structural changes that can be related to the neurological manifestations in COVID-19.

Pathways and Pathogenesis of Hearing Deficits, Tinnitus, and Vertigo in COVID-19.

COVID-19 has been shown to affect the ear and has led to hearing deficits, tinnitus, and vertigo. Very little is known regarding the mechanisms and targets of SARS-CoV-2 that cause the above symptoms. Anatomical extensions from the areas of viral loads to the middle ear appear to enable the SARS-CoV-2 to cause either an inflammatory response or a direct effect on the lining epithelium leading to temporary hearing and equilibrium-related symptoms in COVID-19. Herein the anatomical continuity from the areas of viral loads to the middle and internal ear is debated to uncover the possible covert routes used by SARS-CoV-2 to affect the hearing and equilibrium in COVID-19.

Chronic long-COVID syndrome: A protracted COVID-19 illness with neurological dysfunctions.

After almost a year of COVID-19, the chronic long-COVID syndrome has been recognized as an entity in 2021. The patients with the long-COVID are presenting with ominous neurological deficits that with time are becoming persistent and are causing disabilities in the affected individuals. The mechanisms underlying the neurological syndrome in long-COVID have remained obscure and need to be actively researched to find a resolution for the patients with long-COVID. Here, the factors like site of viral load, the differential immune response, neurodegenerative changes, and inflammation as possible causative factors are debated to understand and investigate the pathogenesis of neuro-COVID in long-COVID syndrome.

Ocular COVID-19: Eyes as a Reservoir to Conceal and Spread SARSCoV- 2.

Ocular tissues can serve as a reservoir for the SARS-CoV-2 virus which can not only cause conjunctivitis but also serve as a source of infection transmission to others. Additionally, the eye and its tear drainage apparatus can track the SARS-CoV-2 from the eye into the respiratory tract of the patient. The potential ocular presence of the SARS-CoV-2 in the eye of a patient can target ACE2 receptors in the endothelium of the conjunctival vessels and use the lacrimal sac a potential space to evade immune detection and clinical isolation. The recently reported case of COVID-19 after the acquisition of SARS-CoV-2 from a COVID-19 patient should alert the healthcare professionals dealing with COVID-19 patients that wearing masks alone cannot guarantee protection against infection transmission. Further studies, like isolation of SARS-CoV-2 from the eyes of patients with COVID-19, are needed to identify the eyes as a potential source of SARS-CoV-2 infection transmission.

Targeting Neuroinvasion by SARS-CoV-2: Emerging Trends in Drug and Antibody Delivery to Combat COVID-19.

Because SARS-CoV-2 uses the nasal cavity as a major route of entry to the human body, nasal administration of drugs and antibodies directed against the virus can prove to be effective for not only pulmonary COVID-19 but also prevention of potential early neuroinvasion caused by this virus. With recent reports of the potential application of antibody-laden nasal spray for the treatment of COVID-19, proposed here is the use of drugs recently proven to be effective against SARS-CoV-2 to be administered via inhalation route using a modified transcribrial device reported previously for its use against Naegleria fowleri, to target SARS-CoV-2 in our fight against COVID-1.

Docking Prediction of Levodopa in the Receptor Binding Domain of Spike Protein of SARS-CoV-2.

Levodopa is a prodrug that is converted into dopamine, which replenishes the deficient dopamine in the brain of patients suffering from Parkinsonism. We hypothesize that levodopa may interact with the receptor binding domain of the SARS-CoV-2 and may act as a physical impediment to the viral entry into the host cell.

Deleterious Outcomes in Long-Hauler COVID-19: The Effects of SARS-CoV-2 on the CNS in Chronic COVID Syndrome.

Amid our understanding of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the mechanisms involved in the causation of acute-phase coronavirus disease (COVID-19), we have come across clinical cases that have been shown to run a protracted course of COVID-19 with complex clinical findings related to organ systems in general and the CNS in particular that deserve to be addressed in the COVID long-haulers, for which the more clinically-related term chronic COVID syndrome (CCS) has been coined recently. An in-depth understanding of the mechanism that forms the basis of CCS and neurological deficits in CCS is needed as this can help in determining the management of cases of neuro-COVID, which is emerging as a less lethal but more disabling disease state. This Viewpoint highlights this syndrome, the possible pathogenetic pathways involved, and the treatment approaches that can be taken to help manage COVID long-haulers in CCS.

Elucidation of cellular targets and exploitation of the receptor-binding domain of SARS-CoV-2 for vaccine and monoclonal antibody synthesis.

The pandemic caused by novel severe acute respiratory syndrome coronavirus (SARS-CoV-2) has resulted in over 452 822 deaths in the first 20 days of June 2020 due to the coronavirus virus disease 2019 (COVID-19). The SARS-CoV-2 uses the host angiotensin-converting enzyme 2 (ACE2) receptor to gain entry inside the human cells where it replicates by using the cell protein synthesis mechanisms. The knowledge of the tissue distribution of ACE2 in human organs is therefore important to predict the clinical course of the COVID-19. Also important is the understanding of the viral receptor-binding domain (RBD), a region within the spike (S) proteins, that enables the entry of the virus into the host cells to synthesize vaccine and monoclonal antibodies (mAbs). We performed an exhaustive search of human protein databases to establish the tissues that express ACE2 and performed an in-depth analysis like sequence alignments and homology modeling of the spike protein (S) of the SARS-CoV-2 to identify antigenic regions in the RBD that can be exploited to synthesize vaccine and mAbs. Our results show that ACE2 is widely expressed in human organs that may explain the pulmonary, systemic, and neurological deficits seen in COVID-19 patients. We show that though the S protein of the SARS-CoV-2 is a homolog of S protein of SARS-CoV-1, it has regions of dissimilarities in the RBD and transmembrane segments. We show peptide sequences in the RBD of SARS-CoV-2 that can bind to the major histocompatibility complex alleles and serve as effective epitopes for vaccine and mAbs synthesis.

Potential neuroinvasive pathways of SARS-CoV-2: Deciphering the spectrum of neurological deficit seen in coronavirus disease-2019 (COVID-19).

Coronavirus disease-2019 (COVID-19) was declared a global pandemic on 11 March 2020. Scientists and clinicians must acknowledge that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has the potential to attack the human body in multiple ways simultaneously and exploit any weaknesses of its host. A multipronged attack could potentially explain the severity and extensive variety of signs and symptoms observed in patients with COVID-19. Understanding the diverse tactics of this virus to infect the human body is both critical and incredibly complex. Although patients diagnosed with COVID-19 have primarily presented with pulmonary involvement, viral invasion, and injury to diverse end organs is also prevalent and well documented in these patients, but has been largely unheeded. Human organs known for angiotensin-converting enzyme 2 (ACE2) expression including the gastrointestinal tract, kidneys, heart, adrenals, brain, and testicles are examples of extra pulmonary tissues with confirmed invasion by SARS-CoV-2. Initial multiple organ involvement may present with vague signs and symptoms to alert health care professionals early in the course of COVID-19. Another example of an ongoing, yet neglected element of the syndromic features of COVID-19, are the reported findings of loss of smell, altered taste, ataxia, headache, dizziness, and loss of consciousness, which suggest a potential for neural involvement. In this review, we further deliberate on the neuroinvasive potential of SARS-CoV-2, the neurologic symptomology observed in COVID-19, the host-virus interaction, possible routes of SARS-CoV-2 to invade the central nervous system, other neurologic considerations for patients with COVID-19, and a collective call to action.

Docking Prediction of Amantadine in the Receptor Binding Domain of Spike Protein of SARS-CoV-2.

Amantadine has recently been shown to improve patients with COVID-19. In addition to its known mechanism of actions, we performed docking prediction of this drug on the receptor-binding domain of severe acute respiratory syndrome coronavirus 2, SARS-CoV-2. We hypothesize that such interaction may possibly have contributed a role in the clinical improvements reported.

Can Neurotropic Free-Living Amoeba Serve as a Model to Study SARS-CoV-2 Pathogenesis?

Of the single-celled eukaryotic microbes, Naegleria fowleri, Balamuthia mandrillaris, and Acanthamoeba spp. are known to cause fatal encephalitis in humans. Being eukaryotes, these cells have been used as a model for studying and understanding complex cellular processes in humans like cell motility, phagocytosis, and metabolism. The ongoing pandemic caused by SARS-CoV-2 that infects multiple organs has emerged as a challenge to unravel its mode of infection and the pathogenicity resulting in eukaryotic cell death. Working with these single-celled eukaryotic microbes provided us the opportunity to plan bioinformatic approaches to look into the likelihood of studying the known and alternative mode of infection of the SARS-CoV-2 in eukaryotic cells. Genome databases of N. fowleri, B. mandrillaris, and Acanthamoeba spp. were used to explore the expression of angiotensin-converting enzyme 2 (ACE2), androgen-regulated serine protease precursor (TMPRSS2), CD4, CD147, and furin that are known to be cardinal for SARS-CoV-2 in recognition and binding to human cells. It was hypothesized that if a receptor-dependent or phagocytosis-assisted SARS-CoV-2 uptake does occur in free-living amoebae (FLA), this model can provide an alternative to human cells to study cellular recognition and binding of SARS-CoV-2 that can help design drugs and treatment modalities in COVID-19. We show that, of the FLA, ACE2 and TMPRSS2 are not expressed in Acanthamoeba spp. and B. mandrillaris, but primitive forms of these cell recognition proteins were seen to be encoded in N. fowleri. Acanthamoeba spp. and N. fowleri encode for human-like furin which is a known SARS-CoV-2 spike protein involved in host cell recognition and binding.