Chemosensory Dysfunction in COVID-19: Integration of Genetic and Epidemiological Data Points to D614G Spike Protein Variant as a Contributing Factor

Optimization of a panel of behavioral tests for use in containment using a golden Syrian hamster model

Golden Syrian hamsters are an often-overlooked model in behavioral testing. While previously utilized for research examining circadian rhythms and mammalian reproduction, they are less common than murine models in both infectious disease and behavioral studies. However, coronavirus disease-19 (COVID-19) quickly pushed hamster modeling to the forefront due to its myriad of advantages over mice in recapitulating human pathology and transmission. At least 10 % of COVID-19 survivors suffer from post-acute sequelae of COVID-19 (PASC), a collection of some 200 sequelae with neurologic sequelae (neuro-PASC) presenting with potentially debilitating symptomology. This presents a clear need for a small animal model that recapitulates human disease with the ability to assess any potential long term neurological changes. We adapted and optimized a panel of behavioral tests from previously accepted murine models utilizing the golden Syrian hamster model for use within biocontainment facilities. Our panel includes grip strength, Porsolt forced swim, and novel object recognition testing to measure muscle fatigue or weakness, depression, and memory loss or cognitive impairment, respectively. Apart from severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), this panel of tests is applicable to other pathogens that cause neurologic sequelae, such as Nipah or eastern equine encephalitis viruses, or any other model systems that require the use of hamsters. In this manuscript, we detail the methods for each of these three behavioral tests, how to interpret and analyze the resulting data, and emphasize additional factors for consideration. We also provide baseline data for both male and female golden Syrian hamsters.

SARS-CoV-2: Prediction of critical ionic amino acid mutations

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), that caused coronavirus disease 2019 (COVID-19), has been studied thoroughly, and several variants are revealed across the world with their corresponding mutations. Studies and vaccines development focus on the genetic mutations of the S protein due to its vital role in allowing the virus attach and fuse with the membrane of a host cell. In this perspective, we study the effects of all ionic amino acid mutations of the SARS-CoV-2 viral spike protein S1 when bound to Antibody CC12.1 within the SARS-CoV-2:CC12.1 complex model. Binding free energy calculations between SARS-CoV-2 and antibody CC12.1 are based on the Analysis of Electrostatic Similarities of Proteins (AESOP) framework, where the electrostatic potentials are calculated using Adaptive Poisson-Boltzmann Solver (APBS). The atomic radii and charges that feed into the APBS calculations are calculated using the PDB2PQR software. Our results are the first to propose in silico potential life-threatening mutations of SARS-CoV-2 beyond the present mutations found in the five common variants worldwide. We find each of the following mutations: K378A, R408A, K424A, R454A, R457A, K458A, and K462A, to play significant roles in the binding to Antibody CC12.1, since they are turned into strong inhibitors on both chains of the S1 protein, whereas the mutations D405A, D420A, and D427A, show to play important roles in this binding, as they are turned into mild inhibitors on both chains of the S1 protein.

SARS-CoV-2: pathogenesis, therapeutics, variants, and vaccines

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged in December 2019 with staggering economic fallout and human suffering. The unique structure of SARS-CoV-2 and its underlying pathogenic mechanism were responsible for the global pandemic. In addition to the direct damage caused by the virus, SARS-CoV-2 triggers an abnormal immune response leading to a cytokine storm, culminating in acute respiratory distress syndrome and other fatal diseases that pose a significant challenge to clinicians. Therefore, potential treatments should focus not only on eliminating the virus but also on alleviating or controlling acute immune/inflammatory responses. Current management strategies for COVID-19 include preventative measures and supportive care, while the role of the host immune/inflammatory response in disease progression has largely been overlooked. Understanding the interaction between SARS-CoV-2 and its receptors, as well as the underlying pathogenesis, has proven to be helpful for disease prevention, early recognition of disease progression, vaccine development, and interventions aimed at reducing immunopathology have been shown to reduce adverse clinical outcomes and improve prognosis. Moreover, several key mutations in the SARS-CoV-2 genome sequence result in an enhanced binding affinity to the host cell receptor, or produce immune escape, leading to either increased virus transmissibility or virulence of variants that carry these mutations. This review characterizes the structural features of SARS-CoV-2, its variants, and their interaction with the immune system, emphasizing the role of dysfunctional immune responses and cytokine storm in disease progression. Additionally, potential therapeutic options are reviewed, providing critical insights into disease management, exploring effective approaches to deal with the public health crises caused by SARS-CoV-2.

Variant-specific Symptoms After COVID-19: A Hospital-based Study in Hiroshima

BACKGROUND

Symptoms after novel coronavirus disease 2019 (COVID-19) recovery by severe acute respiratory syndrome coronavirus 2 strains are unspecified.

METHODS

This self-administered questionnaire-based study was conducted to investigate symptoms after COVID-19 recovery at one of the main hospitals for COVID-19 treatment in Hiroshima, Japan, from September 2020 to March 2022 for patients who visited follow-up consultations after COVID-19. Study subjects were divided into four groups (Wild-type, Alpha, Delta, and Omicron periods) according to COVID-19 onset date. Hierarchical cluster analysis was performed to determine symptom clusters and investigate risk factors for each symptom cluster using multivariate analysis.

RESULTS

Among 385 patients who enrolled in this study, 249 patients had any persistent symptoms at a median of 23.5 (interquartile range, 20-31) days after COVID-19 onset. Among patients with any persistent symptoms, symptom clusters including olfactory or taste disorders, respiratory symptoms, and cardiac symptoms were found. Respiratory symptoms were more frequent among patients infected in the Omicron period compared to the Wild-type period (adjusted odds ratio [AOR] 3.13; 95% confidence interval [CI], 1.31-7.48). Compared to patients who recovered from mild COVID-19, patients who needed oxygen or ventilation support suffered fewer post-COVID-19 respiratory symptoms (AOR 0.46; 95% CI, 0.22-0.97) but more post-COVID-19 cardiac symptoms among them (AOR 2.67; 95% CI, 1.26-5.65). Olfactory or taste disorders were fewer among patients infected in the Omicron period compared to the Wild-type period (AOR 0.14; 95% CI, 0.04-0.46).

CONCLUSION

This study revealed that symptoms after COVID-19 may vary depending on the infected strain.

COVID-19 and anosmia: The story so far

OBJECTIVES

The pandemic has affected over 182 million coronavirus disease 2019 (COVID-19) cases worldwide. Accumulated evidence indicates that anosmia is one of the significant characteristics of COVID-19 with a high prevalence. However, many aspects of COVID-19-induced anosmia are still far from being fully understood. The purpose of this review is to summarize recent developments in COVID-19-induced anosmia to increase awareness of the condition.

METHODS

A literature search was carried out using the PubMed, Embase, Web of Science, and Scopus. We reviewed the latest literature on COVID-19-induced anosmia, including mechanisms of pathogenesis, olfactory testing, anosmia as predictive tool, pathological examinations, imaging findings, affected factors, co-existing diseases, treatments, prognosis, hypothesis theories, and future directions.

RESULTS

The possible pathogenesis of COVID-19-induced anosmia may involve inflammation of the olfactory clefts and damage to the olfactory epithelium or olfactory central nervous system by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The D614G spike variant may also play a role in the increased number of anosmia patients. Anosmia may also be an essential indicator of COVID-19 spread and an early indicator of the effectiveness of political decisions. The occurrence and development of COVID-19-induced anosmia may be influenced by smoking behaviors and underlying diseases such as type 2 diabetes, gastroesophageal disorders, and rhinitis. Most patients with COVID-19-induced anosmia can fully or partially recover their olfactory function for varying durations. COVID-19-induced anosmia can be treated with various approaches such as glucocorticoids and olfactory training.

CONCLUSION

Anosmia is one of the main features of COVID-19 and the underlying disease of the patient may also influence its occurrence and development. The possible pathogenesis of COVID-19-induced anosmia is very complicated, which may involve inflammation of the olfactory clefts and damage to the olfactory epithelium or olfactory central nervous system.

SARS-CoV-2 mechanisms of cell tropism in various organs considering host factors

A critical step in the drug design for SARS-CoV-2 is to discover its molecular targets. This study comprehensively reviewed the molecular mechanisms of SARS-CoV-2, exploring host cell tropism and interaction targets crucial for cell entry. The findings revealed that beyond ACE2 as the primary entry receptor, alternative receptors, co-receptors, and several proteases such as TMPRSS2, Furin, Cathepsin L, and ADAM play critical roles in virus entry and subsequent pathogenesis. Additionally, SARS-CoV-2 displays tropism in various human organs due to its diverse receptors. This review delves into the intricate details of receptors, host proteases, and the involvement of each organ. Polymorphisms in the ACE2 receptor and mutations in the spike or its RBD region contribute to the emergence of variants like Alpha, Beta, Gamma, Delta, and Omicron, impacting the pathogenicity of SARS-CoV-2. The challenge posed by mutations raises questions about the effectiveness of existing vaccines and drugs, necessitating consideration for updates in their formulations. In the urgency of these critical situations, repurposed drugs such as Camostat Mesylate and Nafamostat Mesylate emerge as viable pharmaceutical options. Numerous drugs are involved in inhibiting receptors and host factors crucial for SARS-CoV-2 entry, with most discussed in this review. In conclusion, this study may provide valuable insights to inform decisions in therapeutic approaches.

Evaluating long-term smell or taste dysfunction in mildly symptomatic COVID-19 patients: a 3-year follow-up study

INTRODUCTION

No studies have reported data on 3-year prevalence and recovery rates of self-reported COVID-19-related olfactory and gustatory dysfunction. The aim of the present study was to estimate the 3-year prevalence and recovery rate of self-reported COVID-19-related chemosensory dysfunction in a cohort of patients with antecedent mild COVID-19.

METHODS

This is a prospective observational study, measuring the prevalence of altered sense of smell or taste at follow-up and their variation from baseline, on adult patients consecutively assessed at Treviso and Trieste University Hospitals, who tested positive for SARS-CoV-2 RNA by polymerase chain reaction during March 2020.

RESULTS

Overall, out of 403 respondents, 267 patients (66.3%) reported an altered sense of smell or taste (SNOT-22 > 0) at baseline, while 56 (13.9%), 29 (7.2%), and 21 (5.2%) reported such alterations at 6-24 months, 2 years, and 3 years, respectively. Among the 267 patients with COVID-19-associated smell or taste dysfunction at baseline, 246 (92.1%) reported complete resolution at 3 years. Of the patients who still experienced smell or taste dysfunction 2 years after COVID-19, 27.6% and 37.9% recovered completely and partially, respectively, at the 3-year follow-up.

CONCLUSION

Among subjects with antecedent mildly symptomatic SARS-CoV-2 infection, the 3-year prevalence and recovery rate of COVID-19-related alteration in sense of smell or taste was 5% and 92%, respectively. In approximately two-thirds of patients experiencing chemosensory dysfunction still 2 years after COVID-19, it is still possible to observe a delayed complete or partial recovery after a period of 3 years, while the remaining one-third of individuals continues to have unchanged persistent chemosensory alteration.

Vaccination against SARS-CoV-2 Does Not Protect against the Development of Anosmia in a Hamster Model

Anosmia, a total or partial loss of the ability to smell, is one of the most frequently documented sequelae of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. Persistent anosmia is associated with a decrease in quality of life. Here, we assess the impact of virus lineage and vaccination status on anosmia development in the golden Syrian hamster model. To characterize anosmia driven by current variants, we assessed olfactory function in hamsters infected with SARS-CoV-2 lineages A, BA.2, BA.5, BQ.1, and BQ.1.1 using a buried food detection test. We found that significant anosmia occurs upon infection with all variants with a significant correlation between disease severity and degree of anosmia. Moreover, we found that vaccination with either the Pfizer (BNT16b2) or Moderna (mRNA-1273) mRNA vaccines does not protect against anosmia, despite protection against severe disease.

Psychophysical assessment of olfactory and gustatory function in post-mild COVID-19 patients: A matched case-control study with 2-year follow-up

BACKGROUND

The aim of this study was to psychophysically evaluate the prevalence of smell and taste dysfunction 2 years after mildly symptomatic severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection compared to that observed at 1-year follow-up and while considering the background of chemosensory dysfunction in the no-coronavirus disease 2019 (COVID-19) population.

METHOD

This is a prospective case-control study on 93 patients with polymerase chain reaction (PCR)-positive SARS-CoV-2 infection and 93 matched controls. Self-reported olfactory and gustatory dysfunction was assessed by 22-item Sino-Nasal-Outcome Test (SNOT-22), item "Sense of smell or taste." Psychophysical orthonasal and retronasal olfactory function and gustatory performance were estimated using the extended Sniffin' Sticks test battery, 20 powdered tasteless aromas, and taste strips test, respectively. Nasal trigeminal sensitivity was assessed by sniffing a 70% solution of acetic acid.

RESULTS

The two psychophysical assessments of chemosensory function took place after a median of 409 days (range, 366-461 days) and 765 days (range, 739-800 days) from the first SARS-CoV-2-positive swab, respectively. At 2-year follow-up, cases exhibited a decrease in the prevalence of olfactory (27.9% vs. 42.0%; absolute difference, -14.0%; 95% confidence interval [CI], -21.8% to -2.6%; p = 0.016) and gustatory dysfunction (14.0% vs. 25.8%; absolute difference, -11.8%; 95% CI, -24.2% to 0.6%; p = 0.098). Subjects with prior COVID-19 were more likely than controls to have an olfactory dysfunction (27.9% vs. 10.8 %; absolute difference, 17.2%; 95% CI, 5.2% to 28.8%) but not gustatory dysfunction (14.0% vs. 9.7%; absolute difference, 4.3%; 95% CI, -5.8% to 14.4% p = 0.496) still 2 years after the infection. Overall, 3.2% of cases were still anosmic 2 years after the infection.

CONCLUSIONS

Although a proportion of subjects recovered from long-lasting smell/taste dysfunction more than 1 year after COVID-19, cases still exhibited a significant excess of olfactory dysfunction 2 years after SARS-CoV-2 infection when compared to matched controls.

Sequence Analysis of Hot Spot Regions of Spike and RNA-dependent-RNA polymerase (RdRp) Genes of SARS-CoV-2 in Kerman, Iran

Background

Mutations in the SARS-CoV-2 genome might influence pathogenicity, transmission rate, and evasion of the host immune system. Therefore, the purpose of the present study was to investigate the genetic alteration as well as assess their effects on the receptor binding domain (RBD) of the spike and the putative RNA binding site of the RdRp genes of SARS-CoV-2 using bioinformatics tools.

Materials and Method

In this cross-sectional study, 45 confirmed COVID-19 patients using qRT-PCR were included and divided into mild, severe, and critical groups based on the severity of the disease. RNA was extracted from nasopharyngeal swab samples using a commercial kit. RT-PCR was performed to amplify the target sequences of the spike and RdRp genes and sequence them by the Sanger method. Clustal OMEGA, MEGA 11 software, I-mutant tools, SWISS-MODEL, and HDOCK web servers were used for bioinformatics analyses.

Results

The mean age of the patients was 50.68±2.73. The results showed that four of six mutations (L452R, T478K, N501Y, and D614G) in RBD and three of eight in the putative RNA binding site (P314L, E1084D, V1883T) were missense. In the putative RNA binding site, another deletion was discovered. Among missense mutations, N501Y and V1883T were responsible for increasing structural stability, while others were responsible for decreasing it. The various homology models designed showed that these homologies were like the Wuhan model. The molecular docking analysis revealed that the T478K mutation in RBD had the highest binding affinity. In addition, 35 RBD samples (89.7%) and 33 putative RNA binding site samples (84.6%) were similar to the Delta variant.

Conclusion

Our results indicated that double mutations (T478K and N501Y) in the S protein might increase the binding affinity of SARS-CoV-2 to human ACE2 compared to the wild-type (WT) strain. Moreover, variations in the spike and RdRp genes might influence the stability of encoded proteins.

Transient Anosmia and Dysgeusia in COVID-19 Disease: A Cross Sectional Study

Objective

This study aims to explore the prevalence of anosmia and dysgeusia and their impact on COVID-19 patients.

Methods

This is a cross-sectional study. Patients diagnosed with COVID-19 between 1st October 2020 and 30th June 2021 were randomly selected from a national COVID-19 registry. COVID-19 cases were diagnosed using molecular testing method which measured the viral E gene. The Anosmia Reporting Tool, and a brief version of the questionnaire on olfactory disorders were used to measure the outcomes via telephone interviews. Data were analysed using SPSS 27 statistics software.

Results

A total of 405 COVID-19 adults were included in this study, 220 (54.3%) were males and 185 (45.8%) were females. The mean±SD age of participants was 38.2 ± 11.3 years. Alterations in the sense of smell and taste were reported by 206 (50.9%), and 195 (48.1%) of the patients, respectively. Sex and nationality of participants were significantly associated with anosmia and dysgeusia (p < 0.001) and (p-value=0.001) respectively. Among patients who experienced anosmia and dysgeusia, alterations in eating habits (64.2%), impact on mental wellbeing (38.9%), concerns that the alterations were permanent (35.4%), and physical implications and difficulty performing activities of daily living (34%) were reported.

Conclusion

Anosmia and dysgeusia are prevalent symptoms of COVID-19 disease, especially among females. Although transient, anosmia and dysgeusia had considerable impact on patient's life. Neuropsychological implications of COVID-19 in acute infection phase and prognosis of anosmia and dysgeusia in COVID-19 are areas for further exploration.

Prevalence of Olfactory Dysfunction with the Omicron Variant of SARS-CoV-2: A Systematic Review and Meta-Analysis

The omicron variant is thought to cause less olfactory dysfunction than previous variants of SARS-CoV-2, but the reported prevalence differs greatly between populations and studies. Our systematic review and meta-analysis provide information regarding regional differences in prevalence as well as an estimate of the global prevalence of olfactory dysfunction based on 62 studies reporting information on 626,035 patients infected with the omicron variant. Our estimate of the omicron-induced prevalence of olfactory dysfunction in populations of European ancestry is 11.7%, while it is significantly lower in all other populations, ranging between 1.9% and 4.9%. When ethnic differences and population sizes are considered, the global prevalence of omicron-induced olfactory dysfunction in adults is estimated to be 3.7%. Omicron's effect on olfaction is twofold to tenfold lower than that of the alpha or delta variants according to previous meta-analyses and our analysis of studies that directly compared the prevalence of olfactory dysfunction between omicron and previous variants. The profile of the prevalence differences between ethnicities mirrors the results of a recent genome-wide association study that connected a gene locus encoding an odorant-metabolizing enzyme, UDP glycosyltransferase, to the extent of COVID-19-related loss of smell. Our analysis is consistent with the hypothesis that this enzyme contributes to the observed population differences.

Prevalence of Olfactory Dysfunction with the Omicron Variant of SARS-CoV-2: A Systematic Review and Meta-analysis

The omicron variant is thought to cause less olfactory dysfunction than previous variants of SARS-CoV-2, but the reported prevalence differs greatly between populations and studies. Our systematic review and meta-analysis provide information about regional differences in prevalence as well as an estimate of the global prevalence of olfactory dysfunction based on 62 studies reporting on 626,035 patients infected with the omicron variant. Our estimate of the omicron-induced prevalence of olfactory dysfunction in populations of European ancestry is 11.7%, while it is significantly lower in all other populations, ranging between 1.9% and 4.9%. When ethnic differences and population sizes are taken into account, the global prevalence of omicron-induced olfactory dysfunction in adults is estimated at 3.7%. Omicron’s effect on olfaction is twofold to tenfold lower than that of the alpha or delta variant, according to previous meta-analyses and our analysis of studies that directly compared prevalence of olfactory dysfunction between omicron and previous variants. The profile of prevalence differences between ethnicities mirrors the results of a recent genome-wide association study that implicated a gene locus encoding an odorant-metabolizing enzyme, UDP glycosyltransferase, to be linked to the extent of COVID-related loss of smell. Our analysis is consistent with the hypothesis that this enzyme contributes to the observed population differences.

Olfactory dysfunction in COVID-19: new insights into the underlying mechanisms

The mechanisms of olfactory dysfunction in COVID-19 are still unclear. In this review, we examine potential mechanisms that may explain why the sense of smell is lost or altered. Among the current hypotheses, the most plausible is that death of infected support cells in the olfactory epithelium causes, besides altered composition of the mucus, retraction of the cilia on olfactory receptor neurons, possibly because of the lack of support cell-derived glucose in the mucus, which powers olfactory signal transduction within the cilia. This mechanism is consistent with the rapid loss of smell with COVID-19, and its rapid recovery after the regeneration of support cells. Host immune responses that cause downregulation of genes involved in olfactory signal transduction occur too late to trigger anosmia, but may contribute to the duration of the olfactory dysfunction.

Assessment of Jordanian health care professionals' perception towards new COVID-19 variants of concern

BACKGROUND

Healthcare professionals working at the frontline, dealing with COVID-19 patients or their samples, should know about variants of concern (VOCs) and their transmissibility, disease severity, and vaccine efficacy. Healthcare professionals' (HCPs) perceptions towards new VOCs affect their practice and attitudes towards their patients. Moreover, these perceptions might significantly impact their patients' perceptions of new COVID-19 variants and public vaccine acceptability.

METHODS

Online and paper-based questionnaires were distributed among Healthcare professionals in Jordan between August 2021 and October 2021.

RESULTS

Among 423 HCPs who participated in this study, a majority believe that when viruses mutate, they become more transmissible (77.8%), more deadly (61.7%), and pathogenic (64.8%). In addition, half of the respondents, perceived current treatments as partially effective against VOCs and current diagnostics to be efficient. However, all VOCs were perceived as more transmissible, more virulent, and related to higher mortality rates when compared to the original strain. Regarding immunity against VOCs, (57.4%) of respondents believe in partial immunity against re-infection, and most respondents were either unsure about the current vaccines' efficacy or agreed that available vaccines would be ineffective. However, respondents (44.4%) still believe that people previously infected should get vaccinated. Respondents referred to the Ministry of Health as the most reliable source of information (45.6%) and the party responsible for educating the public about COVID-19 VOCs (57.9%). Travel was not a source of worry among respondents. However, they were worried about their families getting the new COVID-19 VOCs from their work. Similar proportions agreed/disagreed on the efficacy of the precautions and infection control measures currently applied by the government for preventing the spread of the new COVID-19 VOCs.

CONCLUSION

Campaigns, workshops, and webinars targeting vaccines are highly recommended among HCPs to increase public acceptance of the vaccine and further booster shots.

Why Does the Omicron Variant Largely Spare Olfactory Function? Implications for the Pathogenesis of Anosmia in Coronavirus Disease 2019

The omicron variant of severe acute respiratory syndrome coronavirus 2 causes much less olfactory dysfunction than the previous variants. There are several potential mechanisms for how omicron may change tissue tropism and spare olfactory function. The new mutations make omicron more hydrophobic and alkaline than previous variants, which may reduce penetration of the mucus layer. Overall, the new mutations minimally change receptor binding affinity, but entry efficiency into host cells is reduced in cells expressing transmembrane serine protease 2 (TMPRSS2). Because the support cells in the olfactory epithelium abundantly express TMPRSS2, these main target cells in the olfactory epithelium may become infected less by the new omicron variant.

Can we Succeed in the Fight Against SARS-CoV-2 with its Emerging New Variants?

In 2019, the whole world came together to confront a life-threatening virus named SARS-CoV-2, causing COVID-19 illness. The virus infected the human host by attaching to the ACE2 and CD147 receptors in some human cells, resulting in cytokine storm and death. The new variants of the virus that caused concern are Alpha, Beta, Gamma, Delta, and Epsilon, according to the WHO label. However, Pango lineages designated them as B.1.1.7, B.1.351, P.1, B.1.617.2, and B.1.429. Variants may be progressively formed in one chronic COVID-19 patient and transmitted to others. They show some differences in cellular and molecular mechanisms. Mutations in the receptor-binding domain (RBD) and N-terminal domain (NTD) lead to alterations in the host's physiological responses. They show significantly higher transmissibility rates and viral load while evading neutralizing antibodies at different rates. These effects are through mutations, deletion, and conformational alterations in the virus, resulting in the enhanced affinity of RBD to PD of ACE2 protein, virus entry, and spike conformational change. In the clinical laboratory, new variants may diagnose from other variants using specific primers for RBD or NTD. There are some controversial findings regarding the efficacy of the developed vaccines against the new variants. This research aimed to discuss the cellular and molecular mechanisms beyond COVID-19 pathogenesis, focusing on the new variants. We glanced at why the mutations and the ability to transmit the virus increase and how likely the available vaccines will be effective against these variants.

COVID-19, sens chimiques et pathologies métaboliques

Une réduction importante de l’odorat, indépendamment de l’obstruction nasale, et du goût, a été signalée comme un des symptômes majeurs suite à l’infection par la COVID-19. Cette réduction est si fréquente qu’elle a été proposée comme un des prédicteurs le plus relevant pour diagnostiquer l’infection. Différents mécanismes par lesquels les virus affectent l’odorat et le goût ont été proposés. L’ACE2 (enzyme de conversion de l’angiotensine 2) a été caractérisé comme le principal récepteur d’entrée du virus SARS-CoV-2 qui interagit avec les protéines « spikes » du virus, ce qui permet à ce dernier d’entrer dans la cellule hôte par un domaine de fusion. Il est principalement exprimé dans la partie supérieure des voies respiratoires, et la plus forte densité de ces protéines se trouve dans les épithéliums olfactif et gustatif. Les données actuellement disponibles indiquent que la cause la plus probable de l’anosmie pendant la COVID-19 est une altération de la fonction des neurones sensoriels olfactifs, associée à l’infection et à la mort des cellules microvillaires, et des péricytes vasculaires. Les mécanismes généraux sont les mêmes en ce qui concerne le goût. La pathogenèse des troubles olfactifs et gustatifs dans la COVID-19 peut entraîner des altérations diverses, dont des modifications de la prise alimentaire et du métabolisme énergétique. Les individus porteurs de pathologies métaboliques ayant une plus forte susceptibilité à la COVID-19 sont, de ce fait, plus exposés aux perturbations des sens chimiques et à leurs conséquences. De plus, des études récentes montrent que la COVID-19 augmenterait la susceptibilité au diabète en s’attaquant directement aux cellules β-pancréatiques.

Epidemiologic characteristics of SARS-CoV-2 in Wuhan, other regions of China, and globally based on data gathered from January 2020 to February 2021

This observation study examines coronavirus disease 2019 (COVID-19) data from outbreak and other sites in China and worldwide in order to examine the epidemiological pattern of COVID-19 before the acquisition of immunity through widespread vaccination and infection. COVID-19-related morbidity and mortality data for January 2020 to February 2021 were obtained from the Chinese Center for Disease Control and Prevention, Hubei Provincial Center for Disease Control and Prevention, and the World Health Organization. The number of cases was logarithmically transformed for comparison of the rate of increase or decrease with time across areas. From January to February 2020, the number of new confirmed cases in Wuhan grew substantially but returned to zero by May 2020. In other parts of China, the rate of decrease was lower than that in Wuhan, and the mortality rate was lower outside Wuhan (1.93%) than in Wuhan (7.68%). The influenza trends were similar to those of COVID-19, but the mortality rate of influenza was much lower (0.011%) than that of COVID-19. After the early stage, similar increase in the incidence rate with time was observed globally, although the total number of cases differed between regions. The outbreak severe acute respiratory syndrome coronavirus 2 strain in Wuhan had low epidemic intensity and high virulence, but the epidemiological characteristics of severe acute respiratory syndrome coronavirus 2 may not be associated with race, geography, or economic status. Importantly, more effective prevention and control measures and vaccines should be applied for controlling the variants.

The First Geographic Identification by Country of Sustainable Mutations of SARS-COV2 Sequence Samples: Worldwide Natural Selection Trends

The high mutation rates of RNA viruses, coupled with short generation times and large population sizes, allow viruses to evolve rapidly and adapt to the host environment. The rapidity of viral mutation also causes problems in developing successful vaccines and antiviral drugs. With the spread of SARS-CoV-2 worldwide, thousands of mutations have been identified, some of which have relatively high incidences, but their potential impacts on virus characteristics remain unknown. The present study analyzed mutation patterns, SARS-CoV-2 AASs retrieved from the GISAID database containing 10,500,000 samples. Python 3.8.0 programming language was utilized to pre-process FASTA data, align to the reference sequence, and analyze the sequences. Upon completion, all mutations discovered were categorized based on geographical regions and dates. The most stable mutations were found in nsp1(8% S135R), nsp12(99.3% P323L), nsp16 (1.2% R216C), envelope (30.6% T9I), spike (97.6% D614G), and Orf8 (3.5% S24L), and were identified in the United States on April 3, 2020, and England, Gibraltar, and, New Zealand, on January 1, 2020, respectively. The study of mutations is the key to improving understanding of the function of the SARS-CoV-2, and recent information on mutations helps provide strategic planning for the prevention and treatment of this disease. Viral mutation studies could improve the development of vaccines, antiviral drugs, and diagnostic assays designed with high accuracy, specifically useful during pandemics. This knowledge helps to be one step ahead of new emergence variants.

The Impact of D614G Mutation of SARS-COV-2 on the Efficacy of Anti-viral Drugs: A Comparative Molecular Docking and Molecular Dynamics Study

D614G is one of the most reported mutations in the spike protein of SARS-COV-2 that has altered some crucial characteristics of coronaviruses, such as rate of infection and binding affinities. The binding affinity of different antiviral drugs was evaluated using rigid molecular docking. The reliability of the docking results was evaluated with the induced-fit docking method, and a better understanding of the drug-protein interactions was performed using molecular dynamics simulation. The results show that the D614G variant could change the binding affinity of antiviral drugs and spike protein remarkably. Although Cytarabine showed an appropriate interaction with the wild spike protein, Ribavirin and PMEG diphosphate exhibited a significant binding affinity to the mutated spike protein. The parameters of the ADME/T analysis showed that these drugs are suitable for further in-vitro and in-vivo investigation. D614G alteration affected the binding affinity of the RBD and its receptor on the cell surface.

The Prevalence and Pathophysiology of Chemical Sense Disorder Caused by the Novel Coronavirus

Emerging viral infections are a ceaseless challenge and remain a global public health concern. The world has not yet come back to normal from the devastating effects of the highly contagious and pathogenic novel coronavirus, or Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Olfactory and taste dysfunction is common in patients infected by the novel coronavirus. In light of the emergence of different coronavirus variants, it is important to update the prevalence and pathophysiology of these side effects. In this review, articles published on the prevalence of olfactory and taste dysfunction from coronavirus disease (COVID-19) and their possible pathophysiologic mechanisms have been reviewed and reported. The modulatory role of different SARS-CoV-2 variants on the chemical senses is then described. The clinical relevance of chemical sense disorder and its long-term morbidity and management is also discussed.

Olfactory and gustatory dysfunctions of COVID-19 patients in China: A multicenter study

Introduction

With the spread of the epidemic worldwide, an increasing number of doctors abroad have observed the following atypical symptoms of coronavirus disease 2019 (COVID-19): olfactory or taste disorders. Therefore, clarifying the incidence and clinical characteristics of olfactory and taste disorders in Chinese COVID-19 patients is of great significance and urgency.

Materials and Methods

A retrospective study was conducted, which included 229 severe acute respiratory syndrome coronavirus 2 confirmed patients, through face-to-face interviews and telephone follow-up. Following the completion of questionnaires, the patients participating in the study, were categorized according to the degree of olfactory and taste disorders experienced, and the proportion of each clinical type of patient with olfactory and taste disorders and the time when symptoms appeared were recorded.

Results

Among the 229 patients, 31 (13.54%) had olfactory dysfunction, and 44 (19.21%) had gustatory dysfunction. For the patients with olfactory dysfunction, 6 (19.35%) developed severe disease and became critically ill. Olfactory dysfunction appeared before the other symptoms in 21.43% of cases. The proportion of females with olfactory and gustatory dysfunction was higher than that of males (P < 0.001).

Conclusions

The incidence of olfactory and gustatory dysfunction was much lower than that reported abroad; the prognosis of patients with olfactory dysfunction is relatively favorable; olfactory and gustatory dysfunction can be used as a sign for early screening; females are more prone to olfactory and gustatory dysfunction.

The Impact of Age and Gender and Their Association with Chemosensory Dysfunction, in Hospitalized and Self-Quarantine Patients with Covid-19 Infection, in Epirus, Greece

Objective:Olfactory and gustatory dysfunction that relates with the infection from severe acute respiratory syndrome-related coronavirus (SARS-CoV-2) has already improved. The relation between chemosensory dysfunction and age and gender in covid-19 positive patients is the main objective of the present study. Methods:We used a questionnaire to select information about medical history, patient demographics and reported symptoms during infection. Three hundred covid-19 positive patients, who underwent a RT-PCR test in the University Hospital of Ioannina, Grecce, were included in this study; 150 of them recovered at home and the remaining 150 were admitted to hospital. Statistical analysis based on ÉBM-SPSS Statistics 26.0 was done. Results:The total sample included 300 patients, of which 106 females and 194 males. There was a statistically significant difference between the subgroup of patients aged 21-25, 61-65 and 71-75 with loss of smell, that of hospitalized patients aged 41-45 with loss of smell and the subgroup of those aged 31-35 and 71-75 with loss of taste. Conclusion:There is a significant association between chemosensory dysfunction and younger age groups. Olfactory and gustatory dysfunction appears more frequently in women than men. Male gender relates with disease severity.

Self-reported symptom study of COVID-19 chemosensory dysfunction in Malaysia

Alterations in the three chemosensory modalities-smell, taste, and chemesthesis-have been implicated in Coronavirus Disease 2019 (COVID-19), yet emerging data suggest a wide geographic and ethnic variation in the prevalence of these symptoms. Studies on chemosensory disorders in COVID-19 have predominantly focused on Caucasian populations whereas Asians remain understudied. We conducted a nationwide, multicentre cross-sectional study using an online questionnaire on a cohort of RT-PCR-confirmed adult COVID-19 patients in Malaysia between 6 June and 30 November 2020. The aim of our study was to investigate their presenting symptoms and assess their chemosensory function using self-ratings of perceived smell, taste, chemesthesis, and nasal blockage. In this cohort of 498 patients, 41.4% reported smell and/or taste loss when diagnosed with COVID-19, which was the commonest symptom. Blocked nose, loss of appetite, and gastrointestinal disturbances were independent predictors of smell and/or taste loss on multivariate analysis. Self-ratings of chemosensory function revealed a reduction in smell, taste, and chemesthesis across the entire cohort of patients that was more profound among those reporting smell and/or taste loss as their presenting symptom. Perceived nasal obstruction accounted for only a small proportion of changes in smell and taste, but not for chemesthesis, supporting viral disruption of sensorineural mechanisms as the dominant aetiology of chemosensory dysfunction. Our study suggests that chemosensory dysfunction in COVID-19 is more widespread than previously reported among Asians and may be related to the infectivity of viral strains.Study Registration: NMRR-20-934-54803 and NCT04390165.

Prevalence of olfactory dysfunction and quality of life in hospitalised patients 1 year after SARS-CoV-2 infection: a cohort study

OBJECTIVES

To determine the long-term prevalence of olfactory and/or gustatory dysfunction (OD±GD), associated risk factors and impact on quality of life (QoL) in previously hospitalised patients with COVID-19 1 year after infection.

DESIGN

A single-centre cohort study.

SETTING

Patients admitted at a large central London hospital with COVID-19 infection between 10 February 2020 and 22 May 2020.

PARTICIPANTS

150 adult subjects with previously confirmed SARS-CoV-2 infection were recruited between 10 December 2020 and 29 January 2021. Participants were predominantly male (102/150, 68.0%); mean age 58.0±15.9 years and 41.2% (56/136) were of black, Asian and minority ethnic backgrounds.

MAIN OUTCOME MEASURES

EQ-5D-5L values and Sino-Nasal Outcome Test-22 (SNOT-22) scores.

RESULTS

Long-term prevalence of OD±GD was 12.8% (19/149) at median time of 264.5 days following SARS-CoV-2 infection onset. Patients with OD±GD had a significantly higher median total SNOT-22 score (46.1; Q1-Q3: 23.0-60.0; 95% CI 23.0 to 60.0) compared with those without (16.0; Q1-Q3: 5.0-30.5; 95% CI 12.0 to 18.0) (p=0.0002), reflecting poorer QoL, particularly psychological well-being (p=0.0004), which was not alleviated with time (p=0.4977). Median EQ-5D-5L value was not significantly different between patients with OD±GD (0.70; Q1-Q3: 0.38-0.83; 95% CI 0.38 to 0.83) and those without (0.83; Q1-Q3: 0.61-0.94; 95% CI 0.75 to 0.89) (p=0.0627). Age, sex, ethnicity, smoking status, highest C reactive protein value, intubation and ventilation, and oxygen supplementation were not found to influence OD±GD (p>0.05).

CONCLUSIONS

12.8% of previously hospitalised patients with COVID-19 in London still report persistent problems with smell or taste up to a year after infection, impacting their QoL. Increased holistic support including psychological therapy and olfactory rehabilitation for affected patients may help to reduce long-term morbidity.

Recovery of anosmia in hamsters infected with SARS-CoV-2 is correlated with repair of the olfactory epithelium

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is responsible for a pandemic affecting billions of people worldwide. Apart from the extreme global economic impact, the pandemic will likely have a lasting impact through long-term sequelae not yet fully understood. Fully understanding the mechanisms driving the various symptoms and sequelae of SARS-CoV-2 infection will allow for the eventual development of therapeutics to prevent or treat such life-altering symptoms. In this study, we developed a behavioral test of anosmia in SARS-CoV-2-infected hamsters. We find a moderately strong correlation between the level of anosmia and the score of histological damage within the olfactory epithelium. We also find a moderately strong correlation between the level of anosmia and the thickness of the olfactory epithelium, previously demonstrated to be severely damaged upon infection. Thus, this food-searching behavioral test can act as a simple and effective screening method in a hamster model for various therapeutics for SARS-CoV-2-related anosmia.

Comprehensive literature review on COVID-19 vaccines and role of SARS-CoV-2 variants in the pandemic

Since the outbreak of the COVID-19 pandemic, there has been a rapid expansion in vaccine research focusing on exploiting the novel discoveries on the pathophysiology, genomics, and molecular biology of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Although the current preventive measures are primarily socially distancing by maintaining a 1 m distance, it is supplemented using facial masks and other personal hygiene measures. However, the induction of vaccines as primary prevention is crucial to eradicating the disease to attempt restoration to normalcy. This literature review aims to describe the physiology of the vaccines and how the spike protein is used as a target to elicit an antibody-dependent immune response in humans. Furthermore, the overview, dosing strategies, efficacy, and side effects will be discussed for the notable vaccines: BioNTech/Pfizer, Moderna, AstraZeneca, Janssen, Gamaleya, and SinoVac. In addition, the development of other prominent COVID-19 vaccines will be highlighted alongside the sustainability of the vaccine-mediated immune response and current contraindications. As the research is rapidly expanding, we have looked at the association between pregnancy and COVID-19 vaccinations, in addition to the current reviews on the mixing of vaccines. Finally, the prominent emerging variants of concern are described, and the efficacy of the notable vaccines toward these variants has been summarized.

Prevalence of Olfactory Dysfuntion in SARS-COV-2 Positive Patients

Severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) is associated with chemosensory symptoms including olfactory dysfunction and dysgeusia. Multiple studies have reported differing prevalence rates of symptoms and recovery rates depending on geographic location. The purpose of the study was to determine the prevalence and features of Covid19 olfactory dysfunction in a developing nation. We conducted a prospective study at a tertiary, high-volume centre in South Africa, to determine the prevalence of olfactory dysfunction in SARS-COV-2 positive patients. The average recovery time of the olfactory dysfunction was also evaluated. The study included patients diagnosed with SARS-COV-2 infection between November 2020 and January 2021. Patients were recruited to participate in a survey which assessed demographic data, date of diagnosis, initial symptoms, presence and recovery time of olfactory dysfunction symptoms. A total of 86 patients with olfactory dysfunction were included and followed up telephonically over 6 weeks in 2 week intervals to determine recovery time. There was a prevalence rate of 40.7% of olfactory dysfunction in patients in our study. A higher proportion of patients with olfactory dysfunction had fever compared to those without and this was a significant finding in our study population. The overall median recovery time in our study was 7 days. Prevalence of olfactory dysfunction in our population is in keeping with European studies and most patients recover their sense of smell within a week.

The D614G Virus Mutation Enhances Anosmia in COVID-19 Patients: Evidence from a Systematic Review and Meta-analysis of Studies from South Asia

The prevalence of chemosensory dysfunction in patients with COVID-19 varies greatly between populations. It is unclear whether such differences are due to factors at the level of the human host, or at the level of the coronavirus, or both. At the host level, the entry proteins which allow virus binding and entry have variants with distinct properties, and the frequency of such variants differs between ethnicities. At the level of the virus, the D614G mutation enhances virus entry to the host cell. Since the two virus strains (D614 and G614) coexisted in the first six months of the pandemic in most populations, it has been difficult to distinguish between contributions of the virus and contributions of the host for anosmia. To answer this question, we conducted a systematic review and meta-analysis of studies in South Asian populations when either the D614 or the G614 virus was dominant. We show that populations infected predominantly with the G614 virus had a much higher prevalence of anosmia (pooled prevalence of 31.8%) compared with the same ethnic populations infected mostly with the D614 virus strain (pooled anosmia prevalence of 5.3%). We conclude that the D614G mutation is a major contributing factor that increases the prevalence of anosmia in COVID-19, and that this enhanced effect on olfaction constitutes a previously unrecognized phenotype of the D614G mutation. The new virus strains that have additional mutations on the background of the D614G mutation can be expected to cause a similarly increased prevalence of chemosensory dysfunctions.

Evolutionary trajectory of SARS-CoV-2 and emerging variants

The emergence of a novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and more recently, the independent evolution of multiple SARS-CoV-2 variants has generated renewed interest in virus evolution and cross-species transmission. While all known human coronaviruses (HCoVs) are speculated to have originated in animals, very little is known about their evolutionary history and factors that enable some CoVs to co-exist with humans as low pathogenic and endemic infections (HCoV-229E, HCoV-NL63, HCoV-OC43, HCoV-HKU1), while others, such as SARS-CoV, MERS-CoV and SARS-CoV-2 have evolved to cause severe disease. In this review, we highlight the origins of all known HCoVs and map positively selected for mutations within HCoV proteins to discuss the evolutionary trajectory of SARS-CoV-2. Furthermore, we discuss emerging mutations within SARS-CoV-2 and variants of concern (VOC), along with highlighting the demonstrated or speculated impact of these mutations on virus transmission, pathogenicity, and neutralization by natural or vaccine-mediated immunity.

Neuropathophysiology of coronavirus disease 2019: neuroinflammation and blood brain barrier disruption are critical pathophysiological processes that contribute to the clinical symptoms of SARS-CoV-2 infection

Coronavirus disease 2019 (COVID-19) is caused by the novel SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) first discovered in Wuhan, Hubei province, China in December 2019. SARS-CoV-2 has infected several millions of people, resulting in a huge socioeconomic cost and over 2.5 million deaths worldwide. Though the pathogenesis of COVID-19 is not fully understood, data have consistently shown that SARS-CoV-2 mainly affects the respiratory and gastrointestinal tracts. Nevertheless, accumulating evidence has implicated the central nervous system in the pathogenesis of SARS-CoV-2 infection. Unfortunately, however, the mechanisms of SARS-CoV-2 induced impairment of the central nervous system are not completely known. Here, we review the literature on possible neuropathogenic mechanisms of SARS-CoV-2 induced cerebral damage. The results suggest that downregulation of angiotensin converting enzyme 2 (ACE2) with increased activity of the transmembrane protease serine 2 (TMPRSS2) and cathepsin L in SARS-CoV-2 neuroinvasion may result in upregulation of proinflammatory mediators and reactive species that trigger neuroinflammatory response and blood brain barrier disruption. Furthermore, dysregulation of hormone and neurotransmitter signalling may constitute a fundamental mechanism involved in the neuropathogenic sequelae of SARS-CoV-2 infection. The viral RNA or antigenic peptides also activate or interact with molecular signalling pathways mediated by pattern recognition receptors (e.g., toll-like receptors), nuclear factor kappa B, Janus kinase/signal transducer and activator of transcription, complement cascades, and cell suicide molecules. Potential molecular targets and therapeutics of SARS-CoV-2 induced neurologic damage are also discussed.

The virological impacts of SARS-CoV-2 D614G mutation

The coronavirus diseases 2019 (COVID-19) caused by the infection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in December 2019 has caused more than 140 million infections worldwide by the end of April 2021. As an enveloped single-stranded positive-sense RNA virus, SARS-CoV-2 underwent constant evolution that produced novel variants carrying mutation conferring fitness advantages. The current prevalent D614G variant, with glycine substituted for aspartic acid at position 614 in the spike glycoprotein, is one of such variants that became the main circulating strain worldwide in a short period of time. Over the past year, intensive studies from all over the world had defined the epidemiological characteristics of this highly contagious variant and revealed the underlying mechanisms. This review aims at presenting an overall picture of the impacts of D614G mutation on virus transmission, elucidating the underlying mechanisms of D614G in virus pathogenicity, and providing insights into the development of effective therapeutics.

Emerging SARS-CoV-2 variants of concern and potential intervention approaches

The major variant of concerns (VOCs) have shared mutations in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike proteins, mostly on the S1 unit and resulted in higher transmissibility rate and affect viral virulence and clinical outcome. The spike protein mutations and other non-structural protein mutations in the VOCs may lead to escape approved vaccinations in certain extend. We will discuss these VOC mutations and discuss the need for combination therapeutic strategies targeting viral cycle and immune host responses.

Geographic Differences on Clinical Manifestations of COVID-19 Infection Between Overseas Chinese and Local Chinese Patients

Introduction

The novel coronavirus (COVID-19) has become a global pandemic with sharp rises in the number of confirmed cases and rapid spread across the world. Here, we looked at the effects of geographic differences on clinical manifestations of SARS-CoV-2 infected patients.

Methods

A total of 114 confirmed COVID-19 patients were included in this study. The epidemiological, demographic, clinical, as well as laboratory findings were extracted from the electronic medical records of these patients.

Results

We report the observation that patients from overseas residents diagnosed with COVID-19 were mildly symptomatic with cough and presented with lower inflammatory response and attenuated virus clearance rate, as well as correspondingly prolonged days of hospital stay than local Chinese patients. Moreover, the receiver-operating characteristic (ROC) analysis, performed to provide a measure of the difference between two groups, showed that serum albumin had the highest area under the curve value (0.81, p < 0.001).

Discussion

Our results suggested that blood albumin level acted as a predictive value in distinguishing clinical features between local and overseas Chinese. This work underscores the need to identify distinguishably prognostic factors of geographical dissimilarity in COVID-19 patients.

COVID-19 findings revealed via otolaryngological examination: Findings of a Japan Otorhinolaryngologist Association questionnaire

OBJECTIVE

In Japan, many otolaryngologists provide primary care for patients with coronavirus disease 2019 (COVID-19). The purpose of this study was to analyze the characteristics of otorhinolaryngological findings in order to improve COVID-19 diagnostic systems in a primary care setting.

METHODS

A total of 351 patients (mean age, 36.0 ± 15.4 years) diagnosed with COVID-19 by otolaryngologists who belong to the Japan Otorhinolaryngologists Association were included in the study. A web-based questionnaire was used to collect information regarding the timing of positive identification of COVID-19, the route of infection, symptoms, and findings in the tonsils, nasal cavity, pharynx, ear, and neck. A modified Centor score was calculated for cases in which age, symptoms, and tonsil and neck findings were described.

RESULTS

Symptoms included fever (56%), olfactory disturbance (46%), and a sore throat (56%). Of the individuals considered, 63% had ordinary rhinoscopic findings, 21% experienced watery rhinorrhea, and 12% had observable mucosal redness. Further, 87% had ordinary tonsillar findings, 13% displayed tonsillar redness, with enlargement and white mucus observe in 2% and 1% of participants, respectively. A total of 193 patients had a calculated Centor score of 3 points in 2%, and scores of the remaining participants were ≤2 points.

CONCLUSION

Of all patients considered, 40% had nasal findings and 4% had purulent nasal discharge. In contrast, only 13% of the patients had tonsillar findings, and no patients had Centor scores ≥4 points. Symptom differentiation from that of bacterial infections is difficult. In areas where COVID-19 is prevalent, the disease should be considered in patients presenting with fever, olfactory disturbances, and sore throat with minimal or no clinical findings in the nasal cavity and pharynx.

SARS-CoV-2 Induced Neurological Manifestations Entangles Cytokine Storm That Implicates For Therapeutic Strategies

The new coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), can present with neurological symptoms and induce neurological complications. The involvement in both the central and peripheral nervous systems in COVID-19 patients has been associated with direct invasion of the virus and the induction of cytokine storm. This review discussed the pathways for the virus invasion into the nervous system and characterized the SARS-CoV-2 induced cytokine storm. In addition, the mechanisms underlying the immune responses and cytokine storm induction after SARS-CoV-2 infection were also discussed. Although some neurological symptoms are mild and disappear after recovery from infection, some severe neurological complications contribute to the mortality of COVID-19 patients. Therefore, the insight into the cause of SARS-CoV-2 induced cytokine storm in context with neurological complications will formulate the novel management of the disease and further identify new therapeutic targets for COVID-19.

Pathophysiological relationship between COVID-19 and olfactory dysfunction: A systematic review

Introduction

SARS-CoV-2 is the pathogen of COVID-19. The virus is composed of the spike, membrane and envelope. On physiological smell, odoriferous substances bind to proteins secreted by sustentacular cells in order to be processed by olfactory receptor neurons. Olfactory disorder is one of the main manifestations of COVID-19, however, research is still required to clarify the mechanism involved in SARS-CoV-2 induced anosmia.

Objective

This article aims to analyze current scientific evidence intended to elucidate the pathophysiological relationship between COVID-19 and the cause of olfactory disorders.

Methods

Pubmed, Embase, Scopus and ScienceDirect were used to compose this article. The research was conducted on November 24th, 2020. Original articles with experimental studies in human, animal and in vitro, short communications, viewpoint, published in the English language and between 2019 and 2020 were included, all related to the pathophysiological relationship between olfactory disorders and COVID-19 infection.

Results

Both human cell receptors ACE2 and TMPRSS2 are essential for the SARS-CoV-2 entrance. These receptors are mostly present in the olfactory epithelium cells, therefore, the main hypothesis is that anosmia is caused due to damage to non-neuronal cells which, thereafter, affects the normal olfactory metabolism. Furthermore, magnetic resonance imaging studies exhibit a relationship between a reduction on the neuronal epithelium and the olfactory bulb atrophy. Damage to non-neuronal cells explains the average recovery lasting a few weeks. This injury can be exacerbated by an aggressive immune response, which leads to damage to neuronal cells and stem cells inducing a persistent anosmia. Conductive anosmia is not sufficient to explain most cases of COVID-19 induced anosmia.

Conclusion

Olfactory disorders such as anosmia and hyposmia can be caused by COVID-19, the main mechanism is associated with olfactory epithelium damage, targeting predominantly non-neuronal cells. However, neuronal cells can also be affected, worsening the condition of olfactory loss.

Persistent olfactory complaints after COVID-19: a new interpretation of the psychophysical olfactory scores

Background: Sudden olfactory loss is a major symptom of SARS-CoV-2 infection and has a negative impact on daily life quality. Almost 80% of disorders regress spontaneously. No precise characterization of the medium- and long-term olfactory symptoms has been carried out yet, apart from self-assessments. The main objective of this work was to characterize persistent smell disorders in this population. Methodology: Consecutive patients consulting to the ENT department with post-Covid19 olfactory loss were included. The clinical examination included an analog scale for the self-assessment of olfactory recovery), a nasofibroscopy, the Sniffin’ Stick Test and the short version of the Questionnaire of olfactory disorders. Results: Among the 34 patients included, based on the Sniffin’ Sticks Test, 29.4% (n=10) could be classified as normosmic, 55.9% (n=19) as hyposmic and 14.7% (n=5) as functional anosmic). Only olfactory identification impairment was significantly correlated with olfactory complaint and daily anxiety and annoyance related to lack of olfaction recovery. This identification disorder seemed to worsen over time. Conclusions: It is crucial to assess odor identification disorders in case of persistent olfactory complaints after COVID-19. It is fundamental to target this disorder, as it does not improve spontaneously and negatively impact quality of life.

Analysis of Three Mutations in Italian Strains of SARS-CoV-2: Implications for Pathogenesis

Background

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an enveloped virus initially detected in Wuhan in December 2019, responsible for coronavirus disease 2019 (COVID-19), a respiratory syndrome currently affecting >220 countries around the world, with >80 million cases registered and >1.8 million deaths.

Objective

As several vaccines are still being developed and 2 have been approved, it is particularly important to perform evolutionary surveillance to identify mutations potentially affecting vaccine efficacy.

Methods

DynaMut server has been used to evaluate the impact of the mutation found on SARS-CoV-2 isolates available on GISAID.

Results

In this article, we analyze whole genomes sequenced from Italian patients, and we report the characterization of 3 mutations, one of which presents in the spike protein.

Conclusion

The mutations analyzed in this article can be useful to evaluate the evolution of SARS-CoV-2.

Purinergic Signaling of ATP in COVID-19 Associated Guillain-Barré Syndrome

Declared as a global public health emergency, coronavirus disease 2019 (COVID-19) is presented as a disease of the respiratory tract, although severe cases can affect the entire organism. Several studies have shown neurological symptoms, ranging from dizziness and loss of consciousness to cerebrovascular and neurodegenerative diseases. In this context, Guillain-Barré syndrome, an immune-mediated inflammatory neuropathy, has been closely associated with critical cases of infection with "severe acute respiratory syndrome of coronavirus 2" (SARS-CoV-2), the etiological agent of COVID-19. Its pathophysiology is related to a generalized inflammation that affects the nervous system, but neurotropism was also revealed by the new coronavirus, which may increase the risk of neurological sequel, as well as the mortality of the disease. Thus, considering the comorbidities that SARS-CoV-2 infection can promote, the modulation of purinergic signaling can be applied as a potential therapy. In this perspective, given the role of adenosine triphosphate (ATP) in neural intercommunication, the P2X7 receptor (P2X7R) acts on microglia cells and its inhibition may be able to reduce the inflammatory condition of neurodegenerative diseases. Finally, alternative measures to circumvent the reality of the COVID-19 pandemic need to be considered, given the severity of critical cases and the viral involvement of multiple organs.

Regeneration Profiles of Olfactory Epithelium after SARS-CoV-2 Infection in Golden Syrian Hamsters

Olfactory dysfunction is one of the most frequent and specific symptoms of coronavirus disease 2019 (COVID-19). Information on the damage and repair of the neuroepithelium and its impact on olfactory function after COVID-19 is still incomplete. While severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) causes the ongoing worldwide outbreak of COVID-19, little is known about the changes triggered by SARS-CoV-2 in the olfactory epithelium (OE) at the cellular level. Here, we report profiles of the OE after SARS-CoV-2 infection in golden Syrian hamsters, which is a reliable animal model of COVID-19. We observed severe damage in the OE as early as 3 days postinoculation and regionally specific damage and regeneration of the OE within the nasal cavity; the nasal septal region demonstrated the fastest recovery compared to other regions in the nasal turbinates. These findings suggest that anosmia related to SARS-CoV-2 infection may be fully reversible.

Functional importance of the D614G mutation in the SARS-CoV-2 spike protein

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an enveloped virus which binds its cellular receptor angiotensin-converting enzyme 2 (ACE2) and enters hosts cells through the action of its spike (S) glycoprotein displayed on the surface of the virion. Compared to the reference strain of SARS-CoV-2, the majority of currently circulating isolates possess an S protein variant characterized by an aspartic acid-to-glycine substitution at amino acid position 614 (D614G). Residue 614 lies outside the receptor binding domain (RBD) and the mutation does not alter the affinity of monomeric S protein for ACE2. However, S(G614), compared to S(D614), mediates more efficient ACE2-mediated transduction of cells by S-pseudotyped vectors and more efficient infection of cells and animals by live SARS-CoV-2. This review summarizes and synthesizes the epidemiological and functional observations of the D614G spike mutation, with focus on the biochemical and cell-biological impact of this mutation and its consequences for S protein function. We further discuss the significance of these recent findings in the context of the current global pandemic.

COVID 19-Induced Smell and Taste Impairments: Putative Impact on Physiology

Smell and taste impairments are recognized as common symptoms in COVID 19 patients even in an asymptomatic phase. Indeed, depending on the country, in up to 85-90% of cases anosmia and dysgeusia are reported. We will review briefly the main mechanisms involved in the physiology of olfaction and taste focusing on receptors and transduction as well as the main neuroanatomical pathways. Then we will examine the current evidences, even if still fragmented and unsystematic, explaining the disturbances and mode of action of the virus at the level of the nasal and oral cavities. We will focus on its impact on the peripheral and central nervous system. Finally, considering the role of smell and taste in numerous physiological functions, especially in ingestive behavior, we will discuss the consequences on the physiology of the patients as well as management regarding food intake.

Air contamination with SARS-CoV-2 in the operating room

Angiotensin converting enzyme 2 (ACE2) is a target cell receptor for internalization and proliferation of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). When ACE2-highly expressed tissues are manipulated, SARS-CoV-2 containing aerosols may be generated. Normal breathing and speaking are capable of producing aerosols so mask ventilation, suction of airway tract and bucking during tracheal intubation and extubation are clinical procedures capable of significant aerosol production. Whilst no data have been reported on the distribution of SARS-CoV-2 in the operating room (OR), contamination in the OR can be estimated from the intensive care unit (ICU) data. ICU data showed that SARS-CoV-2 was detected on all types of surface and in air within about 4 m from coronavirus disease 2019 (COVID-19) patients. High concentrations of SARS-CoV-2 was detected in the personal protective equipment (PPE) removal room and medical staff office. Submicron virus-laden aerosols could result from resuspension of particles containing SARS-CoV-2 sticking the PPE surface; removal could produce the initial velocity. Supermicron virus-laden aerosol could come from floor deposited SARS-CoV-2, which were carried across different areas by medical staff (e.g., shoe). Knowledge of aerosol generation and distribution in the OR will aid the design of strategies to reduce transmission risk.

Olfactory and gustatory dysfunctions in 100 patients hospitalized for COVID-19: sex differences and recovery time in real-life

Purpose

COVID-19 displays a variety of clinical manifestations; in pauci-symptomatic patients olfactory (OD) and gustatory dysfunctions (GD) may represent the first or only symptom. This topic is currently arousing great interest, and a growing number of papers are being published. Aim of this study is to investigate the timing of recovery from OD and GD in a real-life population hospitalized for COVID-19.

Methods

We followed up by a phone interview the first 100 patients discharged a month earlier from three Italian non-intensive care wards.

Results

All 100 patients were Caucasian, mean age was 65 years, 60% were males. Forty-two patients (mean age 63 years) experienced subjective chemosensory dysfunctions (29 OD and 41 GD): the male/female ratio was 2:1; 83% reported a complete or near complete recovery at follow-up. The recovery rate was not significantly different between males and females. The mean duration of OD and GD was 18 and 16 days, respectively. The mean recovery time from OD or GD resulted significantly longer for females than for males (26 vs 14 days, P = 0.009). Among the 42 symptomatic, the mean age of males was significantly higher than that of females (66 vs 57 years, P = 0.04), while the opposite was observed in the 58 asymptomatic patients (60 vs 73 years, P = 0.0018).

Conclusions

Recovery from OD or GD was rapid, occurring within 4 weeks in most patients. Chemosensory dysfunctions in women was less frequent, but longer lasting. The value of our study is its focus on a population of hospitalized patients significantly older than those previously described, and the additional data on gender differences.