Absence of detectable SARS-CoV-2 replication in ex vivo cultured cornea and cornea-derived epithelial cells.

PURPOSE: To study the possibility of SARS-CoV-2 to infect human corneal cells and tissues under standard corneal culture conditions using explants of COVID-19 donors and primary cornea-derived epithelial cells. METHODS: Cornea isolated from deceased COVID-19 donors was cultured for 4 weeks, and SARS-CoV-2 replication was monitored by qRT-PCR. Furthermore, primary corneal epithelial cells from healthy donors were cultured ex vivo and infected with SARS-CoV-2 and human cytomegalovirus (HCMV) as a control. Infection status was assessed by western blotting and reporter gene expression using green fluorescent protein-expressing viral strains. ACE2 and TMPRSS2 receptor expression levels in cornea and epithelial cells were assessed by qRT-PCR. RESULTS: We did not detect SARS-CoV-2 replication in 10 corneas isolated from deceased COVID-19 patients and cultured for 4 weeks, indicating absence of infection under natural conditions. Furthermore, high-titer SARS-CoV-2 infection of ex vivo cultured cornea-derived epithelial cells did not result in productive virus replication. In contrast, the same cells were highly permissive for HCMV. This phenotype could potentially be explained by low ACE2 and TMPRSS2 transcriptional activity in cornea and cornea-derived epithelial cells. CONCLUSIONS: Our data suggest that cornea and limbal epithelial cells are refractory to productive SARS-CoV-2 infection. This could be due to the absence of robust receptor expression levels necessary for viral entry. This study adds further evidence to support the very low possibility of transmission of SARS-CoV-2 from an infected corneal transplant donor to a recipient in corneal organ cultures.

Human cytomegalovirus infection of epithelial cells increases SARS-CoV-2 superinfection by upregulating the ACE2 receptor.

SARS-CoV-2, the causative agent of COVID-19, has caused widespread morbidity and mortality since its onset in late 2019. Here, we demonstrate that prior infection with human cytomegalovirus (HCMV) substantially increases infection with SARS-CoV-2 in vitro. HCMV is a common herpesvirus carried by 40-100% of the population which can reactivate in the lung under inflammatory conditions, such as those resulting from SARS-CoV-2 infection. We show in both endothelial and epithelial cell types that HCMV infection upregulates ACE2, the SARS-CoV-2 cell entry receptor. These observations suggest that HCMV reactivation events in the lung of healthy HCMV carriers could exacerbate SARS-CoV-2 infection and subsequent COVID-19 symptoms. This effect could contribute to the disparity of disease severity seen in ethnic minorities and those with lower socio-economic status, due to their higher CMV seroprevalence. Our results warrant further clinical investigation as to whether HCMV infection influences the pathogenesis of SARS-CoV-2.

Ready and waiting to go.

Some T cells that have been activated by a herpesvirus can also respond to SARS-CoV-2, even if the original herpesvirus infection happened before the COVID-19 pandemic.

Atherosclerosis by Virus Infection-A Short Review.

Atherosclerosis manifests by the thickening of artery walls and their narrowed channels through the accumulation of plaque. It is one of the most important indicators of cardiovascular disease. It can be caused by various factors, such as smoking, a high cholesterol diet, hypertension, hyperglycemia, and genetic factors. However, atherosclerosis can also develop due to infection. It has been reported that some bacteria and viruses can cause the development of atherosclerosis. Examples of these viruses are influenza viruses, herpes viruses, hepatitis viruses, or papillomaviruses, which are all prevalent and eminent globally for infecting the population worldwide. Moreover, many patients with coronavirus disease 2019 (COVID-19) showed symptoms of cardiovascular disease. In this review paper, the viruses linked to the development of atherosclerosis are introduced, and their viral characteristics, the mechanisms of the development of atherosclerosis, and the current vaccines and antiviral treatment methods are summarized.

An immunologist's guide to immunosenescence and its treatment.

INTRODUCTION: Aging causes several changes in the immune system, although immune aging is strongly influenced by individual immunological history, as well as genetic and environmental factors leading to inter-individual variability. AREAS COVERED: We focused on the biological and clinical meaning of immunosenescence. SARS-CoV-2 and Yellow Fever vaccine have demonstrated the clinical relevance of immunosenescence, while inconsistent results, obtained from longitudinal studies aimed at looking for immune risk phenotypes, have revealed that immunosenescence is highly context-dependent. Large projects allowed the delineation of the drivers of immune system variance, including genetic and environmental factors, sex, smoking, and co-habitation. Therefore, it is difficult to identify the interventions that can be envisaged to maintain or improve immune function in older people. That suggests that drug treatment of immunosenescence should require personalized intervention. Regarding this, we discussed the role of changes in lifestyle as a potential therapeutic approach. EXPERT OPINION: Our review points out that age is only part of the problem of immunosenescence. Everyone ages differently because is unique in genetics and experience of life and this applies even more to the immune system (immunobiography). Finally, the review shows how appreciable results in the modification of immunosenescence biomarkers can be achieved with lifestyle modification.

Promising Role of Emodin as Therapeutics to Against Viral Infections.

Emodin is an anthraquinone derivative that is widely present in natural plants and has a wide spectrum of pharmacological effects, such as antibacterial, anti-inflammatory, anti-fibrotic and anticancer and so on. Through reviewing studies on antiviral effect of emodin in the past decades, we found that emodin exhibits ability of inhibiting the infection and replication of more than 10 viruses in vitro and in vivo, including herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), human cytomegalovirus (HCMV), Epstein-Barr virus (EBV), coxsackievirus B (CVB), hepatitis B virus (HBV), influenza A virus (IAV), SARS-CoV, viral haemorrhagic septicaemia rhabdovirus (VHSV), enterovirus 71 (EV71), dengue virus serotype 2 (DENV-2) and Zika virus (ZIKV). Therefore, this review aims to summarize the antiviral effect of emodin, in order to provide reference and hopes to support the further investigations.

Transcriptomic perspectives of memory-like NK cells and aging.

A recent study highlights the presence of a unique memory-like natural killer (NK) cell subset, which accumulates with aging and appears to associate withdisease severity in COVID-19 patients. While the clinical relevance of memory in NK cells is being debated, the molecular identity of this subset in the form of a single-cell transcriptome is essential to define their origin, longevity, functions, and disease relevance.

Antiviral potential of garlic (Allium sativum) and its organosulfur compounds: A systematic update of pre-clinical and clinical data.

BACKGROUND: Garlic (Allium sativum L.) is a common herb consumed worldwide as functional food and traditional remedy for the prevention of infectious diseases since ancient time. Garlic and its active organosulfur compounds (OSCs) have been reported to alleviate a number of viral infections in pre-clinical and clinical investigations. However, so far no systematic review on its antiviral effects and the underlying molecular mechanisms exists. SCOPE AND APPROACH: The aim of this review is to systematically summarize pre-clinical and clinical investigations on antiviral effects of garlic and its OSCs as well as to further analyse recent findings on the mechanisms that underpin these antiviral actions. PubMed, Cochrane library, Google Scholar and Science Direct databases were searched and articles up to June 2020 were included in this review. KEY FINDINGS AND CONCLUSIONS: Pre-clinical data demonstrated that garlic and its OSCs have potential antiviral activity against different human, animal and plant pathogenic viruses through blocking viral entry into host cells, inhibiting viral RNA polymerase, reverse transcriptase, DNA synthesis and immediate-early gene 1(IEG1) transcription, as well as through downregulating the extracellular-signal-regulated kinase (ERK)/mitogen activated protein kinase (MAPK) signaling pathway. The alleviation of viral infection was also shown to link with immunomodulatory effects of garlic and its OSCs. Clinical studies further demonstrated a prophylactic effect of garlic in the prevention of widespread viral infections in humans through enhancing the immune response. This review highlights that garlic possesses significant antiviral activity and can be used prophylactically in the prevention of viral infections.

Human Brain Organoids as Models for Central Nervous System Viral Infection.

Pathogenesis of viral infections of the central nervous system (CNS) is poorly understood, and this is partly due to the limitations of currently used preclinical models. Brain organoid models can overcome some of these limitations, as they are generated from human derived stem cells, differentiated in three dimensions (3D), and can mimic human neurodevelopmental characteristics. Therefore, brain organoids have been increasingly used as brain models in research on various viruses, such as Zika virus, severe acute respiratory syndrome coronavirus 2, human cytomegalovirus, and herpes simplex virus. Brain organoids allow for the study of viral tropism, the effect of infection on organoid function, size, and cytoarchitecture, as well as innate immune response; therefore, they provide valuable insight into the pathogenesis of neurotropic viral infections and testing of antivirals in a physiological model. In this review, we summarize the results of studies on viral CNS infection in brain organoids, and we demonstrate the broad application and benefits of using a human 3D model in virology research. At the same time, we describe the limitations of the studies in brain organoids, such as the heterogeneity in organoid generation protocols and age at infection, which result in differences in results between studies, as well as the lack of microglia and a blood brain barrier.

mSphere of Influence: Viruses-Pathogens or Expert Cell Biologists?

Chelsey C. Spriggs works in the field of DNA viral entry with a specific interest in virus-host interactions. In this mSphere of Influence article, she reflects on how two papers, "The HCMV assembly compartment is a dynamic Golgi-derived MTOC that controls nuclear rotation and virus spread" (D. J. Procter, A. Banerjee, M. Nukui, K. Kruse, et al., Dev Cell 45:83-100.e7, 2018, https://doi.org/10.1016/j.devcel.2018.03.010) and "Cytoplasmic control of intranuclear polarity by human cytomegalovirus" (D. J. Procter, C. Furey, A. G. Garza-Gongora, S. T. Kosak, D. Walsh, Nature 587:109-114, 2020, https://doi.org/10.1038/s41586-020-2714-x), impacted her research by reinforcing the scientific value in using viruses to understand cell biology.

Affinity Tag Coating Enables Reliable Detection of Antigen-Specific B Cells in Immunospot Assays.

Assessment of humoral immunity to SARS-CoV-2 and other infectious agents is typically restricted to detecting antigen-specific antibodies in the serum. Rarely does immune monitoring entail assessment of the memory B-cell compartment itself, although it is these cells that engage in secondary antibody responses capable of mediating immune protection when pre-existing antibodies fail to prevent re-infection. There are few techniques that are capable of detecting rare antigen-specific B cells while also providing information regarding their relative abundance, class/subclass usage and functional affinity. In theory, the ELISPOT/FluoroSpot (collectively ImmunoSpot) assay platform is ideally suited for antigen-specific B-cell assessments since it provides this information at single-cell resolution for individual antibody-secreting cells (ASC). Here, we tested the hypothesis that antigen-coating efficiency could be universally improved across a diverse set of viral antigens if the standard direct (non-specific, low affinity) antigen absorption to the membrane was substituted by high-affinity capture. Specifically, we report an enhancement in assay sensitivity and a reduction in required protein concentrations through the capture of recombinant proteins via their encoded hexahistidine (6XHis) affinity tag. Affinity tag antigen coating enabled detection of SARS-CoV-2 Spike receptor binding domain (RBD)-reactive ASC, and also significantly improved assay performance using additional control antigens. Collectively, establishment of a universal antigen-coating approach streamlines characterization of the memory B-cell compartment after SARS-CoV-2 infection or COVID-19 vaccinations, and facilitates high-throughput immune-monitoring efforts of large donor cohorts in general.

Immunization with Human Cytomegalovirus Core Fusion Machinery and Accessory Envelope Proteins Elicit Strong Synergistic Neutralizing Activities.

Human cytomegalovirus (HCMV) core fusion machinery proteins gB and gH/gL, and accessory proteins UL128/UL130/UL131A, are the key envelope proteins that mediate HCMV entry into and infection of host cells. To determine whether these HCMV envelope proteins could elicit neutralizing activities synergistically, we immunized rabbits with individual or various combinations of these proteins adsorbed to aluminum hydroxide mixed with CpG-ODN. We then analyzed serum neutralizing activities with multiple HCMV laboratory strains and clinical isolates. HCMV trimeric gB and gH/gL elicited high and moderate titers of HCMV neutralizing activity, respectively. HCMV gB in combination with gH/gL elicited up to 17-fold higher HCMV neutralizing activities compared to the sum of neutralizing activity elicited by the individual proteins analyzed with both fibroblasts and epithelial cells. HCMV gB+gH/gL+UL128/UL130/UL131A in combination increased the neutralizing activity up to 32-fold compared to the sum of neutralizing activities elicited by the individual proteins analyzed with epithelial cells. Adding UL128/UL130/UL131A to gB and gH/gL combination did not increase further the HCMV neutralizing activity analyzed with fibroblasts. These data suggest that the combination of HCMV core fusion machinery envelope proteins gB+gH/gL or the combination of gB and pentameric complex could be ideal vaccine candidates that would induce optimal immune responses against HCMV infection.