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Human cytomegalovirus (HCMV) causes congenital neurological lifelong disabilities. To date, the neuropathogenesis of brain injury related to congenital HCMV (cCMV) infection is poorly understood. This study evaluates the characteristics and pathogenetic mechanisms of encephalic damage in cCMV infection. Ten HCMV-infected human fetuses at 21 weeks of gestation were examined. Specifically, tissues from different brain areas were analyzed by: (i) immunohistochemistry (IHC) to detect HCMV-infected cell distribution, (ii) hematoxylin–eosin staining to evaluate histological damage and (iii) real-time PCR to quantify tissue viral load (HCMV-DNA). The differentiation stage of HCMV-infected neural/neuronal cells was assessed by double IHC to detect simultaneously HCMV-antigens and neural/neuronal markers: nestin (a marker of neural stem/progenitor cells), doublecortin (DCX, marker of cells committed to the neuronal lineage) and neuronal nuclei (NeuN, identifying mature neurons). HCMV-positive cells and viral DNA were found in the brain of 8/10 (80%) fetuses. For these cases, brain damage was classified as mild (n = 4, 50%), moderate (n = 3, 37.5%) and severe (n = 1, 12.5%) based on presence and frequency of pathological findings (necrosis, microglial nodules, microglial activation, astrocytosis, and vascular changes). The highest median HCMV-DNA level was found in the hippocampus (212 copies/5 ng of human DNA [hDNA], range: 10–7,505) as well as the highest mean HCMV-infected cell value (2.9 cells, range: 0–23), followed by that detected in subventricular zone (1.7 cells, range: 0–19). These findings suggested a preferential viral tropism for both neural stem/progenitor cells and neuronal committed cells, residing in these regions, confirmed by the expression of DCX and nestin in 94% and 63.3% of HCMV-positive cells, respectively. NeuN was not found among HCMV-positive cells and was nearly absent in the brain with severe damage, suggesting HCMV does not infect mature neurons and immature neural/neuronal cells do not differentiate into neurons. This could lead to known structural and functional brain defects from cCMV infection. Graphical Abstract

Avian or human influenza A viruses bind preferentially to avian- or human-type sialic acid receptors, respectively, indicating that receptor tropism is an important factor for determining the viral host range. However, there are currently no reliable methods for analyzing receptor tropism biologically under physiological conditions. In this study, we established a novel system using MDCK cells with avian- or human-type sialic acid receptors and with both sialic acid receptors knocked out (KO). When we examined the replication of human and avian influenza viruses in these KO cells, we observed unique viral receptor tropism that could not be detected using a conventional solid-phase sialylglycan binding assay, which directly assesses physical binding between the virus and sialic acids. Furthermore, we serially passaged an engineered avian-derived H4N5 influenza virus, whose PB2 gene was deleted, in avian-type receptor KO cells stably expressing PB2 to select a mutant with enhanced replication in KO cells; however, its binding to human-type sialylglycan was undetectable using the solid-phase binding assay. These data indicate that a panel of sialic acid receptor KO cells could be a useful tool for determining the biological receptor tropism of influenza A viruses. Moreover, the PB2KO virus experimental system could help to safely and efficiently identify the mutations required for avian influenza viruses to adapt to human cells that could trigger a new influenza pandemic. IMPORTANCE The acquisition of mutations that allow avian influenza A virus hemagglutinins to recognize human-type receptors is mandatory for the transmission of avian viruses to humans, which could lead to a pandemic. In this study, we established a novel system using a set of genetically engineered MDCK cells with knocked out sialic acid receptors to biologically evaluate the receptor tropism for influenza A viruses. Using this system, we observed unique receptor tropism in several virus strains that was undetectable using conventional solid-phase binding assays that measure physical binding between the virus and artificially synthesized sialylglycans. This study contributes to elucidation of the relationship between the physical binding of virus and receptor and viral infectivity. Furthermore, the system using sialic acid knockout cells could provide a useful tool to explore the sialic acid-independent entry mechanism. In addition, our system could be safely used to identify mutations that could acquire human-type receptor tropism.

The immunosuppressive tumor microenvironment (TME) is a formidable barrier to the success of adoptive cell therapies for solid tumors. Oncolytic immunotherapy with engineered adenoviruses (OAd) may disrupt the TME by infecting tumor cells, as well as surrounding stroma, to improve the functionality of tumor-directed chimeric antigen receptor (CAR)-T cells, yet efficient delivery of OAds to solid tumors has been challenging. Here we describe how mesenchymal stromal cells (MSCs) can be used to systemically deliver a binary vector containing an OAd together with a helper-dependent Ad (HDAd; combinatorial Ad vector [CAd]) that expresses interleukin-12 (IL-12) and checkpoint PD-L1 (programmed death-ligand 1) blocker. CAd-infected MSCs deliver and produce functional virus to infect and lyse lung tumor cells while stimulating CAR-T cell anti-tumor activity by release of IL-12 and PD-L1 blocker. The combination of this approach with administration of HER.2-specific CAR-T cells eliminates 3D tumor spheroids in vitro and suppresses tumor growth in two orthotopic lung cancer models in vivo. Treatment with CAd MSCs increases the overall numbers of human T cells in vivo compared to CAR-T cell only treatment and enhances their polyfunctional cytokine secretion. These studies combine the predictable targeting of CAR-T cells with the advantages of cancer cell lysis and TME disruption by systemic MSC delivery of oncolytic virotherapy: incorporation of immunostimulation by cytokine and checkpoint inhibitor production through the HDAd further enhances anti-tumor activity.

COVID-19, the clinical syndrome caused by the SARS-CoV-2 virus, has rapidly spread globally causing tens of millions of infections and over a million deaths. The potential animal reservoirs for SARS-CoV-2 are currently unknown, however sequence analysis has provided plausible potential candidate species. SARS-CoV-2 binds to the angiotensin I converting enzyme 2 (ACE2) to enable its entry into host cells and establish infection. We analyzed the binding surface of ACE2 from several important animal species to begin to understand the parameters for the ACE2 recognition by the SARS-CoV-2 spike protein receptor binding domain (RBD). We employed Shannon entropy analysis to determine the variability of ACE2 across its sequence and particularly in its RBD interacting region, and assessed differences between various species’ ACE2 and human ACE2. As cattle are a known reservoir for coronaviruses with previous human zoonotic transfer, and has a relatively divergent ACE2 sequence, we compared the binding kinetics of bovine and human ACE2 to SARS-CoV-2 RBD. This revealed a nanomolar binding affinity for bovine ACE2 but an approximate ten-fold reduction of binding compared to human ACE2. Since cows have been experimentally infected by SARS-CoV-2, this lower affinity sets a threshold for sequences with lower homology to human ACE2 to be able to serve as a productive viral receptor for SARS-CoV-2.

Viruses are the second leading cause of cancer worldwide, and human papillomavirus (HPV)-associated head and neck cancers are increasing in incidence in the United States. HPV preferentially infects the crypts of the tonsils rather than the surface epithelium. The present study sought to characterize the unique microenvironment within the crypts to better understand the viral tropism of HPV to a lymphoid-rich organ. Laser-capture microdissection of distinct anatomic areas (crypts, surface epithelium, and germinal centers) of the tonsil, coupled with transcriptional analysis and multiparameter immunofluorescence staining demonstrated that the tonsillar crypts are enriched with myeloid populations that co-express multiple canonical and noncanonical immune checkpoints, including PD-L1, CTLA-4, HAVCR2 (TIM-3), ADORA2A, IDO1, BTLA, LGALS3, CDH1, CEACAM1, PVR, and C10orf54 (VISTA). The resident monocytes may foster a permissive microenvironment that facilitates HPV infection and persistence. Furthermore, the myeloid populations within HPV-associated tonsil cancers co-express the same immune checkpoints, providing insight into potential novel immunotherapeutic targets for HPV-associated head and neck cancers.

Tilapia lake virus (TiLV) is a notable contagious agent that causes massive economic losses in the tilapia industry globally. Evaluations of the histological changes associated with TiLV infection are not only crucial for diagnosis, but also to gain an understanding of the disease. We therefore synthesized a rabbit polyclonal immunoglobulin G antibody against TiLV and developed an immunohistochemical (IHC) procedure to detect TiLV localization in the tissues of infected fish for comparison with in situ hybridization (ISH) testing. A total of four different sample cohorts derived from TiLV-infected fish was used to validate the IHC procedure. The TiLV IHC application was successfully developed and facilitated nuclear and cytoplasmic immunolabelling in the intestines, gills, brain, liver, pancreas, spleen, and kidneys that corresponded with the ISH results. Apart from the ISH results, TiLV-IHC signals were clearly evident in the endothelial cells of various organs, the circulating leukocytes in the blood vessels, and the areas of tissue inflammation. Among the tested sample cohorts, the intestines, gills, and brain had IHC-positive signals, highlighting the possibility of these organs as common TiLV targets. Immunological staining pattern and distribution corresponded with the TiLV viral load but not the inoculation route. The TiLV IHC was also capable of detecting TiLV infection in the experimentally challenged ornamental cichlids, Mozambique tilapia, giant gourami, and naturally infected tilapia, indicating the dynamic range of IHC for TiLV detection. Overall, our study delivers the first IHC platform to detect TiLV infection and provides novel evidence of cellular tropism during TiLV infection. Our findings also reveal the TiLV distribution pattern of infected fish and propose the endotheliotropism and lymphotropism of this virus, which requires further elaboration. Importantly, this new IHC procedure could be applied to study the pathogenesis and interaction of TiLV in future research.

Poxviruses are a diverse family of double-stranded DNA viruses that cause mild-to-severe disease in selective hosts, including humans. Although most poxviruses are restricted to their hosts, some members can leap host species and cause zoonotic diseases and, therefore, are genuine threats to human and animal health. The recent global spread of monkeypox in humans suggests that zoonotic poxviruses can adapt to a new host, spread rapidly in the new host, and evolve to better evade host innate barriers. Unlike many other viruses, poxviruses express an extensive repertoire of self-defense proteins that play a vital role in the evasion of host innate and adaptive immune responses in their newest host species. The function of these viral immune modulators and host-specific cytokine responses can result in different host tropism and poxvirus disease progression. Here, we review the role of different cytokines that control poxvirus host tropism and adaptation.

The kidney is one of the main targets attacked by viruses in patients with a coronavirus infection. Until now, SARS‐CoV‐2 has been identified as the seventh member of the coronavirus family capable of infecting humans. In the past two decades, humankind has experienced outbreaks triggered by two other extremely infective members of the coronavirus family; the MERS‐CoV and the SARS‐CoV. According to several investigations, SARS‐CoV causes proteinuria and renal impairment or failure. The SARS‐CoV was identified in the distal convoluted tubules of the kidney of infected patients. Also, renal dysfunction was observed in numerous cases of MERS‐CoV infection. And recently, during the 2019‐nCoV pandemic, it was found that the novel coronavirus not only induces acute respiratory distress syndrome (ARDS) but also can induce damages in various organs including the liver, heart, and kidney. The kidney tissue and its cells are targeted massively by the coronaviruses due to the abundant presence of ACE2 and Dpp4 receptors on kidney cells. These receptors are characterized as the main route of coronavirus entry to the victim cells. Renal failure due to massive viral invasion can lead to undesirable complications and enhanced mortality rate, thus more attention should be paid to the pathology of coronaviruses in the kidney. Here, we have provided the most recent knowledge on the coronaviruses (SARS, MERS, and COVID19) pathology and the mechanisms of their impact on the kidney tissue and functions.

COVID-19 is a recent pandemic that is still a major health problem of modern times and already more than 17.5 lakhs people succumbed to this deadly disease. This disease is caused by novel coronavirus which is named SARS-COV-2 by the International Committee on Taxonomy of Viruses. This virus originated from Wuhan city in Hubei province of China in December 2019 and within a short period spread across the many countries in the globe. There are a lot of basic as well as clinical research is going on to study the mode of transmission and the mechanism of action of SARS-COV-2 infection and its therapeutics. SARS-COV-2 is not only known to infect lungs, but it also infects other organs in the human body including the gastrointestinal (GI) tract, the liver, and the pancreas via the angiotensin-converting enzyme (ACE) 2, an important component of the renin-angiotensin system. In this short review, we are mainly discussing the mode of SARS-COV-2 transmission, physiological counterbalancing roles of ACE2 and ACE and the tissue patterns of ACE2 expression, and the overall effect of COVID19 on human gastrointestinal System. Therefore, this review sheds light on the possible mechanism of SARS-COV-2 infection in the GI system and its pathological symptoms raising a potential possibility of GI tract acting as a secondary site for SARS-CoV-2 tropism and infection. Finally, future studies to understand the fecal-oral transmission of the virus and the correlation of viral load and severity of GI symptoms are proposed to gain knowledge of the GI symptoms in COVID-19 to aid in early diagnosis and prognosis.

CD4(dim) CD8(bright) T cells are a mature population of CD8(+) T cells that upon activation upregulate CD4 dimly on their surface. Expression of CD4 on these cells suggests that they can be an additional source of HIV neuroinvasion and persistence in the brain. We used HIV-infected NOD/SCID/IL-2rcγ(−/−) (NSG) humanized mice to track CD4(dim) CD8(bright) T cell homing to the brain and define their role in HIV dissemination into the brain. We report here that CD4(dim) CD8(bright) T cells are found in the brain at a median frequency of 2.6% and in the spleen at median frequency of 7.6% of CD3(+) T cells. In the brain, 10 to 20% of CD4(dim) CD8(bright) T cells contain integrated provirus, which is infectious as demonstrated by viral outgrowth assay. CD4(dim) CD8(bright) T cells in the brain exhibited significantly higher expression of the brain homing receptors CX3CR1 and CXCR3 in comparison to their single-positive CD8(+) T cell counterpart. Blocking lymphocyte trafficking into the brain of humanized mice via anti-VLA4 and anti-LFA1 antibodies reduced CD4(dim) CD8(bright) T cell trafficking into the brain by 60% and diminished brain HIV proviral DNA by 72%. Collectively, our findings demonstrate that CD4(dim) CD8(bright) T cells can home to the brain and support productive HIV replication. These studies also reveal for the first time that CD4(dim) CD8(bright) T cells are capable of HIV neuroinvasion and are a reservoir for HIV. IMPORTANCE We report here a seminal finding of a novel population of T cells, termed CD4(dim) CD8(bright) T cells, that plays a role in HIV neuroinvasion and is a reservoir for HIV in the brain.

Enterovirus A71 (EV-A71) is a human pathogen that causes hand, foot, and mouth disease, which can progress to severe neurological disease. EV-A71 infects humans via the human scavenger receptor B2 (hSCARB2). It can also infect neonatal mice experimentally. Wild-type (WT) EV-A71 strains replicate primarily in the muscle of neonatal mice; however, susceptibility lasts only for a week after birth. Mouse-adapted (MA) strains, which can be obtained by serial passages in neonatal mice, are capable of infecting both muscle and neurons of the central nervous system. It is not clear how the host range and tropism of EV-A71 are regulated and why neonatal mice lose their susceptibility during development. We hypothesized that EV-A71 infection in neonatal mice is mediated by mouse Scarb2 (mScarb2) protein. Rhabdomyosarcoma (RD) cells expressing mScarb2 were prepared. Both WT and MA strains infected mScarb2-expressing cells, but the infection efficiency of the WT strain was much lower than that of the MA strain. Infection by WT and MA strains in vivo was abolished completely in Scarb2(−/−) mice. Scarb2(+/−) mice, in which Scarb2 expression was approximately half of that in Scarb2(+/+) mice, showed a milder pathology than Scarb2(+/+) mice after infection with the WT strain. The Scarb2 expression level in muscle decreased with aging, which was consistent with the reduced susceptibility of aged mice to infection. These results indicated that EV-A71 infection is mediated by mScarb2 and that the severity of the disease, the spread of virus, and the susceptibility period are modulated by mScarb2 expression. IMPORTANCE EV-A71 infects humans naturally but can also infect neonatal mice. The tissue tropism and severity of EV-A71 disease are determined by several factors, among which the virus receptor is thought to be important. We show that EV-A71 can infect neonatal mice using mScarb2. However, the infection efficiency of WT strains via mScarb2 is so low that an elevated virus-receptor interaction associated with mouse adaptation mutation and decrease in mScarb2 expression level during development modulate the severity of the disease, the spread of virus, and the susceptibility period in the artificial neonatal mice model.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) readily infects a variety of cell types impacting the function of vital organ systems, with particularly severe impact on respiratory function. Neurological symptoms, which range in severity, accompany as many as one-third of COVID-19 cases, indicating a potential vulnerability of neural cell types. To assess whether human cortical cells can be directly infected by SARS-CoV-2, we utilized stem-cell-derived cortical organoids as well as primary human cortical tissue, both from developmental and adult stages. We find significant and predominant infection in cortical astrocytes in both primary tissue and organoid cultures, with minimal infection of other cortical populations. Infected and bystander astrocytes have a corresponding increase in inflammatory gene expression, reactivity characteristics, increased cytokine and growth factor signaling, and cellular stress. Although human cortical cells, particularly astrocytes, have no observable ACE2 expression, we find high levels of coronavirus coreceptors in infected astrocytes, including CD147 and DPP4. Decreasing coreceptor abundance and activity reduces overall infection rate, and increasing expression is sufficient to promote infection. Thus, we find tropism of SARS-CoV-2 for human astrocytes resulting in inflammatory gliosis-type injury that is dependent on coronavirus coreceptors.

SUMMARY OBJECTIVE: This study aimed to investigate the effect of mutations by comparing wild-type SARS-CoV-2 and Omicron regarding clinical features in patients with COVID-19. It also aimed to assess whether SARS-CoV-2 cycle threshold value could predict COVID-19 severity. METHODS: A total of 960 wild-type and 411 Omicron variant patients with positive results in SARS-CoV-2 real-time reverse transcriptase polymerase chain reaction test from oropharyngeal and/or nasopharyngeal samples during their hospital admissions were included in this retrospective study. The reference symptoms of the patients were obtained from the hospital database. The correlation between chest computed tomography findings and the “cycle threshold” of patients with wild-type SARS-CoV-2 was assessed. RESULTS: Cough, fever, shortness of breath, loss of taste and smell, and diarrhea were found to be statistically significantly higher (p=0.001; 0.001; 0.001; 0.001; and 0.006; respectively) in the wild-type cohort, while in the Omicron cohort, sore throat and headache were found to be statistically significantly higher (p=0.001 and 0.003, respectively). An inverse relationship was found between chest computed tomography findings and viral load. CONCLUSION: This study revealed that the Omicron variant tended to infect predominantly the upper respiratory tract and showed decreased lung infectivity, and the disease progressed with a milder clinical course. Therefore, the study showed that the tropism of the virus was changed and the viral phenotype was affected. It was also found that SARS-CoV-2 viral load did not predict COVID-19 severity in patients with wild-type SARS-CoV-2.

Vertebrates harbor hundreds of endogenous retroviral (ERV) sequences in their genomes, which are considered signs of past infections that occurred during evolution. On rare occasions, ERV genes like env are maintained and coopted by hosts for physiological functions, but they also participate in recombination events with exogenous retroviruses to generate rearranged viruses with novel tropisms. In domestic cats, feline leukemia virus type D (FeLV-D) has been described as a recombinant virus between the infectious FeLV-A and likely the ERV-DC14 env gene that resulted in an extended tropism due to the usage of a new uncharacterized retroviral receptor. Here, we report the identification of SLC31A1 encoding the copper transporter 1 (CTR1) as a susceptibility gene for ERV-DC14 infection. Expression of human CTR1 into nonpermissive cells was sufficient to confer sensitivity to ERV-DC14 pseudotype infection and to increase the binding of an ERV-DC14 Env ligand. Moreover, inactivation of CTR1 by genome editing or cell surface downmodulation of CTR1 by a high dose of copper dramatically decreased ERV-DC14 infection and binding, while magnesium treatment had no effect. We also investigated the role of CTR1 in the nonpermissivity of feline and hamster cells. While feline CTR1 was fully functional for ERV-DC14, we found that binding was strongly reduced upon treatment with conditioned medium of feline cells, suggesting that the observed resistance to infection was a consequence of CTR1 saturation. In contrast, hamster CTR1 was inactive due to the presence of a N-linked glycosylation site at position 27, which is absent in the human ortholog. These results provide evidence that CTR1 is a receptor for ERV-DC14. Along with chimpanzee endogenous retrovirus type 2, ERV-DC14 is the second family of endogenous retrovirus known to have used CTR1 during past infections of vertebrates. IMPORTANCE Receptor usage is an important determinant of diseases induced by pathogenic retroviruses. In the case of feline leukemia viruses, three subgroups (A, B, and C) based on their ability to recognize different cell host receptors, respectively, the thiamine transporter THTR1, the phosphate transporter PiT1, and the heme exporter FLVCR1, are associated with distinct feline diseases. FeLV-A is horizontally transmitted and found in all naturally infected cats, while FeLV-B and FeLV-C have emerged from FeLV-A, respectively, by recombination with endogenous retroviral env sequences or by mutations in the FeLV-A env gene, both leading to a switch in receptor usage and in subsequent in vivo tropism. Here, we set up a genetic screen to identify the retroviral receptor of ERV-DC14, a feline endogenous provirus whose env gene has been captured by infectious FeLV-A to give rise to FeLV-D in a process similar to FeLV-B. Our results reveal that the copper transporter CTR1 was such a receptor and provide new insights into the acquisition of an expanded tropism by FeLV-D.

Human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) has been the primary interest among studies on antiviral discovery, viral replication kinetics, drug resistance, and viral evolution. Following infection and entry into target cells, the HIV-1 core disassembles, and the viral RT concomitantly converts the viral RNA into double-stranded proviral DNA, which is integrated into the host genome. The successful completion of the viral life cycle highly depends on the enzymatic DNA polymerase activity of RT. Furthermore, HIV-1 RT has long been known as an error-prone DNA polymerase due to its lack of proofreading exonuclease properties. Indeed, the low fidelity of HIV-1 RT has been considered as one of the key factors in the uniquely high rate of mutagenesis of HIV-1, which leads to efficient viral escape from immune and therapeutic antiviral selective pressures. Interestingly, a series of studies on the replication kinetics of HIV-1 in non-dividing myeloid cells and myeloid specific host restriction factor, SAM domain, and HD domain-containing protein, SAMHD1, suggest that the myeloid cell tropism and high rate of mutagenesis of HIV-1 are mechanistically connected. Here, we review not only HIV-1 RT as a key antiviral target, but also potential evolutionary and mechanistic crosstalk among the unique enzymatic features of HIV-1 RT, the replication kinetics of HIV-1, cell tropism, viral genetic mutation, and host SAMHD1 protein.

The ongoing coronavirus disease 2019 pandemic and its overlap with the influenza season lead to concerns over severe disease caused by the influenza virus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) co-infections. Using a Syrian hamster co-infection model with SARS-CoV-2 and the pandemic influenza virus A/California/04/2009 (H1N1), we found (a) more severe disease in co-infected animals, compared to those infected with influenza virus alone but not SARS-CoV-2 infection alone; (b) altered haematological changes in only co-infected animals and (c) altered influenza virus tropism in the respiratory tracts of co-infected animals. Overall, our study revealed that co-infection with SARS-CoV-2 and influenza virus is associated with altered disease severity and tissue tropism, as well as haematological changes, compared to infection with either virus alone.

Background Coronavirus disease 2019 (COVID-19) patients manifest with pulmonary symptoms reflected by diffuse alveolar damage (DAD), excessive inflammation, and thromboembolism. The mechanisms mediating these processes remain unclear. Methods We performed multicolor staining for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) proteins and lineage markers to define viral tropism and lung pathobiology in 5 autopsy cases. Results Lung parenchyma showed severe DAD with thromboemboli. Viral infection was found in an extensive range of cells including pneumocyte type II, ciliated, goblet, club-like, and endothelial cells. More than 90% of infiltrating immune cells were positive for viral proteins including macrophages, monocytes, neutrophils, natural killer (NK) cells, B cells, and T cells. Most but not all infected cells were angiotensin-converting enzyme 2 (ACE2) positive. The numbers of infected and ACE2-positive cells are associated with extensive tissue damage. Infected tissues exhibited high levels of inflammatory cells including macrophages, monocytes, neutrophils, and NK cells, and low levels of B cells but abundant T cells consisting of mainly T helper cells, few cytotoxic T cells, and no regulatory T cells. Robust interleukin-6 expression was present in most cells, with or without infection. Conclusions In fatal COVID-19 lungs, there are broad SARS-CoV-2 cell tropisms, extensive infiltrated innate immune cells, and activation and depletion of adaptive immune cells, contributing to severe tissue damage, thromboemboli, excess inflammation, and compromised immune responses.

Background The gold standard for coronavirus disease (COVID‐19) diagnosis has been the detection of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) RNA by nucleic acid amplification testing (NAAT). On the other hand, serological testing for COVID‐19 may offer advantages in detecting possibly overlooked infections by NAAT. Methods To evaluate seroconversion of NAAT‐negative pneumonia patients, immunoglobulin M (IgM) and IgG targeting the spike protein of SARS‐CoV‐2 were semiquantified by an immunofluorescence assay. Seroconversion was confirmed by another serological method, targeting the nucleocapsid protein. Results Eight suspected but unconfirmed COVID‐19 pneumonia patients (median age, 39 years; range, 21–55) were included. The median period between symptom onset and NAAT sample collection was 6 days (2–27 days). None of them had tested positive for SARS‐CoV‐2 by NAAT. In contrast, all eight patients revealed seropositivity with the two serological methods, indicating actual seroconversion against SARS‐CoV‐2. The median period between onset and blood sampling was 26.5 days (7–51 days). Conclusion Eight patients with COVID‐19 pneumonia, initially tested negative for SARS‐CoV‐2 by NAAT, were finally confirmed of the diagnosis by serological testing. To cover the whole spectrum of this heterogenous infectious disease, serology testing should be implemented to the multitiered diagnostic algorithm for COVID‐19.

Coronaviruses (CoVs) represent enveloped, ss RNA viruses with the ability to infect a range of vertebrates causing mainly lung, CNS, enteric, and hepatic disease. While the infection with human CoV is commonly associated with mild respiratory symptoms, the emergence of SARS‐CoV, MERS‐CoV, and SARS‐CoV‐2 highlights the potential for CoVs to cause severe respiratory and systemic disease. The devastating global health burden caused by SARS‐CoV‐2 has spawned countless studies seeking clinical correlates of disease severity and host susceptibility factors, revealing a complex network of antiviral immune circuits. The mouse hepatitis virus (MHV) is, like SARS‐CoV‐2, a beta‐CoV and is endemic in wild mice. Laboratory MHV strains have been extensively studied to reveal coronavirus virulence factors and elucidate host mechanisms of antiviral immunity. These are reviewed here with the aim to identify translational insights for SARS‐CoV‐2 learned from murine CoVs., Common properties of the infection etiology, host‐pathogen interactions, and immune responses shared between the mouse hepatitis virus (MHV‐A59) and SARS‐CoV‐2. A main distinguisher of MHV from other preclinical animal models of COVID‐19 is the fully adapted host replication machinery that recapitulates a multiorgan disease.

Due to the development of novel functionalities, distinct SARS-CoV-2 variants such as B.1.1.7 fuel the current pandemic. B.1.1.7 is not only more transmissible, but may also cause an increased mortality compared to previous SARS-CoV-2 variants. Human tissue analysis of the SARS-CoV-2 lineage B.1.1.7 is urgently needed, and we here present autopsy data from 7 consecutive SARS-CoV-2 B.1.1.7 cases. The initial RT-qPCR analyses from nasopharyngeal swabs taken post mortem included typing assays for B.1.1.7. We quantitated SARS-CoV-2 B.1.1.7 viral load in autopsy tissue of multiple organs. Highest levels of SARS-CoV-2 B.1.1.7 copies normalized to ß-globin were detected in the respiratory system (lung and pharynx), followed by the liver and heart. Importantly, SARS-CoV-2 lineage B.1.1.7 was found in 100% of cases in the lungs and in 85.7% in pharynx tissue. Detection also in the kidney and brain highlighting a pronounced organ tropism. Comparison of the given results to a former cohort of SARS-CoV-2 deaths during the first wave in spring 2020 showed resembling organ tropism. Our results indicate that also SARS-CoV-2 B.1.1.7 has a relevant organ tropism beyond the respiratory tract. We speculate that B.1.1.7 spike protein’s affinity to human ACE2 facilitates transmission, organ tropism, and ultimately morbidity and mortality. Further studies and larger cohorts are obligatory to proof this link.

The coronavirus disease 2019 (COVID‐19) pandemic, a viral illness caused by the severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2), 1 has produced at the time of this writing nearly 33 million cases of infection, with over a million deaths in 235 countries, 2 causing an unprecedented burden on healthcare systems and a severe global socioeconomic crisis. As the pandemic spreads, knowledge on the disease course, as well as potential risk factors and predictors of severity is increasing daily, and initial data from randomised controlled studies have allowed care providers to refine therapeutic strategies. Nonetheless, mortality is markedly elevated among those presenting with severe disease, long‐term sequelae among survivors are unknown, and vaccine‐based therapies currently remain at early stages of development. Most reported cases are asymptomatic or present with mild symptoms; however, 7–26% of hospitalised patients experience severe disease, often requiring admission to intensive care units (ICUs), with progressive multiple organ dysfunction and high mortality. 3 , 4 , 5 Such differences in clinical outcomes have led physicians to initiate diverse pharmacological therapies at various stages of the disease, generating challenges as to the most appropriate therapeutic choice for COVID‐19. In this context, the use of dexamethasone has significantly reduced mortality rates in critically ill patients requiring supplemental oxygen or mechanical ventilation, 6 and remdesivir has demonstrated clinical benefit in hospitalised patients, but with unknown survival benefit to date 7 ; additional effective treatment options are therefore urgently needed. In an initial attempt to provide a uniform and widely reproducible methodology to guide systematic treatment strategies, a three‐stage classification of COVID‐19 has been proposed. 8 The Stage I or ‘early infection’ occurs at the initial establishment of disease with high viral replication, and commonly presents with a range of complaints that can include mild and often non‐specific influenza‐like signs and symptoms. Stage II is the ‘pulmonary phase’, with preferential viral‐mediated injury of the lung parenchyma and this is characterised by shortness of breath, hypoxia and pulmonary infiltrates with some degree of lung inflammation. Stage III is characterised by an exaggerated host immune‐inflammatory response to the virus, leading to acute respiratory distress syndrome (ARDS) and multi‐organ failure (MOF).

Long-COVID is a postviral illness that can affect survivors of COVID-19, regardless of initial disease severity or age. Symptoms of long-COVID include fatigue, dyspnea, gastrointestinal and cardiac problems, cognitive impairments, myalgia, and others. While the possible causes of long-COVID include long-term tissue damage, viral persistence, and chronic inflammation, the review proposes, perhaps for the first time, that persistent brainstem dysfunction may also be involved. This hypothesis can be split into two parts. The first is the brainstem tropism and damage in COVID-19. As the brainstem has a relatively high expression of ACE2 receptor compared with other brain regions, SARS-CoV-2 may exhibit tropism therein. Evidence also exists that neuropilin-1, a co-receptor of SARS-CoV-2, may be expressed in the brainstem. Indeed, autopsy studies have found SARS-CoV-2 RNA and proteins in the brainstem. The brainstem is also highly prone to damage from pathological immune or vascular activation, which has also been observed in autopsy of COVID-19 cases. The second part concerns functions of the brainstem that overlap with symptoms of long-COVID. The brainstem contains numerous distinct nuclei and subparts that regulate the respiratory, cardiovascular, gastrointestinal, and neurological processes, which can be linked to long-COVID. As neurons do not readily regenerate, brainstem dysfunction may be long-lasting and, thus, is long-COVID. Indeed, brainstem dysfunction has been implicated in other similar disorders, such as chronic pain and migraine and myalgic encephalomyelitis or chronic fatigue syndrome.

During the influenza pandemic or seasonal influenza outbreak, influenza infection can cause acute influenza-associated encephalopathy/encephalitis (IAE), even death. Patients with severe IAE will also have severe neurological sequelae. Neurologic disorders have been demonstrated in the mice treated with peripheral influenza viruses infection, whether neurotropic or non-neurotropic viruses. However, previous studies focused on the acute phase of infection, and rarely paid attention to a longer range of observations. Therefore, the long-term effect of non-neurotropic virus infection on the host is not very clear. In this study, adult mice were infected with influenza virus H1N1/PR8. Then, spontaneous behavior, body weight, expression of cytokines in brain, spatial learning ability and spatial memory ability were observed, until the complete recovery period. The results showed that cytokines in the brain were highly expressed in the convalescent phase (14 day post inoculation, dpi), especially BDNF, IBA1, CX3CL1 and CD200 were still highly expressed in the recovery phase (28 dpi). Otherwise the emotional and spatial memory ability of mice were impacted in the convalescent phase (14 dpi) and the recovery phase (28 dpi). In brief, BALB/c mice infected with non-neurotropic influenza virus H1N1, the weight and motor ability decreased in acute stage. During the recovery period, the body weight and activity ability were completely restored, whereas the emotion disordered, and the ability of spatial learning and memory were impacted in the infected mice. This long-term behavior impact may be the lag injury caused by non-neurotropic influenza infection.

Hepatitis E virus (HEV), the causative agent of hepatitis E, is an understudied but important pathogen. HEV typically causes self-limiting acute viral hepatitis, however chronic infection with neurological and other extrahepatic manifestations has increasingly become a significant clinical problem. The discovery of swine HEV from pigs and demonstration of its zoonotic potential led to the genetic identification of very diverse HEV strains from more than a dozen other animal species. HEV strains from pig, rabbit, deer, camel, and rat have been shown to cross species barriers and infect humans. Zoonotic HEV infections through consumption of raw or undercooked animal meat or direct contact with infected animals have been reported. The discovery of a large number of animal HEV variants does provide an opportunity to develop useful animal models for HEV. In this mini-review, we discuss recent advances in HEV host range, and cross-species and zoonotic transmission.

The chronic dysfunction of neuronal cells, both central and peripheral, a characteristic of neurological disorders, may be caused by irreversible damage and cell death. In 2016, more than 276 million cases of neurological disorders were reported worldwide. Moreover, neurological disorders are the second leading cause of death. Generally, the etiology of neurological diseases is not fully understood. Recent studies have related the onset of neurological disorders to viral infections, which may cause neurological symptoms or lead to immune responses that trigger these pathological signs. Currently, this relationship is mostly based on epidemiological data on infections and seroprevalence of patients who present with neurological disorders. The number of studies aiming to elucidate the mechanism of action by which viral infections may directly or indirectly contribute to the development of neurological disorders has been increasing over the years but these studies are still scarce. Comprehending the pathogenesis of these diseases and exploring novel theories may favor the development of new strategies for diagnosis and therapy in the future. Therefore, the objective of the present study was to review the main pieces of evidence for the relationship between viral infection and neurological disorders such as Alzheimer's disease, Parkinson's disease, Guillain-Barré syndrome, multiple sclerosis, and epilepsy. Viruses belonging to the families Herpesviridae, Orthomyxoviridae, Flaviviridae, and Retroviridae have been reported to be involved in one or more of these conditions. Also, neurological symptoms and the future impact of infection with SARS-CoV-2, a member of the family Coronaviridae that is responsible for the COVID-19 pandemic that started in late 2019, are reported and discussed.

The coronavirus disease 2019 (COVID-19) pandemic is an issue of global significance that has taken the lives of many across the world. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the virus responsible for its pathogenesis. The pulmonary manifestations of COVID-19 have been well described in the literature. Initially, it was thought to be limited to the respiratory system; however, we now recognize that COVID-19 also affects several other organs, including the nervous system. Two similar human coronaviruses (CoV) that cause severe acute respiratory syndrome (SARS-CoV-1) and Middle East respiratory syndrome (MERS-CoV) are also known to cause disease in the nervous system. The neurological manifestations of SARS-CoV-2 infection are growing rapidly, as evidenced by several reports. There are several mechanisms responsible for such manifestations in the nervous system. For instance, post-infectious immune-mediated processes, direct virus infection of the central nervous system (CNS), and virus-induced hyperinflammatory and hypercoagulable states are commonly involved. Guillain-Barré syndrome (GBS) and its variants, dysfunction of taste and smell, and muscle injury are numerous examples of COVID-19 PNS (peripheral nervous system) disease. Likewise, hemorrhagic and ischemic stroke, encephalitis, meningitis, encephalopathy acute disseminated encephalomyelitis, endothelialitis, and venous sinus thrombosis are some instances of COVID-19 CNS disease. Due to multifactorial and complicated pathogenic mechanisms, COVID-19 poses a large-scale threat to the whole nervous system. A complete understanding of SARS-CoV-2 neurological impairments is still lacking, but our knowledge base is rapidly expanding. Therefore, we anticipate that this comprehensive review will provide valuable insights and facilitate the work of neuroscientists in unfolding different neurological dimensions of COVID-19 and other CoV associated abnormalities.

Oculo-centric factors may provide a key to understanding invasion success by SARS-CoV-2, a highly contagious, potentially lethal, virus with ocular tropism. Respiratory infection transmission via the eye and lacrimal-nasal pathway elucidated during the 1918 influenza pandemic, remains to be explored in this crisis. The eye and its adnexae represent a large surface area directly exposed to airborne viral particles and hand contact. The virus may bind to corneal and conjunctival angiotensin converting enzyme 2 (ACE2) receptors and potentially to the lipophilic periocular skin and superficial tear film with downstream carriage into the nasopharynx and subsequent access to the lungs and gut. Adenoviruses and influenza viruses share this ocular tropism and despite differing ocular and systemic manifestations and disease patterns, common lessons, particularly in management, emerge. Slit lamp usage places ophthalmologists at particular risk of exposure to high viral loads (and poor prognosis) and as for adenoviral epidemics, this may be a setting for disease transmission. Local, rather than systemic treatments blocking virus binding in this pathway (advocated for adenovirus) are worth considering. This pathway is accessible with eye drops or aerosols containing drugs which appear efficacious via systemic administration. A combination such as hydroxychloroquine, azithromycin and zinc, all of which have previously been used topically in the eye and which work at least in part by blocking ACE2 receptors, may offer a safe, cost-effective and resource-sparing intervention., Highlights • Coronaviruses are oculotropic – a pathway for transmission and treatment. • Virus may bind ocular surface ACE2 receptors & the lipophilic superficial tear film. • A “wash through” effect with into the nasopharynx accesses lungs and gut. • Local hydroxychloroquine, azithromycin and zinc could block viral binding. • This may offer a safe, cost-effective and resource-sparing intervention.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the ongoing pandemic of coronavirus disease 2019 (COVID-19), belongs to the betacoronavirus genus and shares high homology to the severe acute respiratory syndrome coronavirus (SARS-CoV) that emerged in 2003. These are highly transmissible and pathogenic viruses which very likely originated in bats. SARS-CoV-2 uses the same receptor, angiotensin-converting enzyme 2 (ACE2) as SARS-CoV, and spreads primarily through the respiratory tract. Although several trials for vaccine development are currently underway, investigations into the virology of SARS-CoV-2 to understand the fundamental biology of the infectious cycle and the associated immunopathology underlying the clinical manifestations of COVID-19 are crucial for identification and rational design of effective therapies. This review provides an overview of how SARS-CoV-2 infects and spreads within human hosts with specific emphasis on key aspects of its lifecycle, tropism and immunopathological features.

Severe acute respiratory syndrome coronavirus 2 did not replicate efficiently in 13 bat cell lines, whereas severe acute respiratory syndrome coronavirus replicated efficiently in kidney cells of its ancestral host, the Rhinolophus sinicus bat, suggesting different evolutionary origins. Structural modeling showed that RBD/RsACE2 binding may contribute to the differential cellular tropism.

Viral-mediated gene augmentation offers tremendous promise for the treatment of inherited retinal diseases. The development of effective gene therapy requires an understanding of the vector's tissue-specific behavior, which may vary depending on serotype, route of delivery, or target species. Using an ex vivo organotypic explant system, we previously demonstrated that retinal tropism and transduction of adeno-associated virus type 2 (AAV2) vary significantly depending on serotype in human eyes. However, the ex vivo system has limited ability to assess route of ocular delivery, and relatively little literature exists on tropic differences between serotypes and routes of delivery in vivo. In this study, we demonstrate that retinal tropism and transduction efficiency of five different AAV2 serotypes (AAV2/1, AAV2/2, AAV2/6, AAV2/8, and AAV2/9) expressing enhanced green fluorescent protein driven by a cytomegalovirus promoter vary greatly depending on serotype and route of delivery (intravitreal, subretinal, or suprachoroidal) in rats. With subretinal delivery, all serotypes successfully transduced the retinal pigmented epithelium and outer nuclear layer (ONL), with AAV2/1 displaying the highest transduction efficiency and AAV2/2 and AAV2/6 showing lower ONL transduction. There was minimal transduction of the inner retina through subretinal delivery for any serotype. Tropism by suprachoroidal delivery mirrored that of subretinal delivery for all AAV serotypes but resulted in a wider distribution and greater ONL transduction. With intravitreal delivery, retinal transduction was seen primarily in the inner retina (retinal nerve fiber, ganglion cell, and inner nuclear layers) for AAV2/1 and AAV2/6, with AAV2/6 showing the highest transduction. When compared with data from human explant models, there are substantial differences in tropism and transduction that are important to consider when using rats as preclinical models for the development of ocular gene therapies for humans.

SARS-CoV-2 virus, the cause of COVID-19 disease, establishes infection in the human body via interaction with the angiotensin-converting enzyme 2 (ACE2) receptor on cell membranes. The lung is the major organ affected, and all respiratory epithelium from nose to alveolus is infectable. A recent study published in The Journal of Pathology looked at a wide range of other human tissues, mostly autopsy-derived, to identify susceptible cells. The virus (associated with ACE2) is found in all endothelial cells (an important finding), renal and biliary epithelium, in megakaryocytes, and occasionally in hepatocytes. It was not found in heart myofibres or brain neurones but is present in gut myenteric plexus cells. This work confirms previous work on SARS-CoV-2-infectable cells, and so supports investigations into the pathogenesis of COVID-19 disease as it affects (or does not directly affect) the different organs. © 2022 The Pathological Society of Great Britain and Ireland.

Murine norovirus (MNoV) is a model for human norovirus and for interrogating mechanisms of viral tropism and persistence. We previously demonstrated that the persistent strain MNoV

SARS-CoV-2 has caused the COVID-19 pandemic. B.1.617 variants (including Kappa and Delta) have been transmitted rapidly in India. The transmissibility, pathogenicity, and neutralization characteristics of these variants have received considerable interest. In this study, 22 pseudotyped viruses were constructed for B.1.617 variants and their corresponding single amino acid mutations. B.1.617 variants did not exhibit significant enhanced infectivity in human cells, but mutations T478K and E484Q in the receptor binding domain led to enhanced infectivity in mouse ACE2-overexpressing cells. Furin activities were slightly increased against B.1.617 variants and cell-cell fusion after infection of B.1.617 variants were enhanced. Furthermore, B.1.617 variants escaped neutralization by several mAbs, mainly because of mutations L452R, T478K, and E484Q in the receptor binding domain. The neutralization activities of sera from convalescent patients, inactivated vaccine-immunized volunteers, adenovirus vaccine-immunized volunteers, and SARS-CoV-2 immunized animals against pseudotyped B.1.617 variants were reduced by approximately twofold, compared with the D614G variant.

The recent outbreak of coronavirus disease 2019 (COVID‐19), caused by the Severe Acute Respiratory Syndrome Coronavirus‐2 (SARS‐CoV‐2) has resulted in a world‐wide pandemic. Disseminated lung injury with the development of acute respiratory distress syndrome (ARDS) is the main cause of mortality in COVID‐19. Although liver failure does not seem to occur in the absence of pre‐existing liver disease, hepatic involvement in COVID‐19 may correlate with overall disease severity and serve as a prognostic factor for the development of ARDS. The spectrum of liver injury in COVID‐19 may range from direct infection by SARS‐CoV‐2, indirect involvement by systemic inflammation, hypoxic changes, iatrogenic causes such as drugs and ventilation to exacerbation of underlying liver disease. This concise review discusses the potential pathophysiological mechanisms for SARS‐CoV‐2 hepatic tropism as well as acute and possibly long‐term liver injury in COVID‐19.

Across the fields of virology and neuroscience, the role of neurotropic viruses in Alzheimer’s disease (AD) has received renewed enthusiasm, with a particular focus on human herpesviruses (HHVs). Recent genomic analyses of brain tissue collections and investigations of the antimicrobial responses of amyloid-β do not exclude a role of HHVs in contributing to or accelerating AD pathogenesis. Due to continued expansion in our aging cohort and the lack of effective treatments for AD, this composition examines a potential neuroviral theory of AD in light of these recent data. Consideration reveals a possible viral “Hit-and-Run” scenario of AD, as well as neurobiological mechanisms (i.e., neuroinflammation, protein quality control, oxidative stress) that may increase risk for AD following neurotropic infection. Although limitations exist, this theoretical framework reveals several novel therapeutic targets that may prove efficacious in AD.

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.

Summary: Background: Severe COVID-19 has a high mortality rate. Comprehensive pathological descriptions of COVID-19 are scarce and limited in scope. We aimed to describe the histopathological findings and viral tropism in patients who died of severe COVID-19. Methods: In this case series, patients were considered eligible if they were older than 18 years, with premortem diagnosis of severe acute respiratory syndrome coronavirus 2 infection and COVID-19 listed clinically as the direct cause of death. Between March 1 and April 30, 2020, full post-mortem examinations were done on nine patients with confirmed COVID-19, including sampling of all major organs. A limited autopsy was done on one additional patient. Histochemical and immunohistochemical analyses were done, and histopathological findings were reported by subspecialist pathologists. Viral quantitative RT-PCR analysis was done on tissue samples from a subset of patients. Findings: The median age at death of our cohort of ten patients was 73 years (IQR 52–79). Thrombotic features were observed in at least one major organ in all full autopsies, predominantly in the lung (eight [89%] of nine patients), heart (five [56%]), and kidney (four [44%]). Diffuse alveolar damage was the most consistent lung finding (all ten patients); however, organisation was noted in patients with a longer clinical course. We documented lymphocyte depletion (particularly CD8-positive T cells) in haematological organs and haemophagocytosis. Evidence of acute tubular injury was noted in all nine patients examined. Major unexpected findings were acute pancreatitis (two [22%] of nine patients), adrenal micro-infarction (three [33%]), pericarditis (two [22%]), disseminated mucormycosis (one [10%] of ten patients), aortic dissection (one [11%] of nine patients), and marantic endocarditis (one [11%]). Viral genomes were detected outside of the respiratory tract in four of five patients. The presence of subgenomic viral RNA transcripts provided evidence of active viral replication outside the respiratory tract in three of five patients. Interpretation: Our series supports clinical data showing that the four dominant interrelated pathological processes in severe COVID-19 are diffuse alveolar damage, thrombosis, haemophagocytosis, and immune cell depletion. Additionally, we report here several novel autopsy findings including pancreatitis, pericarditis, adrenal micro-infarction, secondary disseminated mucormycosis, and brain microglial activation, which require additional investigation to understand their role in COVID-19. Funding: Imperial Biomedical Research Centre, Wellcome Trust, Biotechnology and Biological Sciences Research Council.

Viral infection underlies a significant share of the global cancer burden. Merkel cell polyomavirus (MCPyV) is the newest member of the human oncogenic virus family. Its discovery over a decade ago marked the beginning of an exciting era in human tumor virology. Since then, significant evidence has emerged to support the etiologic role of MCPyV in Merkel cell carcinoma (MCC), an extremely lethal form of skin cancer. MCPyV infection is widespread in the general population. MCC diagnoses have tripled over the past 20 years, but effective treatments are currently lacking. In this review, we highlight recent discoveries that have shaped our understanding of MCPyV oncogenic mechanism and host cellular tropism, as well as the molecular events occurring in the viral infectious life cycle. These insights will guide future efforts in developing novel virus-targeted therapeutic strategies for treating the devastating human cancers associated with this new tumorigenic virus.

Background: Coronavirus disease 2019 (COVID-19) is caused by Severe Acute Respiratory Syndrome Coronavirus 2 10 (SARS-CoV-2). Recent studies demonstrated not only retinal impairments but also detected SARS-CoV-2 in the retina of patients with COVID-19. Purpose: This letter discusses the retinal tropism of SARS-CoV-2, describing possible routes for this coronavirus to reach the retina and cellular mechanisms involved in the retinal cell infection. Conclusions: Determining how SARS-CoV-2 can affect the retinal tissue is essential for the development of new therapeutic strategies and preventive measures, as well as for understanding the possible relationship between COVID-19 damage to the retina and to the brain.

The persistence of SARS-CoV-2 after death of infected individuals is unclear. The aim of this study was to investigate the presence of SARS-CoV-2 RNA in different organs in correlation with tissue damage and post-mortem viral dynamics in COVID-19 deceased. Twenty-eight patients (17 males, 11 females; age 66–96 years; mean 82.9, median 82.5 years) diagnosed with COVID-19 were studied. Swabs were taken post-mortem during autopsy (N = 19) from the throat, both lungs, intestine, gallbladder, and brain or without autopsy (N = 9) only from the throat. Selective amplification of target nucleic acid from the samples was achieved by using primers for ORF1a/b non-structural region and the structural protein envelope E-gene of the virus. The results of 125 post-mortem and 47 ante-mortem swabs were presented as cycle threshold (Ct) values and categorized as strong, moderate, and weak. Viral RNA was detected more frequently in the lungs and throat than in the intestine. Blood, bile, and the brain were negative. Consecutive throat swabs were positive up to 128 h after death without significant increase of Ct values. All lungs showed diffuse alveolar damage, thrombosis, and infarction and less frequently bronchopneumonia irrespective of Ct values. In 30% the intestine revealed focal ischemic changes. Nucleocapsid protein of SARS-CoV-2 was detected by immunohistochemistry in bronchial and intestinal epithelium, bronchial glands, and pneumocytes. In conclusion, viral RNA is still present several days after death, most frequently in the respiratory tract and associated with severe and fatal organ damage. Potential infectivity cannot be ruled out post-mortem. Electronic supplementary material The online version of this article (10.1007/s00428-020-02903-8) contains supplementary material, which is available to authorized users.

Albeit primarily a disease of respiratory tract, the 2019 coronavirus infectious disease (COVID-19) has been found to have causal association with a plethora of neurological, neuropsychiatric and psychological effects. This review aims to analyze them with a discussion of evolving therapeutic recommendations.PubMed and Google Scholar were searched from 1 January 2020 to 30 May 2020 with the following key terms: "COVID-19", "SARS-CoV-2", "pandemic", "neuro-COVID", "stroke-COVID", "epilepsy-COVID", "COVID-encephalopathy", "SARS-CoV-2-encephalitis", "SARS-CoV-2-rhabdomyolysis", "COVID-demyelinating disease", "neurological manifestations", "psychosocial manifestations", "treatment recommendations", "COVID-19 and therapeutic changes", "psychiatry", "marginalised", "telemedicine", "mental health", "quarantine", "infodemic" and "social media". A few newspaper reports related to COVID-19 and psychosocial impacts have also been added as per context.Neurological and neuropsychiatric manifestations of COVID-19 are abundant. Clinical features of both central and peripheral nervous system involvement are evident. These have been categorically analyzed briefly with literature support. Most of the psychological effects are secondary to pandemic-associated regulatory, socioeconomic and psychosocial changes.Neurological and neuropsychiatric manifestations of this disease are only beginning to unravel. This demands a wide index of suspicion for prompt diagnosis of SARS-CoV-2 to prevent further complications and mortality.Les impacts neurologiques et neuropsychiatriques d’une infection à la COVID-19.Bien qu’il s’agisse principalement d’une maladie des voies respiratoires, la maladie infectieuse à coronavirus apparue en 2019 (COVID-19) s’est avérée avoir un lien de causalité avec une pléthore d’impacts d’ordre neurologique, neuropsychiatrique et psychologique. Cette étude entend donc analyser ces impacts tout en discutant l’évolution des recommandations thérapeutiques se rapportant à cette maladie.Les bases de données PubMed et Google Scholar ont été interrogées entre les 1er janvier et 30 mai 2020. Les termes clés suivants ont été utilisés : « COVID-19 », « SRAS – CoV-2 », « Pandémie », « Neuro – COVID », « AVC – COVID », « Épilepsie – COVID », « COVID – encéphalopathie », « SRAS – CoV-2 – encéphalite », « SRAS – CoV-2 – rhabdomyolyse », « COVID – maladie démyélinisante », « Manifestations neurologiques », « Manifestations psychosociales », « Recommandations thérapeutiques », « COVID-19 et changement thérapeutiques », « Psychiatrie », « Marginalisés », « Télémédecine », « Santé mentale », « Quarantaine », « Infodémique » et « Médias sociaux ». De plus, quelques articles de journaux relatifs à la pandémie de COVID-19 et à ses impacts psychosociaux ont également été ajoutés en fonction du contexte.Il appert que les manifestations neurologiques et neuropsychiatriques des infections à la COVID-19 sont nombreuses. Les caractéristiques cliniques d’une implication des systèmes nerveux central et périphérique sautent désormais aux yeux. Ces caractéristiques ont fait l’objet d’une brève analyse systématique à l’aide de publications scientifiques. En outre, la plupart des impacts d’ordre psychologique de cette pandémie se sont révélés moins apparents que les changements réglementaires, socioéconomiques et psychosociaux.Les manifestations neurologiques et neuropsychiatriques de cette maladie ne font que commencer à être élucidées. Cela exige donc une capacité accrue de vigilance en vue d’un diagnostic rapide, et ce, afin de prévenir des complications additionnelles et une mortalité accrue.

Sub-Saharan region in Africa still holds the highest burden of HIV/AIDS globally. HIV-1 requires coreceptor to gain entry into permissive cells to initiate infection. Molecular analysis of the chemokine coreceptor usage is important clinically and in the effective management of AIDS virus. This study aims to determine the coreceptor usage among HIV-1 drug-naive patients residing in the rural Eastern cape, South Africa. We collected blood samples from 55 HIV-infected patients into an anticoagulant vacutainer. RNA was extracted from separated plasma, and reverse transcription-polymerase chain reaction (RT-PCR) was performed followed by nested polymerase chain reaction to amplify the partial envelope fragment spanning the C2-C3 region. Sanger sequencing was done on the amplicons using the BigDye Terminator V3.1 sequencing kit (Applied Biosystems, Foster City, CA) while sequences were manually edited using BioEdit and Geneious 10.2.6 tools. The WebPSSM and Geno2pheno online tools were also utilized to predict coreceptor tropism while the phylogenetic analysis of the isolates was determined using MEGA 7. Of the 55 blood samples collected for the study, 50 (91%) were successfully amplified and sequenced. The mean age of the patients was 32 (18-56) years while the ratio of men to women was 35% and 65% correspondingly. Phylogenetic analysis revealed that all 50 sequences clustered with HIV-1 subtype C reference strains. Viral tropism of the V3 loop revealed 47 sequences to be R5 strains, while three sequences (T1E, T10E, and T11E,) were classified as X4 strains based on the WebPSSM and the Geno2pheno algorithm. HIV-1 R5 tropic strains were the most dominant virus obtained from this study, while HIV-1 subtype C still drives the epidemic in South Africa suggesting greater

The number of people infected with SARS-CoV-2, and sadly dying from COVID-19, has exploded, and so the amount of literature on the novel coronavirus and the disease it causes has increased proportionately. The case numbers in some countries are beyond the epidemic peak, but the uncertainty about a second wave keeps politicians and societies under pressure. Appropriate decision-making and winning support from the population depends on precise scientific information rather than leaving the field to scaremongers of all proveniences. This mini-review is an update of earlier reports (Brüssow, Microb Biotechnol 2020a;13:607; Brüssow, Microb Biotechnol 2020b; https://doi.org/10.1111/1751-7915.13592). ispartof: MICROBIAL BIOTECHNOLOGY vol:13 issue:5 pages:1289-1299 ispartof: location:United States status: published

Objective The novel coronavirus, SARS‐CoV‐2 is an international public health emergency. Until now, the intermediate host and mechanisms of interspecies jump of this virus are unknown. Methods Phylogenetic analysis of all available bat coronavirus (CoV) complete genomes was performed in order to analyze the relationships between bat CoV and SARS‐CoV‐2. In order to suggest a possible intermediate host, another phylogenetic reconstruction of CoV genomes obtained from animals which were hypothetically commercialized in the Chinese markets was also carried out. Moreover, mutation analysis was executed to suggest genomic regions which may have permitted the adaptation of SARS‐CoV‐2 to the human host. Results The phylogenetic analysis demonstrated that SARS‐CoV‐2 formed a cluster with the bat CoV isolate RaTG13. Possible CoV interspecies jumps among bat isolates were also observed. The phylogenetic tree reconstructed from CoV strains belonging to different animals demonstrated that SARS‐CoV‐2, bat RaTG13 and pangolin CoV genomes formed a monophyletic cluster, demonstrating that pangolins may be suggested as SARS‐CoV‐2 intermediate hosts. Three AA substitutions localized in the S1 portion of the S gene were observed, some of which have been correlated to structural modifications of the S protein which may facilitate SARS‐CoV‐2 tropism to human cells. Conclusions Our analysis shows the tight relationship between SARS‐CoV‐2 and bat SARS‐like strains. It also hypothesizes that pangolins might have been possible intermediate hosts of the infection. Some of the observed AA substitutions in the S binding protein may serve as possible adaptation mutations in humans but more studies are needed to elucidate their function. This article is protected by copyright. All rights reserved.

We previously reported the coinfection of novel porcine epidemic diarrhoea virus (PEDV) variants bearing large deletions in the S protein and PEDVs possessing an intact S protein (S-intact PEDV) in domestic pigs in Japan. The variants were frequently observed in pig farms with persistent or recurrent infection. To elucidate the role of the variants in persistent infections and their tropism properties, we genetically characterized and immunohistochemically detected PEDVs collected in primary and recurrent outbreaks in two persistently infected farms. Our results revealed coinfection of the PEDV variants bearing a 214-amino acid deletion in the S protein and S-intact PEDVs in the lungs of the naturally infected pigs. New tropisms of PEDV, including epithelial cells and submucosal glands of the airway tract, epithelial cells of the bile duct, and monocytes/macrophages were identified. The findings elucidate the mechanism of PEDV infection, epidemiology and pattern changes in the disease.

Résumé L’infection par le SARS-CoV-2, nommée COVID-19, peut conduire à une réaction immunitaire inadaptée et à une coagulopathie responsables d’un véritable sepsis viral. Dans cette revue, nous précisons les mécanismes physiopathologiques propres à chacune des phases de la COVID-19 - virale, immunitaire et pro-thrombotique - en soulignant les différentes perspectives thérapeutiques qui en découlent. Enfin, nous précisons les mécanismes physiopathologiques mis en jeu dans chaque organe dont l’atteinte a été décrite dans les études cliniques.

Capitalizing on liver tropism of adeno-associated viral (AAV) vectors, intravenous vector administration is commonly used to genetically modify hepatocytes, a strategy currently in clinical trials for a number of liver-based hereditary disorders. Although hepatocytes are known to exhibit extensive phenotypic heterogeneity influenced by liver zonation and dietary cycle, there is little data available for the tropism capacity, as well as the potential transcriptional dysregulation, of AAV vectors for specific liver cell types. To assess these issues, we employed single-cell RNA sequencing of the mouse liver after intravenous administration of the liver tropic AAVrh.10 vector to characterize cell-specific AAV-mediated transgene expression and transcriptome dysregulation. Wild-type 8-week-old male C57Bl/6 mice under normal feed cycle were randomly divided into three groups and intravenously administered phosphate-buffered saline (PBS), AAVrh.10Null (no transgene), or AAVrh.10mCherry (marker gene). Overall, a total of 46,500 liver cells were sequenced. The single-cell transcriptomic profiles were grouped into three separate clusters of hepatocytes (Ttr-enriched “Hep1,” Tat-enriched “Hep2,” and Alb-enriched “Hep3”) and multiple other cell types. The hepatocyte diversity was driven by glucose and lipid homeostasis signaling. Assessment of the transgene expression demonstrated that AAVrh.10 is primarily Hep1-tropic, with a 10-gene signature positively correlated with AAVrh.10-mediated transgene expression. The transgene expression was less in Hep2 and Hep3 cells with a high receptor tyrosine kinase phenotype. Importantly, AAVrh.10 vector interactions with the liver markedly altered the transcriptional patterns of all cell types, with modified genes enriched in pathways of complement and coagulation cascade, cytochrome P450, peroxisome, antigen processing and presentation, and endoplasmic reticulum protein processing. These observations provide insights into the liver cell-specific consequences of AAV-mediated liver gene transfer, far beyond the well-known organ-specific expression of the vector-delivered transgene.

SARS-CoV-2 causes the recent global COVID-19 public health emergency. ACE2 is the receptor for both SARS-CoV-2 and SARS-CoV. To predict the potential host range of SARS-CoV-2, we analyzed the key residues of ACE2 for recognizing S protein. We found that most of the selected mammals including pets (dog and cat), pangolin and Circetidae mammals remained the most of key residues for association with S protein from SARS-CoV and SARS-CoV-2. The interaction interface between cat/dog/pangolin/Chinese hamster ACE2 and SARS-CoV/SARS-CoV-2 S protein was simulated through homology modeling. We identified that N82 in ACE2 showed a closer contact with SARS-CoV-2 S protein than M82 in human ACE2. Our finding will provide important insights into the host range of SARS-CoV-2 and a new strategy to design an optimized ACE2 for SARS-CoV-2 infection.

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer, despite improvements in the clinical trial and diagnosis, HCC still remains high mortality due to the 70% recurrence and lung metastasis after surgical resection. Exosomes are small membrane vesicles, which are shuttled from donor cells to recipient cells, contributing to the recruitment and reprogramming of constituents via an autocrine or paracrine fashion. HCC derived exosomes could redirect metastasis of tumor cells which lack the capacity to metastasize to a specific organ via generating pre-metastatic niche. These findings emphasize a practical and potentially feasible role of exosomes in the treatment of patients with HCC, both as a target and a vehicle for drug design. We herein summarize recent findings that implicate oncogenes and non-canonical signaling of HCC exosomes, as well as the impact of exosomal bioactive molecules in high recurrence induced by organ-specific metastasis. The aim of review is to illustrate the underlying mechanism of exosomes in tumor metastasis, immune evasion, and the potential application of prognostic biomarker in HCC process.