scholarly journals Murine cytomegalovirus disseminates independently of CX3CR1, CCL2 or its m131/m129 chemokine homologue

2019 ◽  
Vol 100 (12) ◽  
pp. 1695-1700 ◽  
Author(s):  
Helen E. Farrell ◽  
Kimberley Bruce ◽  
Alec J. Redwood ◽  
Philip G. Stevenson
Keyword(s):  
Salivary Gland ◽  
Murine Cytomegalovirus ◽  
Entry Site ◽  
Fractalkine Receptor ◽  
Systemic Spread ◽  
Infected Cells ◽  
Initial Seeding ◽  
Receptor Cx3cr1 ◽  
Patrolling Monocytes

Cytomegaloviruses (CMVs) use myeloid cells to move within their hosts. Murine CMV (MCMV) colonizes the salivary glands for long-term shedding, and reaches them via CD11c+ infected cells. A need to recruit patrolling monocytes for systemic spread has been proposed, based on poor salivary gland infection in fractalkine receptor (CX3CR1)-deficient mice. We found no significant CX3CR1 dependence of salivary gland infection. CCL2 and the viral m131/m129 chemokine homologue were also redundant for acute MCMV spread, arguing against a need for inflammation or infection to recruit additional monocytes to the entry site. M131/m129 promoted salivary gland infection, but only after the initial seeding of infected cells to this site. Our data support the idea that MCMV disseminates by infecting and mobilizing tissue-resident dendritic cells.

Covid-19 In Man: A Very Dangerous Affair.

2021 ◽  
Vol 21 ◽  
Author(s):  
Giuseppe Lisco ◽  
Vito A. Giagulli ◽  
Giovanni De Pergola ◽  
Anna De Tullio ◽  
Edoardo Guastamacchia ◽  
...  
Keyword(s):  
Poor Prognosis ◽  
Metabolic Diseases ◽  
Systemic Disease ◽  
Public Health Issue ◽  
Immune System Dysfunction ◽  
Data Support ◽  
Systemic Spread ◽  
The Impact

Background: The novel pandemic of Coronavirus disease 2019 (COVID-19) has becoming a public health issue since March 2020 considering that more than 30 million people were found to be infected worldwide. Particularly, recent evidences suggested that men may be considered as at higher risk of poor prognosis or death once the infection occurred and concerns surfaced in regard of the risk of a possible testicular injury due to SARS-CoV-2 infection. Results: Several data support the existence of a bivalent role of testosterone (T) in driving poor prognosis in patients with COVID-19. On one hand, this is attributable to the fact that T may facilitate SARS-CoV-2 entry in human cells by means of an enhanced expression of transmembrane serine-protease 2 (TMPRSS2) and angiotensin-converting enzyme 2 (ACE2). At the same time, younger man with normal testicular function compared to women of similar age are prone to develop a blunted immune response against SARS-CoV-2, being exposed to less viral clearance and more viral shedding and systemic spread of the disease. Conversely, low levels of serum T observed in hypogonadal men predispose them to a greater background systemic inflammation, cardiovascular and metabolic diseases, and immune system dysfunction, hence driving harmful consequences once SARS-CoV-2 infection occurred. Finally, SARS-CoV-2, as a systemic disease, may also affect testicles with possible concerns for current and future testicular efficiency. Preliminary data suggested that SARS-CoV-2 genome is not normally found in gonads and gametes, therefore sex transmission could be excluded as a possible way to spread the COVID-19. Conclusion: Most data support a role of T as a bivalent risk factor for poor prognosis (high/normal in younger; lower in elderly) in COVID-19. However, the impact of medical treatment aimed to modify T homeostasis for improving the prognosis of affected patients is unknown in this clinical setting. In addition, testicular damage may be a harmful consequence of the infection even in case it occurred asymptomatically but no long-term evidences are currently available to confirm and quantify this phenomenon. Different authors excluded the presence of SARS-CoV-2 in sperm and oocytes, thus limiting worries about both a potential sexual and gamete-to-embryos transmission of COVID-19. Despite these evidence, long-term and well-designed studies are needed to clarify these issues.

scholarly journals Immunodominant Cytomegalovirus Epitopes Suppress Subdominant Epitopes in the Generation of High-Avidity CD8 T Cells

Pathogens ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 956
Author(s):  
Kirsten Freitag ◽  
Sara Hamdan ◽  
Matthias J. Reddehase ◽  
Rafaela Holtappels
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Immune Escape ◽  
Cd8 T Cell ◽  
Antigenic Drift ◽  
Murine Cytomegalovirus ◽  
High Avidity ◽  
Infected Cells ◽  
Cd8 T Cell Memory

CD8+ T-cell responses to pathogens are directed against infected cells that present pathogen-encoded peptides on MHC class-I molecules. Although natural responses are polyclonal, the spectrum of peptides that qualify for epitopes is remarkably small even for pathogens with high coding capacity. Among those few that are successful at all, a hierarchy exists in the magnitude of the response that they elicit in terms of numbers of CD8+ T cells generated. This led to a classification into immunodominant and non-immunodominant or subordinate epitopes, IDEs and non-IDEs, respectively. IDEs are favored in the design of vaccines and are chosen for CD8+ T-cell immunotherapy. Using murine cytomegalovirus as a model, we provide evidence to conclude that epitope hierarchy reflects competition on the level of antigen recognition. Notably, high-avidity cells specific for non-IDEs were found to expand only when IDEs were deleted. This may be a host’s back-up strategy to avoid viral immune escape through antigenic drift caused by IDE mutations. Importantly, our results are relevant for the design of vaccines based on cytomegaloviruses as vectors to generate high-avidity CD8+ T-cell memory specific for unrelated pathogens or tumors. We propose the deletion of vector-encoded IDEs to avoid the suppression of epitopes of the vaccine target.

scholarly journals Bystander Attenuation of Neuronal and Astrocyte Intercellular Communication by Murine Cytomegalovirus Infection of Glia

2007 ◽  
Vol 81 (13) ◽  
pp. 7286-7292 ◽  
Author(s):  
Winson S. C. Ho ◽  
Anthony N. van den Pol
Keyword(s):  
Intercellular Communication ◽  
Neuronal Development ◽  
Primary Cultures ◽  
Synaptic Activity ◽  
Murine Cytomegalovirus ◽  
Intercellular Signaling ◽  
Mcmv Infection ◽  
High Potassium ◽  
Infected Cells ◽  
The Brain

ABSTRACT Astrocytes are the first cells infected by murine cytomegalovirus (MCMV) in primary cultures of brain. These cells play key roles in intercellular signaling and neuronal development, and they modulate synaptic activity within the nervous system. Using ratiometric fura-2 digital calcium imaging of >8,000 neurons and glia, we found that MCMV-infected astrocytes showed an increase in intracellular basal calcium levels and an enhanced response to neuroactive substances, including glutamate and ATP, and to high potassium levels. Cultured neurons with no sign of MCMV infection showed attenuated synaptic signaling after infection of the underlying astrocyte substrate, and intercellular communication between astrocytes with no sign of infection was reduced by the presence of infected glia. These bystander effects would tend to cause further deterioration of cellular communication in the brain in addition to the problems caused by the loss of directly infected cells.

scholarly journals The evolving definition of salivary gland stem cells

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Cecilia Rocchi ◽  
Lara Barazzuol ◽  
Rob P. Coppes
Keyword(s):  
Stem Cells ◽  
Salivary Gland ◽  
Adult Stem Cell ◽  
Cell Types ◽  
Research Field ◽  
New Therapeutic Approaches ◽  
Recent Developments ◽  
Radiation Induced ◽  
Definition Of

AbstractDysfunction of the salivary gland and irreversible hyposalivation are the main side effects of radiotherapy treatment for head and neck cancer leading to a drastic decrease of the quality of life of the patients. Approaches aimed at regenerating damaged salivary glands have been proposed as means to provide long-term restoration of tissue function in the affected patients. In studies to elucidate salivary gland regenerative mechanisms, more and more evidence suggests that salivary gland stem/progenitor cell behavior, like many other adult tissues, does not follow that of the hard-wired professional stem cells of the hematopoietic system. In this review, we provide evidence showing that several cell types within the salivary gland epithelium can serve as stem/progenitor-like cells. While these cell populations seem to function mostly as lineage-restricted progenitors during homeostasis, we indicate that upon damage specific plasticity mechanisms might be activated to take part in regeneration of the tissue. In light of these insights, we provide an overview of how recent developments in the adult stem cell research field are changing our thinking of the definition of salivary gland stem cells and their potential plasticity upon damage. These new perspectives may have important implications on the development of new therapeutic approaches to rescue radiation-induced hyposalivation.

scholarly journals Latently KSHV-Infected Cells Promote Further Establishment of Latency upon Superinfection with KSHV

2021 ◽  
Vol 22 (21) ◽  
pp. 11994
Author(s):  
Chen Gam ze Letova ◽  
Inna Kalt ◽  
Meir Shamay ◽  
Ronit Sarid
Keyword(s):  
Latent Infection ◽  
Fluorescent Proteins ◽  
Cell Types ◽  
Lytic Cycle ◽  
Viral Reservoir ◽  
Virus Spread ◽  
Viral Genomes ◽  
Latently Infected ◽  
Infected Cells

Kaposi’s sarcoma-associated herpesvirus (KSHV) is a cancer-related virus which engages in two forms of infection: latent and lytic. Latent infection allows the virus to establish long-term persistent infection, whereas the lytic cycle is needed for the maintenance of the viral reservoir and for virus spread. By using recombinant KSHV viruses encoding mNeonGreen and mCherry fluorescent proteins, we show that various cell types that are latently-infected with KSHV can be superinfected, and that the new incoming viruses establish latent infection. Moreover, we show that latency establishment is enhanced in superinfected cells compared to primary infected ones. Further analysis revealed that cells that ectopically express the major latency protein of KSHV, LANA-1, prior to and during infection exhibit enhanced establishment of latency, but not cells expressing LANA-1 fragments. This observation supports the notion that the expression level of LANA-1 following infection determines the efficiency of latency establishment and avoids loss of viral genomes. These findings imply that a host can be infected with more than a single viral genome and that superinfection may support the maintenance of long-term latency.

scholarly journals COVID-19-related anosmia is associated with viral persistence and inflammation in human olfactory epithelium and brain infection in hamsters

2021 ◽  
pp. eabf8396
Author(s):  
Guilherme Dias de Melo ◽  
Françoise Lazarini ◽  
Sylvain Levallois ◽  
Charlotte Hautefort ◽  
Vincent Michel ◽  
...  
Keyword(s):  
Olfactory Epithelium ◽  
Cell Types ◽  
Brain Infection ◽  
Olfactory Neuroepithelium ◽  
Optimal Medical Management ◽  
Infected Cells ◽  
Multiple Cell ◽  
Lung Pathogenesis ◽  
Taste Dysfunction

Whereas recent investigations have revealed viral, inflammatory and vascular factors involved in SARS-CoV-2 lung pathogenesis, the pathophysiology of neurological disorders in COVID-19 remains poorly understood. Olfactory and taste dysfunction are common in COVID-19, especially in mildly symptomatic patients. Here, we conducted a virologic, molecular, and cellular study of the olfactory neuroepithelium of seven patients with COVID-19 presenting with acute loss of smell. We report evidence that the olfactory neuroepithelium may be a major site of SARS-CoV2 infection with multiple cell types, including olfactory sensory neurons, support cells, and immune cells, becoming infected. SARS-CoV-2 replication in the olfactory neuroepithelium was associated with local inflammation. Furthermore, we showed that SARS-CoV-2 induced acute anosmia and ageusia in golden Syrian hamsters, lasting as long as the virus remained in the olfactory epithelium and the olfactory bulb. Finally, olfactory mucosa sampling from patients showing long-term persistence of COVID-19-associated anosmia revealed the presence of virus transcripts and of SARS-CoV-2-infected cells, together with protracted inflammation. SARS-CoV-2 persistence and associated inflammation in the olfactory neuroepithelium may account for prolonged or relapsing symptoms of COVID-19, such as loss of smell, which should be considered for optimal medical management of this disease.

scholarly journals Long-term persistence of crAss-like phage crAss001 is associated with phase variation in Bacteroides intestinalis

2020 ◽  
Author(s):  
Andrey N Shkoporov ◽  
Ekaterina V Khokhlova ◽  
Niamh Stephens ◽  
Cara Hueston ◽  
Samuel Seymour ◽  
...  
Keyword(s):  
Dynamic Equilibrium ◽  
Phase Variation ◽  
Carrier State ◽  
Human Gut ◽  
Rapid Phase ◽  
Host Interaction ◽  
Infected Cells ◽  
Phage Sensitivity

The crAss-like phages are ubiquitous and highly abundant members of the human gut virome that infect commensal bacteria of the order Bacteroidales. Although incapable of classical lysogeny, these viruses demonstrate unexplained long-term persistence in the human gut microbiome, dominating the virome in some individuals. Here we demonstrate that rapid phase variation of alternate capsular polysaccharides plays an important role in dynamic equilibrium between phage sensitivity and resistance in B. intestinalis cultures, allowing phage and bacteria to multiply in parallel. The data also suggests the role of concomitant phage persistence mechanisms associated with delayed lysis of infected cells, such as carrier state infection. From an ecological and evolutionary standpoint this type of phage-host interaction is consistent with the Piggyback-the-Winner model, which suggests a preference towards lysogenic or other 'benign' forms of phage infection when the host is stably present at high abundance.

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