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Frontiers in Immunology 2023Memory B cells are comprised of unswitched (CD27+IgD+) and switched (CD27+IgD-) subsets. The origin and function of unswitched human memory B cells are debated in the...
Memory B cells are comprised of unswitched (CD27+IgD+) and switched (CD27+IgD-) subsets. The origin and function of unswitched human memory B cells are debated in the literature, whereas switched memory B cells are primed to respond to recurrent infection. Unswitched memory B cells have been described to be reduced in frequency with severe SARS-CoV2 infection and here we characterize their activation status, BCR functionality, and contribution to virally-induced cytokine production. Analyses of whole blood from healthy individuals, people immunized against SARS-CoV2, and those who have had mild and severe SARS-CoV2 infection, confirm a reduction in the frequency of unswitched memory B cells during severe SARS-CoV2 infection and demonstrate this reduction is associated with increased levels of systemic TNFα. We further document how severe viral infection is associated with an increased frequency of 'IgD+' only memory B cells that correlate with increased IgG autoantibody levels. Unswitched and switched memory B cells from severe SARS-CoV2 infection displayed evidence of heightened activation with a concomitant reduction in the expression of the inhibitory receptor CD72. Functionally, both populations of memory B cells from severe SARS-COV2 infection harbored a signaling-competent BCR that displayed enhanced BCR signaling activity in the unswitched population. Finally, we demonstrate that B cells from mild SARS-CoV2 infection are poised to secrete pro-inflammatory cytokines IL-6 and TNFα. Importantly, unswitched memory B cells were a major producer of IL-6 and switched memory B cells were a major producer of TNFα in response to viral TLR ligands. Together these data indicate that B cells contribute to the inflammatory milieu during viral infection.
Topics: Humans; Memory B Cells; COVID-19; Tumor Necrosis Factor-alpha; Interleukin-6; RNA, Viral; SARS-CoV-2; Cytokines
PubMed: 37638016
DOI: 10.3389/fimmu.2023.1213344 -
Frontiers in Microbiology 2024
PubMed: 38371940
DOI: 10.3389/fmicb.2024.1354424 -
The Journal of Biological Chemistry Sep 2023Hepatitis B virus (HBV) is a hepatotropic DNA virus that has a very compact genome. Due to this genomic density, several distinct mechanisms are used to facilitate the...
Hepatitis B virus (HBV) is a hepatotropic DNA virus that has a very compact genome. Due to this genomic density, several distinct mechanisms are used to facilitate the viral life cycle. Recently, accumulating evidence show that G-quadruplex (G4) in different viruses play essential regulatory roles in key steps of the viral life cycle. Although G4 structures in the HBV genome have been reported, their function in HBV replication remains elusive. In this study, we treated an HBV replication-competent cell line and HBV-infected cells with the G4 structure stabilizer pyridostatin (PDS) and evaluated different HBV replication markers to better understand the role played by the G4. In both models, we found PDS had no effect on viral precore RNA (pcRNA) or pre-genomic RNA (pgRNA), but treatment did increase HBeAg/HBc ELISA reads and intracellular levels of viral core/capsid protein (HBc) in a dose-dependent manner, suggesting post-transcriptional regulation. To further dissect the mechanism of G4 involvement, we used in vitro-synthesized HBV pcRNA and pgRNA. Interestingly, we found PDS treatment only enhanced HBc expression from pgRNA but not HBeAg expression from pcRNA. Our bioinformatic analysis and CD spectroscopy revealed that pgRNA harbors a conserved G4 structure. Finally, we introduced point mutations in pgRNA to disrupt its G4 structure and observed the resulting mutant failed to respond to PDS treatment and decreased HBc level in in vitro translation assay. Taken together, our data demonstrate that HBV pgRNA contains a G4 structure that plays a vital role in the regulation of viral mRNA translation.
Topics: Humans; Capsid Proteins; Hepatitis B; Hepatitis B e Antigens; Hepatitis B virus; RNA, Viral; Viral Core Proteins; Virus Replication; Cell Line; G-Quadruplexes; Protein Biosynthesis; Mutation; Aminoquinolines
PubMed: 37567479
DOI: 10.1016/j.jbc.2023.105151 -
Journal of Medical Microbiology May 2024Infectious bronchitis virus (IBV) is a highly contagious avian that affects mainly chickens () but can circulate in other avian species. IBV constitutes a significant... (Review)
Review
Infectious bronchitis virus (IBV) is a highly contagious avian that affects mainly chickens () but can circulate in other avian species. IBV constitutes a significant threat to the poultry industry, causing reduced egg yield, growth and mortality levels that can vary in impact. The virus can be transmitted horizontally by inhalation or direct/indirect contact with infected birds or contaminated fomites, vehicles, farm personnel and litter (Figure 1). The error-prone viral polymerase and recombination mechanisms mean diverse viral population results, with multiple genotypes, serotypes, pathotypes and protectotypes. This significantly complicates control and mitigation strategies based on vigilance in biosecurity and the deployment of vaccination.
Topics: Infectious bronchitis virus; Animals; Chickens; Poultry Diseases; Coronavirus Infections
PubMed: 38771617
DOI: 10.1099/jmm.0.001828 -
International Journal of Molecular... May 2024While considerable attention has been devoted to respiratory manifestations, such as pneumonia and acute respiratory distress syndrome (ARDS), emerging evidence...
While considerable attention has been devoted to respiratory manifestations, such as pneumonia and acute respiratory distress syndrome (ARDS), emerging evidence underlines the significance of extrapulmonary involvement. In this study, we examined 15 hospitalized patients who succumbed to severe complications following SARS-CoV-2 infection. These patients were admitted to the Sibiu County Clinical Emergency Hospital in Sibiu, Romania, between March and October 2021. All patients were ethnic Romanians. Conducted within a COVID-19-restricted environment and adhering to national safety protocols, autopsies provided a comprehensive understanding of the disease's multisystemic impact. Detailed macroscopic evaluations and histopathological analyses of myocardial, renal, hepatic, splenic, and gastrointestinal tissues were performed. Additionally, reverse transcription-quantitative polymerase chain reaction (rt-qPCR) assays and immunohistochemical staining were employed to detect the viral genome and nucleocapsid within the tissues. Myocardial lesions, including ischemic microstructural changes and inflammatory infiltrates, were prevalent, indicative of COVID-19's cardiac implications, while renal pathology revealed the chronic alterations, acute tubular necrosis, and inflammatory infiltrates most evident. Hepatic examination identified hepatocellular necroinflammatory changes and hepatocytic cytopathy, highlighting the hepatic involvement of SARS-CoV-2 infection. Splenic parenchymal disorganization was prominent, indicating systemic immune dysregulation. Furthermore, gastrointestinal examinations unveiled nonspecific changes. Molecular analyses detected viral genes in various organs, with immunohistochemical assays confirming viral presence predominantly in macrophages and fibroblasts. These findings highlighted the systemic nature of SARS-CoV-2 infection, emphasizing the need for comprehensive clinical management strategies and targeted therapeutic approaches beyond respiratory systems.
Topics: Humans; SARS-CoV-2; COVID-19; Male; Female; Middle Aged; Genome, Viral; Aged; Kidney; Liver; Adult; Spleen; Romania; Nucleocapsid; Myocardium; Autopsy; Aged, 80 and over; Coronavirus Nucleocapsid Proteins
PubMed: 38891942
DOI: 10.3390/ijms25115755 -
Molecular Neurobiology May 2024Viral infections of the central nervous system (CNS) cause variable outcomes from acute to severe neurological sequelae with increased morbidity and mortality. Viral... (Review)
Review
Viral infections of the central nervous system (CNS) cause variable outcomes from acute to severe neurological sequelae with increased morbidity and mortality. Viral neuroinvasion directly or indirectly induces encephalitis via dysregulation of the immune response and contributes to the alteration of neuronal function and the degeneration of neuronal cells. This review provides an overview of the cellular and molecular mechanisms of virus-induced neurodegeneration. Neurotropic viral infections influence many aspects of neuronal dysfunction, including promoting chronic inflammation, inducing cellular oxidative stress, impairing mitophagy, encountering mitochondrial dynamics, enhancing metabolic rewiring, altering neurotransmitter systems, and inducing misfolded and aggregated pathological proteins associated with neurodegenerative diseases. These pathogenetic mechanisms create a multidimensional injury of the brain that leads to specific neuronal and brain dysfunction. The understanding of the molecular mechanisms underlying the neurophathogenesis associated with neurodegeneration of viral infection may emphasize the strategies for prevention, protection, and treatment of virus infection of the CNS.
Topics: Humans; Animals; Neurodegenerative Diseases; Nerve Degeneration; Virus Diseases; Oxidative Stress; Neurons
PubMed: 37946006
DOI: 10.1007/s12035-023-03761-6 -
PloS One 2024The Central African Republic (CAR) is one of the countries with the highest prevalence of viral hepatitis infection in the world. Coinfection with HIV increases the...
BACKGROUND
The Central African Republic (CAR) is one of the countries with the highest prevalence of viral hepatitis infection in the world. Coinfection with HIV increases the morbidity and mortality beyond that of mono-infection with either hepatitis or HIV. The present study describes the geographic distribution of viral hepatitis infections and molecular characterization of these viruses in the CAR.
METHODOLOGY
Out of 12,599 persons enrolled during the fourth Multiple Indicator Cluster Survey of 2010 in the CAR, 10,621 Dried Blood Spot (DBS) samples were obtained and stored at -20°C. Of these DBS, 4,317 samples were randomly selected to represent all regions of the CAR. Serological tests for hepatitis B, D, and C viruses were performed using the ELISA technique. Molecular characterization was performed to identify strains.
RESULTS
Of the 4,317 samples included, 53.2% were from men and 46.8% from women. The HBsAg prevalence among participants was 12.9% and that HBc-Ab was 19.7%. The overall prevalence of HCV was 0.6%. Co-infection of HIV/HBV was 1.1% and that of HBV/HDV was 16.6%. A total of 77 HBV, 6 HIV, and 6 HDV strains were successfully sequenced, with 72 HBV (93.5%) strains belonging to genotype E and 5 (6.5%) strains belonging to genotype D. The 6 HDV strains all belonged to clade 1, while 4 recombinants subtype were identified among the 6 strains of HIV.
CONCLUSION
Our study found a high prevalence of HBV, HBV/HDV and HBV/HIV co-infection, but a low prevalence of HCV. CAR remains an area of high HBV endemicity. This study's data and analyses would be useful for establishing an integrated viral hepatitis and HIV surveillance program in the CAR.
Topics: Humans; HIV Infections; Female; Male; Coinfection; Adult; Seroepidemiologic Studies; Central African Republic; Middle Aged; Adolescent; Young Adult; Hepatitis, Viral, Human; Hepatitis B; Hepatitis B virus; Child; Hepatitis C; Phylogeny; Child, Preschool; Prevalence
PubMed: 38722944
DOI: 10.1371/journal.pone.0291155 -
Acta Neuropathologica Apr 2024Influenza-associated encephalopathy (IAE) is extremely acute in onset, with high lethality and morbidity within a few days, while the direct pathogenesis by influenza...
Influenza-associated encephalopathy (IAE) is extremely acute in onset, with high lethality and morbidity within a few days, while the direct pathogenesis by influenza virus in this acute phase in the brain is largely unknown. Here we show that influenza virus enters into the cerebral endothelium and thereby induces IAE. Three-weeks-old young mice were inoculated with influenza A virus (IAV). Physical and neurological scores were recorded and temporal-spatial analyses of histopathology and viral studies were performed up to 72 h post inoculation. Histopathological examinations were also performed using IAE human autopsy brains. Viral infection, proliferation and pathogenesis were analyzed in cell lines of endothelium and astrocyte. The effects of anti-influenza viral drugs were tested in the cell lines and animal models. Upon intravenous inoculation of IAV in mice, the mice developed encephalopathy with brain edema and pathological lesions represented by micro bleeding and injured astrocytic process (clasmatodendrosis) within 72 h. Histologically, massive deposits of viral nucleoprotein were observed as early as 24 h post infection in the brain endothelial cells of mouse models and the IAE patients. IAV inoculated endothelial cell lines showed deposition of viral proteins and provoked cell death, while IAV scarcely amplified. Inhibition of viral transcription and translation suppressed the endothelial cell death and the lethality of mouse models. These data suggest that the onset of encephalopathy should be induced by cerebral endothelial infection with IAV. Thus, IAV entry into the endothelium, and transcription and/or translation of viral RNA, but not viral proliferation, should be the key pathogenesis of IAE.
Topics: Animals; Humans; Mice; Brain; Orthomyxoviridae Infections; Virus Internalization; Influenza A virus; Endothelial Cells; Influenza, Human; Brain Diseases; Male; Disease Models, Animal; Female; Endothelium; Mice, Inbred C57BL
PubMed: 38687393
DOI: 10.1007/s00401-024-02723-z -
Nature Communications May 2024Outbreaks of highly pathogenic H5N1 clade 2.3.4.4b viruses in farmed mink and seals combined with isolated human infections suggest these viruses pose a pandemic threat....
Outbreaks of highly pathogenic H5N1 clade 2.3.4.4b viruses in farmed mink and seals combined with isolated human infections suggest these viruses pose a pandemic threat. To assess this threat, using the ferret model, we show an H5N1 isolate derived from mink transmits by direct contact to 75% of exposed ferrets and, in airborne transmission studies, the virus transmits to 37.5% of contacts. Sequence analyses show no mutations were associated with transmission. The H5N1 virus also has a low infectious dose and remains virulent at low doses. This isolate carries the adaptive mutation, PB2 T271A, and reversing this mutation reduces mortality and airborne transmission. This is the first report of a H5N1 clade 2.3.4.4b virus exhibiting direct contact and airborne transmissibility in ferrets. These data indicate heightened pandemic potential of the panzootic H5N1 viruses and emphasize the need for continued efforts to control outbreaks and monitor viral evolution.
Topics: Animals; Mink; Ferrets; Influenza A Virus, H5N1 Subtype; Orthomyxoviridae Infections; Risk Assessment; Humans; Mutation; Viral Proteins; Female; Disease Outbreaks; Male; Influenza, Human
PubMed: 38750016
DOI: 10.1038/s41467-024-48475-y -
Journal of Virology Oct 2023This study highlights the crucial role RNA processing plays in regulating viral gene expression and replication. By targeting SR kinases, we identified harmine as a...
This study highlights the crucial role RNA processing plays in regulating viral gene expression and replication. By targeting SR kinases, we identified harmine as a potent inhibitor of HIV-1 as well as coronavirus (HCoV-229E and multiple SARS-CoV-2 variants) replication. Harmine inhibits HIV-1 protein expression and reduces accumulation of HIV-1 RNAs in both cell lines and primary CD4 T cells. Harmine also suppresses coronavirus replication post-viral entry by preferentially reducing coronavirus sub-genomic RNA accumulation. By focusing on host factors rather than viral targets, our study offers a novel approach to combating viral infections that is effective against a range of unrelated viruses. Moreover, at doses required to inhibit virus replication, harmine had limited toxicity and minimal effect on the host transcriptome. These findings support the viability of targeting host cellular processes as a means of developing broad-spectrum anti-virals.
Topics: Humans; Antiviral Agents; Coronavirus; Coronavirus Infections; Harmine; HIV-1; Virus Replication
PubMed: 37706687
DOI: 10.1128/jvi.00396-23